This code:
# 1 "fs.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "fs.c"
int foo(unsigned int bar)
{
unsigned int mask = bar & 0x80000001;
if (mask & 0x80000000)
mask = 0x80000000;
return mask;
}
produces incorrect assembly code with -Os or -O2:
.file "fs.c"
.text
.align 2
.global foo
.type foo, %function
foo:
@ Function supports interworking.
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
cmp r0, #0
andge r0, r0, #-2147483648 <== should be -2147483647
movlt r0, #-2147483648
@ lr needed for prologue
bx lr
.size foo, .-foo
.ident "GCC: (GNU) 4.1.2"
*** Command line: arm-v4t-linux-gnueabi -save-temps -O2 fs.c
*** Output:
Using built-in specs.
Target: arm-v4t-linux-gnueabi
Configured with:
/home/alarsen/projects/toolchain/OSELAS.Toolchain-1.1.1/build-cross/gcc-4.1.2/configure
--host=i686-host-linux-gnu --target=arm-v4t-linux-gnueabi
--prefix=/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18
--with-sysroot=/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/sysroot-arm-v4t-linux-gnueabi
--with-arch=armv4t --with-float=soft --with-fpu=vfp --disable-nls
--disable-multilib --enable-symvers=gnu --enable-__cxa_atexit --enable-shared
--enable-threads=posix --enable-languages=c,c++ --enable-c99 --enable-long-long
Thread model: posix
gcc version 4.1.2
/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/libexec/gcc/arm-v4t-linux-gnueabi/4.1.2/cc1
-E -quiet -v fs.c -march=armv4t -mfloat-abi=soft -mfpu=vfp -O2 -fpch-preprocess
-o fs.i
ignoring nonexistent directory
"/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/sysroot-arm-v4t-linux-gnueabi/usr/local/include"
#include "..." search starts here:
#include <...> search starts here:
/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/lib/gcc/arm-v4t-linux-gnueabi/4.1.2/include
/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/lib/gcc/arm-v4t-linux-gnueabi/4.1.2/../../../../arm-v4t-linux-gnueabi/include
/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/sysroot-arm-v4t-linux-gnueabi/usr/include
End of search list.
/opt/OSELAS.Toolchain-1.1.1/arm-v4t-linux-gnueabi/gcc-4.1.2-glibc-2.5-kernel-2.6.18/libexec/gcc/arm-v4t-linux-gnueabi/4.1.2/cc1
-fpreprocessed fs.i -quiet -dumpbase fs.c -march=armv4t -mfloat-abi=soft
-mfpu=vfp -auxbase fs -O2 -version -o fs.s
GNU C version 4.1.2 (arm-v4t-linux-gnueabi)
compiled by GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu3).
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: 2befb21690236570f62e4f3b11d6068c
--
Summary: [ARM] Incorrect optimized code >= -O2
Product: gcc
Version: 4.1.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: al at alarsen dot net
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: arm-v4t-linux-gnueabi
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40128
