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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/112526] [14 regression] Miscompilation of ffmpeg test for -m32 since r14-4968-g89e5d902fc55ad Date: Wed, 15 Nov 2023 15:16:07 +0000 [thread overview] Message-ID: <bug-112526-4-zGcbABuhAU@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-112526-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112526 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2023-11-15 Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |jakub at gcc dot gnu.org Status|UNCONFIRMED |ASSIGNED --- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I think --- gcc/config/i386/i386.md.jj 2023-11-14 21:38:38.667046713 +0100 +++ gcc/config/i386/i386.md 2023-11-15 16:06:30.638353592 +0100 @@ -9918,7 +9918,10 @@ && REGNO (operands[0]) != REGNO (operands[3]) && (REGNO (operands[0]) == REGNO (operands[4]) || REGNO (operands[0]) == REGNO (operands[5]) - || peep2_reg_dead_p (3, operands[0]))" + || peep2_reg_dead_p (3, operands[0])) + && (REGNO (operands[2]) == REGNO (operands[4]) + || REGNO (operands[2]) == REGNO (operands[5]) + || peep2_reg_dead_p (3, operands[2]))" [(set (match_dup 2) (match_dup 1)) (parallel [(set (match_dup 4) (mult:DWIH (match_dup 2) (match_dup 3))) ought to fix this. Unlike the normal imul case where the destination is always %[re]dx:%[re]ax and operands[2] must be %[re]ax, so it is naturally dead at the end and all we need is verify operands[0], in the mulx case the destination is arbitrary pair of registers, so we need to check that both operands[0] and operands[2] (the latter must be %[re]dx) are dead so that we can optimize, because we stop initializing operands[0] altogether and set operands[2] to the immediate rather than the previous value. The question is if I manage to create a small reproducer or not for the testsuite.
next prev parent reply other threads:[~2023-11-15 15:16 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-11-14 9:07 [Bug target/112526] New: " sjames at gcc dot gnu.org 2023-11-14 9:08 ` [Bug target/112526] " sjames at gcc dot gnu.org 2023-11-14 9:28 ` rguenth at gcc dot gnu.org 2023-11-14 9:30 ` jakub at gcc dot gnu.org 2023-11-14 9:50 ` sjames at gcc dot gnu.org 2023-11-14 10:19 ` sjames at gcc dot gnu.org 2023-11-14 10:20 ` sjames at gcc dot gnu.org 2023-11-14 10:20 ` sjames at gcc dot gnu.org 2023-11-14 11:57 ` sjames at gcc dot gnu.org 2023-11-14 11:58 ` sjames at gcc dot gnu.org 2023-11-15 15:16 ` jakub at gcc dot gnu.org [this message] 2023-11-15 16:11 ` jakub at gcc dot gnu.org 2023-11-16 7:33 ` cvs-commit at gcc dot gnu.org 2023-11-16 7:34 ` jakub at gcc dot gnu.org 2023-11-16 16:28 ` sjames at gcc dot gnu.org 2023-11-22 10:34 ` jakub at gcc dot gnu.org
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