[Bug gcov-profile/89470] New: [GCOV] wrong frequencies when if statement is executed after a complicated "?:"statement

[yangyibiao at nju dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89470

            Bug ID: 89470
           Summary: [GCOV] wrong frequencies when if statement is executed
                    after a complicated "?:"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
int foo()
{
  int hints = 2, xi = 1, dy = 18481, adx = 0, ady = 18481;
  if (dy != 0 && (adx <= ady >> 4))
  {
    hints = dy > 0 ? 2 : 1;
    if (xi) {
      hints ^= 3;
    }
  }
  else
  {
    hints = 0;
  }
  return hints;
}

int main()
{
  foo();
}

$ gcc -O0 --coverage small.c -w; ./a.out; gcov small.c; cat small.c.gcov
File 'small.c'
Lines executed:90.00% of 10
Creating 'small.c.gcov'

        -:    0:Source:small.c
        -:    0:Graph:small.gcno
        -:    0:Data:small.gcda
        -:    0:Runs:1
        -:    0:Programs:1
        1:    1:int foo()
        -:    2:{
        1:    3:  int hints = 2, xi = 1, dy = 18481, adx = 0, ady = 18481;
        1:    4:  if (dy != 0 && (adx <= ady >> 4)) {
       1*:    5:    hints = dy > 0 ? 2 : 1;
        2:    6:    if (xi) {
        1:    7:      hints ^= 3;
        -:    8:    }
        -:    9:  }
        -:   10:  else
        -:   11:  {
    #####:   12:    hints = 0;
        -:   13:  }
        1:   14:  return hints;
        -:   15:}
        -:   16:
        1:   17:int main()
        -:   18:{
        1:   19:  foo();
        -:   20:}

Line # 6 is wrongly marked as executed twice which should be only executed
once.

When Line #12 is removed, the result is correst as:
$ gcc -O0 --coverage small.c -w; ./a.out; gcov small.c; cat small.c.gcov
File 'small.c'
Lines executed:100.00% of 9
Creating 'small.c.gcov'

        -:    0:Source:small.c
        -:    0:Graph:small.gcno
        -:    0:Data:small.gcda
        -:    0:Runs:1
        -:    0:Programs:1
        1:    1:int foo()
        -:    2:{
        1:    3:  int hints = 2, xi = 1, dy = 18481, adx = 0, ady = 18481;
        1:    4:  if (dy != 0 && (adx <= ady >> 4)) {
       1*:    5:    hints = dy > 0 ? 2 : 1;
        1:    6:    if (xi) {
        1:    7:      hints ^= 3;
        -:    8:    }
        -:    9:  }
        -:   10:  else
        -:   11:  {
        -:   12:    // hints = 0;
        -:   13:  }
        1:   14:  return hints;
        -:   15:}
        -:   16:
        1:   17:int main()
        -:   18:{
        1:   19:  foo();
        -:   20:}