[llvm-bugs] [Bug 37092] New: [LLVM-COV] Wrong coverage with comparison for a malloced memory address and NULL

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=37092

            Bug ID: 37092
           Summary: [LLVM-COV] Wrong coverage with comparison for a
                    malloced memory address and NULL
           Product: Runtime Libraries
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: enhancement
          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 <stdlib.h>

int main (void)
{
  static int *p;

  p = malloc (sizeof (int));
  if (p == NULL)
    return 0;

  *p = 7;
  return 1;
}

$ clang -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
    1|       |#include <stdlib.h>
    2|       |
    3|       |int main (void)
    4|      1|{
    5|      1|  static int *p;
    6|      1|
    7|      1|  p = malloc (sizeof (int));
    8|      1|  if (p == NULL)
    9|      1|    return 0;
   10|      1|
   11|      1|  *p = 7;
   12|      1|  return 1;
   13|      1|}


Line #9 is wrongly marked as executed.

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