This is a friendly reminder there's still no way to enjoy pextrw without undue
zero/sign extension unless inline asm is used; there's even a gradient of
ignominy from intrinsic to builtins, as exemplified by:
$ cat pextrw.cc
#include <smmintrin.h>
long unsigned int foo1(__m128i x) { return _mm_extract_epi16(x, 3); }
long unsigned int foo2(__v8hi x) { return __builtin_ia32_vec_ext_v8hi((__v8hi)
x, 3); }
int main() { return 0; }
$ /usr/local/gcc-4.6-20100811/bin/g++ -O3 -march=native pextrw.cc
00000000004004a0 <_Z4foo1Dv2_x>:
4004a0: 66 0f c5 c0 03 pextrw $0x3,%xmm0,%eax
4004a5: 98 cwtl
4004a6: 48 98 cltq
4004a8: c3 retq
00000000004004b0 <_Z4foo2Dv8_s>:
4004b0: 66 0f c5 c0 03 pextrw $0x3,%xmm0,%eax
4004b5: 48 0f bf c0 movswq %ax,%rax
4004b9: c3 retq
That's on x86-64, on a Intel I7 which, incidentally, is much faster at that
whole pextrw business than previous generations.
This report may or may not be construed as a duplicate of the long forgotten PR
41323.
--
Summary: pextrw, redundant zero (or otherwise) extension
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tbptbp at gmail dot com
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45294
