From 268bb8ecc5b0c0a58491c78e2dded9ff5fb15d51 Mon Sep 17 00:00:00 2001 From: Sylvestre Ledru Date: Mon, 31 Oct 2016 10:24:31 +0000 Subject: [PATCH] Fix the patch --- debian/patches/bug-30342.diff | 4909 +-------------------------------- 1 file changed, 8 insertions(+), 4901 deletions(-) diff --git a/debian/patches/bug-30342.diff b/debian/patches/bug-30342.diff index c3c3cd85..a94ecaeb 100644 --- a/debian/patches/bug-30342.diff +++ b/debian/patches/bug-30342.diff @@ -1,174 +1,8 @@ -Index: llvm/trunk/test/Transforms/InstCombine/indexed-gep-compares.ll +Index: llvm-toolchain-3.9-3.9/test/Transforms/InstCombine/indexed-gep-compares.ll =================================================================== ---- llvm/trunk/test/Transforms/InstCombine/indexed-gep-compares.ll (revision 281649) -+++ llvm/trunk/test/Transforms/InstCombine/indexed-gep-compares.ll (revision 281650) -@@ -1,170 +1,190 @@ - ; RUN: opt -instcombine -S < %s | FileCheck %s - - target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:64:64-v128:128:128-a0:0:64" - - define i32 *@test1(i32* %A, i32 %Offset) { - entry: - %tmp = getelementptr inbounds i32, i32* %A, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ] - %LHS = getelementptr inbounds i32, i32* %A, i32 100 - %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1 - %cond = icmp ult i32 * %LHS, %RHS - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - ; CHECK-LABEL: @test1( - ; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ] - ; CHECK: %[[ADD]] = add nsw i32 %[[INDEX]], 1 - ; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100 - ; CHECK: br i1 %cond, label %bb2, label %bb - ; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %A, i32 %[[INDEX]] - ; CHECK: ret i32* %[[PTR]] - } - - define i32 *@test2(i32 %A, i32 %Offset) { - entry: - %A.ptr = inttoptr i32 %A to i32* - %tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ] - %LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100 - %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1 - %cmp0 = ptrtoint i32 *%LHS to i32 - %cmp1 = ptrtoint i32 *%RHS to i32 - %cond = icmp ult i32 %cmp0, %cmp1 - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - ; CHECK-LABEL: @test2( - ; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %entry ] - ; CHECK: %[[ADD]] = add nsw i32 %[[INDEX]], 1 - ; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100 - ; CHECK: br i1 %cond, label %bb2, label %bb - ; CHECK: %[[TOPTR:[0-9A-Za-z.]+]] = inttoptr i32 %[[ADD:[0-9A-Za-z.]+]] to i32* - ; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %[[TOPTR]], i32 %[[INDEX]] - ; CHECK: ret i32* %[[PTR]] - } - - ; Perform the transformation only if we know that the GEPs used are inbounds. - define i32 *@test3(i32* %A, i32 %Offset) { - entry: - %tmp = getelementptr i32, i32* %A, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ] - %LHS = getelementptr i32, i32* %A, i32 100 - %RHS.next = getelementptr i32, i32* %RHS, i64 1 - %cond = icmp ult i32 * %LHS, %RHS - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - ; CHECK-LABEL: @test3( - ; CHECK-NOT: %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100 - } - - ; An inttoptr that requires an extension or truncation will be opaque when determining - ; the base pointer. In this case we can still perform the transformation by considering - ; A.ptr as being the base pointer. - define i32 *@test4(i16 %A, i32 %Offset) { - entry: - %A.ptr = inttoptr i16 %A to i32* - %tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %entry ] - %LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100 - %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1 - %cmp0 = ptrtoint i32 *%LHS to i32 - %cmp1 = ptrtoint i32 *%RHS to i32 - %cond = icmp ult i32 %cmp0, %cmp1 - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - ; CHECK-LABEL: @test4( - ; CHECK: %cond = icmp sgt i32 %{{[0-9A-Za-z.]+}}, 100 - } - - declare i32* @fun_ptr() - - define i32 *@test5(i32 %Offset) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) { - entry: - %A = invoke i32 *@fun_ptr() to label %cont unwind label %lpad - - cont: - %tmp = getelementptr inbounds i32, i32* %A, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %cont ] - %LHS = getelementptr inbounds i32, i32* %A, i32 100 - %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1 - %cond = icmp ult i32 * %LHS, %RHS - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - lpad: - %l = landingpad { i8*, i32 } cleanup - ret i32* null - - ; CHECK-LABEL: @test5( - ; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %cont ] - ; CHECK: %[[ADD]] = add nsw i32 %[[INDEX]], 1 - ; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100 - ; CHECK: br i1 %cond, label %bb2, label %bb - ; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %A, i32 %[[INDEX]] - ; CHECK: ret i32* %[[PTR]] - } - - declare i32 @fun_i32() - - define i32 *@test6(i32 %Offset) personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) { - entry: - %A = invoke i32 @fun_i32() to label %cont unwind label %lpad - - cont: - %A.ptr = inttoptr i32 %A to i32* - %tmp = getelementptr inbounds i32, i32* %A.ptr, i32 %Offset - br label %bb - - bb: - %RHS = phi i32* [ %RHS.next, %bb ], [ %tmp, %cont ] - %LHS = getelementptr inbounds i32, i32* %A.ptr, i32 100 - %RHS.next = getelementptr inbounds i32, i32* %RHS, i64 1 - %cond = icmp ult i32 * %LHS, %RHS - br i1 %cond, label %bb2, label %bb - - bb2: - ret i32* %RHS - - lpad: - %l = landingpad { i8*, i32 } cleanup - ret i32* null - - ; CHECK-LABEL: @test6( - ; CHECK: %[[INDEX:[0-9A-Za-z.]+]] = phi i32 [ %[[ADD:[0-9A-Za-z.]+]], %bb ], [ %Offset, %cont ] - ; CHECK: %[[ADD]] = add nsw i32 %[[INDEX]], 1 - ; CHECK: %cond = icmp sgt i32 %[[INDEX]], 100 - ; CHECK: br i1 %cond, label %bb2, label %bb - ; CHECK: %[[TOPTR:[0-9A-Za-z.]+]] = inttoptr i32 %[[ADD:[0-9A-Za-z.]+]] to i32* - ; CHECK: %[[PTR:[0-9A-Za-z.]+]] = getelementptr inbounds i32, i32* %[[TOPTR]], i32 %[[INDEX]] +--- llvm-toolchain-3.9-3.9.orig/test/Transforms/InstCombine/indexed-gep-compares.ll ++++ llvm-toolchain-3.9-3.9/test/Transforms/InstCombine/indexed-gep-compares.ll +@@ -167,4 +167,24 @@ lpad: ; CHECK: ret i32* %[[PTR]] } @@ -193,635 +27,11 @@ Index: llvm/trunk/test/Transforms/InstCombine/indexed-gep-compares.ll + + declare i32 @__gxx_personality_v0(...) -Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp +Index: llvm-toolchain-3.9-3.9/lib/Transforms/InstCombine/InstCombineCompares.cpp =================================================================== ---- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (revision 281649) -+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (revision 281650) -@@ -1,4734 +1,4734 @@ - //===- InstCombineCompares.cpp --------------------------------------------===// - // - // The LLVM Compiler Infrastructure - // - // This file is distributed under the University of Illinois Open Source - // License. See LICENSE.TXT for details. - // - //===----------------------------------------------------------------------===// - // - // This file implements the visitICmp and visitFCmp functions. - // - //===----------------------------------------------------------------------===// - - #include "InstCombineInternal.h" - #include "llvm/ADT/APSInt.h" - #include "llvm/ADT/SetVector.h" - #include "llvm/ADT/Statistic.h" - #include "llvm/Analysis/ConstantFolding.h" - #include "llvm/Analysis/InstructionSimplify.h" - #include "llvm/Analysis/MemoryBuiltins.h" - #include "llvm/Analysis/TargetLibraryInfo.h" - #include "llvm/Analysis/VectorUtils.h" - #include "llvm/IR/ConstantRange.h" - #include "llvm/IR/DataLayout.h" - #include "llvm/IR/GetElementPtrTypeIterator.h" - #include "llvm/IR/IntrinsicInst.h" - #include "llvm/IR/PatternMatch.h" - #include "llvm/Support/Debug.h" - - using namespace llvm; - using namespace PatternMatch; - - #define DEBUG_TYPE "instcombine" - - // How many times is a select replaced by one of its operands? - STATISTIC(NumSel, "Number of select opts"); - - - static ConstantInt *extractElement(Constant *V, Constant *Idx) { - return cast(ConstantExpr::getExtractElement(V, Idx)); - } - - static bool hasAddOverflow(ConstantInt *Result, - ConstantInt *In1, ConstantInt *In2, - bool IsSigned) { - if (!IsSigned) - return Result->getValue().ult(In1->getValue()); - - if (In2->isNegative()) - return Result->getValue().sgt(In1->getValue()); - return Result->getValue().slt(In1->getValue()); - } - - /// Compute Result = In1+In2, returning true if the result overflowed for this - /// type. - static bool addWithOverflow(Constant *&Result, Constant *In1, - Constant *In2, bool IsSigned = false) { - Result = ConstantExpr::getAdd(In1, In2); - - if (VectorType *VTy = dyn_cast(In1->getType())) { - for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { - Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); - if (hasAddOverflow(extractElement(Result, Idx), - extractElement(In1, Idx), - extractElement(In2, Idx), - IsSigned)) - return true; - } - return false; - } - - return hasAddOverflow(cast(Result), - cast(In1), cast(In2), - IsSigned); - } - - static bool hasSubOverflow(ConstantInt *Result, - ConstantInt *In1, ConstantInt *In2, - bool IsSigned) { - if (!IsSigned) - return Result->getValue().ugt(In1->getValue()); - - if (In2->isNegative()) - return Result->getValue().slt(In1->getValue()); - - return Result->getValue().sgt(In1->getValue()); - } - - /// Compute Result = In1-In2, returning true if the result overflowed for this - /// type. - static bool subWithOverflow(Constant *&Result, Constant *In1, - Constant *In2, bool IsSigned = false) { - Result = ConstantExpr::getSub(In1, In2); - - if (VectorType *VTy = dyn_cast(In1->getType())) { - for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) { - Constant *Idx = ConstantInt::get(Type::getInt32Ty(In1->getContext()), i); - if (hasSubOverflow(extractElement(Result, Idx), - extractElement(In1, Idx), - extractElement(In2, Idx), - IsSigned)) - return true; - } - return false; - } - - return hasSubOverflow(cast(Result), - cast(In1), cast(In2), - IsSigned); - } - - /// Given an icmp instruction, return true if any use of this comparison is a - /// branch on sign bit comparison. - static bool isBranchOnSignBitCheck(ICmpInst &I, bool isSignBit) { - for (auto *U : I.users()) - if (isa(U)) - return isSignBit; - return false; - } - - /// Given an exploded icmp instruction, return true if the comparison only - /// checks the sign bit. If it only checks the sign bit, set TrueIfSigned if the - /// result of the comparison is true when the input value is signed. - static bool isSignBitCheck(ICmpInst::Predicate Pred, const APInt &RHS, - bool &TrueIfSigned) { - switch (Pred) { - case ICmpInst::ICMP_SLT: // True if LHS s< 0 - TrueIfSigned = true; - return RHS == 0; - case ICmpInst::ICMP_SLE: // True if LHS s<= RHS and RHS == -1 - TrueIfSigned = true; - return RHS.isAllOnesValue(); - case ICmpInst::ICMP_SGT: // True if LHS s> -1 - TrueIfSigned = false; - return RHS.isAllOnesValue(); - case ICmpInst::ICMP_UGT: - // True if LHS u> RHS and RHS == high-bit-mask - 1 - TrueIfSigned = true; - return RHS.isMaxSignedValue(); - case ICmpInst::ICMP_UGE: - // True if LHS u>= RHS and RHS == high-bit-mask (2^7, 2^15, 2^31, etc) - TrueIfSigned = true; - return RHS.isSignBit(); - default: - return false; - } - } - - /// Returns true if the exploded icmp can be expressed as a signed comparison - /// to zero and updates the predicate accordingly. - /// The signedness of the comparison is preserved. - /// TODO: Refactor with decomposeBitTestICmp()? - static bool isSignTest(ICmpInst::Predicate &Pred, const APInt &C) { - if (!ICmpInst::isSigned(Pred)) - return false; - - if (C == 0) - return ICmpInst::isRelational(Pred); - - if (C == 1) { - if (Pred == ICmpInst::ICMP_SLT) { - Pred = ICmpInst::ICMP_SLE; - return true; - } - } else if (C.isAllOnesValue()) { - if (Pred == ICmpInst::ICMP_SGT) { - Pred = ICmpInst::ICMP_SGE; - return true; - } - } - - return false; - } - - /// Given a signed integer type and a set of known zero and one bits, compute - /// the maximum and minimum values that could have the specified known zero and - /// known one bits, returning them in Min/Max. - static void computeSignedMinMaxValuesFromKnownBits(const APInt &KnownZero, - const APInt &KnownOne, - APInt &Min, APInt &Max) { - assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && - KnownZero.getBitWidth() == Min.getBitWidth() && - KnownZero.getBitWidth() == Max.getBitWidth() && - "KnownZero, KnownOne and Min, Max must have equal bitwidth."); - APInt UnknownBits = ~(KnownZero|KnownOne); - - // The minimum value is when all unknown bits are zeros, EXCEPT for the sign - // bit if it is unknown. - Min = KnownOne; - Max = KnownOne|UnknownBits; - - if (UnknownBits.isNegative()) { // Sign bit is unknown - Min.setBit(Min.getBitWidth()-1); - Max.clearBit(Max.getBitWidth()-1); - } - } - - /// Given an unsigned integer type and a set of known zero and one bits, compute - /// the maximum and minimum values that could have the specified known zero and - /// known one bits, returning them in Min/Max. - static void computeUnsignedMinMaxValuesFromKnownBits(const APInt &KnownZero, - const APInt &KnownOne, - APInt &Min, APInt &Max) { - assert(KnownZero.getBitWidth() == KnownOne.getBitWidth() && - KnownZero.getBitWidth() == Min.getBitWidth() && - KnownZero.getBitWidth() == Max.getBitWidth() && - "Ty, KnownZero, KnownOne and Min, Max must have equal bitwidth."); - APInt UnknownBits = ~(KnownZero|KnownOne); - - // The minimum value is when the unknown bits are all zeros. - Min = KnownOne; - // The maximum value is when the unknown bits are all ones. - Max = KnownOne|UnknownBits; - } - - /// This is called when we see this pattern: - /// cmp pred (load (gep GV, ...)), cmpcst - /// where GV is a global variable with a constant initializer. Try to simplify - /// this into some simple computation that does not need the load. For example - /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". - /// - /// If AndCst is non-null, then the loaded value is masked with that constant - /// before doing the comparison. This handles cases like "A[i]&4 == 0". - Instruction *InstCombiner::foldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, - GlobalVariable *GV, - CmpInst &ICI, - ConstantInt *AndCst) { - Constant *Init = GV->getInitializer(); - if (!isa(Init) && !isa(Init)) - return nullptr; - - uint64_t ArrayElementCount = Init->getType()->getArrayNumElements(); - if (ArrayElementCount > 1024) return nullptr; // Don't blow up on huge arrays. - - // There are many forms of this optimization we can handle, for now, just do - // the simple index into a single-dimensional array. - // - // Require: GEP GV, 0, i {{, constant indices}} - if (GEP->getNumOperands() < 3 || - !isa(GEP->getOperand(1)) || - !cast(GEP->getOperand(1))->isZero() || - isa(GEP->getOperand(2))) - return nullptr; - - // Check that indices after the variable are constants and in-range for the - // type they index. Collect the indices. This is typically for arrays of - // structs. - SmallVector