[llvm-bugs] [Bug 51009] New: [llvm-cov] "__builtin_setjump(buf)" statement leads to the incorrect coverage of the next statement.

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51009

            Bug ID: 51009
           Summary: [llvm-cov] "__builtin_setjump(buf)" statement leads to
                    the incorrect coverage of the next statement.
           Product: Runtime Libraries
           Version: 12.0
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: libprofile library
          Assignee: unassignedbugs at nondot.org
          Reporter: byone.heng at gmail.com
                CC: llvm-bugs at lists.llvm.org

$./clang -v                                                                     
clang version 12.0.0 (https://github.com/llvm/llvm-project.git
b6c8feb29fce39121884f7e08ec6eb0f58da3fb7)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/x/project/llvm-project/build/install/bin/.
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64

$cat test.c
———————————————————
#include <setjmp.h>

short int true_var = 1;
const volatile unsigned short int false_var = 0;

extern void abort (void);

jmp_buf buf;

void raise0(void)
{
  __builtin_longjmp (buf, 1);
}

int execute(int cmd)
{
  int last = 0;

  __builtin_setjmp (buf);

  if( true_var > 0 )
  {
  if (last == 0)
    while (1)
      {
        last = 1;
        raise0 ();
      }
  }

  if (last == 0)
    return 0;
  else
    return cmd;
}

int main(void)
{
  if (execute (1) == 0)
    abort ();

  return 0;
}

——————————————————

$clang -O0 -g -fcoverage-mapping -fprofile-instr-generate=test.profraw test.c;
./a.out; llvm-profdata merge test.profraw -o test.profdata; llvm-cov show a.out
-instr-profile=test.profdata test.c > test.lcov; cat test.lcov

    5|       |#include <setjmp.h>
    6|       |
    7|       |short int true_var = 1;
    8|       |const volatile unsigned short int false_var = 0;
    9|       |
   10|       |extern void abort (void);
   11|       |
   12|       |jmp_buf buf;
   13|       |
   14|       |void raise0(void)
   15|      1|{
   16|      1|  __builtin_longjmp (buf, 1);
   17|      1|}
   18|       |
   19|       |int execute(int cmd)
   20|      1|{
   21|      1|  int last = 0;
   22|       |
   23|      1|  __builtin_setjmp (buf);
   24|       |
   25|      1|  if( true_var > 0 )
   26|      2|  {
   27|      2|  if (last == 0)
   28|      2|    while (1)
   29|      1|    {
   30|      1|       last = 1;
   31|      1|       raise0 ();
   32|      1|    }
   33|      2|  }
   34|       |
   35|      1|  if (last == 0)
   36|      0|    return 0;
   37|      1|  else
   38|      1|    return cmd;
   39|      1|}
   40|       |
   41|       |int main(void)
   42|      1|{
   43|      1|  if (execute (1) == 0)
   44|      0|    abort ();
   45|       |
   46|      1|  return 0;
   47|      1|}

Line 25 should be executed twice.

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