https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71467
Bug ID: 71467
Summary: extra store for -mavx -mno-avx
Product: gcc
Version: 5.3.1
Status: UNCONFIRMED
Keywords: missed-optimization, ssemmx
Severity: minor
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: mirq-gccboogs at rere dot qmqm.pl
Target Milestone: ---
Host: x86_64-linux-gnu
Target: x86_64-linux-gnu
Created attachment 38664
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=38664&action=edit
test case
Code:
typedef int __v8si __attribute__ ((__vector_size__ (32)));
void vz(__v8si *v)
{
*v <<= 1;
}
Compiles to:
vz:
.LFB0:
.cfi_startproc
leaq 8(%rsp), %r10
.cfi_def_cfa 10, 0
andq $-32, %rsp
pushq -8(%r10)
pushq %rbp
.cfi_escape 0x10,0x6,0x2,0x76,0
movq %rsp, %rbp
pushq %r10
.cfi_escape 0xf,0x3,0x76,0x78,0x6
vmovdqa (%rdi), %xmm2
vmovdqa 16(%rdi), %xmm4
vpslld $1, %xmm2, %xmm1
vpslld $1, %xmm4, %xmm3
vmovaps %xmm1, -48(%rbp)
vmovaps %xmm3, -32(%rbp)
vmovdqa -48(%rbp), %ymm5
vmovdqa %ymm5, (%rdi)
vzeroupper
popq %r10
.cfi_def_cfa 10, 0
popq %rbp
leaq -8(%r10), %rsp
.cfi_def_cfa 7, 8
ret
.cfi_endproc
.LFE0:
.size vz, .-vz
This should be no more than:
vmovdqa (%rdi), %xmm2
vmovdqa 16(%rdi), %xmm4
vpslld $1, %xmm2, %xmm1
vpslld $1, %xmm4, %xmm3
vmovaps %xmm1, (%rdi)
vmovaps %xmm3, 16(%rdi)
ret
Compiled with:
$ gcc -O3 -mavx -mno-avx2 -S -o - a.c
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/5/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 5.3.1-21'
--with-bugurl=file:///usr/share/doc/gcc-5/README.Bugs
--enable-languages=c,ada,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-5 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --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 --with-system-zlib
--disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-5-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-5-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-5-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 5.3.1 20160528 (Debian 5.3.1-21)
Same with:
Using built-in specs.
COLLECT_GCC=gcc-4.9
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.9/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.9.3-14'
--with-bugurl=file:///usr/share/doc/gcc-4.9/README.Bugs
--enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr
--program-suffix=-4.9 --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.9 --libdir=/usr/lib --enable-nls
--with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-vtable-verify
--enable-plugin --with-system-zlib --disable-browser-plugin
--enable-java-awt=gtk --enable-gtk-cairo
--with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64/jre --enable-java-home
--with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.9-amd64
--with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.9-amd64
--with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar
--enable-objc-gc --enable-multiarch --with-arch-32=i586 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 4.9.3 (Debian 4.9.3-14)
