On 11/22/2015 05:57 PM, Segher Boessenkool wrote:
Hi Richard,
On Sun, Nov 22, 2015 at 11:38:31AM +0100, Richard Henderson wrote:
One of which I believe I've worked around in the i386 backend, but I
believe to be a latent problem within combine.
With the following patch, disable the add<mode>3_*_overflow_2 patterns.
Then compile c-c++-common/torture/builtin-arith-overflow-4.c with -O2 and
you'll see
t151_2add:
testb %dil, %dil
leal -1(%rdi), %eax
jne .L644
0xff + x < 0xff (everything as unsigned char) is the same as x != 0 .
You'd think yes. But certainly something right there triggered the abort that
fails the test case. Perhaps I simply mis-identified the error, but the "fix"
for this fixed the other as well.
r~
