------- Comment #6 from vmakarov at redhat dot com 2010-02-09 19:56 -------
The patch which I'll send in a few minutes solves the problem. The patch
avoids the creation of shuffle copies if an involved operand should be bound to
some other operand in the current insn. The test code generated with the patch
looks like
.L2:
movapd %xmm0, %xmm8
subsd %xmm3, %xmm8
movsd a(%rax), %xmm6
mulsd %xmm8, %xmm8
movsd b(%rax), %xmm7
subsd %xmm8, %xmm7
movsd %xmm7, b(%rax)
leaq 8(%rax), %r10
movapd %xmm0, %xmm5
subsd %xmm6, %xmm5
movsd a(%r10), %xmm3
mulsd %xmm5, %xmm5
movsd b(%r10), %xmm4
subsd %xmm5, %xmm4
movsd %xmm4, b(%r10)
leaq 16(%rax), %r9
movapd %xmm0, %xmm1
subsd %xmm3, %xmm1
movsd a(%r9), %xmm15
mulsd %xmm1, %xmm1
movsd b(%r9), %xmm2
subsd %xmm1, %xmm2
movsd %xmm2, b(%r9)
leaq 24(%rax), %r8
SPEC2000 benchmarking on x86/x86_64 (Core i7) shows that the patch usage
results in a bit better code.
x86: The code is different on gzip, vpr, gcc, crafty, perlbmk, gap,
vortex, bzip2, twolf and mesa. The patch results in always not bigger
code (in average about 0.02% smaller). The rate is a bit better with
patch but practically the same (the biggest improvement is on crafty
and perlbmk about 1%).
x86_64: The code is different on gzip, vpr, gcc, crafty, parser, perlbmk,
gap,
vortex, bzip2, twolf and mesa, art, ammp. The patch results in
average about 0.01% smaller code. The rate is a bit better with patch
but practically the same (the biggest improvement is on vortex 1.3%
and on crafty and bzip2 0.7%).
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42973
