Bug 85201 - [GCOV] A statement with two && operators and a comma operator in the for loop body is wrongly marked in gcov
Summary: [GCOV] A statement with two && operators and a comma operator in the for loop...
Status: NEW
Alias: None
Product: gcc
Classification: Unclassified
Component: gcov-profile (show other bugs)
Version: 8.0
: P5 normal
Target Milestone: 9.0
Assignee: Not yet assigned to anyone
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-04-04 14:31 UTC by Yibiao Yang
Modified: 2018-07-25 11:11 UTC (History)
3 users (show)

See Also:
Host:
Target:
Build:
Known to work:
Known to fail:
Last reconfirmed: 2018-04-24 00:00:00


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Description Yibiao Yang 2018-04-04 14:31:08 UTC
$ gcc -v 
gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 8-20170923-1ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs --enable-languages=c,c++,go,brig,fortran,objc,obj-c++ --prefix=/usr --with-gcc-major-version-only --program-suffix=-8 --program-prefix=x86_64-linux-gnu- --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 --enable-default-pie --with-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 8.0.0 20170923 (experimental) [trunk revision 253118] (Ubuntu 8-20170923-1ubuntu2)

$ cat small.c
void main() {
  int a = 0;
  int b = 0;
  int c = 0;
  for (; a >= 0; a--) {
    (c && b, 1) && b;
  }
}

$ gcc -w --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
File 'small.c'
Lines executed:100.00% of 7
Creating 'small.c.gcov'

        -:    0:Source:small.c
        -:    0:Graph:small.gcno
        -:    0:Data:small.gcda
        -:    0:Runs:1
        -:    0:Programs:1
        1:    1:void main() {
        1:    2:  int a = 0;
        1:    3:  int b = 0;
        1:    4:  int c = 0;
        2:    5:  for (; a >= 0; a--) {
        2:    6:    (c && b, 1) && b;
        -:    7:  }
        1:    8:}


Line #6 is wrongly marked as executed twice.
Comment 1 Yibiao Yang 2018-04-05 07:52:30 UTC
(In reply to Yibiao Yang from comment #0)
> $ gcc -v 
> gcc -v
> Using built-in specs.
> COLLECT_GCC=gcc
> COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/8/lto-wrapper
> OFFLOAD_TARGET_NAMES=nvptx-none
> OFFLOAD_TARGET_DEFAULT=1
> Target: x86_64-linux-gnu
> Configured with: ../src/configure -v --with-pkgversion='Ubuntu
> 8-20170923-1ubuntu2' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
> --enable-languages=c,c++,go,brig,fortran,objc,obj-c++ --prefix=/usr
> --with-gcc-major-version-only --program-suffix=-8
> --program-prefix=x86_64-linux-gnu- --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 --enable-default-pie
> --with-system-zlib --enable-objc-gc=auto --enable-multiarch --disable-werror
> --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32
> --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none
> --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
> --target=x86_64-linux-gnu
> Thread model: posix
> gcc version 8.0.0 20170923 (experimental) [trunk revision 253118] (Ubuntu
> 8-20170923-1ubuntu2)
> 
> $ cat small.c
> void main() {
>   int a = 0;
>   int b = 0;
>   int c = 0;
>   for (; a >= 0; a--) {
>     (c && b, 1) && b;
>   }
> }
> 
> $ gcc -w --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
> File 'small.c'
> Lines executed:100.00% of 7
> Creating 'small.c.gcov'
> 
>         -:    0:Source:small.c
>         -:    0:Graph:small.gcno
>         -:    0:Data:small.gcda
>         -:    0:Runs:1
>         -:    0:Programs:1
>         1:    1:void main() {
>         1:    2:  int a = 0;
>         1:    3:  int b = 0;
>         1:    4:  int c = 0;
>         2:    5:  for (; a >= 0; a--) {
>         2:    6:    (c && b, 1) && b;

I am not sure this is a duplication of bug 85163. When changing the operators in the code of bug 85163, the result is correct. While  changing '&&' to '||' of the code here, the problem is still exist. 

>         -:    7:  }
>         1:    8:}
> 
> 
> Line #6 is wrongly marked as executed twice.
Comment 2 Yibiao Yang 2018-04-23 15:37:06 UTC
@marxin Is this a real bug? or this bug is only default behavior?
Comment 3 Martin Liška 2018-04-24 08:00:08 UTC
(In reply to Yibiao Yang from comment #2)
> @marxin Is this a real bug? or this bug is only default behavior?

I have to take a look. I'm planning to return to it in summer in batch.
Comment 4 Martin Liška 2018-07-25 11:11:49 UTC
Confirmed, but low priority.