https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119090
Bug ID: 119090
Summary: [MAME] [Model 1] 3D graphics are full of glitches if
built with CXXFLAGS="-march=native -mtune=native"
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redwindwanderer at gmail dot com
Target Milestone: ---
Created attachment 60638
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60638&action=edit
Complete MAME (Model1 only) building logs
----GCC Version: 14.2.0 (Debian 14.2.0-16)
----System Type: x86_64 GNU/Linux running up to date Debian Testing
### GCC Build information begins: ###
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/14/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 14.2.0-16'
--with-bugurl=file:///usr/share/doc/gcc-14/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2,rust --prefix=/usr
--with-gcc-major-version-only --program-suffix=-14
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace
--enable-gnu-unique-object --disable-vtable-verify --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/reproducible-path/gcc-14-14.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/reproducible-path/gcc-14-14.2.0/debian/tmp-gcn/usr
--enable-offload-defaulted --without-cuda-driver --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
--with-build-config=bootstrap-lto-lean --enable-link-serialization=3
Thread model: posix
Supported LTO compression algorithms: zlib zstd
### GCC Build information ENDS ###
####Complete commandline that triggers the bug####
For faster building times, edit makefile, search for "SOURCES =" and add this
line so only the Sega Model 1 emulation is built:
SOURCES = src/mame/sega/model1.cpp
Then build MAME with these FLAGS (the rest of parameters have no impact on the
issue at all):
CFLAGS="-march=native -mtune=native" \
CXXFLAGS="-march=native -mtune=native" \
make USE_WAYLAND=1 NO_X11=1 USE_QTDEBUG=0 NO_USE_XINPUT=1 NO_USE_PULSEAUDIO=1
REGENIE=1 -j$(nproc)
Then run Virtua Racing on the Model 1 emulation with:
mame vr
#### POSSIBLE CLUES ####
Building with these FLAGS instead:
CFLAGS="-march=znver3 -mtune=znver3" \
CXXFLAGS="-march=znver3 -mtune=znver3"
...There is no bug: the game's 3D simulation runs as expected.
Other Model 1 games like VF don't have any issues with the "native" flags, only
VR seems to be affected.
#### MORE INFORMATION ####
I'm attaching the complete building logs of latest MAME sources with only the
Model 1 system enabled.
No warnings are presented when building the Model1-related objects, which are:
src/mame/sega/model1_m.cpp
src/mame/sega/model1_v.cpp
src/mame/sega/model1io2.cpp
src/mame/sega/model1io.cpp
src/mame/sega/model1.cpp
...so it looks like a compiler bug to me.
