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From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/113542] gcc.target/arm/bics_3.c regression after change for pr111267 Date: Wed, 24 Jan 2024 12:48:44 +0000 [thread overview] Message-ID: <bug-113542-4-aJZTiFoD33@http.gcc.gnu.org/bugzilla/> (raw) In-Reply-To: <bug-113542-4@http.gcc.gnu.org/bugzilla/> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113542 Richard Earnshaw <rearnsha at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Ever confirmed|0 |1 Status|UNCONFIRMED |NEW Last reconfirmed| |2024-01-24 --- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> --- Options to reproduce -O2 -mcpu=cortex-m3 -mthumb The problem is really a back-end issue. But the cause is that the fwprop pass is now merging propagating insn 9 into insn 10, replacing: (set (reg:SI 124 [ _7 ]) (ne:SI (reg:CC 100 cc) (const_int 0 [0]))) with the flag setting instruction to form (parallel [ (set (reg:SI 124 [ _7 ]) (ne:SI (reg:SI 122 [ _2 ]) (const_int 0 [0]))) (clobber (reg:CC 100 cc)) ]) That's OK, but it means that the combine pass is no-longer able to merge the flag setter with an earlier result producer. A similar thing starts to happen arm state this is dropped because the costs are working out as the same (it has to reduce the cost). So I think it's that the cost model for thumb2 needs tweaking.
next prev parent reply other threads:[~2024-01-24 12:48 UTC|newest] Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-01-22 15:46 [Bug rtl-optimization/113542] New: " roger at nextmovesoftware dot com 2024-01-24 12:48 ` rearnsha at gcc dot gnu.org [this message] 2024-01-24 16:42 ` [Bug target/113542] [14 Regression] " rearnsha at gcc dot gnu.org 2024-01-25 9:51 ` mkuvyrkov at gcc dot gnu.org 2024-01-31 14:33 ` rguenth at gcc dot gnu.org 2024-02-21 12:47 ` mkuvyrkov at gcc dot gnu.org 2024-03-07 20:47 ` law at gcc dot gnu.org 2024-03-08 17:08 ` cvs-commit at gcc dot gnu.org 2024-03-08 17:15 ` rearnsha at gcc dot gnu.org
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