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From: "inform at tiker dot net" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/107127] New: [Regression 11/12] Long compile times on code
 with C complex
Date: Mon, 03 Oct 2022 02:03:23 +0000
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X-Bugzilla-Version: 12.2.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107127

            Bug ID: 107127
           Summary: [Regression 11/12] Long compile times on code with C
                    complex
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: inform at tiker dot net
  Target Milestone: ---

A generated code using C-style complex arithmetic that compiled nearly
instantaneously with gcc 10.4 takes >=3D30s with gcc 11.3.0 and 12.2.0.

How to reproduce:

git clone https://gist.github.com/inducer/802e227e86e3ff4fd95aa0fefae462fe.=
git=20
cd 802e227e86e3ff4fd95aa0fefae462fe
git checkout 9eb600e
$ time gcc-10 -c post-110.c
gcc-10 -c post-110.c  0,05s user 0,02s system 45% cpu 0,155 total
$ time gcc-11 -c post-110.c
^C
gcc-11 -c post-110.c  0,00s user 0,00s system 0% cpu 23,757 total
$ time gcc-12 -c post-110.c
^C
gcc-12 -c post-110.c  0,00s user 0,00s system 0% cpu 31,574 total

This does not seem to be very sensitive to headers, so I'm not including
preprocessed source to start. Happy to supply it if needed.

Target: x86_64-linux-gnu
Precise versions:

gcc version 10.4.0 (Debian 10.4.0-5)
gcc version 11.3.0 (Debian 11.3.0-5)
gcc version 12.2.0 (Debian 12.2.0-3)

x-ref: https://github.com/inducer/loopy/issues/686=