LaterIndices; - - Type *EltTy = Init->getType()->getArrayElementType(); - for (unsigned i = 3, e = GEP->getNumOperands(); i != e; ++i) { - ConstantInt *Idx = dyn_cast(GEP->getOperand(i)); - if (!Idx) return nullptr; // Variable index. - - uint64_t IdxVal = Idx->getZExtValue(); - if ((unsigned)IdxVal != IdxVal) return nullptr; // Too large array index. - - if (StructType *STy = dyn_cast(EltTy)) - EltTy = STy->getElementType(IdxVal); - else if (ArrayType *ATy = dyn_cast(EltTy)) { - if (IdxVal >= ATy->getNumElements()) return nullptr; - EltTy = ATy->getElementType(); - } else { - return nullptr; // Unknown type. - } - - LaterIndices.push_back(IdxVal); - } - - enum { Overdefined = -3, Undefined = -2 }; - - // Variables for our state machines. - - // FirstTrueElement/SecondTrueElement - Used to emit a comparison of the form - // "i == 47 | i == 87", where 47 is the first index the condition is true for, - // and 87 is the second (and last) index. FirstTrueElement is -2 when - // undefined, otherwise set to the first true element. SecondTrueElement is - // -2 when undefined, -3 when overdefined and >= 0 when that index is true. - int FirstTrueElement = Undefined, SecondTrueElement = Undefined; - - // FirstFalseElement/SecondFalseElement - Used to emit a comparison of the - // form "i != 47 & i != 87". Same state transitions as for true elements. - int FirstFalseElement = Undefined, SecondFalseElement = Undefined; - - /// TrueRangeEnd/FalseRangeEnd - In conjunction with First*Element, these - /// define a state machine that triggers for ranges of values that the index - /// is true or false for. This triggers on things like "abbbbc"[i] == 'b'. - /// This is -2 when undefined, -3 when overdefined, and otherwise the last - /// index in the range (inclusive). We use -2 for undefined here because we - /// use relative comparisons and don't want 0-1 to match -1. - int TrueRangeEnd = Undefined, FalseRangeEnd = Undefined; - - // MagicBitvector - This is a magic bitvector where we set a bit if the - // comparison is true for element 'i'. If there are 64 elements or less in - // the array, this will fully represent all the comparison results. - uint64_t MagicBitvector = 0; - - // Scan the array and see if one of our patterns matches. - Constant *CompareRHS = cast(ICI.getOperand(1)); - for (unsigned i = 0, e = ArrayElementCount; i != e; ++i) { - Constant *Elt = Init->getAggregateElement(i); - if (!Elt) return nullptr; - - // If this is indexing an array of structures, get the structure element. - if (!LaterIndices.empty()) - Elt = ConstantExpr::getExtractValue(Elt, LaterIndices); - - // If the element is masked, handle it. - if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); - - // Find out if the comparison would be true or false for the i'th element. - Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, - CompareRHS, DL, &TLI); - // If the result is undef for this element, ignore it. - if (isa(C)) { - // Extend range state machines to cover this element in case there is an - // undef in the middle of the range. - if (TrueRangeEnd == (int)i-1) - TrueRangeEnd = i; - if (FalseRangeEnd == (int)i-1) - FalseRangeEnd = i; - continue; - } - - // If we can't compute the result for any of the elements, we have to give - // up evaluating the entire conditional. - if (!isa(C)) return nullptr; - - // Otherwise, we know if the comparison is true or false for this element, - // update our state machines. - bool IsTrueForElt = !cast(C)->isZero(); - - // State machine for single/double/range index comparison. - if (IsTrueForElt) { - // Update the TrueElement state machine. - if (FirstTrueElement == Undefined) - FirstTrueElement = TrueRangeEnd = i; // First true element. - else { - // Update double-compare state machine. - if (SecondTrueElement == Undefined) - SecondTrueElement = i; - else - SecondTrueElement = Overdefined; - - // Update range state machine. - if (TrueRangeEnd == (int)i-1) - TrueRangeEnd = i; - else - TrueRangeEnd = Overdefined; - } - } else { - // Update the FalseElement state machine. - if (FirstFalseElement == Undefined) - FirstFalseElement = FalseRangeEnd = i; // First false element. - else { - // Update double-compare state machine. - if (SecondFalseElement == Undefined) - SecondFalseElement = i; - else - SecondFalseElement = Overdefined; - - // Update range state machine. - if (FalseRangeEnd == (int)i-1) - FalseRangeEnd = i; - else - FalseRangeEnd = Overdefined; - } - } - - // If this element is in range, update our magic bitvector. - if (i < 64 && IsTrueForElt) - MagicBitvector |= 1ULL << i; - - // If all of our states become overdefined, bail out early. Since the - // predicate is expensive, only check it every 8 elements. This is only - // really useful for really huge arrays. - if ((i & 8) == 0 && i >= 64 && SecondTrueElement == Overdefined && - SecondFalseElement == Overdefined && TrueRangeEnd == Overdefined && - FalseRangeEnd == Overdefined) - return nullptr; - } - - // Now that we've scanned the entire array, emit our new comparison(s). We - // order the state machines in complexity of the generated code. - Value *Idx = GEP->getOperand(2); - - // If the index is larger than the pointer size of the target, truncate the - // index down like the GEP would do implicitly. We don't have to do this for - // an inbounds GEP because the index can't be out of range. - if (!GEP->isInBounds()) { - Type *IntPtrTy = DL.getIntPtrType(GEP->getType()); - unsigned PtrSize = IntPtrTy->getIntegerBitWidth(); - if (Idx->getType()->getPrimitiveSizeInBits() > PtrSize) - Idx = Builder->CreateTrunc(Idx, IntPtrTy); - } - - // If the comparison is only true for one or two elements, emit direct - // comparisons. - if (SecondTrueElement != Overdefined) { - // None true -> false. - if (FirstTrueElement == Undefined) - return replaceInstUsesWith(ICI, Builder->getFalse()); - - Value *FirstTrueIdx = ConstantInt::get(Idx->getType(), FirstTrueElement); - - // True for one element -> 'i == 47'. - if (SecondTrueElement == Undefined) - return new ICmpInst(ICmpInst::ICMP_EQ, Idx, FirstTrueIdx); - - // True for two elements -> 'i == 47 | i == 72'. - Value *C1 = Builder->CreateICmpEQ(Idx, FirstTrueIdx); - Value *SecondTrueIdx = ConstantInt::get(Idx->getType(), SecondTrueElement); - Value *C2 = Builder->CreateICmpEQ(Idx, SecondTrueIdx); - return BinaryOperator::CreateOr(C1, C2); - } - - // If the comparison is only false for one or two elements, emit direct - // comparisons. - if (SecondFalseElement != Overdefined) { - // None false -> true. - if (FirstFalseElement == Undefined) - return replaceInstUsesWith(ICI, Builder->getTrue()); - - Value *FirstFalseIdx = ConstantInt::get(Idx->getType(), FirstFalseElement); - - // False for one element -> 'i != 47'. - if (SecondFalseElement == Undefined) - return new ICmpInst(ICmpInst::ICMP_NE, Idx, FirstFalseIdx); - - // False for two elements -> 'i != 47 & i != 72'. - Value *C1 = Builder->CreateICmpNE(Idx, FirstFalseIdx); - Value *SecondFalseIdx = ConstantInt::get(Idx->getType(),SecondFalseElement); - Value *C2 = Builder->CreateICmpNE(Idx, SecondFalseIdx); - return BinaryOperator::CreateAnd(C1, C2); - } - - // If the comparison can be replaced with a range comparison for the elements - // where it is true, emit the range check. - if (TrueRangeEnd != Overdefined) { - assert(TrueRangeEnd != FirstTrueElement && "Should emit single compare"); - - // Generate (i-FirstTrue) getType(), -FirstTrueElement); - Idx = Builder->CreateAdd(Idx, Offs); - } - - Value *End = ConstantInt::get(Idx->getType(), - TrueRangeEnd-FirstTrueElement+1); - return new ICmpInst(ICmpInst::ICMP_ULT, Idx, End); - } - - // False range check. - if (FalseRangeEnd != Overdefined) { - assert(FalseRangeEnd != FirstFalseElement && "Should emit single compare"); - // Generate (i-FirstFalse) >u (FalseRangeEnd-FirstFalse). - if (FirstFalseElement) { - Value *Offs = ConstantInt::get(Idx->getType(), -FirstFalseElement); - Idx = Builder->CreateAdd(Idx, Offs); - } - - Value *End = ConstantInt::get(Idx->getType(), - FalseRangeEnd-FirstFalseElement); - return new ICmpInst(ICmpInst::ICMP_UGT, Idx, End); - } - - // If a magic bitvector captures the entire comparison state - // of this load, replace it with computation that does: - // ((magic_cst >> i) & 1) != 0 - { - Type *Ty = nullptr; - - // Look for an appropriate type: - // - The type of Idx if the magic fits - // - The smallest fitting legal type if we have a DataLayout - // - Default to i32 - if (ArrayElementCount <= Idx->getType()->getIntegerBitWidth()) - Ty = Idx->getType(); - else - Ty = DL.getSmallestLegalIntType(Init->getContext(), ArrayElementCount); - - if (Ty) { - Value *V = Builder->CreateIntCast(Idx, Ty, false); - V = Builder->CreateLShr(ConstantInt::get(Ty, MagicBitvector), V); - V = Builder->CreateAnd(ConstantInt::get(Ty, 1), V); - return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); - } - } - - return nullptr; - } - - /// Return a value that can be used to compare the *offset* implied by a GEP to - /// zero. For example, if we have &A[i], we want to return 'i' for - /// "icmp ne i, 0". Note that, in general, indices can be complex, and scales - /// are involved. The above expression would also be legal to codegen as - /// "icmp ne (i*4), 0" (assuming A is a pointer to i32). - /// This latter form is less amenable to optimization though, and we are allowed - /// to generate the first by knowing that pointer arithmetic doesn't overflow. - /// - /// If we can't emit an optimized form for this expression, this returns null. - /// - static Value *evaluateGEPOffsetExpression(User *GEP, InstCombiner &IC, - const DataLayout &DL) { - gep_type_iterator GTI = gep_type_begin(GEP); - - // Check to see if this gep only has a single variable index. If so, and if - // any constant indices are a multiple of its scale, then we can compute this - // in terms of the scale of the variable index. For example, if the GEP - // implies an offset of "12 + i*4", then we can codegen this as "3 + i", - // because the expression will cross zero at the same point. - unsigned i, e = GEP->getNumOperands(); - int64_t Offset = 0; - for (i = 1; i != e; ++i, ++GTI) { - if (ConstantInt *CI = dyn_cast(GEP->getOperand(i))) { - // Compute the aggregate offset of constant indices. - if (CI->isZero()) continue; - - // Handle a struct index, which adds its field offset to the pointer. - if (StructType *STy = dyn_cast(*GTI)) { - Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); - } else { - uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()); - Offset += Size*CI->getSExtValue(); - } - } else { - // Found our variable index. - break; - } - } - - // If there are no variable indices, we must have a constant offset, just - // evaluate it the general way. - if (i == e) return nullptr; - - Value *VariableIdx = GEP->getOperand(i); - // Determine the scale factor of the variable element. For example, this is - // 4 if the variable index is into an array of i32. - uint64_t VariableScale = DL.getTypeAllocSize(GTI.getIndexedType()); - - // Verify that there are no other variable indices. If so, emit the hard way. - for (++i, ++GTI; i != e; ++i, ++GTI) { - ConstantInt *CI = dyn_cast(GEP->getOperand(i)); - if (!CI) return nullptr; - - // Compute the aggregate offset of constant indices. - if (CI->isZero()) continue; - - // Handle a struct index, which adds its field offset to the pointer. - if (StructType *STy = dyn_cast(*GTI)) { - Offset += DL.getStructLayout(STy)->getElementOffset(CI->getZExtValue()); - } else { - uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()); - Offset += Size*CI->getSExtValue(); - } - } - - // Okay, we know we have a single variable index, which must be a - // pointer/array/vector index. If there is no offset, life is simple, return - // the index. - Type *IntPtrTy = DL.getIntPtrType(GEP->getOperand(0)->getType()); - unsigned IntPtrWidth = IntPtrTy->getIntegerBitWidth(); - if (Offset == 0) { - // Cast to intptrty in case a truncation occurs. If an extension is needed, - // we don't need to bother extending: the extension won't affect where the - // computation crosses zero. - if (VariableIdx->getType()->getPrimitiveSizeInBits() > IntPtrWidth) { - VariableIdx = IC.Builder->CreateTrunc(VariableIdx, IntPtrTy); - } - return VariableIdx; - } - - // Otherwise, there is an index. The computation we will do will be modulo - // the pointer size, so get it. - uint64_t PtrSizeMask = ~0ULL >> (64-IntPtrWidth); - - Offset &= PtrSizeMask; - VariableScale &= PtrSizeMask; - - // To do this transformation, any constant index must be a multiple of the - // variable scale factor. For example, we can evaluate "12 + 4*i" as "3 + i", - // but we can't evaluate "10 + 3*i" in terms of i. Check that the offset is a - // multiple of the variable scale. - int64_t NewOffs = Offset / (int64_t)VariableScale; - if (Offset != NewOffs*(int64_t)VariableScale) - return nullptr; - - // Okay, we can do this evaluation. Start by converting the index to intptr. - if (VariableIdx->getType() != IntPtrTy) - VariableIdx = IC.Builder->CreateIntCast(VariableIdx, IntPtrTy, - true /*Signed*/); - Constant *OffsetVal = ConstantInt::get(IntPtrTy, NewOffs); - return IC.Builder->CreateAdd(VariableIdx, OffsetVal, "offset"); - } - - /// Returns true if we can rewrite Start as a GEP with pointer Base - /// and some integer offset. The nodes that need to be re-written - /// for this transformation will be added to Explored. - static bool canRewriteGEPAsOffset(Value *Start, Value *Base, - const DataLayout &DL, - SetVector &Explored) { - SmallVector WorkList(1, Start); - Explored.insert(Base); - - // The following traversal gives us an order which can be used - // when doing the final transformation. Since in the final - // transformation we create the PHI replacement instructions first, - // we don't have to get them in any particular order. - // - // However, for other instructions we will have to traverse the - // operands of an instruction first, which means that we have to - // do a post-order traversal. - while (!WorkList.empty()) { - SetVector PHIs; - - while (!WorkList.empty()) { - if (Explored.size() >= 100) - return false; - - Value *V = WorkList.back(); - - if (Explored.count(V) != 0) { - WorkList.pop_back(); - continue; +--- llvm-toolchain-3.9-3.9.orig/lib/Transforms/InstCombine/InstCombineCompares.cpp ++++ llvm-toolchain-3.9-3.9/lib/Transforms/InstCombine/InstCombineCompares.cpp +@@ -634,7 +634,7 @@ static bool canRewriteGEPAsOffset(Value } if (!isa(V) && !isa(V) && @@ -830,4106 +40,3 @@ Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp // We've found some value that we can't explore which is different from // the base. Therefore we can't do this transformation. return false; - - if (isa(V) || isa(V)) { - auto *CI = dyn_cast(V); - if (!CI->isNoopCast(DL)) - return false; - - if (Explored.count(CI->getOperand(0)) == 0) - WorkList.push_back(CI->getOperand(0)); - } - - if (auto *GEP = dyn_cast(V)) { - // We're limiting the GEP to having one index. This will preserve - // the original pointer type. We could handle more cases in the - // future. - if (GEP->getNumIndices() != 1 || !GEP->isInBounds() || - GEP->getType() != Start->getType()) - return false; - - if (Explored.count(GEP->getOperand(0)) == 0) - WorkList.push_back(GEP->getOperand(0)); - } - - if (WorkList.back() == V) { - WorkList.pop_back(); - // We've finished visiting this node, mark it as such. - Explored.insert(V); - } - - if (auto *PN = dyn_cast(V)) { - // We cannot transform PHIs on unsplittable basic blocks. - if (isa(PN->getParent()->getTerminator())) - return false; - Explored.insert(PN); - PHIs.insert(PN); - } - } - - // Explore the PHI nodes further. - for (auto *PN : PHIs) - for (Value *Op : PN->incoming_values()) - if (Explored.count(Op) == 0) - WorkList.push_back(Op); - } - - // Make sure that we can do this. Since we can't insert GEPs in a basic - // block before a PHI node, we can't easily do this transformation if - // we have PHI node users of transformed instructions. - for (Value *Val : Explored) { - for (Value *Use : Val->uses()) { - - auto *PHI = dyn_cast(Use); - auto *Inst = dyn_cast(Val); - - if (Inst == Base || Inst == PHI || !Inst || !PHI || - Explored.count(PHI) == 0) - continue; - - if (PHI->getParent() == Inst->getParent()) - return false; - } - } - return true; - } - - // Sets the appropriate insert point on Builder where we can add - // a replacement Instruction for V (if that is possible). - static void setInsertionPoint(IRBuilder<> &Builder, Value *V, - bool Before = true) { - if (auto *PHI = dyn_cast(V)) { - Builder.SetInsertPoint(&*PHI->getParent()->getFirstInsertionPt()); - return; - } - if (auto *I = dyn_cast(V)) { - if (!Before) - I = &*std::next(I->getIterator()); - Builder.SetInsertPoint(I); - return; - } - if (auto *A = dyn_cast(V)) { - // Set the insertion point in the entry block. - BasicBlock &Entry = A->getParent()->getEntryBlock(); - Builder.SetInsertPoint(&*Entry.getFirstInsertionPt()); - return; - } - // Otherwise, this is a constant and we don't need to set a new - // insertion point. - assert(isa(V) && "Setting insertion point for unknown value!"); - } - - /// Returns a re-written value of Start as an indexed GEP using Base as a - /// pointer. - static Value *rewriteGEPAsOffset(Value *Start, Value *Base, - const DataLayout &DL, - SetVector &Explored) { - // Perform all the substitutions. This is a bit tricky because we can - // have cycles in our use-def chains. - // 1. Create the PHI nodes without any incoming values. - // 2. Create all the other values. - // 3. Add the edges for the PHI nodes. - // 4. Emit GEPs to get the original pointers. - // 5. Remove the original instructions. - Type *IndexType = IntegerType::get( - Base->getContext(), DL.getPointerTypeSizeInBits(Start->getType())); - - DenseMap NewInsts; - NewInsts[Base] = ConstantInt::getNullValue(IndexType); - - // Create the new PHI nodes, without adding any incoming values. - for (Value *Val : Explored) { - if (Val == Base) - continue; - // Create empty phi nodes. This avoids cyclic dependencies when creating - // the remaining instructions. - if (auto *PHI = dyn_cast(Val)) - NewInsts[PHI] = PHINode::Create(IndexType, PHI->getNumIncomingValues(), - PHI->getName() + ".idx", PHI); - } - IRBuilder<> Builder(Base->getContext()); - - // Create all the other instructions. - for (Value *Val : Explored) { - - if (NewInsts.find(Val) != NewInsts.end()) - continue; - - if (auto *CI = dyn_cast(Val)) { - NewInsts[CI] = NewInsts[CI->getOperand(0)]; - continue; - } - if (auto *GEP = dyn_cast(Val)) { - Value *Index = NewInsts[GEP->getOperand(1)] ? NewInsts[GEP->getOperand(1)] - : GEP->getOperand(1); - setInsertionPoint(Builder, GEP); - // Indices might need to be sign extended. GEPs will magically do - // this, but we need to do it ourselves here. - if (Index->getType()->getScalarSizeInBits() != - NewInsts[GEP->getOperand(0)]->getType()->getScalarSizeInBits()) { - Index = Builder.CreateSExtOrTrunc( - Index, NewInsts[GEP->getOperand(0)]->getType(), - GEP->getOperand(0)->getName() + ".sext"); - } - - auto *Op = NewInsts[GEP->getOperand(0)]; - if (isa(Op) && dyn_cast(Op)->isZero()) - NewInsts[GEP] = Index; - else - NewInsts[GEP] = Builder.CreateNSWAdd( - Op, Index, GEP->getOperand(0)->getName() + ".add"); - continue; - } - if (isa(Val)) - continue; - - llvm_unreachable("Unexpected instruction type"); - } - - // Add the incoming values to the PHI nodes. - for (Value *Val : Explored) { - if (Val == Base) - continue; - // All the instructions have been created, we can now add edges to the - // phi nodes. - if (auto *PHI = dyn_cast(Val)) { - PHINode *NewPhi = static_cast(NewInsts[PHI]); - for (unsigned I = 0, E = PHI->getNumIncomingValues(); I < E; ++I) { - Value *NewIncoming = PHI->getIncomingValue(I); - - if (NewInsts.find(NewIncoming) != NewInsts.end()) - NewIncoming = NewInsts[NewIncoming]; - - NewPhi->addIncoming(NewIncoming, PHI->getIncomingBlock(I)); - } - } - } - - for (Value *Val : Explored) { - if (Val == Base) - continue; - - // Depending on the type, for external users we have to emit - // a GEP or a GEP + ptrtoint. - setInsertionPoint(Builder, Val, false); - - // If required, create an inttoptr instruction for Base. - Value *NewBase = Base; - if (!Base->getType()->isPointerTy()) - NewBase = Builder.CreateBitOrPointerCast(Base, Start->getType(), - Start->getName() + "to.ptr"); - - Value *GEP = Builder.CreateInBoundsGEP( - Start->getType()->getPointerElementType(), NewBase, - makeArrayRef(NewInsts[Val]), Val->getName() + ".ptr"); - - if (!Val->getType()->isPointerTy()) { - Value *Cast = Builder.CreatePointerCast(GEP, Val->getType(), - Val->getName() + ".conv"); - GEP = Cast; - } - Val->replaceAllUsesWith(GEP); - } - - return NewInsts[Start]; - } - - /// Looks through GEPs, IntToPtrInsts and PtrToIntInsts in order to express - /// the input Value as a constant indexed GEP. Returns a pair containing - /// the GEPs Pointer and Index. - static std::pair - getAsConstantIndexedAddress(Value *V, const DataLayout &DL) { - Type *IndexType = IntegerType::get(V->getContext(), - DL.getPointerTypeSizeInBits(V->getType())); - - Constant *Index = ConstantInt::getNullValue(IndexType); - while (true) { - if (GEPOperator *GEP = dyn_cast(V)) { - // We accept only inbouds GEPs here to exclude the possibility of - // overflow. - if (!GEP->isInBounds()) - break; - if (GEP->hasAllConstantIndices() && GEP->getNumIndices() == 1 && - GEP->getType() == V->getType()) { - V = GEP->getOperand(0); - Constant *GEPIndex = static_cast(GEP->getOperand(1)); - Index = ConstantExpr::getAdd( - Index, ConstantExpr::getSExtOrBitCast(GEPIndex, IndexType)); - continue; - } - break; - } - if (auto *CI = dyn_cast(V)) { - if (!CI->isNoopCast(DL)) - break; - V = CI->getOperand(0); - continue; - } - if (auto *CI = dyn_cast(V)) { - if (!CI->isNoopCast(DL)) - break; - V = CI->getOperand(0); - continue; - } - break; - } - return {V, Index}; - } - - /// Converts (CMP GEPLHS, RHS) if this change would make RHS a constant. - /// We can look through PHIs, GEPs and casts in order to determine a common base - /// between GEPLHS and RHS. - static Instruction *transformToIndexedCompare(GEPOperator *GEPLHS, Value *RHS, - ICmpInst::Predicate Cond, - const DataLayout &DL) { - if (!GEPLHS->hasAllConstantIndices()) - return nullptr; - - Value *PtrBase, *Index; - std::tie(PtrBase, Index) = getAsConstantIndexedAddress(GEPLHS, DL); - - // The set of nodes that will take part in this transformation. - SetVector Nodes; - - if (!canRewriteGEPAsOffset(RHS, PtrBase, DL, Nodes)) - return nullptr; - - // We know we can re-write this as - // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) - // Since we've only looked through inbouds GEPs we know that we - // can't have overflow on either side. We can therefore re-write - // this as: - // OFFSET1 cmp OFFSET2 - Value *NewRHS = rewriteGEPAsOffset(RHS, PtrBase, DL, Nodes); - - // RewriteGEPAsOffset has replaced RHS and all of its uses with a re-written - // GEP having PtrBase as the pointer base, and has returned in NewRHS the - // offset. Since Index is the offset of LHS to the base pointer, we will now - // compare the offsets instead of comparing the pointers. - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Index, NewRHS); - } - - /// Fold comparisons between a GEP instruction and something else. At this point - /// we know that the GEP is on the LHS of the comparison. - Instruction *InstCombiner::foldGEPICmp(GEPOperator *GEPLHS, Value *RHS, - ICmpInst::Predicate Cond, - Instruction &I) { - // Don't transform signed compares of GEPs into index compares. Even if the - // GEP is inbounds, the final add of the base pointer can have signed overflow - // and would change the result of the icmp. - // e.g. "&foo[0] (RHS)) - RHS = RHS->stripPointerCasts(); - - Value *PtrBase = GEPLHS->getOperand(0); - if (PtrBase == RHS && GEPLHS->isInBounds()) { - // ((gep Ptr, OFFSET) cmp Ptr) ---> (OFFSET cmp 0). - // This transformation (ignoring the base and scales) is valid because we - // know pointers can't overflow since the gep is inbounds. See if we can - // output an optimized form. - Value *Offset = evaluateGEPOffsetExpression(GEPLHS, *this, DL); - - // If not, synthesize the offset the hard way. - if (!Offset) - Offset = EmitGEPOffset(GEPLHS); - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), Offset, - Constant::getNullValue(Offset->getType())); - } else if (GEPOperator *GEPRHS = dyn_cast(RHS)) { - // If the base pointers are different, but the indices are the same, just - // compare the base pointer. - if (PtrBase != GEPRHS->getOperand(0)) { - bool IndicesTheSame = GEPLHS->getNumOperands()==GEPRHS->getNumOperands(); - IndicesTheSame &= GEPLHS->getOperand(0)->getType() == - GEPRHS->getOperand(0)->getType(); - if (IndicesTheSame) - for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) - if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { - IndicesTheSame = false; - break; - } - - // If all indices are the same, just compare the base pointers. - if (IndicesTheSame) - return new ICmpInst(Cond, GEPLHS->getOperand(0), GEPRHS->getOperand(0)); - - // If we're comparing GEPs with two base pointers that only differ in type - // and both GEPs have only constant indices or just one use, then fold - // the compare with the adjusted indices. - if (GEPLHS->isInBounds() && GEPRHS->isInBounds() && - (GEPLHS->hasAllConstantIndices() || GEPLHS->hasOneUse()) && - (GEPRHS->hasAllConstantIndices() || GEPRHS->hasOneUse()) && - PtrBase->stripPointerCasts() == - GEPRHS->getOperand(0)->stripPointerCasts()) { - Value *LOffset = EmitGEPOffset(GEPLHS); - Value *ROffset = EmitGEPOffset(GEPRHS); - - // If we looked through an addrspacecast between different sized address - // spaces, the LHS and RHS pointers are different sized - // integers. Truncate to the smaller one. - Type *LHSIndexTy = LOffset->getType(); - Type *RHSIndexTy = ROffset->getType(); - if (LHSIndexTy != RHSIndexTy) { - if (LHSIndexTy->getPrimitiveSizeInBits() < - RHSIndexTy->getPrimitiveSizeInBits()) { - ROffset = Builder->CreateTrunc(ROffset, LHSIndexTy); - } else - LOffset = Builder->CreateTrunc(LOffset, RHSIndexTy); - } - - Value *Cmp = Builder->CreateICmp(ICmpInst::getSignedPredicate(Cond), - LOffset, ROffset); - return replaceInstUsesWith(I, Cmp); - } - - // Otherwise, the base pointers are different and the indices are - // different. Try convert this to an indexed compare by looking through - // PHIs/casts. - return transformToIndexedCompare(GEPLHS, RHS, Cond, DL); - } - - // If one of the GEPs has all zero indices, recurse. - if (GEPLHS->hasAllZeroIndices()) - return foldGEPICmp(GEPRHS, GEPLHS->getOperand(0), - ICmpInst::getSwappedPredicate(Cond), I); - - // If the other GEP has all zero indices, recurse. - if (GEPRHS->hasAllZeroIndices()) - return foldGEPICmp(GEPLHS, GEPRHS->getOperand(0), Cond, I); - - bool GEPsInBounds = GEPLHS->isInBounds() && GEPRHS->isInBounds(); - if (GEPLHS->getNumOperands() == GEPRHS->getNumOperands()) { - // If the GEPs only differ by one index, compare it. - unsigned NumDifferences = 0; // Keep track of # differences. - unsigned DiffOperand = 0; // The operand that differs. - for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) - if (GEPLHS->getOperand(i) != GEPRHS->getOperand(i)) { - if (GEPLHS->getOperand(i)->getType()->getPrimitiveSizeInBits() != - GEPRHS->getOperand(i)->getType()->getPrimitiveSizeInBits()) { - // Irreconcilable differences. - NumDifferences = 2; - break; - } else { - if (NumDifferences++) break; - DiffOperand = i; - } - } - - if (NumDifferences == 0) // SAME GEP? - return replaceInstUsesWith(I, // No comparison is needed here. - Builder->getInt1(ICmpInst::isTrueWhenEqual(Cond))); - - else if (NumDifferences == 1 && GEPsInBounds) { - Value *LHSV = GEPLHS->getOperand(DiffOperand); - Value *RHSV = GEPRHS->getOperand(DiffOperand); - // Make sure we do a signed comparison here. - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), LHSV, RHSV); - } - } - - // Only lower this if the icmp is the only user of the GEP or if we expect - // the result to fold to a constant! - if (GEPsInBounds && (isa(GEPLHS) || GEPLHS->hasOneUse()) && - (isa(GEPRHS) || GEPRHS->hasOneUse())) { - // ((gep Ptr, OFFSET1) cmp (gep Ptr, OFFSET2) ---> (OFFSET1 cmp OFFSET2) - Value *L = EmitGEPOffset(GEPLHS); - Value *R = EmitGEPOffset(GEPRHS); - return new ICmpInst(ICmpInst::getSignedPredicate(Cond), L, R); - } - } - - // Try convert this to an indexed compare by looking through PHIs/casts as a - // last resort. - return transformToIndexedCompare(GEPLHS, RHS, Cond, DL); - } - - Instruction *InstCombiner::foldAllocaCmp(ICmpInst &ICI, - const AllocaInst *Alloca, - const Value *Other) { - assert(ICI.isEquality() && "Cannot fold non-equality comparison."); - - // It would be tempting to fold away comparisons between allocas and any - // pointer not based on that alloca (e.g. an argument). However, even - // though such pointers cannot alias, they can still compare equal. - // - // But LLVM doesn't specify where allocas get their memory, so if the alloca - // doesn't escape we can argue that it's impossible to guess its value, and we - // can therefore act as if any such guesses are wrong. - // - // The code below checks that the alloca doesn't escape, and that it's only - // used in a comparison once (the current instruction). The - // single-comparison-use condition ensures that we're trivially folding all - // comparisons against the alloca consistently, and avoids the risk of - // erroneously folding a comparison of the pointer with itself. - - unsigned MaxIter = 32; // Break cycles and bound to constant-time. - - SmallVector Worklist; - for (const Use &U : Alloca->uses()) { - if (Worklist.size() >= MaxIter) - return nullptr; - Worklist.push_back(&U); - } - - unsigned NumCmps = 0; - while (!Worklist.empty()) { - assert(Worklist.size() <= MaxIter); - const Use *U = Worklist.pop_back_val(); - const Value *V = U->getUser(); - --MaxIter; - - if (isa(V) || isa(V) || isa(V) || - isa(V)) { - // Track