$ testcase:
void transpose4x4
(
unsigned char* dst,
unsigned char* src,
int dst_stride,
int src_stride
)
{
asm volatile(
"movd %4, %%mm0 \n\t"
"movd %5, %%mm1 \n\t"
"movd %6, %%mm2 \n\t"
"movd %7, %%mm3 \n\t"
"punpcklbw %%mm1, %%mm0 \n\t"
"punpcklbw %%mm3, %%mm2 \n\t"
"movq %%mm0, %%mm1 \n\t"
"punpcklwd %%mm2, %%mm0 \n\t"
"punpckhwd %%mm2, %%mm1 \n\t"
"movd %%mm0, %0 \n\t"
"punpckhdq %%mm0, %%mm0 \n\t"
"movd %%mm0, %1 \n\t"
"movd %%mm1, %2 \n\t"
"punpckhdq %%mm1, %%mm1 \n\t"
"movd %%mm1, %3 \n\t"
: "=m" (*(unsigned*)(dst + 0*dst_stride)),
"=m" (*(unsigned*)(dst + 1*dst_stride)),
"=m" (*(unsigned*)(dst + 2*dst_stride)),
"=m" (*(unsigned*)(dst + 3*dst_stride))
: "m" (*(unsigned*)(src + 0*src_stride)),
"m" (*(unsigned*)(src + 1*src_stride)),
"m" (*(unsigned*)(src + 2*src_stride)),
"m" (*(unsigned*)(src + 3*src_stride))
);
}
gcc-4.1 / -O2 produces:
transpose4x4:
leal (%rdx,%rdx), %r9d
leal (%rcx,%rcx), %eax
movslq %edx,%r11
movslq %ecx,%r8
movslq %r9d,%r10
addl %edx, %r9d
movslq %eax,%rdx
addl %ecx, %eax
movslq %r9d,%r9
cltq
#APP
movd (%rsi), %mm0
movd (%rsi,%r8), %mm1
movd (%rsi,%rdx), %mm2
movd (%rsi,%rax), %mm3
punpcklbw %mm1, %mm0
punpcklbw %mm3, %mm2
movq %mm0, %mm1
punpcklwd %mm2, %mm0
punpckhwd %mm2, %mm1
movd %mm0, (%rdi)
punpckhdq %mm0, %mm0
movd %mm0, (%rdi,%r11)
movd %mm1, (%rdi,%r10)
punpckhdq %mm1, %mm1
movd %mm1, (%rdi,%r9)
#NO_APP
ret
[ 4.0.2 / -O2 ] produces smaller/faster code:
transpose4x4:
leal (%rdx,%rdx), %r8d
movslq %edx,%r10
leaq (%rcx,%rcx,2), %rax
movslq %r8d,%r9
addl %edx, %r8d
movslq %r8d,%r8
#APP
movd (%rsi), %mm0
movd (%rsi,%rcx), %mm1
movd (%rsi,%rcx,2), %mm2
movd (%rax,%rsi), %mm3
punpcklbw %mm1, %mm0
punpcklbw %mm3, %mm2
movq %mm0, %mm1
punpcklwd %mm2, %mm0
punpckhwd %mm2, %mm1
movd %mm0, (%rdi)
punpckhdq %mm0, %mm0
movd %mm0, (%rdi,%r10)
movd %mm1, (%rdi,%r9)
punpckhdq %mm1, %mm1
movd %mm1, (%rdi,%r8)
#NO_APP
ret
--
Summary: code quality regression.
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: pluto at agmk dot net
GCC build triplet: x86-64
GCC host triplet: x86-64
GCC target triplet: x86-64
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26056
