* [PATCH] Fix UB in expmed.c (PR middle-end/61903)
@ 2014-08-25 19:21 Marek Polacek
2014-08-29 20:08 ` Jeff Law
0 siblings, 1 reply; 2+ messages in thread
From: Marek Polacek @ 2014-08-25 19:21 UTC (permalink / raw)
To: GCC Patches
The following ought to fix two spots where an undefined behavior
can occur when compiling pr28045.c with instrumented compiler.
It does so by changing the type of V to an unsigned HOST_WIDE_INT
and performing the shift on unsigned HOST_WIDE_INT.
Hopefully it doesn't break anything...
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2014-08-25 Marek Polacek <polacek@redhat.com>
PR middle-end/61903
* expmed.c (store_fixed_bit_field_1): Shift UHWI 1 instead of HWI 1.
Change the type of V to unsigned HOST_WIDE_INT.
diff --git gcc/expmed.c gcc/expmed.c
index 7b71616a2..e8d5c23 100644
--- gcc/expmed.c
+++ gcc/expmed.c
@@ -1051,16 +1051,17 @@ store_fixed_bit_field_1 (rtx op0, unsigned HOST_WIDE_INT bitsize,
if (CONST_INT_P (value))
{
- HOST_WIDE_INT v = INTVAL (value);
+ unsigned HOST_WIDE_INT v = UINTVAL (value);
if (bitsize < HOST_BITS_PER_WIDE_INT)
- v &= ((HOST_WIDE_INT) 1 << bitsize) - 1;
+ v &= ((unsigned HOST_WIDE_INT) 1 << bitsize) - 1;
if (v == 0)
all_zero = 1;
else if ((bitsize < HOST_BITS_PER_WIDE_INT
- && v == ((HOST_WIDE_INT) 1 << bitsize) - 1)
- || (bitsize == HOST_BITS_PER_WIDE_INT && v == -1))
+ && v == ((unsigned HOST_WIDE_INT) 1 << bitsize) - 1)
+ || (bitsize == HOST_BITS_PER_WIDE_INT
+ && v == (unsigned HOST_WIDE_INT) -1))
all_one = 1;
value = lshift_value (mode, v, bitnum);
Marek
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] Fix UB in expmed.c (PR middle-end/61903)
2014-08-25 19:21 [PATCH] Fix UB in expmed.c (PR middle-end/61903) Marek Polacek
@ 2014-08-29 20:08 ` Jeff Law
0 siblings, 0 replies; 2+ messages in thread
From: Jeff Law @ 2014-08-29 20:08 UTC (permalink / raw)
To: Marek Polacek, GCC Patches
On 08/25/14 13:21, Marek Polacek wrote:
> The following ought to fix two spots where an undefined behavior
> can occur when compiling pr28045.c with instrumented compiler.
> It does so by changing the type of V to an unsigned HOST_WIDE_INT
> and performing the shift on unsigned HOST_WIDE_INT.
> Hopefully it doesn't break anything...
>
> Bootstrapped/regtested on x86_64-linux, ok for trunk?
>
> 2014-08-25 Marek Polacek <polacek@redhat.com>
>
> PR middle-end/61903
> * expmed.c (store_fixed_bit_field_1): Shift UHWI 1 instead of HWI 1.
> Change the type of V to unsigned HOST_WIDE_INT.
OK.
Jeff
^ permalink raw reply [flat|nested] 2+ messages in thread
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2014-08-25 19:21 [PATCH] Fix UB in expmed.c (PR middle-end/61903) Marek Polacek
2014-08-29 20:08 ` Jeff Law
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