the uses. - } else if (isa(V)) { - // Loading from the pointer doesn't escape it. - continue; - } else if (const auto *SI = dyn_cast(V)) { - // Storing *to* the pointer is fine, but storing the pointer escapes it. - if (SI->getValueOperand() == U->get()) - return nullptr; - continue; - } else if (isa(V)) { - if (NumCmps++) - return nullptr; // Found more than one cmp. - continue; - } else if (const auto *Intrin = dyn_cast(V)) { - switch (Intrin->getIntrinsicID()) { - // These intrinsics don't escape or compare the pointer. Memset is safe - // because we don't allow ptrtoint. Memcpy and memmove are safe because - // we don't allow stores, so src cannot point to V. - case Intrinsic::lifetime_start: case Intrinsic::lifetime_end: - case Intrinsic::dbg_declare: case Intrinsic::dbg_value: - case Intrinsic::memcpy: case Intrinsic::memmove: case Intrinsic::memset: - continue; - default: - return nullptr; - } - } else { - return nullptr; - } - for (const Use &U : V->uses()) { - if (Worklist.size() >= MaxIter) - return nullptr; - Worklist.push_back(&U); - } - } - - Type *CmpTy = CmpInst::makeCmpResultType(Other->getType()); - return replaceInstUsesWith( - ICI, - ConstantInt::get(CmpTy, !CmpInst::isTrueWhenEqual(ICI.getPredicate()))); - } - - /// Fold "icmp pred (X+CI), X". - Instruction *InstCombiner::foldICmpAddOpConst(Instruction &ICI, - Value *X, ConstantInt *CI, - ICmpInst::Predicate Pred) { - // From this point on, we know that (X+C <= X) --> (X+C < X) because C != 0, - // so the values can never be equal. Similarly for all other "or equals" - // operators. - - // (X+1) X >u (MAXUINT-1) --> X == 255 - // (X+2) X >u (MAXUINT-2) --> X > 253 - // (X+MAXUINT) X >u (MAXUINT-MAXUINT) --> X != 0 - if (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_ULE) { - Value *R = - ConstantExpr::getSub(ConstantInt::getAllOnesValue(CI->getType()), CI); - return new ICmpInst(ICmpInst::ICMP_UGT, X, R); - } - - // (X+1) >u X --> X X != 255 - // (X+2) >u X --> X X u X --> X X X == 0 - if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_UGE) - return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantExpr::getNeg(CI)); - - unsigned BitWidth = CI->getType()->getPrimitiveSizeInBits(); - ConstantInt *SMax = ConstantInt::get(X->getContext(), - APInt::getSignedMaxValue(BitWidth)); - - // (X+ 1) X >s (MAXSINT-1) --> X == 127 - // (X+ 2) X >s (MAXSINT-2) --> X >s 125 - // (X+MAXSINT) X >s (MAXSINT-MAXSINT) --> X >s 0 - // (X+MINSINT) X >s (MAXSINT-MINSINT) --> X >s -1 - // (X+ -2) X >s (MAXSINT- -2) --> X >s 126 - // (X+ -1) X >s (MAXSINT- -1) --> X != 127 - if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) - return new ICmpInst(ICmpInst::ICMP_SGT, X, ConstantExpr::getSub(SMax, CI)); - - // (X+ 1) >s X --> X X != 127 - // (X+ 2) >s X --> X X s X --> X X s X --> X X s X --> X X s X --> X X == -128 - - assert(Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE); - Constant *C = Builder->getInt(CI->getValue()-1); - return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantExpr::getSub(SMax, C)); - } - - /// Handle "(icmp eq/ne (ashr/lshr const2, A), const1)" -> - /// (icmp eq/ne A, Log2(const2/const1)) -> - /// (icmp eq/ne A, Log2(const2) - Log2(const1)). - Instruction *InstCombiner::foldICmpCstShrConst(ICmpInst &I, Value *Op, Value *A, - ConstantInt *CI1, - ConstantInt *CI2) { - assert(I.isEquality() && "Cannot fold icmp gt/lt"); - - auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) { - if (I.getPredicate() == I.ICMP_NE) - Pred = CmpInst::getInversePredicate(Pred); - return new ICmpInst(Pred, LHS, RHS); - }; - - const APInt &AP1 = CI1->getValue(); - const APInt &AP2 = CI2->getValue(); - - // Don't bother doing any work for cases which InstSimplify handles. - if (AP2 == 0) - return nullptr; - bool IsAShr = isa(Op); - if (IsAShr) { - if (AP2.isAllOnesValue()) - return nullptr; - if (AP2.isNegative() != AP1.isNegative()) - return nullptr; - if (AP2.sgt(AP1)) - return nullptr; - } - - if (!AP1) - // 'A' must be large enough to shift out the highest set bit. - return getICmp(I.ICMP_UGT, A, - ConstantInt::get(A->getType(), AP2.logBase2())); - - if (AP1 == AP2) - return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType())); - - int Shift; - if (IsAShr && AP1.isNegative()) - Shift = AP1.countLeadingOnes() - AP2.countLeadingOnes(); - else - Shift = AP1.countLeadingZeros() - AP2.countLeadingZeros(); - - if (Shift > 0) { - if (IsAShr && AP1 == AP2.ashr(Shift)) { - // There are multiple solutions if we are comparing against -1 and the LHS - // of the ashr is not a power of two. - if (AP1.isAllOnesValue() && !AP2.isPowerOf2()) - return getICmp(I.ICMP_UGE, A, ConstantInt::get(A->getType(), Shift)); - return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); - } else if (AP1 == AP2.lshr(Shift)) { - return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); - } - } - - // Shifting const2 will never be equal to const1. - // FIXME: This should always be handled by InstSimplify? - auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE); - return replaceInstUsesWith(I, TorF); - } - - /// Handle "(icmp eq/ne (shl const2, A), const1)" -> - /// (icmp eq/ne A, TrailingZeros(const1) - TrailingZeros(const2)). - Instruction *InstCombiner::foldICmpCstShlConst(ICmpInst &I, Value *Op, Value *A, - ConstantInt *CI1, - ConstantInt *CI2) { - assert(I.isEquality() && "Cannot fold icmp gt/lt"); - - auto getICmp = [&I](CmpInst::Predicate Pred, Value *LHS, Value *RHS) { - if (I.getPredicate() == I.ICMP_NE) - Pred = CmpInst::getInversePredicate(Pred); - return new ICmpInst(Pred, LHS, RHS); - }; - - const APInt &AP1 = CI1->getValue(); - const APInt &AP2 = CI2->getValue(); - - // Don't bother doing any work for cases which InstSimplify handles. - if (AP2 == 0) - return nullptr; - - unsigned AP2TrailingZeros = AP2.countTrailingZeros(); - - if (!AP1 && AP2TrailingZeros != 0) - return getICmp(I.ICMP_UGE, A, - ConstantInt::get(A->getType(), AP2.getBitWidth() - AP2TrailingZeros)); - - if (AP1 == AP2) - return getICmp(I.ICMP_EQ, A, ConstantInt::getNullValue(A->getType())); - - // Get the distance between the lowest bits that are set. - int Shift = AP1.countTrailingZeros() - AP2TrailingZeros; - - if (Shift > 0 && AP2.shl(Shift) == AP1) - return getICmp(I.ICMP_EQ, A, ConstantInt::get(A->getType(), Shift)); - - // Shifting const2 will never be equal to const1. - // FIXME: This should always be handled by InstSimplify? - auto *TorF = ConstantInt::get(I.getType(), I.getPredicate() == I.ICMP_NE); - return replaceInstUsesWith(I, TorF); - } - - /// The caller has matched a pattern of the form: - /// I = icmp ugt (add (add A, B), CI2), CI1 - /// If this is of the form: - /// sum = a + b - /// if (sum+128 >u 255) - /// Then replace it with llvm.sadd.with.overflow.i8. - /// - static Instruction *processUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B, - ConstantInt *CI2, ConstantInt *CI1, - InstCombiner &IC) { - // The transformation we're trying to do here is to transform this into an - // llvm.sadd.with.overflow. To do this, we have to replace the original add - // with a narrower add, and discard the add-with-constant that is part of the - // range check (if we can't eliminate it, this isn't profitable). - - // In order to eliminate the add-with-constant, the compare can be its only - // use. - Instruction *AddWithCst = cast(I.getOperand(0)); - if (!AddWithCst->hasOneUse()) - return nullptr; - - // If CI2 is 2^7, 2^15, 2^31, then it might be an sadd.with.overflow. - if (!CI2->getValue().isPowerOf2()) - return nullptr; - unsigned NewWidth = CI2->getValue().countTrailingZeros(); - if (NewWidth != 7 && NewWidth != 15 && NewWidth != 31) - return nullptr; - - // The width of the new add formed is 1 more than the bias. - ++NewWidth; - - // Check to see that CI1 is an all-ones value with NewWidth bits. - if (CI1->getBitWidth() == NewWidth || - CI1->getValue() != APInt::getLowBitsSet(CI1->getBitWidth(), NewWidth)) - return nullptr; - - // This is only really a signed overflow check if the inputs have been - // sign-extended; check for that condition. For example, if CI2 is 2^31 and - // the operands of the add are 64 bits wide, we need at least 33 sign bits. - unsigned NeededSignBits = CI1->getBitWidth() - NewWidth + 1; - if (IC.ComputeNumSignBits(A, 0, &I) < NeededSignBits || - IC.ComputeNumSignBits(B, 0, &I) < NeededSignBits) - return nullptr; - - // In order to replace the original add with a narrower - // llvm.sadd.with.overflow, the only uses allowed are the add-with-constant - // and truncates that discard the high bits of the add. Verify that this is - // the case. - Instruction *OrigAdd = cast(AddWithCst->getOperand(0)); - for (User *U : OrigAdd->users()) { - if (U == AddWithCst) - continue; - - // Only accept truncates for now. We would really like a nice recursive - // predicate like SimplifyDemandedBits, but which goes downwards the use-def - // chain to see which bits of a value are actually demanded. If the - // original add had another add which was then immediately truncated, we - // could still do the transformation. - TruncInst *TI = dyn_cast(U); - if (!TI || TI->getType()->getPrimitiveSizeInBits() > NewWidth) - return nullptr; - } - - // If the pattern matches, truncate the inputs to the narrower type and - // use the sadd_with_overflow intrinsic to efficiently compute both the - // result and the overflow bit. - Type *NewType = IntegerType::get(OrigAdd->getContext(), NewWidth); - Value *F = Intrinsic::getDeclaration(I.getModule(), - Intrinsic::sadd_with_overflow, NewType); - - InstCombiner::BuilderTy *Builder = IC.Builder; - - // Put the new code above the original add, in case there are any uses of the - // add between the add and the compare. - Builder->SetInsertPoint(OrigAdd); - - Value *TruncA = Builder->CreateTrunc(A, NewType, A->getName() + ".trunc"); - Value *TruncB = Builder->CreateTrunc(B, NewType, B->getName() + ".trunc"); - CallInst *Call = Builder->CreateCall(F, {TruncA, TruncB}, "sadd"); - Value *Add = Builder->CreateExtractValue(Call, 0, "sadd.result"); - Value *ZExt = Builder->CreateZExt(Add, OrigAdd->getType()); - - // The inner add was the result of the narrow add, zero extended to the - // wider type. Replace it with the result computed by the intrinsic. - IC.replaceInstUsesWith(*OrigAdd, ZExt); - - // The original icmp gets replaced with the overflow value. - return ExtractValueInst::Create(Call, 1, "sadd.overflow"); - } - - // Fold icmp Pred X, C. - Instruction *InstCombiner::foldICmpWithConstant(ICmpInst &Cmp) { - CmpInst::Predicate Pred = Cmp.getPredicate(); - Value *X = Cmp.getOperand(0); - - const APInt *C; - if (!match(Cmp.getOperand(1), m_APInt(C))) - return nullptr; - - Value *A = nullptr, *B = nullptr; - - // Match the following pattern, which is a common idiom when writing - // overflow-safe integer arithmetic functions. The source performs an addition - // in wider type and explicitly checks for overflow using comparisons against - // INT_MIN and INT_MAX. Simplify by using the sadd_with_overflow intrinsic. - // - // TODO: This could probably be generalized to handle other overflow-safe - // operations if we worked out the formulas to compute the appropriate magic - // constants. - // - // sum = a + b - // if (sum+128 >u 255) ... -> llvm.sadd.with.overflow.i8 - { - ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI - if (Pred == ICmpInst::ICMP_UGT && - match(X, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2)))) - if (Instruction *Res = processUGT_ADDCST_ADD( - Cmp, A, B, CI2, cast(Cmp.getOperand(1)), *this)) - return Res; - } - - // (icmp sgt smin(PosA, B) 0) -> (icmp sgt B 0) - if (*C == 0 && Pred == ICmpInst::ICMP_SGT) { - SelectPatternResult SPR = matchSelectPattern(X, A, B); - if (SPR.Flavor == SPF_SMIN) { - if (isKnownPositive(A, DL)) - return new ICmpInst(Pred, B, Cmp.getOperand(1)); - if (isKnownPositive(B, DL)) - return new ICmpInst(Pred, A, Cmp.getOperand(1)); - } - } - - // FIXME: Use m_APInt to allow folds for splat constants. - ConstantInt *CI = dyn_cast(Cmp.getOperand(1)); - if (!CI) - return nullptr; - - if (Cmp.isEquality()) { - ConstantInt *CI2; - if (match(X, m_AShr(m_ConstantInt(CI2), m_Value(A))) || - match(X, m_LShr(m_ConstantInt(CI2), m_Value(A)))) { - // (icmp eq/ne (ashr/lshr const2, A), const1) - if (Instruction *Inst = foldICmpCstShrConst(Cmp, X, A, CI, CI2)) - return Inst; - } - if (match(X, m_Shl(m_ConstantInt(CI2), m_Value(A)))) { - // (icmp eq/ne (shl const2, A), const1) - if (Instruction *Inst = foldICmpCstShlConst(Cmp, X, A, CI, CI2)) - return Inst; - } - } - - // Canonicalize icmp instructions based on dominating conditions. - BasicBlock *Parent = Cmp.getParent(); - BasicBlock *Dom = Parent->getSinglePredecessor(); - auto *BI = Dom ? dyn_cast(Dom->getTerminator()) : nullptr; - ICmpInst::Predicate Pred2; - BasicBlock *TrueBB, *FalseBB; - ConstantInt *CI2; - if (BI && match(BI, m_Br(m_ICmp(Pred2, m_Specific(X), m_ConstantInt(CI2)), - TrueBB, FalseBB)) && - TrueBB != FalseBB) { - ConstantRange CR = - ConstantRange::makeAllowedICmpRegion(Pred, CI->getValue()); - ConstantRange DominatingCR = - (Parent == TrueBB) - ? ConstantRange::makeExactICmpRegion(Pred2, CI2->getValue()) - : ConstantRange::makeExactICmpRegion( - CmpInst::getInversePredicate(Pred2), CI2->getValue()); - ConstantRange Intersection = DominatingCR.intersectWith(CR); - ConstantRange Difference = DominatingCR.difference(CR); - if (Intersection.isEmptySet()) - return replaceInstUsesWith(Cmp, Builder->getFalse()); - if (Difference.isEmptySet()) - return replaceInstUsesWith(Cmp, Builder->getTrue()); - - // If this is a normal comparison, it demands all bits. If it is a sign - // bit comparison, it only demands the sign bit. - bool UnusedBit; - bool IsSignBit = isSignBitCheck(Pred, CI->getValue(), UnusedBit); - - // Canonicalizing a sign bit comparison that gets used in a branch, - // pessimizes codegen by generating branch on zero instruction instead - // of a test and branch. So we avoid canonicalizing in such situations - // because test and branch instruction has better branch displacement - // than compare and branch instruction. - if (!isBranchOnSignBitCheck(Cmp, IsSignBit) && !Cmp.isEquality()) { - if (auto *AI = Intersection.getSingleElement()) - return new ICmpInst(ICmpInst::ICMP_EQ, X, Builder->getInt(*AI)); - if (auto *AD = Difference.getSingleElement()) - return new ICmpInst(ICmpInst::ICMP_NE, X, Builder->getInt(*AD)); - } - } - - return nullptr; - } - - /// Fold icmp (trunc X, Y), C. - Instruction *InstCombiner::foldICmpTruncConstant(ICmpInst &Cmp, - Instruction *Trunc, - const APInt *C) { - ICmpInst::Predicate Pred = Cmp.getPredicate(); - Value *X = Trunc->getOperand(0); - if (*C == 1 && C->getBitWidth() > 1) { - // icmp slt trunc(signum(V)) 1 --> icmp slt V, 1 - Value *V = nullptr; - if (Pred == ICmpInst::ICMP_SLT && match(X, m_Signum(m_Value(V)))) - return new ICmpInst(ICmpInst::ICMP_SLT, V, - ConstantInt::get(V->getType(), 1)); - } - - if (Cmp.isEquality() && Trunc->hasOneUse()) { - // Simplify icmp eq (trunc x to i8), 42 -> icmp eq x, 42|highbits if all - // of the high bits truncated out of x are known. - unsigned DstBits = Trunc->getType()->getScalarSizeInBits(), - SrcBits = X->getType()->getScalarSizeInBits(); - APInt KnownZero(SrcBits, 0), KnownOne(SrcBits, 0); - computeKnownBits(X, KnownZero, KnownOne, 0, &Cmp); - - // If all the high bits are known, we can do this xform. - if ((KnownZero | KnownOne).countLeadingOnes() >= SrcBits - DstBits) { - // Pull in the high bits from known-ones set. - APInt NewRHS = C->zext(SrcBits); - NewRHS |= KnownOne & APInt::getHighBitsSet(SrcBits, SrcBits - DstBits); - return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), NewRHS)); - } - } - - return nullptr; - } - - /// Fold icmp (xor X, Y), C. - Instruction *InstCombiner::foldICmpXorConstant(ICmpInst &Cmp, - BinaryOperator *Xor, - const APInt *C) { - Value *X = Xor->getOperand(0); - Value *Y = Xor->getOperand(1); - const APInt *XorC; - if (!match(Y, m_APInt(XorC))) - return nullptr; - - // If this is a comparison that tests the signbit (X < 0) or (x > -1), - // fold the xor. - ICmpInst::Predicate Pred = Cmp.getPredicate(); - if ((Pred == ICmpInst::ICMP_SLT && *C == 0) || - (Pred == ICmpInst::ICMP_SGT && C->isAllOnesValue())) { - - // If the sign bit of the XorCst is not set, there is no change to - // the operation, just stop using the Xor. - if (!XorC->isNegative()) { - Cmp.setOperand(0, X); - Worklist.Add(Xor); - return &Cmp; - } - - // Was the old condition true if the operand is positive? - bool isTrueIfPositive = Pred == ICmpInst::ICMP_SGT; - - // If so, the new one isn't. - isTrueIfPositive ^= true; - - Constant *CmpConstant = cast(Cmp.getOperand(1)); - if (isTrueIfPositive) - return new ICmpInst(ICmpInst::ICMP_SGT, X, SubOne(CmpConstant)); - else - return new ICmpInst(ICmpInst::ICMP_SLT, X, AddOne(CmpConstant)); - } - - if (Xor->hasOneUse()) { - // (icmp u/s (xor X SignBit), C) -> (icmp s/u X, (xor C SignBit)) - if (!Cmp.isEquality() && XorC->isSignBit()) { - Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate() - : Cmp.getSignedPredicate(); - return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), *C ^ *XorC)); - } - - // (icmp u/s (xor X ~SignBit), C) -> (icmp s/u X, (xor C ~SignBit)) - if (!Cmp.isEquality() && XorC->isMaxSignedValue()) { - Pred = Cmp.isSigned() ? Cmp.getUnsignedPredicate() - : Cmp.getSignedPredicate(); - Pred = Cmp.getSwappedPredicate(Pred); - return new ICmpInst(Pred, X, ConstantInt::get(X->getType(), *C ^ *XorC)); - } - } - - // (icmp ugt (xor X, C), ~C) -> (icmp ult X, C) - // iff -C is a power of 2 - if (Pred == ICmpInst::ICMP_UGT && *XorC == ~(*C) && (*C + 1).isPowerOf2()) - return new ICmpInst(ICmpInst::ICMP_ULT, X, Y); - - // (icmp ult (xor X, C), -C) -> (icmp uge X, C) - // iff -C is a power of 2 - if (Pred == ICmpInst::ICMP_ULT && *XorC == -(*C) && C->isPowerOf2()) - return new ICmpInst(ICmpInst::ICMP_UGE, X, Y); - - return nullptr; - } - - /// Fold icmp (and (sh X, Y), C2), C1. - Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And, - const APInt *C1, const APInt *C2) { - BinaryOperator *Shift = dyn_cast(And->getOperand(0)); - if (!Shift || !Shift->isShift()) - return nullptr; - - // If this is: (X >> C3) & C2 != C1 (where any shift and any compare could - // exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in - // code produced by the clang front-end, for bitfield access. - // This seemingly simple opportunity to fold away a shift turns out to be - // rather complicated. See PR17827 for details. - unsigned ShiftOpcode = Shift->getOpcode(); - bool IsShl = ShiftOpcode == Instruction::Shl; - const APInt *C3; - if (match(Shift->getOperand(1), m_APInt(C3))) { - bool CanFold = false; - if (ShiftOpcode == Instruction::AShr) { - // There may be some constraints that make this possible, but nothing - // simple has been discovered yet. - CanFold = false; - } else if (ShiftOpcode == Instruction::Shl) { - // For a left shift, we can fold if the comparison is not signed. We can - // also fold a signed comparison if the mask value and comparison value - // are not negative. These constraints may not be obvious, but we can - // prove that they are correct using an SMT solver. - if (!Cmp.isSigned() || (!C2->isNegative() && !C1->isNegative())) - CanFold = true; - } else if (ShiftOpcode == Instruction::LShr) { - // For a logical right shift, we can fold if the comparison is not signed. - // We can also fold a signed comparison if the shifted mask value and the - // shifted comparison value are not negative. These constraints may not be - // obvious, but we can prove that they are correct using an SMT solver. - if (!Cmp.isSigned() || - (!C2->shl(*C3).isNegative() && !C1->shl(*C3).isNegative())) - CanFold = true; - } - - if (CanFold) { - APInt NewCst = IsShl ? C1->lshr(*C3) : C1->shl(*C3); - APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3); - // Check to see if we are shifting out any of the bits being compared. - if (SameAsC1 != *C1) { - // If we shifted bits out, the fold is not going to work out. As a - // special case, check to see if this means that the result is always - // true or false now. - if (Cmp.getPredicate() == ICmpInst::ICMP_EQ) - return replaceInstUsesWith(Cmp, ConstantInt::getFalse(Cmp.getType())); - if (Cmp.getPredicate() == ICmpInst::ICMP_NE) - return replaceInstUsesWith(Cmp, ConstantInt::getTrue(Cmp.getType())); - } else { - Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst)); - APInt NewAndCst = IsShl ? C2->lshr(*C3) : C2->shl(*C3); - And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst)); - And->setOperand(0, Shift->getOperand(0)); - Worklist.Add(Shift); // Shift is dead. - return &Cmp; - } - } - } - - // Turn ((X >> Y) & C2) == 0 into (X & (C2 << Y)) == 0. The latter is - // preferable because it allows the C2 << Y expression to be hoisted out of a - // loop if Y is invariant and X is not. - if (Shift->hasOneUse() && *C1 == 0 && Cmp.isEquality() && - !Shift->isArithmeticShift() && !isa(Shift->getOperand(0))) { - // Compute C2 << Y. - Value *NewShift = - IsShl ? Builder->CreateLShr(And->getOperand(1), Shift->getOperand(1)) - : Builder->CreateShl(And->getOperand(1), Shift->getOperand(1)); - - // Compute X & (C2 << Y). - Value *NewAnd = Builder->CreateAnd(Shift->getOperand(0), NewShift); - Cmp.setOperand(0, NewAnd); - return &Cmp; - } - - return nullptr; - } - - /// Fold icmp (and X, C2), C1. - Instruction *InstCombiner::foldICmpAndConstConst(ICmpInst &Cmp, - BinaryOperator *And, - const APInt *C1) { - const APInt *C2; - if (!match(And->getOperand(1), m_APInt(C2))) - return nullptr; - - if (!And->hasOneUse() || !And->getOperand(0)->hasOneUse()) - return nullptr; - - // If the LHS is an 'and' of a truncate and we can widen the and/compare to - // the input width without changing the value produced, eliminate the cast: - // - // icmp (and (trunc W), C2), C1 -> icmp (and W, C2'), C1' - // - // We can do this transformation if the constants do not have their sign bits - // set or if it is an equality comparison. Extending a relational comparison - // when we're checking the sign bit would not work. - Value *W; - if (match(And->getOperand(0), m_Trunc(m_Value(W))) && - (Cmp.isEquality() || (!C1->isNegative() && !C2->isNegative()))) { - // TODO: Is this a good transform for vectors? Wider types may reduce - // throughput. Should this transform be limited (even for scalars) by using - // ShouldChangeType()? - if (!Cmp.getType()->isVectorTy()) { - Type *WideType = W->getType(); - unsigned WideScalarBits = WideType->getScalarSizeInBits(); - Constant *ZextC1 = ConstantInt::get(WideType, C1->zext(WideScalarBits)); - Constant *ZextC2 = ConstantInt::get(WideType, C2->zext(WideScalarBits)); - Value *NewAnd = Builder->CreateAnd(W, ZextC2, And->getName()); - return new ICmpInst(Cmp.getPredicate(), NewAnd, ZextC1); - } - } - - if (Instruction *I = foldICmpAndShift(Cmp, And, C1, C2)) - return I; - - // (icmp pred (and (or (lshr A, B), A), 1), 0) --> - // (icmp pred (and A, (or (shl 1, B), 1), 0)) - // - // iff pred isn't signed - if (!Cmp.isSigned() && *C1 == 0 && match(And->getOperand(1), m_One())) { - Constant *One = cast(And->getOperand(1)); - Value *Or = And->getOperand(0); - Value *A, *B, *LShr; - if (match(Or, m_Or(m_Value(LShr), m_Value(A))) && - match(LShr, m_LShr(m_Specific(A), m_Value(B)))) { - unsigned UsesRemoved = 0; - if (And->hasOneUse()) - ++UsesRemoved; - if (Or->hasOneUse()) - ++UsesRemoved; - if (LShr->hasOneUse()) - ++UsesRemoved; - - // Compute A & ((1 << B) | 1) - Value *NewOr = nullptr; - if (auto *C = dyn_cast(B)) { - if (UsesRemoved >= 1) - NewOr = ConstantExpr::getOr(ConstantExpr::getNUWShl(One, C), One); - } else { - if (UsesRemoved >= 3) - NewOr = Builder->CreateOr(Builder->CreateShl(One, B, LShr->getName(), - /*HasNUW=*/true), - One, Or->getName()); - } - if (NewOr) { - Value *NewAnd = Builder->CreateAnd(A, NewOr, And->getName()); - Cmp.setOperand(0, NewAnd); - return &Cmp; - } - } - } - - // (X & C2) > C1 --> (X & C2) != 0, if any bit set in (X & C2) will produce a - // result greater than C1. - unsigned NumTZ = C2->countTrailingZeros(); - if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && NumTZ < C2->getBitWidth() && - APInt::getOneBitSet(C2->getBitWidth(), NumTZ).ugt(*C1)) { - Constant *Zero = Constant::getNullValue(And->getType()); - return new ICmpInst(ICmpInst::ICMP_NE, And, Zero); - } - - return nullptr; - } - - /// Fold icmp (and X, Y), C. - Instruction *InstCombiner::foldICmpAndConstant(ICmpInst &Cmp, - BinaryOperator *And, - const APInt *C) { - if (Instruction *I = foldICmpAndConstConst(Cmp, And, C)) - return I; - - // TODO: These all require that Y is constant too, so refactor with the above. - - // Try to optimize things like "A[i] & 42 == 0" to index computations. - Value *X = And->getOperand(0); - Value *Y = And->getOperand(1); - if (auto *LI = dyn_cast(X)) - if (auto *GEP = dyn_cast(LI->getOperand(0))) - if (auto *GV = dyn_cast(GEP->getOperand(0))) - if (GV->isConstant() && GV->hasDefinitiveInitializer() && - !LI->isVolatile() && isa(Y)) { - ConstantInt *C2 = cast(Y); - if (Instruction *Res = foldCmpLoadFromIndexedGlobal(GEP, GV, Cmp, C2)) - return Res; - } - - if (!Cmp.isEquality()) - return nullptr; - - // X & -C == -C -> X > u ~C - // X & -C != -C -> X <= u ~C - // iff C is a power of 2 - if (Cmp.getOperand(1) == Y && (-(*C)).isPowerOf2()) { - auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_UGT - : CmpInst::ICMP_ULE; - return new ICmpInst(NewPred, X, SubOne(cast(Cmp.getOperand(1)))); - } - - // (X & C2) == 0 -> (trunc X) >= 0 - // (X & C2) != 0 -> (trunc X) < 0 - // iff C2 is a power of 2 and it masks the sign bit of a legal integer type. - const APInt *C2; - if (And->hasOneUse() && *C == 0 && match(Y, m_APInt(C2))) { - int32_t ExactLogBase2 = C2->exactLogBase2(); - if (ExactLogBase2 != -1 && DL.isLegalInteger(ExactLogBase2 + 1)) { - Type *NTy = IntegerType::get(Cmp.getContext(), ExactLogBase2 + 1); - if (And->getType()->isVectorTy()) - NTy = VectorType::get(NTy, And->getType()->getVectorNumElements()); - Value *Trunc = Builder->CreateTrunc(X, NTy); - auto NewPred = Cmp.getPredicate() == CmpInst::ICMP_EQ ? CmpInst::ICMP_SGE - : CmpInst::ICMP_SLT; - return new ICmpInst(NewPred, Trunc, Constant::getNullValue(NTy)); - } - } - - return nullptr; - } - - /// Fold icmp (or X, Y), C. - Instruction *InstCombiner::foldICmpOrConstant(ICmpInst &Cmp, BinaryOperator *Or, - const APInt *C) { - ICmpInst::Predicate Pred = Cmp.getPredicate(); - if (*C == 1) { - // icmp slt signum(V) 1 --> icmp slt V, 1 - Value *V = nullptr; - if (Pred == ICmpInst::ICMP_SLT && match(Or, m_Signum(m_Value(V)))) - return new ICmpInst(ICmpInst::ICMP_SLT, V, - ConstantInt::get(V->getType(), 1)); - } - - if (!Cmp.isEquality() || *C != 0 || !Or->hasOneUse()) - return nullptr; - - Value *P, *Q; - if (match(Or, m_Or(m_PtrToInt(m_Value(P)), m_PtrToInt(m_Value(Q))))) { - // Simplify icmp eq (or (ptrtoint P), (ptrtoint Q)), 0 - // -> and (icmp eq P, null), (icmp eq Q, null). - Value *CmpP = - Builder->CreateICmp(Pred, P, ConstantInt::getNullValue(P->getType())); - Value *CmpQ = - Builder->CreateICmp(Pred, Q, ConstantInt::getNullValue(Q->getType())); - auto LogicOpc = Pred == ICmpInst::Predicate::ICMP_EQ ? Instruction::And - : Instruction::Or; - return BinaryOperator::Create(LogicOpc, CmpP, CmpQ); - } - - return nullptr; - } - - /// Fold icmp (mul X, Y), C. - Instruction *InstCombiner::foldICmpMulConstant(ICmpInst &Cmp, - BinaryOperator *Mul, - const APInt *C) { - const APInt *MulC; - if (!match(Mul->getOperand(1), m_APInt(MulC))) - return nullptr; - - // If this is a test of the sign bit and the multiply is sign-preserving with - // a constant operand, use the multiply LHS operand instead. - ICmpInst::Predicate Pred = Cmp.getPredicate(); - if (isSignTest(Pred, *C) && Mul->hasNoSignedWrap()) { - if (MulC->isNegative()) - Pred = ICmpInst::getSwappedPredicate(Pred); - return new ICmpInst(Pred, Mul->getOperand(0), - Constant::getNullValue(Mul->getType())); - } - - return nullptr; - } - - /// Fold icmp (shl 1, Y), C. - static Instruction *foldICmpShlOne(ICmpInst &Cmp, Instruction *Shl, - const APInt *C) { - Value *Y; - if (!match(Shl, m_Shl(m_One(), m_Value(Y)))) - return nullptr; - - Type *ShiftType = Shl->getType(); - uint32_t TypeBits = C->getBitWidth(); - bool CIsPowerOf2 = C->isPowerOf2(); - ICmpInst::Predicate Pred = Cmp.getPredicate(); - if (Cmp.isUnsigned()) { - // (1 << Y) pred C -> Y pred Log2(C) - if (!CIsPowerOf2) { - // (1 << Y) < 30 -> Y <= 4 - // (1 << Y) <= 30 -> Y <= 4 - // (1 << Y) >= 30 -> Y > 4 - // (1 << Y) > 30 -> Y > 4 - if (Pred == ICmpInst::ICMP_ULT) - Pred = ICmpInst::ICMP_ULE; - else if (Pred == ICmpInst::ICMP_UGE) - Pred = ICmpInst::ICMP_UGT; - } - - // (1 << Y) >= 2147483648 -> Y >= 31 -> Y == 31 - // (1 << Y) < 2147483648 -> Y < 31 -> Y != 31 - unsigned CLog2 = C->logBase2(); - if (CLog2 == TypeBits - 1) { - if (Pred == ICmpInst::ICMP_UGE) - Pred = ICmpInst::ICMP_EQ; - else if (Pred == ICmpInst::ICMP_ULT) - Pred = ICmpInst::ICMP_NE; - } - return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, CLog2)); - } else if (Cmp.isSigned()) { - Constant *BitWidthMinusOne = ConstantInt::get(ShiftType, TypeBits - 1); - if (C->isAllOnesValue()) { - // (1 << Y) <= -1 -> Y == 31 - if (Pred == ICmpInst::ICMP_SLE) - return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne); - - // (1 << Y) > -1 -> Y != 31 - if (Pred == ICmpInst::ICMP_SGT) - return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne); - } else if (!