[llvm-bugs] [Bug 51022] New: [llvm-cov] wrong coverage for a return statement with ternary operator

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51022

            Bug ID: 51022
           Summary: [llvm-cov] wrong coverage for a return statement with
                    ternary operator
           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
———————————————————

static volatile signed char true_var = 1;
static const volatile signed char false_var = 0;
extern void abort ();

int f(int x)
{
  return (x >> (sizeof (x) * __CHAR_BIT__ - 1)) ? -1 : 1;
}

volatile int one = 1;
int main (void)
{
  /* Test that the function above returns different values for
     different signs.  */
  if (f(one) == f(-one))
    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

    2|       |static volatile signed char true_var = 1;
    3|       |static const volatile signed char false_var = 0;
    4|       |extern void abort ();
    5|       |
    6|       |int f(int x)
    7|      2|{
    8|      1|  return (x >> (sizeof (x) * __CHAR_BIT__ - 1)) ? -1 : 1;
    9|      2|}
   10|       |
   11|       |volatile int one = 1;
   12|       |int main (void)
   13|      1|{
   14|       |  /* Test that the function above returns different values for
   15|       |     different signs.  */
   16|      1|  if (f(one) == f(-one))
   17|      0|    abort ();
   18|      1|  return 0;
   19|      1|}
   20|       |

Line 8 should be executed twice.

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