[Bug gcov-profile/85372] New: [GCOV] Wrong coverage with setjmp and longjmp function

[yangyibiao at nju dot edu.cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85372

            Bug ID: 85372
           Summary: [GCOV] Wrong coverage with setjmp and longjmp function
           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/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 *buf[5];

void fjmp (void) {
  __builtin_longjmp (buf, 1);
}

int main(void)
{
  int last = 0;

  if (__builtin_setjmp (buf) == 0) {
    __builtin_printf("True  branch\n");
    while (1) {
      last = 1;
      fjmp ();
    }
  } else {
    __builtin_printf("False branch\n");
  }

  return 0;
}

$ gcc --coverage small.c; ./a.out; gcov-8 small.c; cat small.c.gcov
True  branch
False branch
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:void *buf[5];
        -:    2:
        1:    3:void fjmp (void) {
        1:    4:  __builtin_longjmp (buf, 1);
        -:    5:}
        -:    6:
        1:    7:int main(void)
        -:    8:{
        1:    9:  int last = 0;
        -:   10:
        2:   11:  if (__builtin_setjmp (buf) == 0) {
        1:   12:    __builtin_printf("True  branch\n");
        -:   13:    while (1) {
    #####:   14:      last = 1;
        1:   15:      fjmp ();
        -:   16:    }
        -:   17:  } else {
        1:   18:    __builtin_printf("False branch\n");
        -:   19:  }
        -:   20:
        1:   21:  return 0;
        -:   22:}


Line #14 is wrongly marked as not executed with "#####". 
In the first setjmp always return 0, then execute the true branch. Thus, Line
#14 should be executed.