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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/46391] false dependencies are computed after vectorization (#2) Date: Wed, 08 Sep 2021 11:04:07 +0000 [thread overview] Message-ID: <bug-46391-4-1dKnJ775CJ@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-46391-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46391 Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |RESOLVED Known to work| |12.0, 7.5.0 Resolution|--- |FIXED Known to fail| |4.3.5 --- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> --- It is. Slightly altered testcase (to avoid unrolling on GIMPLE), with -fno-schedule-insn2 on x86_64: .L2: movdqu (%rdi,%rax), %xmm1 paddb %xmm0, %xmm1 movups %xmm1, (%rsi,%rax) movdqu 16(%rdi,%rax), %xmm2 paddb %xmm0, %xmm2 movups %xmm2, 16(%rsi,%rax) movdqu 32(%rdi,%rax), %xmm3 paddb %xmm0, %xmm3 movups %xmm3, 32(%rsi,%rax) movdqu 48(%rdi,%rax), %xmm4 paddb %xmm0, %xmm4 movups %xmm4, 48(%rsi,%rax) movdqu 64(%rdi,%rax), %xmm5 paddb %xmm0, %xmm5 movups %xmm5, 64(%rsi,%rax) movdqu 80(%rdi,%rax), %xmm6 paddb %xmm0, %xmm6 movups %xmm6, 80(%rsi,%rax) movdqu 96(%rdi,%rax), %xmm7 paddb %xmm0, %xmm7 movups %xmm7, 96(%rsi,%rax) movdqu 112(%rdi,%rax), %xmm8 paddb %xmm0, %xmm8 movups %xmm8, 112(%rsi,%rax) subq $-128, %rax cmpq $4096, %rax jne .L2 and without: .L2: movdqu (%rdi,%rax), %xmm1 movdqu 16(%rdi,%rax), %xmm2 movdqu 32(%rdi,%rax), %xmm3 movdqu 48(%rdi,%rax), %xmm4 movdqu 64(%rdi,%rax), %xmm5 paddb %xmm0, %xmm1 paddb %xmm0, %xmm2 movdqu 80(%rdi,%rax), %xmm6 movdqu 96(%rdi,%rax), %xmm7 paddb %xmm0, %xmm3 paddb %xmm0, %xmm4 movups %xmm1, (%rsi,%rax) movdqu 112(%rdi,%rax), %xmm8 paddb %xmm0, %xmm5 paddb %xmm0, %xmm6 movups %xmm2, 16(%rsi,%rax) paddb %xmm0, %xmm7 movups %xmm3, 32(%rsi,%rax) paddb %xmm0, %xmm8 movups %xmm4, 48(%rsi,%rax) movups %xmm5, 64(%rsi,%rax) movups %xmm6, 80(%rsi,%rax) movups %xmm7, 96(%rsi,%rax) movups %xmm8, 112(%rsi,%rax) subq $-128, %rax cmpq $4096, %rax jne .L2 and that's only possible if this dependence is not visible. 4.3 shows the problem still, GCC 7 doesn't.
prev parent reply other threads:[~2021-09-08 11:04 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-11-09 12:35 [Bug rtl-optimization/46391] New: " roy.1rosen at gmail dot com 2010-11-09 13:19 ` [Bug rtl-optimization/46391] " rguenth at gcc dot gnu.org 2010-11-09 13:48 ` roy.1rosen at gmail dot com 2010-11-11 8:04 ` roy.1rosen at gmail dot com 2021-08-16 4:29 ` pinskia at gcc dot gnu.org 2021-09-08 11:04 ` rguenth at gcc dot gnu.org [this message]
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