[Bug gcov-profile/89467] New: [GCOV] wrong freqencies when there is comparison operator in the right side of the assignment statement

[yangyibiao at nju dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89467

            Bug ID: 89467
           Summary: [GCOV] wrong freqencies when there is comparison
                    operator in the right side of the assignment statement
           Product: gcc
           Version: 8.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yangyibiao at nju dot edu.cn
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$ 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
8.2.0-1ubuntu2~18.04' --with-bugurl=file:///usr/share/doc/gcc-8/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,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 --with-target-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 --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu
Thread model: posix
gcc version 8.2.0 (Ubuntu 8.2.0-1ubuntu2~18.04)

$ cat small.c
void foo(int p)
{
  int e;
  int b = 0, f = 0, d = 0;
  if ((p < f) && p) {
L:
    for (e = 0; 0;) ;
  } else if (d) {
    b = (0 >= b);
  }

  for (; e <= 3; e++) {
    if (b) { continue; }
    b = 3;
    goto L;
  }
}

void main()
{
  int a = -1;
  foo(a);
}

$ gcc -O0 --coverage small.c -w; ./a.out; gcov small.c; cat small.c.gcov
File 'small.c'
Lines executed:87.50% of 16
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 foo(int p)
        -:    2:{
        -:    3:  int e;
        1:    4:  int b = 0, f = 0, d = 0;
        3:    5:  if ((p < f) && p) {
        1:    6:L:
        2:    7:    for (e = 0; 0;) ;
    #####:    8:  } else if (d) {
    #####:    9:    b = (0 >= b);
        -:   10:  }
        -:   11:
        6:   12:  for (; e <= 3; e++) {
        5:   13:    if (b) { continue; }
        1:   14:    b = 3;
        1:   15:    goto L;
        -:   16:  }
        1:   17:}
        -:   18:
        1:   19:void main()
        -:   20:{
        1:   21:  int a = -1;
        1:   22:  foo(a);
        1:   23:}

Line #5 is wrongly marked as executed 3 times which should be only executed
once. 

When Line #9 is removed, the coverage report will be correct as:

$ gcc -O0 --coverage small.c -w; ./a.out; gcov small.c; cat small.c.gcov
File 'small.c'
Lines executed:100.00% of 14
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 foo(int p)
        -:    2:{
        -:    3:  int e;
        1:    4:  int b = 0, f = 0, d = 0;
        1:    5:  if ((p < f) && p) {
        1:    6:L:
        2:    7:    for (e = 0; 0;) ;
        -:    8:  } else if (d) {
        -:    9:    // b = (0 >= b);
        -:   10:  }
        -:   11:
        6:   12:  for (; e <= 3; e++) {
        5:   13:    if (b) { continue; }
        1:   14:    b = 3;
        1:   15:    goto L;
        -:   16:  }
        1:   17:}
        -:   18:
        1:   19:void main()
        -:   20:{
        1:   21:  int a = -1;
        1:   22:  foo(a);
        1:   23:}