[Bug c/115227] New: [15 Regression] i686-linux fails frequently with cc1: out of memory allocating x bytes after a total of ~4GB

["slyfox at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115227

            Bug ID: 115227
           Summary: [15 Regression] i686-linux fails frequently with cc1:
                    out of memory allocating x bytes after a total of ~4GB
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
  Target Milestone: ---

Created attachment 58286
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=58286&action=edit
bug.c.c.xz

Initially noticed on libepoxy, doxygen, llvm, p11-kit. They all fail to build
by 32-bit gcc-15. The symptoms are similar: 4GB limit is hit and `gcc` fails on
allocation.

Attached preprocessed and compressed example of libepoxy:

    $ gcc-15 -std=gnu99 -fno-strict-aliasing -fvisibility=hidden  -c bug.c.c -o
bug.o -O2
    cc1: out of memory allocating 65536 bytes after a total of 3774660608 bytes

For comparison gcc-13 is able to survive:

    $ gcc-13 -std=gnu99 -fno-strict-aliasing -fvisibility=hidden  -c bug.c.c -o
bug.o -O2
    <ok>

$ gcc-15 -v
Using built-in specs.
COLLECT_GCC=/<<NIX>>/gcc-15.0.0/bin/gcc
COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-15.0.0/libexec/gcc/i686-unknown-linux-gnu/15.0.0/lto-wrapper
Target: i686-unknown-linux-gnu
Configured with: ../source/configure --prefix=/<<NIX>>/gcc-15.0.0
--with-gmp-include=/<<NIX>>/gmp-6.3.0-dev/include
--with-gmp-lib=/<<NIX>>/gmp-6.3.0/lib
--with-mpfr-include=/<<NIX>>/mpfr-4.2.1-dev/include
--with-mpfr-lib=/<<NIX>>/mpfr-4.2.1/lib --with-mpc=/<<NIX>>/libmpc-1.3.1
--with-native-system-header-dir=/<<NIX>>/glibc-2.39-52-dev/include
--with-build-sysroot=/
--with-gxx-include-dir=/<<NIX>>/gcc-15.0.0/include/c++/15.0.0/
--program-prefix= --enable-lto --disable-libstdcxx-pch
--without-included-gettext --with-system-zlib --enable-checking=release
--enable-static --enable-languages=c,c++ --disable-multilib --enable-plugin
--disable-libcc1 --with-isl=/<<NIX>>/isl-0.20 --disable-bootstrap
--with-arch=i686 --build=i686-unknown-linux-gnu --host=i686-unknown-linux-gnu
--target=i686-unknown-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 15.0.0 99999999 (experimental) (GCC)