http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57954
Yuri Rumyantsev <ysrumyan at gmail dot com> changed:
What |Removed |Added
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CC| |ysrumyan at gmail dot com
--- Comment #9 from Yuri Rumyantsev <ysrumyan at gmail dot com> ---
Uros,
I assume that this fix is not good and must be reverted - I will prepare
another fix for your reviewing. There are at least 2 problems:
1. New split for int --> fp converisons is done under TARGET_SSE2 and
TARGET_SSE_PARTIAL_REG_DEPENDENCY which include both Atom chips - SLT and SLM.
I checked that zeroing of xmm register before conversion leads to performance
slowdown on SLM (-5%) for proveded test-case. I assume that TARGET_AVX must be
used instead of TARGET_SSE2.
2. This zeroing must redundant and should not be inserted, e.g. for the
following simple test-case:
void foo (float* p, int n)
{
int i;
for (i=0; i<n; i++)
p[i] = (float) i;
}
with H.J patch we got the following assembly (I compiled it for slm but it does
not matter):
.L3:
xorps %xmm0, %xmm0
cvtsi2ss %eax, %xmm0
movss %xmm0, (%ecx,%eax,4)
addl $1, %eax
cmpl %edx, %eax
jne .L3
It is clear that zeroing is redundant for it and must be deleted.
