[llvm-bugs] [Bug 51011] New: [llvm-cov] wrong coverage for a for loop within "exit(0)" statement

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=51011

            Bug ID: 51011
           Summary: [llvm-cov] wrong coverage for a for loop within
                    "exit(0)" 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
———————————————————
unsigned int true_var = 1;
static const unsigned int false_var = 0;
extern void exit (int);
extern void abort (void);

volatile int a = 1;
volatile int b = 0;
volatile int x = 2;
volatile signed int r = 8;

void __attribute__((noinline))
foo (void)
{
  exit (0);
}

int
main (void)
{
  int si1 = a;
  int si2 = b;
  int i;

  for (i = 0; i < 100; ++i) {
      foo ();
      if (x == 8)
        i++;
      r += i + si1 % si2;
  }
  abort ();
}
——————————————————

$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

    1|       |
    2|       |unsigned int true_var = 1;
    3|       |static const unsigned int false_var = 0;
    4|       |extern void exit (int);
    5|       |extern void abort (void);
    6|       |
    7|       |volatile int a = 1;
    8|       |volatile int b = 0;
    9|       |volatile int x = 2;
   10|       |volatile signed int r = 8;
   11|       |
   12|       |void __attribute__((noinline))
   13|       |foo (void)
   14|      1|{
   15|      1|  exit (0);
   16|      1|}
   17|       |
   18|       |int
   19|       |main (void)
   20|      1|{
   21|      1|  int si1 = a;
   22|      1|  int si2 = b;
   23|      1|  int i;
   24|       |
   25|      2|  for (i = 0; i < 100; ++i) {
   26|      1|      foo ();
   27|      1|      if (x == 8)
   28|      0|          i++;
   29|      1|      r += i + si1 % si2;
   30|      1|  }
   31|      1|  abort ();
   32|      1|}

This bug is similar to bug 51003, I am not sure whether they belong to the same
bug. 
Line 25 should be executed once. Line 27 and 29 should not be executed.

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