[llvm-bugs] [Bug 37081] New: [LLVM-COV] wrong coverage with setjmp

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=37081

            Bug ID: 37081
           Summary: [LLVM-COV] wrong coverage with setjmp
           Product: Runtime Libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: libprofile library
          Assignee: unassignedbugs at nondot.org
          Reporter: yangyibiao at nju.edu.cn
                CC: llvm-bugs at lists.llvm.org

$ clang -v
clang version 7.0.0- (trunk)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.1
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/6.4.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.2.0
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8.0.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.4.1
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.4.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.2.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8.0.0
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8.0.0
Candidate multilib: .;@m64
Selected multilib: .;@m64

$ cat small.c
#include <setjmp.h>
#include <stdio.h>

int bar(jmp_buf buf, int i)
{
  printf("Inside bar %d\n", i);
  longjmp(buf, i);
}

int main()
{
  jmp_buf buf;
  int ret;

  if ((ret = setjmp(buf)) != 0) {
    printf("True  branch.\n");
  } else {
    printf("False branch.\n");
    bar(buf, 2);
  }

  return 0;
}


$ clang -w -O0 -g -fcoverage-mapping -fprofile-instr-generate=small.profraw
small.c; ./a.out; llvm-profdata merge small.profraw -o small.profdata; llvm-cov
show a.out -instr-profile=small.profdata small.c > small.gcov; cat small.gcov
False branch.
Inside bar 2
True  branch.
    1|       |#include <setjmp.h>
    2|       |#include <stdio.h>
    3|       |
    4|       |int bar(jmp_buf buf, int i)
    5|      1|{
    6|      1|  printf("Inside bar %d\n", i);
    7|      1|  longjmp(buf, i);
    8|      1|}
    9|       |
   10|       |int main()
   11|      1|{
   12|      1|  jmp_buf buf;
   13|      1|  int ret;
   14|      1|
   15|      1|  if ((ret = setjmp(buf)) != 0) {
   16|      1|    printf("True  branch.\n");
   17|      1|  } else {
   18|      0|    printf("False branch.\n");
   19|      0|    bar(buf, 2);
   20|      0|  }
   21|      1|
   22|      1|  return 0;
   23|      1|}


*****
Line #18 and Line 19 are wrongly marked as not executed. 
However, in terms of output, Line #18 and #19 are executed.

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