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hw/intc/i8259: Refactor pic_read_irq() to avoid uninitialized variable

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Some compiler versions are smart enough to detect a potentially
uninitialized variable, but are not smart enough to detect that this
cannot happen due to the code flow:

../hw/intc/i8259.c: In function ‘pic_read_irq’:
../hw/intc/i8259.c:203:13: error: ‘irq2’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
   203 |         irq = irq2 + 8;
       |         ~~~~^~~~~~~~~~

Restrict irq2 variable use to the inner statement.

Fixes: 78ef2b6989 ("i8259: Reorder intack in pic_read_irq")
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210318163059.3686596-1-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Philippe Mathieu-Daudé 2021-03-18 17:30:59 +01:00 committed by Paolo Bonzini
parent 561dbb41b1
commit 52ad57a9b6
1 changed files with 6 additions and 6 deletions
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12
hw/intc/i8259.c
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@ -176,10 +176,12 @@ static void pic_intack(PICCommonState *s, int irq)
int pic_read_irq(DeviceState *d) int pic_read_irq(DeviceState *d)
{ {
PICCommonState *s = PIC_COMMON(d); PICCommonState *s = PIC_COMMON(d);
int irq, irq2, intno; int irq, intno;
irq = pic_get_irq(s); irq = pic_get_irq(s);
if (irq >= 0) { if (irq >= 0) {
int irq2;
if (irq == 2) { if (irq == 2) {
irq2 = pic_get_irq(slave_pic); irq2 = pic_get_irq(slave_pic);
if (irq2 >= 0) { if (irq2 >= 0) {
@ -189,20 +191,18 @@ int pic_read_irq(DeviceState *d)
irq2 = 7; irq2 = 7;
} }
intno = slave_pic->irq_base + irq2; intno = slave_pic->irq_base + irq2;
pic_intack(s, irq);
irq = irq2 + 8;
} else { } else {
intno = s->irq_base + irq; intno = s->irq_base + irq;
pic_intack(s, irq);
} }
pic_intack(s, irq);
} else { } else {
/* spurious IRQ on host controller */ /* spurious IRQ on host controller */
irq = 7; irq = 7;
intno = s->irq_base + irq; intno = s->irq_base + irq;
} }
if (irq == 2) {
irq = irq2 + 8;
}
#ifdef DEBUG_IRQ_LATENCY #ifdef DEBUG_IRQ_LATENCY
printf("IRQ%d latency=%0.3fus\n", printf("IRQ%d latency=%0.3fus\n",
irq, irq,