[llvm-bugs] [Bug 49427] New: [LLVM-COV] Wrong coverage with the default label in switch statement

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=49427

            Bug ID: 49427
           Summary: [LLVM-COV] Wrong coverage with the default label in
                    switch statement
           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
void foo(int v, int w) {
  int i;
  if (w) {
    goto do_default;
  }
  switch (v) {
  case 0:
    i = 27;
    break;
  case 1:
    i = 8;
    break;
  default:
  do_default:
    i = 10;
    break;
  }
}

int main(){
int i;
for(i=0;i<6;i++){
    if(i<4)
        foo(i,0);
    else
        foo(i,1);
}
}

$ 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|      6|void foo(int v, int w) {
    2|      6|  int i;
    3|      6|  if (w) {
    4|      2|    goto do_default;
    5|      2|  }
    6|      4|  switch (v) {
    7|      1|  case 0:
    8|      1|    i = 27;
    9|      1|    break;
   10|      1|  case 1:
   11|      1|    i = 8;
   12|      1|    break;
   13|      4|  default:
   14|      4|  do_default:
   15|      4|    i = 10;
   16|      4|    break;
   17|      4|  }
   18|      4|}
   19|       |
   20|      1|int main(){
   21|      1|int i;
   22|      7|for(i=0;i<6;i++){
   23|      6|    if(i<4)
   24|      4|        foo(i,0);
   25|      2|    else
   26|      2|        foo(i,1);
   27|      6|}
   28|      1|}

Line #13 should be executed twice instead of 4 times

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