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From: "krebbel at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/101523] New: Huge number of combine attempts
Date: Tue, 20 Jul 2021 09:35:37 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101523

            Bug ID: 101523
           Summary: Huge number of combine attempts
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: krebbel at gcc dot gnu.org
  Target Milestone: ---

Compiling the attached testcase on s390x with:

cc1plus -fpreprocessed t.ii -quiet -march=3Dz196 -g -O2 -std=3Dc++11

produces a huge amount of combine attempts compared to x86 consuming more t=
han
11GB of memory:

x86:      27264 combine attempts for 170631 insns
s390x: 40009540 combine attempts for 164327 insns

gcc g:6d4da4aeef5b20f7f9693ddc27d26740d0dbe36c=