(*C)) { - // (1 << Y) < 0 -> Y == 31 - // (1 << Y) <= 0 -> Y == 31 - if (Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_SLE) - return new ICmpInst(ICmpInst::ICMP_EQ, Y, BitWidthMinusOne); - - // (1 << Y) >= 0 -> Y != 31 - // (1 << Y) > 0 -> Y != 31 - if (Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_SGE) - return new ICmpInst(ICmpInst::ICMP_NE, Y, BitWidthMinusOne); - } - } else if (Cmp.isEquality() && CIsPowerOf2) { - return new ICmpInst(Pred, Y, ConstantInt::get(ShiftType, C->logBase2())); - } - - return nullptr; - } - - /// Fold icmp (shl X, Y), C. - Instruction *InstCombiner::foldICmpShlConstant(ICmpInst &Cmp, - BinaryOperator *Shl, - const APInt *C) { - const APInt *ShiftAmt; - if (!match(Shl->getOperand(1), m_APInt(ShiftAmt))) - return foldICmpShlOne(Cmp, Shl, C); - - // Check that the shift amount is in range. If not, don't perform undefined - // shifts. When the shift is visited it will be simplified. - unsigned TypeBits = C->getBitWidth(); - if (ShiftAmt->uge(TypeBits)) - return nullptr; - - ICmpInst::Predicate Pred = Cmp.getPredicate(); - Value *X = Shl->getOperand(0); - if (Cmp.isEquality()) { - // If the shift is NUW, then it is just shifting out zeros, no need for an - // AND. - Constant *LShrC = ConstantInt::get(Shl->getType(), C->lshr(*ShiftAmt)); - if (Shl->hasNoUnsignedWrap()) - return new ICmpInst(Pred, X, LShrC); - - // If the shift is NSW and we compare to 0, then it is just shifting out - // sign bits, no need for an AND either. - if (Shl->hasNoSignedWrap() && *C == 0) - return new ICmpInst(Pred, X, LShrC); - - if (Shl->hasOneUse()) { - // Otherwise strength reduce the shift into an and. - Constant *Mask = ConstantInt::get(Shl->getType(), - APInt::getLowBitsSet(TypeBits, TypeBits - ShiftAmt->getZExtValue())); - - Value *And = Builder->CreateAnd(X, Mask, Shl->getName() + ".mask"); - return new ICmpInst(Pred, And, LShrC); - } - } - - // If this is a signed comparison to 0 and the shift is sign preserving, - // use the shift LHS operand instead; isSignTest may change 'Pred', so only - // do that if we're sure to not continue on in this function. - if (Shl->hasNoSignedWrap() && isSignTest(Pred, *C)) - return new ICmpInst(Pred, X, Constant::getNullValue(X->getType())); - - // Otherwise, if this is a comparison of the sign bit, simplify to and/test. - bool TrueIfSigned = false; - if (Shl->hasOneUse() && isSignBitCheck(Pred, *C, TrueIfSigned)) { - // (X << 31) (X & 1) != 0 - Constant *Mask = ConstantInt::get( - X->getType(), - APInt::getOneBitSet(TypeBits, TypeBits - ShiftAmt->getZExtValue() - 1)); - Value *And = Builder->CreateAnd(X, Mask, Shl->getName() + ".mask"); - return new ICmpInst(TrueIfSigned ? ICmpInst::ICMP_NE : ICmpInst::ICMP_EQ, - And, Constant::getNullValue(And->getType())); - } - - // Transform (icmp pred iM (shl iM %v, N), C) - // -> (icmp pred i(M-N) (trunc %v iM to i(M-N)), (trunc (C>>N)) - // Transform the shl to a trunc if (trunc (C>>N)) has no loss and M-N. - // This enables us to get rid of the shift in favor of a trunc which can be - // free on the target. It has the additional benefit of comparing to a - // smaller constant, which will be target friendly. - unsigned Amt = ShiftAmt->getLimitedValue(TypeBits - 1); - if (Shl->hasOneUse() && Amt != 0 && C->countTrailingZeros() >= Amt) { - Type *TruncTy = IntegerType::get(Cmp.getContext(), TypeBits - Amt); - if (X->getType()->isVectorTy()) - TruncTy = VectorType::get(TruncTy, X->getType()->getVectorNumElements()); - Constant *NewC = - ConstantInt::get(TruncTy, C->ashr(*ShiftAmt).trunc(TypeBits - Amt)); - return new ICmpInst(Pred, Builder->CreateTrunc(X, TruncTy), NewC); - } - - return nullptr; - } - - /// Fold icmp ({al}shr X, Y), C. - Instruction *InstCombiner::foldICmpShrConstant(ICmpInst &Cmp, - BinaryOperator *Shr, - const APInt *C) { - // An exact shr only shifts out zero bits, so: - // icmp eq/ne (shr X, Y), 0 --> icmp eq/ne X, 0 - Value *X = Shr->getOperand(0); - CmpInst::Predicate Pred = Cmp.getPredicate(); - if (Cmp.isEquality() && Shr->isExact() && Shr->hasOneUse() && *C == 0) - return new ICmpInst(Pred, X, Cmp.getOperand(1)); - - const APInt *ShiftAmt; - if (!match(Shr->getOperand(1), m_APInt(ShiftAmt))) - return nullptr; - - // Check that the shift amount is in range. If not, don't perform undefined - // shifts. When the shift is visited it will be simplified. - unsigned TypeBits = C->getBitWidth(); - unsigned ShAmtVal = ShiftAmt->getLimitedValue(TypeBits); - if (ShAmtVal >= TypeBits || ShAmtVal == 0) - return nullptr; - - bool IsAShr = Shr->getOpcode() == Instruction::AShr; - if (!Cmp.isEquality()) { - // If we have an unsigned comparison and an ashr, we can't simplify this. - // Similarly for signed comparisons with lshr. - if (Cmp.isSigned() != IsAShr) - return nullptr; - - // Otherwise, all lshr and most exact ashr's are equivalent to a udiv/sdiv - // by a power of 2. Since we already have logic to simplify these, - // transform to div and then simplify the resultant comparison. - if (IsAShr && (!Shr->isExact() || ShAmtVal == TypeBits - 1)) - return nullptr; - - // Revisit the shift (to delete it). - Worklist.Add(Shr); - - Constant *DivCst = ConstantInt::get( - Shr->getType(), APInt::getOneBitSet(TypeBits, ShAmtVal)); - - Value *Tmp = IsAShr ? Builder->CreateSDiv(X, DivCst, "", Shr->isExact()) - : Builder->CreateUDiv(X, DivCst, "", Shr->isExact()); - - Cmp.setOperand(0, Tmp); - - // If the builder folded the binop, just return it. - BinaryOperator *TheDiv = dyn_cast(Tmp); - if (!TheDiv) - return &Cmp; - - // Otherwise, fold this div/compare. - assert(TheDiv->getOpcode() == Instruction::SDiv || - TheDiv->getOpcode() == Instruction::UDiv); - - Instruction *Res = foldICmpDivConstant(Cmp, TheDiv, C); - assert(Res && "This div/cst should have folded!"); - return Res; - } - - // Handle equality comparisons of shift-by-constant. - - // If the comparison constant changes with the shift, the comparison cannot - // succeed (bits of the comparison constant cannot match the shifted value). - // This should be known by InstSimplify and already be folded to true/false. - assert(((IsAShr && C->shl(ShAmtVal).ashr(ShAmtVal) == *C) || - (!IsAShr && C->shl(ShAmtVal).lshr(ShAmtVal) == *C)) && - "Expected icmp+shr simplify did not occur."); - - // Check if the bits shifted out are known to be zero. If so, we can compare - // against the unshifted value: - // (X & 4) >> 1 == 2 --> (X & 4) == 4. - Constant *ShiftedCmpRHS = ConstantInt::get(Shr->getType(), *C << ShAmtVal); - if (Shr->hasOneUse()) { - if (Shr->isExact()) - return new ICmpInst(Pred, X, ShiftedCmpRHS); - - // Otherwise strength reduce the shift into an 'and'. - APInt Val(APInt::getHighBitsSet(TypeBits, TypeBits - ShAmtVal)); - Constant *Mask = ConstantInt::get(Shr->getType(), Val); - Value *And = Builder->CreateAnd(X, Mask, Shr->getName() + ".mask"); - return new ICmpInst(Pred, And, ShiftedCmpRHS); - } - - return nullptr; - } - - /// Fold icmp (udiv X, Y), C. - Instruction *InstCombiner::foldICmpUDivConstant(ICmpInst &Cmp, - BinaryOperator *UDiv, - const APInt *C) { - const APInt *C2; - if (!match(UDiv->getOperand(0), m_APInt(C2))) - return nullptr; - - assert(C2 != 0 && "udiv 0, X should have been simplified already."); - - // (icmp ugt (udiv C2, Y), C) -> (icmp ule Y, C2/(C+1)) - Value *Y = UDiv->getOperand(1); - if (Cmp.getPredicate() == ICmpInst::ICMP_UGT) { - assert(!C->isMaxValue() && - "icmp ugt X, UINT_MAX should have been simplified already."); - return new ICmpInst(ICmpInst::ICMP_ULE, Y, - ConstantInt::get(Y->getType(), C2->udiv(*C + 1))); - } - - // (icmp ult (udiv C2, Y), C) -> (icmp ugt Y, C2/C) - if (Cmp.getPredicate() == ICmpInst::ICMP_ULT) { - assert(C != 0 && "icmp ult X, 0 should have been simplified already."); - return new ICmpInst(ICmpInst::ICMP_UGT, Y, - ConstantInt::get(Y->getType(), C2->udiv(*C))); - } - - return nullptr; - } - - /// Fold icmp ({su}div X, Y), C. - Instruction *InstCombiner::foldICmpDivConstant(ICmpInst &Cmp, - BinaryOperator *Div, - const APInt *C) { - // Fold: icmp pred ([us]div X, C2), C -> range test - // Fold this div into the comparison, producing a range check. - // Determine, based on the divide type, what the range is being - // checked. If there is an overflow on the low or high side, remember - // it, otherwise compute the range [low, hi) bounding the new value. - // See: InsertRangeTest above for the kinds of replacements possible. - const APInt *C2; - if (!match(Div->getOperand(1), m_APInt(C2))) - return nullptr; - - // FIXME: If the operand types don't match the type of the divide - // then don't attempt this transform. The code below doesn't have the - // logic to deal with a signed divide and an unsigned compare (and - // vice versa). This is because (x /s C2) getOpcode() == Instruction::SDiv; - if (!Cmp.isEquality() && DivIsSigned != Cmp.isSigned()) - return nullptr; - - // The ProdOV computation fails on divide by 0 and divide by -1. Cases with - // INT_MIN will also fail if the divisor is 1. Although folds of all these - // division-by-constant cases should be present, we can not assert that they - // have happened before we reach this icmp instruction. - if (*C2 == 0 || *C2 == 1 || (DivIsSigned && C2->isAllOnesValue())) - return nullptr; - - // TODO: We could do all of the computations below using APInt. - Constant *CmpRHS = cast(Cmp.getOperand(1)); - Constant *DivRHS = cast(Div->getOperand(1)); - - // Compute Prod = CmpRHS * DivRHS. We are essentially solving an equation of - // form X / C2 = C. We solve for X by multiplying C2 (DivRHS) and C (CmpRHS). - // By solving for X, we can turn this into a range check instead of computing - // a divide. - Constant *Prod = ConstantExpr::getMul(CmpRHS, DivRHS); - - // Determine if the product overflows by seeing if the product is not equal to - // the divide. Make sure we do the same kind of divide as in the LHS - // instruction that we're folding. - bool ProdOV = (DivIsSigned ? ConstantExpr::getSDiv(Prod, DivRHS) - : ConstantExpr::getUDiv(Prod, DivRHS)) != CmpRHS; - - ICmpInst::Predicate Pred = Cmp.getPredicate(); - - // If the division is known to be exact, then there is no remainder from the - // divide, so the covered range size is unit, otherwise it is the divisor. - Constant *RangeSize = - Div->isExact() ? ConstantInt::get(Div->getType(), 1) : DivRHS; - - // Figure out the interval that is being checked. For example, a comparison - // like "X /u 5 == 0" is really checking that X is in the interval [0, 5). - // Compute this interval based on the constants involved and the signedness of - // the compare/divide. This computes a half-open interval, keeping track of - // whether either value in the interval overflows. After analysis each - // overflow variable is set to 0 if it's corresponding bound variable is valid - // -1 if overflowed off the bottom end, or +1 if overflowed off the top end. - int LoOverflow = 0, HiOverflow = 0; - Constant *LoBound = nullptr, *HiBound = nullptr; - - if (!DivIsSigned) { // udiv - // e.g. X/5 op 3 --> [15, 20) - LoBound = Prod; - HiOverflow = LoOverflow = ProdOV; - if (!HiOverflow) { - // If this is not an exact divide, then many values in the range collapse - // to the same result value. - HiOverflow = addWithOverflow(HiBound, LoBound, RangeSize, false); - } - } else if (C2->isStrictlyPositive()) { // Divisor is > 0. - if (*C == 0) { // (X / pos) op 0 - // Can't overflow. e.g. X/2 op 0 --> [-1, 2) - LoBound = ConstantExpr::getNeg(SubOne(RangeSize)); - HiBound = RangeSize; - } else if (C->isStrictlyPositive()) { // (X / pos) op pos - LoBound = Prod; // e.g. X/5 op 3 --> [15, 20) - HiOverflow = LoOverflow = ProdOV; - if (!HiOverflow) - HiOverflow = addWithOverflow(HiBound, Prod, RangeSize, true); - } else { // (X / pos) op neg - // e.g. X/5 op -3 --> [-15-4, -15+1) --> [-19, -14) - HiBound = AddOne(Prod); - LoOverflow = HiOverflow = ProdOV ? -1 : 0; - if (!LoOverflow) { - Constant *DivNeg = ConstantExpr::getNeg(RangeSize); - LoOverflow = addWithOverflow(LoBound, HiBound, DivNeg, true) ? -1 : 0; - } - } - } else if (C2->isNegative()) { // Divisor is < 0. - if (Div->isExact()) - RangeSize = ConstantExpr::getNeg(RangeSize); - if (*C == 0) { // (X / neg) op 0 - // e.g. X/-5 op 0 --> [-4, 5) - LoBound = AddOne(RangeSize); - HiBound = ConstantExpr::getNeg(RangeSize); - if (HiBound == DivRHS) { // -INTMIN = INTMIN - HiOverflow = 1; // [INTMIN+1, overflow) - HiBound = nullptr; // e.g. X/INTMIN = 0 --> X > INTMIN - } - } else if (C->isStrictlyPositive()) { // (X / neg) op pos - // e.g. X/-5 op 3 --> [-19, -14) - HiBound = AddOne(Prod); - HiOverflow = LoOverflow = ProdOV ? -1 : 0; - if (!LoOverflow) - LoOverflow = addWithOverflow(LoBound, HiBound, RangeSize, true) ? -1:0; - } else { // (X / neg) op neg - LoBound = Prod; // e.g. X/-5 op -3 --> [15, 20) - LoOverflow = HiOverflow = ProdOV; - if (!HiOverflow) - HiOverflow = subWithOverflow(HiBound, Prod, RangeSize, true); - } - - // Dividing by a negative swaps the condition. LT <-> GT - Pred = ICmpInst::getSwappedPredicate(Pred); - } - - Value *X = Div->getOperand(0); - switch (Pred) { - default: llvm_unreachable("Unhandled icmp opcode!"); - case ICmpInst::ICMP_EQ: - if (LoOverflow && HiOverflow) - return replaceInstUsesWith(Cmp, Builder->getFalse()); - if (HiOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : - ICmpInst::ICMP_UGE, X, LoBound); - if (LoOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : - ICmpInst::ICMP_ULT, X, HiBound); - return replaceInstUsesWith( - Cmp, insertRangeTest(X, LoBound->getUniqueInteger(), - HiBound->getUniqueInteger(), DivIsSigned, true)); - case ICmpInst::ICMP_NE: - if (LoOverflow && HiOverflow) - return replaceInstUsesWith(Cmp, Builder->getTrue()); - if (HiOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SLT : - ICmpInst::ICMP_ULT, X, LoBound); - if (LoOverflow) - return new ICmpInst(DivIsSigned ? ICmpInst::ICMP_SGE : - ICmpInst::ICMP_UGE, X, HiBound); - return replaceInstUsesWith(Cmp, - insertRangeTest(X, LoBound->getUniqueInteger(), - HiBound->getUniqueInteger(), - DivIsSigned, false)); - case ICmpInst::ICMP_ULT: - case ICmpInst::ICMP_SLT: - if (LoOverflow == +1) // Low bound is greater than input range. - return replaceInstUsesWith(Cmp, Builder->getTrue()); - if (LoOverflow == -1) // Low bound is less than input range. - return replaceInstUsesWith(Cmp, Builder->getFalse()); - return new ICmpInst(Pred, X, LoBound); - case ICmpInst::ICMP_UGT: - case ICmpInst::ICMP_SGT: - if (HiOverflow == +1) // High bound greater than input range. - return replaceInstUsesWith(Cmp, Builder->getFalse()); - if (HiOverflow == -1) // High bound less than input range. - return replaceInstUsesWith(Cmp, Builder->getTrue()); - if (Pred == ICmpInst::ICMP_UGT) - return new ICmpInst(ICmpInst::ICMP_UGE, X, HiBound); - return new ICmpInst(ICmpInst::ICMP_SGE, X, HiBound); - } - - return nullptr; - } - - /// Fold icmp (sub X, Y), C. - Instruction *InstCombiner::foldICmpSubConstant(ICmpInst &Cmp, - BinaryOperator *Sub, - const APInt *C) { - Value *X = Sub->getOperand(0), *Y = Sub->getOperand(1); - ICmpInst::Predicate Pred = Cmp.getPredicate(); - - // The following transforms are only worth it if the only user of the subtract - // is the icmp. - if (!Sub->hasOneUse()) - return nullptr; - - if (Sub->hasNoSignedWrap()) { - // (icmp sgt (sub nsw X, Y), -1) -> (icmp sge X, Y) - if (Pred == ICmpInst::ICMP_SGT && C->isAllOnesValue()) - return new ICmpInst(ICmpInst::ICMP_SGE, X, Y); - - // (icmp sgt (sub nsw X, Y), 0) -> (icmp sgt X, Y) - if (Pred == ICmpInst::ICMP_SGT && *C == 0) - return new ICmpInst(ICmpInst::ICMP_SGT, X, Y); - - // (icmp