https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103052
Bug ID: 103052
Summary: Function call omitted at -O1 optimization level.
Product: gcc
Version: 10.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: tor at ccxvii dot net
Target Milestone: ---
Created attachment 51724
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51724&action=edit
xxx.c
With the attached sample program the function call to checkfutureword() in
main() is completely omitted if compiled with gcc -O1. With -O0 or -O2 or
greater the function is called as expected.
Changing any line in the program is likely to make the bug disappear, and
reordering the functions within the file can also make the bug appear and
disappear.
The example is from a much larger program cut down to the very smallest I could
make it and still replicate the bug.
$ gcc -O0 xxx.c && ./a.out
SUCCESS: exit with exception as expected!
$ gcc -O1 xxx.c && ./a.out
FAIL: should NOT get here :(
The output of gcc -v:
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/10/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa:hsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 10.3.0-11'
--with-bugurl=file:///usr/share/doc/gcc-10/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-10
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --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-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 --with-arch-32=i686
--with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib
--with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-10-Fsusqo/gcc-10-10.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-10-Fsusqo/gcc-10-10.3.0/debian/tmp-gcn/usr,hsa
--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-mutex
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 10.3.0 (Debian 10.3.0-11)
