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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/66369] gcc 4.8.3/5.1.0 miss optimisation with vpmovmskb
Date: Wed, 03 Jun 2015 18:00:00 -0000 [thread overview]
Message-ID: <bug-66369-4-E0HKsbCmSl@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-66369-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66369
Uroš Bizjak <ubizjak at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed| |2015-06-03
Assignee|unassigned at gcc dot gnu.org |ubizjak at gmail dot com
Ever confirmed|0 |1
--- Comment #5 from Uroš Bizjak <ubizjak at gmail dot com> ---
Created attachment 35693
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35693&action=edit
Patch to add zero-extended MOVMSK patterns
This patch adds zero-extended MOVMSK patterns.
However, one more cast from (int) to (unsigned int) is needed in the source,
due to the definition of the intrinsic:
long v;
regchx256 = _mm256_set1_epi8( ch );
regset256 = _mm256_loadu_si256( (__m256i const *) set );
v = (unsigned int) _mm256_movemask_epi8
( _mm256_cmpeq_epi8(regchx256,regset256) );
Using patched gcc, the code compiles to:
lookup32:
vmovdqu charset32(%rip), %ymm0 # 10 *avx_loaddquv32qi
vmovd %edi, %xmm1 # 54 vec_setv4si_0/4
movl $11141307, %eax # 5 *movdi_internal/3
vpbroadcastb %xmm1, %ymm1 # 55 avx2_pbroadcastv32qi
vpcmpeqb %ymm0, %ymm1, %ymm0 # 13 *avx2_eqv32qi3
vpmovmskb %ymm0, %edx # 16 *avx2_pmovmskb_zext
testl %edx, %edx # 19 *cmpsi_ccno_1/1
je .L5 # 20 *jcc_1
tzcntq %rdx, %rdx # 53 *ctzdi2_falsedep
movq mytable+32(,%rdx,8), %rax # 28 *movdi_internal/4
.L5:
vzeroupper # 51 avx_vzeroupper
ret # 58 simple_return_internal
>From gcc-bugs-return-488025-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jun 03 18:05:56 2015
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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/66275] __attribute__((sysv_abi)) with x86_64-w64-mingw32-gcc generates incorrect code
Date: Wed, 03 Jun 2015 18:05:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66275
Uroš Bizjak <ubizjak at gmail dot com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |5.2
--- Comment #7 from Uroš Bizjak <ubizjak at gmail dot com> ---
Fixed in mainline, will be backported to gcc-5 branch.
>From gcc-bugs-return-488026-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jun 03 18:08:06 2015
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From: "ubizjak at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/66275] __attribute__((sysv_abi)) with x86_64-w64-mingw32-gcc generates incorrect code
Date: Wed, 03 Jun 2015 18:08:00 -0000
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--- Comment #8 from Uroš Bizjak <ubizjak at gmail dot com> ---
(In reply to Peter Cordes from comment #0)
> I wrote it in that ugly way initially because I was basically porting my ASM
> code to intrinsics. BTW, the results were terrible. gcc generates
> ridiculously bad code for getting the src bytes into zero-extended 64bit
> regs, for use as scaled-offsets in an address, compared to
>
> movzx %dl, %eax
> movxz %dh, %ebx
> shr $16, %rdx
> use rax/rbx
> movzx %dl, %eax
> movxz %dh, %ebx
> shr $16, %rdx
> use rax/rbx
> ...
>
> gcc never just shifts the reg holding src data. Instead if copies, and
> shifts the copy by $16, $32, or $48.
>
> gcc's code is about 35% slower than the hand-written version, even letting
> it use avx so it doesn't emit useless movdqa instructions when it doesn't
> realize that an old value is no longer needed. Just un-comment the
> mostly-commented loop body in the testcase (attachment version).
>
> Anyway, slow code is off-topic, this bug is about wrong code!
Please open a new PR for this bug.
>From gcc-bugs-return-488027-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jun 03 18:10:49 2015
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From: "avi@cloudius-systems.com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/65942] [5/6 Regression] [C++14] cannot use std::function as comparator in algorithms
Date: Wed, 03 Jun 2015 18:10:00 -0000
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--- Comment #14 from Avi Kivity <avi@cloudius-systems.com> ---
Please consider backporting this to 5.2.
next prev parent reply other threads:[~2015-06-03 18:00 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-01 21:53 [Bug c/66369] New: " marcus.kool at urlfilterdb dot com
2015-06-01 21:57 ` [Bug c/66369] " marcus.kool at urlfilterdb dot com
2015-06-02 9:05 ` [Bug target/66369] " rguenth at gcc dot gnu.org
2015-06-02 10:21 ` ubizjak at gmail dot com
2015-06-02 11:21 ` marcus.kool at urlfilterdb dot com
2015-06-02 14:51 ` marcus.kool at urlfilterdb dot com
2015-06-03 18:00 ` ubizjak at gmail dot com [this message]
2015-06-04 10:06 ` uros at gcc dot gnu.org
2015-06-04 10:11 ` ubizjak at gmail dot com
2015-06-04 17:50 ` marcus.kool at urlfilterdb dot com
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