slt (sub nsw X, Y), 0) -> (icmp slt X, Y) - if (Pred == ICmpInst::ICMP_SLT && *C == 0) - return new ICmpInst(ICmpInst::ICMP_SLT, X, Y); - - // (icmp slt (sub nsw X, Y), 1) -> (icmp sle X, Y) - if (Pred == ICmpInst::ICMP_SLT && *C == 1) - return new ICmpInst(ICmpInst::ICMP_SLE, X, Y); - } - - const APInt *C2; - if (!match(X, m_APInt(C2))) - return nullptr; - - // C2 - Y (Y | (C - 1)) == C2 - // iff (C2 & (C - 1)) == C - 1 and C is a power of 2 - if (Pred == ICmpInst::ICMP_ULT && C->isPowerOf2() && - (*C2 & (*C - 1)) == (*C - 1)) - return new ICmpInst(ICmpInst::ICMP_EQ, Builder->CreateOr(Y, *C - 1), X); - - // C2 - Y >u C -> (Y | C) != C2 - // iff C2 & C == C and C + 1 is a power of 2 - if (Pred == ICmpInst::ICMP_UGT && (*C + 1).isPowerOf2() && (*C2 & *C) == *C) - return new ICmpInst(ICmpInst::ICMP_NE, Builder->CreateOr(Y, *C), X); - - return nullptr; - } - - /// Fold icmp (add X, Y), C. - Instruction *InstCombiner::foldICmpAddConstant(ICmpInst &Cmp, - BinaryOperator *Add, - const APInt *C) { - Value *Y = Add->getOperand(1); - const APInt *C2; - if (Cmp.isEquality() || !match(Y, m_APInt(C2))) - return nullptr; - - // Fold icmp pred (add X, C2), C. - Value *X = Add->getOperand(0); - Type *Ty = Add->getType(); - auto CR = Cmp.makeConstantRange(Cmp.getPredicate(), *C).subtract(*C2); - const APInt &Upper = CR.getUpper(); - const APInt &Lower = CR.getLower(); - if (Cmp.isSigned()) { - if (Lower.isSignBit()) - return new ICmpInst(ICmpInst::ICMP_SLT, X, ConstantInt::get(Ty, Upper)); - if (Upper.isSignBit()) - return new ICmpInst(ICmpInst::ICMP_SGE, X, ConstantInt::get(Ty, Lower)); - } else { - if (Lower.isMinValue()) - return new ICmpInst(ICmpInst::ICMP_ULT, X, ConstantInt::get(Ty, Upper)); - if (Upper.isMinValue()) - return new ICmpInst(ICmpInst::ICMP_UGE, X, ConstantInt::get(Ty, Lower)); - } - - if (!Add->hasOneUse()) - return nullptr; - - // X+C (X & -C2) == C - // iff C & (C2-1) == 0 - // C2 is a power of 2 - if (Cmp.getPredicate() == ICmpInst::ICMP_ULT && C->isPowerOf2() && - (*C2 & (*C - 1)) == 0) - return new ICmpInst(ICmpInst::ICMP_EQ, Builder->CreateAnd(X, -(*C)), - ConstantExpr::getNeg(cast(Y))); - - // X+C >u C2 -> (X & ~C2) != C - // iff C & C2 == 0 - // C2+1 is a power of 2 - if (Cmp.getPredicate() == ICmpInst::ICMP_UGT && (*C + 1).isPowerOf2() && - (*C2 & *C) == 0) - return new ICmpInst(ICmpInst::ICMP_NE, Builder->CreateAnd(X, ~(*C)), - ConstantExpr::getNeg(cast(Y))); - - return nullptr; - } - - /// Try to fold integer comparisons with a constant operand: icmp Pred X, C - /// where X is some kind of instruction. - Instruction *InstCombiner::foldICmpInstWithConstant(ICmpInst &Cmp) { - const APInt *C; - if (!match(Cmp.getOperand(1), m_APInt(C))) - return nullptr; - - BinaryOperator *BO; - if (match(Cmp.getOperand(0), m_BinOp(BO))) { - switch (BO->getOpcode()) { - case Instruction::Xor: - if (Instruction *I = foldICmpXorConstant(Cmp, BO, C)) - return I; - break; - case Instruction::And: - if (Instruction *I = foldICmpAndConstant(Cmp, BO, C)) - return I; - break; - case Instruction::Or: - if (Instruction *I = foldICmpOrConstant(Cmp, BO, C)) - return I; - break; - case Instruction::Mul: - if (Instruction *I = foldICmpMulConstant(Cmp, BO, C)) - return I; - break; - case Instruction::Shl: - if (Instruction *I = foldICmpShlConstant(Cmp, BO, C)) - return I; - break; - case Instruction::LShr: - case Instruction::AShr: - if (Instruction *I = foldICmpShrConstant(Cmp, BO, C)) - return I; - break; - case Instruction::UDiv: - if (Instruction *I = foldICmpUDivConstant(Cmp, BO, C)) - return I; - LLVM_FALLTHROUGH; - case Instruction::SDiv: - if (Instruction *I = foldICmpDivConstant(Cmp, BO, C)) - return I; - break; - case Instruction::Sub: - if (Instruction *I = foldICmpSubConstant(Cmp, BO, C)) - return I; - break; - case Instruction::Add: - if (Instruction *I = foldICmpAddConstant(Cmp, BO, C)) - return I; - break; - default: - break; - } - // TODO: These folds could be refactored to be part of the above calls. - if (Instruction *I = foldICmpBinOpEqualityWithConstant(Cmp, BO, C)) - return I; - } - - Instruction *LHSI; - if (match(Cmp.getOperand(0), m_Instruction(LHSI)) && - LHSI->getOpcode() == Instruction::Trunc) - if (Instruction *I = foldICmpTruncConstant(Cmp, LHSI, C)) - return I; - - if (Instruction *I = foldICmpIntrinsicWithConstant(Cmp, C)) - return I; - - return nullptr; - } - - /// Fold an icmp equality instruction with binary operator LHS and constant RHS: - /// icmp eq/ne BO, C. - Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp, - BinaryOperator *BO, - const APInt *C) { - // TODO: Some of these folds could work with arbitrary constants, but this - // function is limited to scalar and vector splat constants. - if (!Cmp.isEquality()) - return nullptr; - - ICmpInst::Predicate Pred = Cmp.getPredicate(); - bool isICMP_NE = Pred == ICmpInst::ICMP_NE; - Constant *RHS = cast(Cmp.getOperand(1)); - Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1); - - switch (BO->getOpcode()) { - case Instruction::SRem: - // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one. - if (*C == 0 && BO->hasOneUse()) { - const APInt *BOC; - if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) { - Value *NewRem = Builder->CreateURem(BOp0, BOp1, BO->getName()); - return new ICmpInst(Pred, NewRem, - Constant::getNullValue(BO->getType())); - } - } - break; - case Instruction::Add: { - // Replace ((add A, B) != C) with (A != C-B) if B & C are constants. - const APInt *BOC; - if (match(BOp1, m_APInt(BOC))) { - if (BO->hasOneUse()) { - Constant *SubC = ConstantExpr::getSub(RHS, cast(BOp1)); - return new ICmpInst(Pred, BOp0, SubC); - } - } else if (*C == 0) { - // Replace ((add A, B) != 0) with (A != -B) if A or B is - // efficiently invertible, or if the add has just this one use. - if (Value *NegVal = dyn_castNegVal(BOp1)) - return new ICmpInst(Pred, BOp0, NegVal); - if (Value *NegVal = dyn_castNegVal(BOp0)) - return new ICmpInst(Pred, NegVal, BOp1); - if (BO->hasOneUse()) { - Value *Neg = Builder->CreateNeg(BOp1); - Neg->takeName(BO); - return new ICmpInst(Pred, BOp0, Neg); - } - } - break; - } - case Instruction::Xor: - if (BO->hasOneUse()) { - if (Constant *BOC = dyn_cast(BOp1)) { - // For the xor case, we can xor two constants together, eliminating - // the explicit xor. - return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC)); - } else if (*C == 0) { - // Replace ((xor A, B) != 0) with (A != B) - return new ICmpInst(Pred, BOp0, BOp1); - } - } - break; - case Instruction::Sub: - if (BO->hasOneUse()) { - const APInt *BOC; - if (match(BOp0, m_APInt(BOC))) { - // Replace ((sub BOC, B) != C) with (B != BOC-C). - Constant *SubC = ConstantExpr::getSub(cast(BOp0), RHS); - return new ICmpInst(Pred, BOp1, SubC); - } else if (*C == 0) { - // Replace ((sub A, B) != 0) with (A != B). - return new ICmpInst(Pred, BOp0, BOp1); - } - } - break; - case Instruction::Or: { - const APInt *BOC; - if (match(BOp1, m_APInt(BOC)) && BO->hasOneUse() && RHS->isAllOnesValue()) { - // Comparing if all bits outside of a constant mask are set? - // Replace (X | C) == -1 with (X & ~C) == ~C. - // This removes the -1 constant. - Constant *NotBOC = ConstantExpr::getNot(cast(BOp1)); - Value *And = Builder->CreateAnd(BOp0, NotBOC); - return new ICmpInst(Pred, And, NotBOC); - } - break; - } - case Instruction::And: { - const APInt *BOC; - if (match(BOp1, m_APInt(BOC))) { - // If we have ((X & C) == C), turn it into ((X & C) != 0). - if (C == BOC && C->isPowerOf2()) - return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE, - BO, Constant::getNullValue(RHS->getType())); - - // Don't perform the following transforms if the AND has multiple uses - if (!BO->hasOneUse()) - break; - - // Replace (and X, (1 << size(X)-1) != 0) with x s< 0 - if (BOC->isSignBit()) { - Constant *Zero = Constant::getNullValue(BOp0->getType()); - auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE; - return new ICmpInst(NewPred, BOp0, Zero); - } - - // ((X & ~7) == 0) --> X < 8 - if (*C == 0 && (~(*BOC) + 1).isPowerOf2()) { - Constant *NegBOC = ConstantExpr::getNeg(cast(BOp1)); - auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT; - return new ICmpInst(NewPred, BOp0, NegBOC); - } - } - break; - } - case Instruction::Mul: - if (*C == 0 && BO->hasNoSignedWrap()) { - const APInt *BOC; - if (match(BOp1, m_APInt(BOC)) && *BOC != 0) { - // The trivial case (mul X, 0) is handled by InstSimplify. - // General case : (mul X, C) != 0 iff X != 0 - // (mul X, C) == 0 iff X == 0 - return new ICmpInst(Pred, BOp0, Constant::getNullValue(RHS->getType())); - } - } - break; - case Instruction::UDiv: - if (*C == 0) { - // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A) - auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT; - return new ICmpInst(NewPred, BOp1, BOp0); - } - break; - default: - break; - } - return nullptr; - } - - /// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C. - Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &Cmp, - const APInt *C) { - IntrinsicInst *II = dyn_cast(Cmp.getOperand(0)); - if (!II || !Cmp.isEquality()) - return nullptr; - - // Handle icmp {eq|ne} , intcst. - switch (II->getIntrinsicID()) { - case Intrinsic::bswap: - Worklist.Add(II); - Cmp.setOperand(0, II->getArgOperand(0)); - Cmp.setOperand(1, Builder->getInt(C->byteSwap())); - return &Cmp; - case Intrinsic::ctlz: - case Intrinsic::cttz: - // ctz(A) == bitwidth(A) -> A == 0 and likewise for != - if (*C == C->getBitWidth()) { - Worklist.Add(II); - Cmp.setOperand(0, II->getArgOperand(0)); - Cmp.setOperand(1, ConstantInt::getNullValue(II->getType())); - return &Cmp; - } - break; - case Intrinsic::ctpop: { - // popcount(A) == 0 -> A == 0 and likewise for != - // popcount(A) == bitwidth(A) -> A == -1 and likewise for != - bool IsZero = *C == 0; - if (IsZero || *C == C->getBitWidth()) { - Worklist.Add(II); - Cmp.setOperand(0, II->getArgOperand(0)); - auto *NewOp = IsZero ? Constant::getNullValue(II->getType()) - : Constant::getAllOnesValue(II->getType()); - Cmp.setOperand(1, NewOp); - return &Cmp; - } - break; - } - default: - break; - } - return nullptr; - } - - /// Handle icmp (cast x to y), (cast/cst). We only handle extending casts so - /// far. - Instruction *InstCombiner::foldICmpWithCastAndCast(ICmpInst &ICmp) { - const CastInst *LHSCI = cast(ICmp.getOperand(0)); - Value *LHSCIOp = LHSCI->getOperand(0); - Type *SrcTy = LHSCIOp->getType(); - Type *DestTy = LHSCI->getType(); - Value *RHSCIOp; - - // Turn icmp (ptrtoint x), (ptrtoint/c) into a compare of the input if the - // integer type is the same size as the pointer type. - if (LHSCI->getOpcode() == Instruction::PtrToInt && - DL.getPointerTypeSizeInBits(SrcTy) == DestTy->getIntegerBitWidth()) { - Value *RHSOp = nullptr; - if (auto *RHSC = dyn_cast(ICmp.getOperand(1))) { - Value *RHSCIOp = RHSC->getOperand(0); - if (RHSCIOp->getType()->getPointerAddressSpace() == - LHSCIOp->getType()->getPointerAddressSpace()) { - RHSOp = RHSC->getOperand(0); - // If the pointer types don't match, insert a bitcast. - if (LHSCIOp->getType() != RHSOp->getType()) - RHSOp = Builder->CreateBitCast(RHSOp, LHSCIOp->getType()); - } - } else if (auto *RHSC = dyn_cast(ICmp.getOperand(1))) { - RHSOp = ConstantExpr::getIntToPtr(RHSC, SrcTy); - } - - if (RHSOp) - return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSOp); - } - - // The code below only handles extension cast instructions, so far. - // Enforce this. - if (LHSCI->getOpcode() != Instruction::ZExt && - LHSCI->getOpcode() != Instruction::SExt) - return nullptr; - - bool isSignedExt = LHSCI->getOpcode() == Instruction::SExt; - bool isSignedCmp = ICmp.isSigned(); - - if (auto *CI = dyn_cast(ICmp.getOperand(1))) { - // Not an extension from the same type? - RHSCIOp = CI->getOperand(0); - if (RHSCIOp->getType() != LHSCIOp->getType()) - return nullptr; - - // If the signedness of the two casts doesn't agree (i.e. one is a sext - // and the other is a zext), then we can't handle this. - if (CI->getOpcode() != LHSCI->getOpcode()) - return nullptr; - - // Deal with equality cases early. - if (ICmp.isEquality()) - return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp); - - // A signed comparison of sign extended values simplifies into a - // signed comparison. - if (isSignedCmp && isSignedExt) - return new ICmpInst(ICmp.getPredicate(), LHSCIOp, RHSCIOp); - - // The other three cases all fold into an unsigned comparison. - return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, RHSCIOp); - } - - // If we aren't dealing with a constant on the RHS, exit early. - auto *C = dyn_cast(ICmp.getOperand(1)); - if (!C) - return nullptr; - - // Compute the constant that would happen if we truncated to SrcTy then - // re-extended to DestTy. - Constant *Res1 = ConstantExpr::getTrunc(C, SrcTy); - Constant *Res2 = ConstantExpr::getCast(LHSCI->getOpcode(), Res1, DestTy); - - // If the re-extended constant didn't change... - if (Res2 == C) { - // Deal with equality cases early. - if (ICmp.isEquality()) - return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1); - - // A signed comparison of sign extended values simplifies into a - // signed comparison. - if (isSignedExt && isSignedCmp) - return new ICmpInst(ICmp.getPredicate(), LHSCIOp, Res1); - - // The other three cases all fold into an unsigned comparison. - return new ICmpInst(ICmp.getUnsignedPredicate(), LHSCIOp, Res1); - } - - // The re-extended constant changed, partly changed (in the case of a vector), - // or could not be determined to be equal (in the case of a constant - // expression), so the constant cannot be represented in the shorter type. - // Consequently, we cannot emit a simple comparison. - // All the cases that fold to true or false will have already been handled - // by SimplifyICmpInst, so only deal with the tricky case. - - if (isSignedCmp || !isSignedExt || !isa(C)) - return nullptr; - - // Evaluate the comparison for LT (we invert for GT below). LE and GE cases - // should have been folded away previously and not enter in here. - - // We're performing an unsigned comp with a sign extended value. - // This is true if the input is >= 0. [aka >s -1] - Constant *NegOne = Constant::getAllOnesValue(SrcTy); - Value *Result = Builder->CreateICmpSGT(LHSCIOp, NegOne, ICmp.getName()); - - // Finally, return the value computed. - if (ICmp.getPredicate() == ICmpInst::ICMP_ULT) - return replaceInstUsesWith(ICmp, Result); - - assert(ICmp.getPredicate() == ICmpInst::ICMP_UGT && "ICmp should be folded!"); - return BinaryOperator::CreateNot(Result); - } - - bool InstCombiner::OptimizeOverflowCheck(OverflowCheckFlavor OCF, Value *LHS, - Value *RHS, Instruction &OrigI, - Value *&Result, Constant *&Overflow) { - if (OrigI.isCommutative() && isa(LHS) && !isa(RHS)) - std::swap(LHS, RHS); - - auto SetResult = [&](Value *OpResult, Constant *OverflowVal, bool ReuseName) { - Result = OpResult; - Overflow = OverflowVal; - if (ReuseName) - Result->takeName(&OrigI); - return true; - }; - - // If the overflow check was an add followed by a compare, the insertion