https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67949
Bug ID: 67949
Summary: Regression in GCC-6.0.0's optimizer
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: ishiura-compiler at ml dot kwansei.ac.jp
Target Milestone: ---
We compiled a program (A.c) by GCC-5.1.0 and GCC-6.0.0 with -O3 option.
GCC-5.1.0 performed better optimization than GCC-6.0.0.
(A.c)
#include <stdio.h>
int x110 = 0;
int main (void)
{
volatile int x129 = 1;
int t0 = 1;
t0 = (x129==1)<=(2U^(-(1-x110<<2)));
if (t0 == 1) { }
else { __builtin_abort(); }
return 0;
}
+-----------------------------------------+-----------------------------------------+
| gcc-5.1.0.s (gcc-5.1.0 A.c -O3 -S) | gcc-6.0.0.s (gcc-6.0.0 A.c -O3
-S) |
+-----------------------------------------+-----------------------------------------+
| .globl main | .globl main
|
| .type main, @function | .type main, @function
|
|main: |main:
|
|.LFB23: |.LFB11:
|
| .cfi_startproc | .cfi_startproc
|
| movl $1, -4(%rsp) | subq $24, %rsp
|
| movl -4(%rsp), %eax | .cfi_def_cfa_offset 32
|
| | xorl %edx, %edx
|
| | movl $1, 12(%rsp)
|
| | movl 12(%rsp), %eax
|
| | cmpl $1, %eax
|
| | movl $1, %eax
|
| | sete %dl
|
| | subl x110(%rip), %eax
|
| | sall $2, %eax
|
| | negl %eax
|
| | xorl $2, %eax
|
| | cmpl %eax, %edx
|
| | ja .L5
|
| xorl %eax, %eax | xorl %eax, %eax
|
| | addq $24, %rsp
|
| | .cfi_remember_state
|
| | .cfi_def_cfa_offset 8
|
| ret | ret
|
| |.L5:
|
| | .cfi_restore_state
|
| | call abort
|
| .cfi_endproc | .cfi_endproc
|
|.LFE23: |.LFE11:
|
| .size main, .-main | .size main, .-main
|
| .section .text.unlikely | .section
.text.unlikely |
|.LCOLDE0: |.LCOLDE0:
|
| .size x110, 4 | .size x110, 4
|
|x110: |x110:
|
| .zero 4 | .zero 4
|
+-----------------------------------------+-----------------------------------------+
Using built-in specs.
COLLECT_GCC=gcc-5
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='Ubuntu
5.1.0-0ubuntu11~14.04.1' --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=c++98 --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 --disable-werror --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 5.1.0 (Ubuntu 5.1.0-0ubuntu11~14.04.1)
Using built-in specs.
COLLECT_GCC=gcc-6.0.0
COLLECT_LTO_WRAPPER=/home/iwatsuji/opt/gcc-6.0.0/libexec/gcc/x86_64-unknown-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-build/gcc-master/configure
--prefix=/home/iwatsuji/opt/gcc-6.0.0 --enable-language=c --disable-nls
--disable-multilib
Thread model: posix
gcc version 6.0.0 20150416 (experimental) (GCC)
