https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90701
Bug ID: 90701
Summary: GCC inserts a call to memset when compiling with
-nostdlib
Product: gcc
Version: 8.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: translation
Assignee: unassigned at gcc dot gnu.org
Reporter: jynelson at email dot sc.edu
Target Milestone: ---
Created attachment 46440
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=46440&action=edit
The pre-processed source file (as minimal as I could make it)
GCC incorrectly optimizes a function call equivalent to memset to a runtime
call to memset even when compiling with -nostdlib. While normally this would be
a useful optimization, in this case it causes compilation to fail.
The bad optimization disappears when compiling with -O2 or without
optimization. I have also been able to replicate the problem on gcc 7.3.0 and
7.4.0.
Output of gcc-8 -v -save-temps -nostdlib -O3 -Wall repro2.c:
Using built-in specs.
COLLECT_GCC=gcc-8
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
8.3.0-6ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-8
--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-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --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 --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.3.0 (Ubuntu 8.3.0-6ubuntu1~18.04)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostdlib' '-O3' '-Wall'
'-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -E -quiet -v -imultiarch x86_64-linux-gnu
repro2.c -mtune=generic -march=x86-64 -Wall -O3 -fpch-preprocess
-Wformat-security -o repro2.i
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-linux-gnu/8/../../../../x86_64-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-linux-gnu/8/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/8/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostdlib' '-O3' '-Wall'
'-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/8/cc1 -fpreprocessed repro2.i -quiet -dumpbase
repro2.c -mtune=generic -march=x86-64 -auxbase repro2 -O3 -Wall -version
-Wformat-security -o repro2.s
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C17 (Ubuntu 8.3.0-6ubuntu1~18.04) version 8.3.0 (x86_64-linux-gnu)
compiled by GNU C version 8.3.0, GMP version 6.1.2, MPFR version 4.0.1,
MPC version 1.1.0, isl version isl-0.19-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 0eab16efc1441b53648b1f7b4f2c76bc
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostdlib' '-O3' '-Wall'
'-mtune=generic' '-march=x86-64'
as -v --64 -o repro2.o repro2.s
GNU assembler version 2.30 (x86_64-linux-gnu) using BFD version (GNU Binutils
for Ubuntu) 2.30
COMPILER_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/x86_64-linux-gnu/8/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib/:/lib/x86_64-linux-gnu/:/lib/../lib/:/usr/lib/x86_64-linux-gnu/:/usr/lib/../lib/:/usr/lib/gcc/x86_64-linux-gnu/8/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostdlib' '-O3' '-Wall'
'-mtune=generic' '-march=x86-64'
/usr/lib/gcc/x86_64-linux-gnu/8/collect2 -plugin
/usr/lib/gcc/x86_64-linux-gnu/8/liblto_plugin.so
-plugin-opt=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
-plugin-opt=-fresolution=repro2.res --build-id --eh-frame-hdr -m elf_x86_64
--hash-style=gnu --as-needed -dynamic-linker /lib64/ld-linux-x86-64.so.2 -pie
-z now -z relro -L/usr/lib/gcc/x86_64-linux-gnu/8
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../../x86_64-linux-gnu
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../../../lib -L/lib/x86_64-linux-gnu
-L/lib/../lib -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib
-L/usr/lib/gcc/x86_64-linux-gnu/8/../../.. repro2.o
repro2.o: In function `_start':
repro2.c:(.text+0x49): undefined reference to `memset'
repro2.c:(.text+0x6b): undefined reference to `memset'
repro2.c:(.text+0x94): undefined reference to `memset'
