[Bug middle-end/40122] missed optimization when using union of __m128i and int[4]
--- Comment #3 from jamborm at gcc dot gnu dot org 2009-05-21 16:02 ---
With he new SRA, the optimized dump looks like:
D.6886_10 = {1, 1, 1, 1};
D.6887_11 = VIEW_CONVERT_EXPRvector long long int(D.6886_10);
D.6893_12 = VIEW_CONVERT_EXPRvector int(D.6887_11);
D.6891_14 = __builtin_ia32_pcmpeqd128 (D.6893_12, D.6893_12);
D.6890_15 = VIEW_CONVERT_EXPRvector long long int(D.6891_14);
D.6897_16 = VIEW_CONVERT_EXPRvector char(D.6890_15);
D.6896_17 = __builtin_ia32_pmovmskb128 (D.6897_16);
D.6933_21 = D.6896_17 != 65535;
return D.6933_21;
x is completely gone.
The (relevant) assembly output is
main:
movdqa .LC0, %xmm0
pcmpeqd %xmm0, %xmm0
pmovmskb%xmm0, %eax
cmpl$65535, %eax
pushl %ebp
setne %al
movl%esp, %ebp
movzbl %al, %eax
popl%ebp
ret
So even though I don't really understand the SSE instructions I
believe the new SRA does indeed help. I'll add a testcase checking
that x vanishes to the patch series as I am finalizing the final patch
set now.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40122
[Bug middle-end/40122] missed optimization when using union of __m128i and int[4]
--- Comment #1 from rguenth at gcc dot gnu dot org 2009-05-12 15:00 ---
The union copy confuses GCC:
r.v = VIEW_CONVERT_EXPRvector long long int({1, 1, 1, 1});
D.6990 = r;
x = D.6990;
D.6997 = VIEW_CONVERT_EXPRvector int(x.v);
D.6994 = __builtin_ia32_pcmpeqd128 (D.6997, D.6997);
D.7000 = __builtin_ia32_pmovmskb128 (VIEW_CONVERT_EXPRvector
char(VIEW_CONVERT_EXPRvector long long int(D.6994)));
return D.7000 != 65535;
this will likely be fixed with the new SRA or is a duplicate of PR36327.
Martin, can you check this (and maybe add a testcase)?
--
rguenth at gcc dot gnu dot org changed:
What|Removed |Added
CC||rguenth at gcc dot gnu dot
||org, mjambor at suse dot cz
Severity|normal |enhancement
Keywords||missed-optimization
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40122
[Bug middle-end/40122] missed optimization when using union of __m128i and int[4]
--- Comment #2 from pinskia at gcc dot gnu dot org 2009-05-12 15:24 --- This is a dup of bug 36327. *** This bug has been marked as a duplicate of 36327 *** -- pinskia at gcc dot gnu dot org changed: What|Removed |Added Status|UNCONFIRMED |RESOLVED Resolution||DUPLICATE http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40122
