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From: "glaubitz at physik dot fu-berlin.de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113341] New: Using GCC as the bootstrap compiler breaks
 LLVM on 32-bit PowerPC
Date: Thu, 11 Jan 2024 22:07:12 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113341

            Bug ID: 113341
           Summary: Using GCC as the bootstrap compiler breaks LLVM on
                    32-bit PowerPC
           Product: gcc
           Version: 13.2.1
               URL: https://github.com/llvm/llvm-project/issues/72279
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: glaubitz at physik dot fu-berlin.de
                CC: jrtc27 at jrtc27 dot com, segher at gcc dot gnu.org,
                    sjames at gcc dot gnu.org
  Target Milestone: ---

Using GCC on 32-bit PowerPC as the bootstrap compiler to build LLVM leads to
clang crashing during stage 2 with a backtrace. This does not happen when L=
LVM
is used as the bootstrap compiler.

The backtrace that clang generates can be found in the LLVM bug report [1].

The problem was observed with LLVM 17, so I initially suspected a regressio=
n in
LLVM. I was able to bisect issue which lead to the following commit in LLVM:

bc73ef0031b50f7443615fef614fb4ecaaa4bd11 is the first bad commit
commit bc73ef0031b50f7443615fef614fb4ecaaa4bd11
Author: Richard Smith <richard@metafoo.co.uk>
Date:   Thu Mar 30 14:21:31 2023 -0700

    PR60985: Fix merging of lambda closure types across modules.

However, since the problem does not show when using LLVM as the bootstrap
compiler instead of GCC, I'm suspecting that GCC is miscompiling the code.

> [1] https://github.com/llvm/llvm-project/issues/72279=