https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65077
Bug ID: 65077
Summary: memcpy generates incorrect code with floating point
numbers and -O1
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: anders.blomdell at control dot lth.se
Created attachment 34774
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34774&action=edit
Program that triggers bug
The attached code (heavily downsized), generates incorrect code with -O1 and if
compiled with -fPIC or -fpic it generates incorrect code for most optimizations
(-O1, -O2, -O3, -Os, -Ofast).
Here is the command line and output.
> gcc -v -save-temps -o bug bug.c -fno-strict-aliasing -fwrapv
> -fno-aggressive-loop-optimizations -O1 -Wall -Werror
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man
--infodir=/usr/share/info --with-bugurl=http://bugzilla.redhat.com/bugzilla
--enable-bootstrap --enable-shared --enable-threads=posix
--enable-checking=release --enable-multilib --with-system-zlib
--enable-__cxa_atexit --disable-libunwind-exceptions --enable-gnu-unique-object
--enable-linker-build-id --with-linker-hash-style=gnu
--enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --enable-plugin
--enable-initfini-array --disable-libgcj
--with-isl=/builddir/build/BUILD/gcc-4.9.2-20141101/obj-x86_64-redhat-linux/isl-install
--with-cloog=/builddir/build/BUILD/gcc-4.9.2-20141101/obj-x86_64-redhat-linux/cloog-install
--enable-gnu-indirect-function --with-tune=generic --with-arch_32=i686
--build=x86_64-redhat-linux
Thread model: posix
gcc version 4.9.2 20141101 (Red Hat 4.9.2-1) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-o' 'bug' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-O1' '-Wall' '-Werror'
'-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/cc1 -E -quiet -v bug.c
-mtune=generic -march=x86-64 -Wall -Werror -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations -O1 -fpch-preprocess -o bug.i
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include-fixed"
ignoring nonexistent directory
"/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../x86_64-redhat-linux/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/include
/usr/local/include
/usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-o' 'bug' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-O1' '-Wall' '-Werror'
'-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/cc1 -fpreprocessed bug.i -quiet
-dumpbase bug.c -mtune=generic -march=x86-64 -auxbase bug -O1 -Wall -Werror
-version -fno-strict-aliasing -fwrapv -fno-aggressive-loop-optimizations -o
bug.s
GNU C (GCC) version 4.9.2 20141101 (Red Hat 4.9.2-1) (x86_64-redhat-linux)
compiled by GNU C version 4.9.2 20141101 (Red Hat 4.9.2-1), GMP version
6.0.0, MPFR version 3.1.2, MPC version 1.0.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
GNU C (GCC) version 4.9.2 20141101 (Red Hat 4.9.2-1) (x86_64-redhat-linux)
compiled by GNU C version 4.9.2 20141101 (Red Hat 4.9.2-1), GMP version
6.0.0, MPFR version 3.1.2, MPC version 1.0.2
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 03cfec3867418ce243292e9ba51d447c
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-o' 'bug' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-O1' '-Wall' '-Werror'
'-mtune=generic' '-march=x86-64'
as -v --64 -o bug.o bug.s
GNU assembler version 2.24 (x86_64-redhat-linux) using BFD version version 2.24
COMPILER_PATH=/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/:/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/:/usr/libexec/gcc/x86_64-redhat-linux/:/usr/lib/gcc/x86_64-redhat-linux/4.9.2/:/usr/lib/gcc/x86_64-redhat-linux/
LIBRARY_PATH=/usr/lib/gcc/x86_64-redhat-linux/4.9.2/:/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../lib64/:/lib/../lib64/:/usr/lib/../lib64/:/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-o' 'bug' '-fno-strict-aliasing'
'-fwrapv' '-fno-aggressive-loop-optimizations' '-O1' '-Wall' '-Werror'
'-mtune=generic' '-march=x86-64'
/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/collect2 -plugin
/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/liblto_plugin.so
-plugin-opt=/usr/libexec/gcc/x86_64-redhat-linux/4.9.2/lto-wrapper
-plugin-opt=-fresolution=bug.res -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lgcc_s -plugin-opt=-pass-through=-lc
-plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lgcc_s --build-id
--no-add-needed --eh-frame-hdr --hash-style=gnu -m elf_x86_64 -dynamic-linker
/lib64/ld-linux-x86-64.so.2 -o bug
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../lib64/crt1.o
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../lib64/crti.o
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/crtbegin.o
-L/usr/lib/gcc/x86_64-redhat-linux/4.9.2
-L/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../lib64 -L/lib/../lib64
-L/usr/lib/../lib64 -L/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../.. bug.o
-lgcc --as-needed -lgcc_s --no-as-needed -lc -lgcc --as-needed -lgcc_s
--no-as-needed /usr/lib/gcc/x86_64-redhat-linux/4.9.2/crtend.o
/usr/lib/gcc/x86_64-redhat-linux/4.9.2/../../../../lib64/crtn.o
