From: Jakub Jelinek <jakub@redhat.com>
To: Uros Bizjak <ubizjak@gmail.com>,
Richard Biener <rguenther@suse.de>,
Jeff Law <law@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Patch ping (Re: [PATCH] Fix x86 bzhi/bextr iff zero_extract with zero size is undefined (PR rtl-optimization/87817))
Date: Wed, 21 Nov 2018 10:20:00 -0000 [thread overview]
Message-ID: <20181121101959.GJ11625@tucnak> (raw)
In-Reply-To: <20181113233702.GI11625@tucnak>
Hi!
On Wed, Nov 14, 2018 at 12:37:02AM +0100, Jakub Jelinek wrote:
> 2018-11-13 Jakub Jelinek <jakub@redhat.com>
>
> PR rtl-optimization/87817
> * config/i386/i386.md (nmi2_bzhi_<mode>3, *bmi2_bzhi_<mode>3,
> *bmi2_bzhi_<mode>3_1, *bmi2_bzhi_<mode>3_1_ccz): Use IF_THEN_ELSE
> in the pattern to avoid triggering UB when operands[2] is zero.
> (tbm_bextri_<mode>): New expander. Renamed the old define_insn to ...
> (*tbm_bextri_<mode>): ... this.
I'd like to ping this patch, while the folding committed for the PR
often triggers and so the RTL passes see literal zero propagated there less
often, e.g. the testcase with:
-O2 -mbmi2 -fno-tree-ccp -fno-tree-forwprop -fno-tree-fre -fno-tree-pre -fno-tree-vrp -fno-tree-dominator-opts -fno-code-hoisting
is still miscompiled and there could be other reasons why a zero appears
only after expansion.
From what I understood, the agreement was that zero_extract with 0 size
(either literal or just at runtime is incorrect in the middle-end).
Jakub
next prev parent reply other threads:[~2018-11-21 10:20 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-13 23:37 [PATCH] Fix x86 bzhi/bextr iff zero_extract with zero size is undefined (PR rtl-optimization/87817) Jakub Jelinek
2018-11-14 8:29 ` Richard Biener
2018-11-14 8:58 ` Jakub Jelinek
2018-11-14 12:21 ` [PATCH] Fold x86 bzhi with zero last operand " Jakub Jelinek
2018-11-14 12:28 ` Uros Bizjak
2018-11-14 12:38 ` Richard Biener
2018-11-21 10:20 ` Jakub Jelinek [this message]
2018-11-21 10:32 ` Patch ping (Re: [PATCH] Fix x86 bzhi/bextr iff zero_extract with zero size is undefined (PR rtl-optimization/87817)) Uros Bizjak
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