https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113611
Bug ID: 113611
Summary: [14 Regression] gcc.dg/pr110279-1.c fails on cross
build since gcc-14-5779-g746344dd538
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: thiago.bauermann at linaro dot org
CC: dizhao at os dot amperecomputing.com
Target Milestone: ---
Target: arm-linux-gnueabihf
After commit g:746344dd5380 ("swap ops in reassoc to reduce cross backedge
FMA") the following failure started appearing on cross builds of 32 bits Arm:
Running gcc:gcc.dg/dg.exp ...
FAIL: gcc.dg/pr110279-1.c scan-tree-dump-times widening_mul "Generated FMA" 3
We're seeing it with toolchains built with --host=x86_64-linux-gnu and targets
arm-linux-gnueabihf and arm-none-eabi. Both targets with and without
--with-mode=thumb.
Interestingly, with a native compiler (with --host=arm-linux-gnueabihf and
--target=arm-linux-gnueabihf) I can't reproduce the problem.
I tested on today's trunk (commit ffeab69e1ffc) and the failures are still
present.
Here's how to reproduce on an x86_64-linux machine with
--target=arm-linux-gnueabihf:
1. Build and install GCC:
$ ~/src/gcc/configure" \
SHELL=/bin/bash \
--with-gnu-as \
--with-gnu-ld \
--disable-libmudflap \
--enable-lto \
--enable-shared \
--without-included-gettext \
--enable-nls \
--with-system-zlib \
--disable-sjlj-exceptions \
--enable-gnu-unique-object \
--enable-linker-build-id \
--disable-libstdcxx-pch \
--enable-c99 \
--enable-clocale=gnu \
--enable-libstdcxx-debug \
--enable-long-long \
--with-cloog=no \
--with-ppl=no \
--with-isl=no \
--disable-multilib \
--with-float=hard \
--with-fpu=vfpv3-d16 \
--with-tune=cortex-a9 \
--with-arch=armv7-a \
--enable-threads=posix \
--enable-multiarch \
--enable-libstdcxx-time=yes \
--enable-gnu-indirect-function \
--with-sysroot=/var/tmp/sysroot-arm-linux-gnueabihf \
--enable-checking=yes \
--disable-bootstrap \
--enable-languages=default \
--prefix=/tmp/arm-linux-gnueabihf \
--build=x86_64-pc-linux-gnu \
--host=x86_64-pc-linux-gnu \
--target=arm-linux-gnueabihf \
&& make \
SHELL=/bin/bash \
-w \
-j $(nproc) \
CFLAGS_FOR_BUILD="-pipe -g -O2" \
CXXFLAGS_FOR_BUILD="-pipe -g -O2" \
LDFLAGS_FOR_BUILD="-static-libgcc" \
MAKEINFOFLAGS=--force \
BUILD_INFO="" \
MAKEINFO=echo \
&& make install
2. Finally, use it to compile the problematic .c file:
$ /tmp/arm-linux-gnueabihf/bin/arm-linux-gnueabihf-gcc
/home/bauermann/src/gcc/gcc/testsuite/gcc.dg/pr110279-1.c
-fdiagnostics-plain-output -Ofast --param avoid-fma-max-bits=512 --param
tree-reassoc-width=4 -fdump-tree-widening_mul-details -S -o pr110279-1.s
$ grep "Generated FMA" pr110279-1.c.215t.widening_mul || echo FAIL
FAIL
