http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53340
--- Comment #2 from Dominique d'Humieres <dominiq at lps dot ens.fr> 2012-05-14
09:49:22 UTC ---
If I understand correctly the profiling, the slowdown comes from the first
inlined function minlst. The fast assembly is
L45:
movss (%r10), %xmm10
leal -1(%rsi), %edi
movss -4(%r10), %xmm11
comiss %xmm10, %xmm6
movss -8(%r10), %xmm12
minss %xmm10, %xmm6
movss -12(%r10), %xmm13
cmova %esi, %edx
comiss %xmm11, %xmm6
minss %xmm11, %xmm6
cmova %edi, %edx
comiss %xmm12, %xmm6
minss %xmm12, %xmm6
leal -2(%rsi), %edi
cmova %edi, %edx
comiss %xmm13, %xmm6
leal -3(%rsi), %edi
minss %xmm13, %xmm6
cmova %edi, %edx
subl $4, %esi
subq $16, %r10
cmpl %r8d, %esi
jne L45
while the slow one is
L39:
movslq %edx, %r9
movss -4(%rdi,%r9,4), %xmm9
leal -1(%r8), %r9d
comiss (%rbx), %xmm9
cmova %r8d, %edx
movslq %edx, %r14
movss -4(%rdi,%r14,4), %xmm10
comiss -4(%rbx), %xmm10
cmova %r9d, %edx
leal -2(%r8), %r9d
movslq %edx, %r14
movss -4(%rdi,%r14,4), %xmm11
comiss -8(%rbx), %xmm11
cmova %r9d, %edx
leal -3(%r8), %r9d
movslq %edx, %r14
movss -4(%rdi,%r14,4), %xmm12
comiss -12(%rbx), %xmm12
cmova %r9d, %edx
subl $4, %r8d
subq $16, %rbx
cmpl %r10d, %r8d
jne L39