point - // may be pointing to the compare. We want to insert the new instructions - // before the add in case there are uses of the add between the add and the - // compare. - Builder->SetInsertPoint(&OrigI); - - switch (OCF) { - case OCF_INVALID: - llvm_unreachable("bad overflow check kind!"); - - case OCF_UNSIGNED_ADD: { - OverflowResult OR = computeOverflowForUnsignedAdd(LHS, RHS, &OrigI); - if (OR == OverflowResult::NeverOverflows) - return SetResult(Builder->CreateNUWAdd(LHS, RHS), Builder->getFalse(), - true); - - if (OR == OverflowResult::AlwaysOverflows) - return SetResult(Builder->CreateAdd(LHS, RHS), Builder->getTrue(), true); - - // Fall through uadd into sadd - LLVM_FALLTHROUGH; - } - case OCF_SIGNED_ADD: { - // X + 0 -> {X, false} - if (match(RHS, m_Zero())) - return SetResult(LHS, Builder->getFalse(), false); - - // We can strength reduce this signed add into a regular add if we can prove - // that it will never overflow. - if (OCF == OCF_SIGNED_ADD) - if (WillNotOverflowSignedAdd(LHS, RHS, OrigI)) - return SetResult(Builder->CreateNSWAdd(LHS, RHS), Builder->getFalse(), - true); - break; - } - - case OCF_UNSIGNED_SUB: - case OCF_SIGNED_SUB: { - // X - 0 -> {X, false} - if (match(RHS, m_Zero())) - return SetResult(LHS, Builder->getFalse(), false); - - if (OCF == OCF_SIGNED_SUB) { - if (WillNotOverflowSignedSub(LHS, RHS, OrigI)) - return SetResult(Builder->CreateNSWSub(LHS, RHS), Builder->getFalse(), - true); - } else { - if (WillNotOverflowUnsignedSub(LHS, RHS, OrigI)) - return SetResult(Builder->CreateNUWSub(LHS, RHS), Builder->getFalse(), - true); - } - break; - } - - case OCF_UNSIGNED_MUL: { - OverflowResult OR = computeOverflowForUnsignedMul(LHS, RHS, &OrigI); - if (OR == OverflowResult::NeverOverflows) - return SetResult(Builder->CreateNUWMul(LHS, RHS), Builder->getFalse(), - true); - if (OR == OverflowResult::AlwaysOverflows) - return SetResult(Builder->CreateMul(LHS, RHS), Builder->getTrue(), true); - LLVM_FALLTHROUGH; - } - case OCF_SIGNED_MUL: - // X * undef -> undef - if (isa(RHS)) - return SetResult(RHS, UndefValue::get(Builder->getInt1Ty()), false); - - // X * 0 -> {0, false} - if (match(RHS, m_Zero())) - return SetResult(RHS, Builder->getFalse(), false); - - // X * 1 -> {X, false} - if (match(RHS, m_One())) - return SetResult(LHS, Builder->getFalse(), false); - - if (OCF == OCF_SIGNED_MUL) - if (WillNotOverflowSignedMul(LHS, RHS, OrigI)) - return SetResult(Builder->CreateNSWMul(LHS, RHS), Builder->getFalse(), - true); - break; - } - - return false; - } - - /// \brief Recognize and process idiom involving test for multiplication - /// overflow. - /// - /// The caller has matched a pattern of the form: - /// I = cmp u (mul(zext A, zext B), V - /// The function checks if this is a test for overflow and if so replaces - /// multiplication with call to 'mul.with.overflow' intrinsic. - /// - /// \param I Compare instruction. - /// \param MulVal Result of 'mult' instruction. It is one of the arguments of - /// the compare instruction. Must be of integer type. - /// \param OtherVal The other argument of compare instruction. - /// \returns Instruction which must replace the compare instruction, NULL if no - /// replacement required. - static Instruction *processUMulZExtIdiom(ICmpInst &I, Value *MulVal, - Value *OtherVal, InstCombiner &IC) { - // Don't bother doing this transformation for pointers, don't do it for - // vectors. - if (!isa(MulVal->getType())) - return nullptr; - - assert(I.getOperand(0) == MulVal || I.getOperand(1) == MulVal); - assert(I.getOperand(0) == OtherVal || I.getOperand(1) == OtherVal); - auto *MulInstr = dyn_cast(MulVal); - if (!MulInstr) - return nullptr; - assert(MulInstr->getOpcode() == Instruction::Mul); - - auto *LHS = cast(MulInstr->getOperand(0)), - *RHS = cast(MulInstr->getOperand(1)); - assert(LHS->getOpcode() == Instruction::ZExt); - assert(RHS->getOpcode() == Instruction::ZExt); - Value *A = LHS->getOperand(0), *B = RHS->getOperand(0); - - // Calculate type and width of the result produced by mul.with.overflow. - Type *TyA = A->getType(), *TyB = B->getType(); - unsigned WidthA = TyA->getPrimitiveSizeInBits(), - WidthB = TyB->getPrimitiveSizeInBits(); - unsigned MulWidth; - Type *MulType; - if (WidthB > WidthA) { - MulWidth = WidthB; - MulType = TyB; - } else { - MulWidth = WidthA; - MulType = TyA; - } - - // In order to replace the original mul with a narrower mul.with.overflow, - // all uses must ignore upper bits of the product. The number of used low - // bits must be not greater than the width of mul.with.overflow. - if (MulVal->hasNUsesOrMore(2)) - for (User *U : MulVal->users()) { - if (U == &I) - continue; - if (TruncInst *TI = dyn_cast(U)) { - // Check if truncation ignores bits above MulWidth. - unsigned TruncWidth = TI->getType()->getPrimitiveSizeInBits(); - if (TruncWidth > MulWidth) - return nullptr; - } else if (BinaryOperator *BO = dyn_cast(U)) { - // Check if AND ignores bits above MulWidth. - if (BO->getOpcode() != Instruction::And) - return nullptr; - if (ConstantInt *CI = dyn_cast(BO->getOperand(1))) { - const APInt &CVal = CI->getValue(); - if (CVal.getBitWidth() - CVal.countLeadingZeros() > MulWidth) - return nullptr; - } - } else { - // Other uses prohibit this transformation. - return nullptr; - } - } - - // Recognize patterns - switch (I.getPredicate()) { - case ICmpInst::ICMP_EQ: - case ICmpInst::ICMP_NE: - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp eq/neq mulval, zext trunc mulval - if (ZExtInst *Zext = dyn_cast(OtherVal)) - if (Zext->hasOneUse()) { - Value *ZextArg = Zext->getOperand(0); - if (TruncInst *Trunc = dyn_cast(ZextArg)) - if (Trunc->getType()->getPrimitiveSizeInBits() == MulWidth) - break; //Recognized - } - - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp eq/neq mulval, and(mulval, mask), mask selects low MulWidth bits. - ConstantInt *CI; - Value *ValToMask; - if (match(OtherVal, m_And(m_Value(ValToMask), m_ConstantInt(CI)))) { - if (ValToMask != MulVal) - return nullptr; - const APInt &CVal = CI->getValue() + 1; - if (CVal.isPowerOf2()) { - unsigned MaskWidth = CVal.logBase2(); - if (MaskWidth == MulWidth) - break; // Recognized - } - } - return nullptr; - - case ICmpInst::ICMP_UGT: - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp ugt mulval, max - if (ConstantInt *CI = dyn_cast(OtherVal)) { - APInt MaxVal = APInt::getMaxValue(MulWidth); - MaxVal = MaxVal.zext(CI->getBitWidth()); - if (MaxVal.eq(CI->getValue())) - break; // Recognized - } - return nullptr; - - case ICmpInst::ICMP_UGE: - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp uge mulval, max+1 - if (ConstantInt *CI = dyn_cast(OtherVal)) { - APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth); - if (MaxVal.eq(CI->getValue())) - break; // Recognized - } - return nullptr; - - case ICmpInst::ICMP_ULE: - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp ule mulval, max - if (ConstantInt *CI = dyn_cast(OtherVal)) { - APInt MaxVal = APInt::getMaxValue(MulWidth); - MaxVal = MaxVal.zext(CI->getBitWidth()); - if (MaxVal.eq(CI->getValue())) - break; // Recognized - } - return nullptr; - - case ICmpInst::ICMP_ULT: - // Recognize pattern: - // mulval = mul(zext A, zext B) - // cmp ule mulval, max + 1 - if (ConstantInt *CI = dyn_cast(OtherVal)) { - APInt MaxVal = APInt::getOneBitSet(CI->getBitWidth(), MulWidth); - if (MaxVal.eq(CI->getValue())) - break; // Recognized - } - return nullptr; - - default: - return nullptr; - } - - InstCombiner::BuilderTy *Builder = IC.Builder; - Builder->SetInsertPoint(MulInstr); - - // Replace: mul(zext A, zext B) --> mul.with.overflow(A, B) - Value *MulA = A, *MulB = B; - if (WidthA < MulWidth) - MulA = Builder->CreateZExt(A, MulType); - if (WidthB < MulWidth) - MulB = Builder->CreateZExt(B, MulType); - Value *F = Intrinsic::getDeclaration(I.getModule(), - Intrinsic::umul_with_overflow, MulType); - CallInst *Call = Builder->CreateCall(F, {MulA, MulB}, "umul"); - IC.Worklist.Add(MulInstr); - - // If there are uses of mul result other than the comparison, we know that - // they are truncation or binary AND. Change them to use result of - // mul.with.overflow and adjust properly mask/size. - if (MulVal->hasNUsesOrMore(2)) { - Value *Mul = Builder->CreateExtractValue(Call, 0, "umul.value"); - for (User *U : MulVal->users()) { - if (U == &I || U == OtherVal) - continue; - if (TruncInst *TI = dyn_cast(U)) { - if (TI->getType()->getPrimitiveSizeInBits() == MulWidth) - IC.replaceInstUsesWith(*TI, Mul); - else - TI->setOperand(0, Mul); - } else if (BinaryOperator *BO = dyn_cast(U)) { - assert(BO->getOpcode() == Instruction::And); - // Replace (mul & mask) --> zext (mul.with.overflow & short_mask) - ConstantInt *CI = cast(BO->getOperand(1)); - APInt ShortMask = CI->getValue().trunc(MulWidth); - Value *ShortAnd = Builder->CreateAnd(Mul, ShortMask); - Instruction *Zext = - cast(Builder->CreateZExt(ShortAnd, BO->getType())); - IC.Worklist.Add(Zext); - IC.replaceInstUsesWith(*BO, Zext); - } else { - llvm_unreachable("Unexpected Binary operation"); - } - IC.Worklist.Add(cast(U)); - } - } - if (isa(OtherVal)) - IC.Worklist.Add(cast(OtherVal)); - - // The original icmp gets replaced with the overflow value, maybe inverted - // depending on predicate. - bool Inverse = false; - switch (I.getPredicate()) { - case ICmpInst::ICMP_NE: - break; - case ICmpInst::ICMP_EQ: - Inverse = true; - break; - case ICmpInst::ICMP_UGT: - case ICmpInst::ICMP_UGE: - if (I.getOperand(0) == MulVal) - break; - Inverse = true; - break; - case ICmpInst::ICMP_ULT: - case ICmpInst::ICMP_ULE: - if (I.getOperand(1) == MulVal) - break; - Inverse = true; - break; - default: - llvm_unreachable("Unexpected predicate"); - } - if (Inverse) { - Value *Res = Builder->CreateExtractValue(Call, 1); - return BinaryOperator::CreateNot(Res); - } - - return ExtractValueInst::Create(Call, 1); - } - - /// When performing a comparison against a constant, it is possible that not all - /// the bits in the LHS are demanded. This helper method computes the mask that - /// IS demanded. - static APInt getDemandedBitsLHSMask(ICmpInst &I, unsigned BitWidth, - bool isSignCheck) { - if (isSignCheck) - return APInt::getSignBit(BitWidth); - - ConstantInt *CI = dyn_cast(I.getOperand(1)); - if (!CI) return APInt::getAllOnesValue(BitWidth); - const APInt &RHS = CI->getValue(); - - switch (I.getPredicate()) { - // For a UGT comparison, we don't care about any bits that - // correspond to the trailing ones of the comparand. The value of these - // bits doesn't impact the outcome of the comparison, because any value - // greater than the RHS must differ in a bit higher than these due to carry. - case ICmpInst::ICMP_UGT: { - unsigned trailingOnes = RHS.countTrailingOnes(); - APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingOnes); - return ~lowBitsSet; - } - - // Similarly, for a ULT comparison, we don't care about the trailing zeros. - // Any value less than the RHS must differ in a higher bit because of carries. - case ICmpInst::ICMP_ULT: { - unsigned trailingZeros = RHS.countTrailingZeros(); - APInt lowBitsSet = APInt::getLowBitsSet(BitWidth, trailingZeros); - return ~lowBitsSet; - } - - default: - return APInt::getAllOnesValue(BitWidth); - } - } - - /// \brief Check if the order of \p Op0 and \p Op1 as operand in an ICmpInst - /// should be swapped. - /// The decision is based on how many times these two operands are reused - /// as subtract operands and their positions in those instructions. - /// The rational is that several architectures use the same instruction for - /// both subtract and cmp, thus it is better if the order of those operands - /// match. - /// \return true if Op0 and Op1 should be swapped. - static bool swapMayExposeCSEOpportunities(const Value * Op0, - const Value * Op1) { - // Filter out pointer value as those cannot appears directly in subtract. - // FIXME: we may want to go through inttoptrs or bitcasts. - if (Op0->getType()->isPointerTy()) - return false; - // Count every uses of both Op0 and Op1 in a subtract. - // Each time Op0 is the first operand, count -1: swapping is bad, the - // subtract has already the same layout as the compare. - // Each time Op0 is the second operand, count +1: swapping is good, the - // subtract has a different layout as the compare. - // At the end, if the benefit is greater than 0, Op0 should come second to - // expose more CSE opportunities. - int GlobalSwapBenefits = 0; - for (const User *U : Op0->users()) { - const BinaryOperator *BinOp = dyn_cast(U); - if (!BinOp || BinOp->getOpcode() != Instruction::Sub) - continue; - // If Op0 is the first argument, this is not beneficial to swap the - // arguments. - int LocalSwapBenefits = -1; - unsigned Op1Idx = 1; - if (BinOp->getOperand(Op1Idx) == Op0) { - Op1Idx = 0; - LocalSwapBenefits = 1; - } - if (BinOp->getOperand(Op1Idx) != Op1) - continue; - GlobalSwapBenefits += LocalSwapBenefits; - } - return GlobalSwapBenefits > 0; - } - - /// \brief Check that one use is in the same block as the definition and all - /// other uses are in blocks dominated by a given block. - /// - /// \param DI Definition - /// \param UI Use - /// \param DB Block that must dominate all uses of \p DI outside - /// the parent block - /// \return true when \p UI is the only use of \p DI in the parent block - /// and all other uses of \p DI are in blocks dominated by \p DB. - /// - bool InstCombiner::dominatesAllUses(const Instruction *DI, - const Instruction *UI, - const BasicBlock *DB) const { - assert(DI && UI && "Instruction not defined\n"); - // Ignore incomplete definitions. - if (!DI->getParent()) - return false; - // DI and UI must be in the same block. - if (DI->getParent() != UI->getParent()) - return false; - // Protect from self-referencing blocks. - if (DI->getParent() == DB) - return false; - for (const User *U : DI->users()) { - auto *Usr = cast(U); - if (Usr != UI && !DT.dominates(DB, Usr->getParent())) - return false; - } - return true; - } - - /// Return true when the instruction sequence within a block is select-cmp-br. - static bool isChainSelectCmpBranch(const SelectInst *SI) { - const BasicBlock *BB = SI->getParent(); - if (!BB) - return false; - auto *BI = dyn_cast_or_null(BB->getTerminator()); - if (!BI || BI->getNumSuccessors() != 2) - return false; - auto *IC = dyn_cast(BI->getCondition()); - if (!IC || (IC->getOperand(0) != SI && IC->getOperand(1) != SI)) - return false; - return true; - } - - /// \brief True when a select result is replaced by one of its operands - /// in select-icmp sequence. This will eventually result in the elimination - /// of the select. - /// - /// \param SI Select instruction - /// \param Icmp Compare instruction - /// \param SIOpd Operand that replaces the select - /// - /// Notes: - /// - The replacement is global and requires dominator information - /// - The caller is responsible for the actual replacement - /// - /// Example: - /// - /// entry: - /// %4 = select i1 %3, %C* %0, %C* null - /// %5 = icmp eq %C* %4, null - /// br i1 %5, label %9, label %7 - /// ... - /// ;