On Thu, 18 Mar 2021, Philippe Mathieu-Daudé wrote:
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: 78ef2b6989f ("i8259: Reorder intack in pic_read_irq")
Reported-by: Christian Borntraeger <borntrae...@de.ibm.com>
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
Supersedes: <20210318154738.27094-1-borntrae...@de.ibm.com>
---
hw/intc/i8259.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/hw/intc/i8259.c b/hw/intc/i8259.c
index 344fd04db14..52c039c6c03 100644
--- a/hw/intc/i8259.c
+++ b/hw/intc/i8259.c
@@ -176,10 +176,12 @@ static void pic_intack(PICCommonState *s, int irq)
int pic_read_irq(DeviceState *d)
{
PICCommonState *s = PIC_COMMON(d);
- int irq, irq2, intno;
+ int irq, intno;
irq = pic_get_irq(s);
if (irq >= 0) {
+ int irq2;
+
if (irq == 2) {
irq2 = pic_get_irq(slave_pic);
if (irq2 >= 0) {
@@ -189,8 +191,11 @@ int pic_read_irq(DeviceState *d)
irq2 = 7;
}
intno = slave_pic->irq_base + irq2;
+ pic_intack(s, irq);
+ irq = irq2 + 8;
} else {
intno = s->irq_base + irq;
+ pic_intack(s, irq);
}
pic_intack(s, irq);
Do you still need this pic_intack() here or did you intend to move it in
the if above?
Regards,
BALATON Zoltan
} else {
@@ -199,10 +204,6 @@ int pic_read_irq(DeviceState *d)
intno = s->irq_base + irq;
}
- if (irq == 2) {
- irq = irq2 + 8;
- }
-
#ifdef DEBUG_IRQ_LATENCY
printf("IRQ%d latency=%0.3fus\n",
irq,
