[Bug gcov-profile/85332] New: [GCOV] wrong coverage with do-while in swith-case statement

[yangyibiao at nju dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85332

            Bug ID: 85332
           Summary: [GCOV] wrong coverage with do-while in swith-case
                    statement
           Product: gcc
           Version: 8.0
            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/7/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 7.2.0-8ubuntu3'
--with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--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 7.2.0 (Ubuntu 7.2.0-8ubuntu3)

$ cat small.c
int doit(int sel, int n, void *p)
{
  int * const p0 = p;

  switch (sel)
  {
    case 0:
      do {*p0 += *p0;} while (--n);
      return *p0 == 0;

    default:
      abort ();
  }
}

int main()
{
  int v0;
  v0 = 1; doit(0, 3, &v0);
  exit (0);
}


$ gcc -w --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
File 'small.c'
Lines executed:81.82% of 11
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 doit(int sel, int n, void *p)
        -:    2:{
        1:    3:  int * const p0 = p;
        -:    4:
        1:    5:  switch (sel)
        -:    6:  {
        2:    7:    case 0:
        3:    8:      do {*p0 += *p0;} while (--n);
        1:    9:      return *p0 == 0;
        -:   10:
    #####:   11:    default:
    #####:   12:      abort ();
        -:   13:  }
        -:   14:}
        -:   15:
        1:   16:int main()
        -:   17:{
        -:   18:  int v0;
        1:   19:  v0 = 1; doit(0, 3, &v0);
        1:   20:  exit (0);
        -:   21:}

***
Line #7 is wrongly marked as executed twice.