[llvm-bugs] [Bug 49426] New: [LLVM-COV] Dead code after goto statement was wrongly marked as executed

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49426

            Bug ID: 49426
           Summary: [LLVM-COV] Dead code after goto statement was wrongly
                    marked as executed
           Product: Runtime Libraries
           Version: 11.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: libprofile library
          Assignee: unassignedbugs at nondot.org
          Reporter: cnwy1996 at outlook.com
                CC: llvm-bugs at lists.llvm.org

$ clang -v
clang version 11.0.0
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/wangyang/llvm-project/build/bin
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
Selected multilib: .;@m64

$ cat test.c
extern void abort(void);
extern void exit(int);

int sub1(int val) { return val; }

int testcond(int val) {
  int flag1;

  {
    int t1 = val;
    {
      int t2 = t1;
      {
        flag1 = sub1(t2) == 0;
        goto lab1;
        t2++;
      };
    }
  lab1:;
  }

  if (flag1 != 0)
    return 0x4d0000;
  else
    return 0;
}

int main(void) {
  if (testcond(1))
    abort();
  exit(0);
}

$ clang -w -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|       |extern void abort(void);
    2|       |extern void exit(int);
    3|       |
    4|      1|int sub1(int val) { return val; }
    5|       |
    6|      1|int testcond(int val) {
    7|      1|  int flag1;
    8|      1|
    9|      1|  {
   10|      1|    int t1 = val;
   11|      1|    {
   12|      1|      int t2 = t1;
   13|      1|      {
   14|      1|        flag1 = sub1(t2) == 0;
   15|      1|        goto lab1;
   16|      1|        t2++;
   17|      0|      };
   18|      0|    }
   19|      1|  lab1:;
   20|      1|  }
   21|      1|
   22|      1|  if (flag1 != 0)
   23|      0|    return 0x4d0000;
   24|      1|  else
   25|      1|    return 0;
   26|      1|}
   27|       |
   28|      1|int main(void) {
   29|      1|  if (testcond(1))
   30|      0|    abort();
   31|      1|  exit(0);
   32|      1|}

Line #16 should never be excuted.

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