https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122021
Bug ID: 122021
Summary: [16 regression] libvpx miscompiled with -m32
Product: gcc
Version: 16.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: sjames at gcc dot gnu.org
Target Milestone: ---
Created attachment 62429
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=62429&action=edit
vpx.c
This comes from libvpx which was crashing with -m32 and LTO. For a while, it
needed ipa-cp but in the end, that's not required:
```
$ gcc vpx.c -o vpx -O2 -m32 && ./vpx
Aborted (core dumped) ./vpx
$ gcc vpx.c -o vpx -O2 && ./vpx
```
-fno-tree-vrp -fno-tree-forwprop works.
Between 15 and trunk, the difference in range info seems to be:
```
-Global Exported: _3 = [irange] unsigned short [0, 0][2, +INF] MASK 0xfffe
VALUE 0x0
-Global Exported: _4 = [irange] short int [-INF, 0][2, +INF] MASK 0xfffe VALUE
0x0
-Global Exported: _7 = [irange] unsigned short [0, 0][2, +INF] MASK 0xfffe
VALUE 0x0
-Global Exported: _8 = [irange] short int [-INF, 0][2, +INF] MASK 0xfffe VALUE
0x0
+Global Exported: _3 = [irange] unsigned short [0, 0][2, 65534] MASK 0xfffe
VALUE 0x0
+Global Exported: _4 = [irange] short int [-INF, -2][0, 0][2, 32766] MASK
0xfffe VALUE 0x0
+Global Exported: _7 = [irange] unsigned short [0, 0][2, 65534] MASK 0xfffe
VALUE 0x0
+Global Exported: _8 = [irange] short int [-INF, -2][0, 0][2, 32766] MASK
0xfffe VALUE 0x0
```
```
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-pc-linux-gnu/16/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-pc-linux-gnu
Configured with:
/var/tmp/portage/sys-devel/gcc-16.0.9999/work/gcc-16.0.9999/configure
--host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --prefix=/usr
--bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/16
--includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/16/include
--datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16
--mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16/man
--infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/16/info
--with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/16/include/g++-v16
--disable-silent-rules --disable-dependency-tracking
--with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/16/python
--enable-libphobos --enable-objc-gc
--enable-languages=c,c++,d,objc,obj-c++,fortran,ada,cobol,m2,rust
--enable-obsolete --enable-secureplt --disable-werror --with-system-zlib
--enable-nls --without-included-gettext --disable-libunwind-exceptions
--enable-checking=yes,extra,rtl --with-bugurl=https://bugs.gentoo.org/
--with-pkgversion='Gentoo Hardened 16.0.9999 p, commit
9ce7a56d3f95fb805601d2f9630f2ae311f323fa' --with-gcc-major-version-only
--enable-libstdcxx-time --enable-lto --disable-libstdcxx-pch --enable-shared
--enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu
--enable-multilib --with-multilib-list=m32,mx32,m64 --disable-fixed-point
--with-abi=m64 --enable-targets=all --enable-offload-defaulted
--enable-offload-targets=nvptx-none --enable-libgomp --disable-libssp
--enable-libada --disable-cet --enable-systemtap --enable-valgrind-annotations
--disable-vtable-verify --disable-libvtv --with-zstd --with-isl
--disable-isl-version-check --enable-default-pie --enable-host-pie
--enable-host-bind-now --enable-default-ssp --disable-fixincludes
--with-gxx-libcxx-include-dir=/usr/include/c++/v1 --enable-linker-build-id
--with-build-config='bootstrap-O3 bootstrap-lto'
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.0 20250920 (experimental)
396e9118849c4b918eaf3edcfa60d36e2b973019 (Gentoo Hardened 16.0.9999 p, commit
9ce7a56d3f95fb805601d2f9630f2ae311f323fa)
```
