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emmalloc: use __heap_end instead of sbrk(0) (#462)

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Josh Stone 2024-01-10 13:31:37 -08:00 committed by GitHub
parent 925ad6d758
commit 03b228e46b
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1 changed files with 8 additions and 3 deletions
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11
emmalloc/emmalloc.c
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@ -56,6 +56,7 @@
// Defind by the linker to have the address of the start of the heap. // Defind by the linker to have the address of the start of the heap.
extern unsigned char __heap_base; extern unsigned char __heap_base;
extern unsigned char __heap_end;
// Behavior of right shifting a signed integer is compiler implementation defined. // Behavior of right shifting a signed integer is compiler implementation defined.
static_assert((((int32_t)0x80000000U) >> 31) == -1, "This malloc implementation requires that right-shifting a signed integer produces a sign-extending (arithmetic) shift!"); static_assert((((int32_t)0x80000000U) >> 31) == -1, "This malloc implementation requires that right-shifting a signed integer produces a sign-extending (arithmetic) shift!");
@ -545,9 +546,13 @@ static bool claim_more_memory(size_t numBytes)
// If this is the first time we're called, see if we can use // If this is the first time we're called, see if we can use
// the initial heap memory set up by wasm-ld. // the initial heap memory set up by wasm-ld.
if (!listOfAllRegions) { if (!listOfAllRegions) {
unsigned char *heap_end = sbrk(0); unsigned char *heap_base = &__heap_base;
if (numBytes <= (size_t)(heap_end - &__heap_base)) { unsigned char *heap_end = &__heap_end;
startPtr = &__heap_base; if (heap_end < heap_base) {
__builtin_trap();
}
if (numBytes <= (size_t)(heap_end - heap_base)) {
startPtr = heap_base;
endPtr = heap_end; endPtr = heap_end;
break; break;
} }