http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49468
Summary: SH Target: inefficient integer abs code
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: oleg.e...@t-online.de
The generated code for abs:SI and abs:DI is a bit inefficient:
int abs (int i)
{
return (i < 0) ? -i : i;
}
mov r4,r1
shll r1
subc r1,r1
mov r1,r0
xor r4,r0
rts
sub r1,r0
long long abs (long long i)
{
return (i < 0) ? -i : i;
}
mov r4,r3
shll r3
subc r3,r3
mov r5,r1
xor r3,r1
mov r3,r0
clrt
xor r4,r0
subc r3,r1
rts
subc r3,r0
There is a define_split in sh.md which is supposed to handle the special case
for SH4 but it is not doing anything. The problem has been around since a
couple of GCC 4.x versions.
sh-elf-gcc -v
Using built-in specs.
COLLECT_GCC=sh-elf-gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/sh-elf/4.7.0/lto-wrapper
Target: sh-elf
Configured with: ../gcc-trunk/configure --target=sh-elf --prefix=/usr/local
--enable-languages=c,c++ --enable-multilib --disable-libssp --without-headers
--disable-nls --disable-werror --enable-lto --with-newlib --with-gnu-as
--with-gnu-ld --with-system-zlib : (reconfigured) ../gcc-trunk/configure
--target=sh-elf --prefix=/usr/local --enable-languages=c,c++ --enable-multilib
--disable-libssp --without-headers --disable-nls --disable-werror --enable-lto
--with-newlib --with-gnu-as --with-gnu-ld --with-system-zlib : (reconfigured)
../gcc-trunk/configure --target=sh-elf --prefix=/usr/local
--enable-languages=c,c++ --enable-multilib --disable-libssp --without-headers
--disable-nls --disable-werror --enable-lto --with-newlib --with-gnu-as
--with-gnu-ld --with-system-zlib : (reconfigured) ../gcc-trunk/configure
--target=sh-elf --prefix=/usr/local --enable-multilib --disable-libssp
--without-headers --disable-nls --disable-werror --enable-lto --with-newlib
--with-gnu-as --with-gnu-ld --with-system-zlib target_alias=sh-elf CFLAGS=-Os
CXXFLAGS=-Os --enable-languages=c,c++,lto --no-create --no-recursion
Thread model: single
gcc version 4.7.0 20110619 (experimental) (GCC)
