[Bug sanitizer/109313] New: Incorrect line number in Use-After-Scope report

[Bug sanitizer/109313] New: Incorrect line number in Use-After-Scope report

[shaohua.li at inf dot ethz.ch]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109313

            Bug ID: 109313
           Summary: Incorrect line number in Use-After-Scope report
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: shaohua.li at inf dot ethz.ch
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org, marxin at gcc dot gnu.org
  Target Milestone: ---

For the following code, Asan reports an incorrect line number at -O1 and above. 

Compiler explorer: https://godbolt.org/z/KsroWf9M6

% cat -n a.c
     1  int a, b;
     2  int main() {
     3    int *c=&a;
     4    b = 0;
     5    for (; b < 1; b++) {
     6      int d=1;
     7      c = &d;
     8      if (a)
     9        break;
    10    }
    11    if (*c) {
    12      int e[1]={2};
    13      return e[0];
    14    }
    15  }
%
% gcc-tk -O0 -fsanitize=address a.c && ./a.out
=================================================================
==1==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f2293700030
at pc 0x0000004012de bp 0x7ffca6ef0690 sp 0x7ffca6ef0688
READ of size 4 at 0x7f2293700030 thread T0
    #0 0x4012dd in main /a.c:11
...
%
% gcc-tk -O1 -fsanitize=address a.c && ./a.out
=================================================================
==1==ERROR: AddressSanitizer: stack-use-after-scope on address 0x7f7c4d200020
at pc 0x0000004011ee bp 0x7fff0179f250 sp 0x7fff0179f248
READ of size 4 at 0x7f7c4d200020 thread T0
    #0 0x4011ed in main /a.c:5
...
%

[Bug sanitizer/109313] Incorrect line number in Use-After-Scope report

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109313

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
When ccp3 changes (correctly):
  <bb 4> [local count: 958878296]:
  .ASAN_MARK (POISON, &d, 4);
  [/app/example.cpp:6:24] b.1_2 = b;
  [/app/example.cpp:6:24] _3 = b.1_2 + 1;
  [/app/example.cpp:6:24] b = _3;
  [/app/example.cpp:6:18] if (_3 <= 0)
    goto <bb 3>; [94.50%]
  else
    goto <bb 6>; [5.50%]

  <bb 5> [local count: 55807731]:
  .ASAN_MARK (POISON, &d, 4);

  <bb 6> [local count: 114863531]:
  [/app/example.cpp:12:13] _5 = d;

Into:
  <bb 4> [local count: 958878296]:
  d_9 = .ASAN_POISON ();
  [/app/example.cpp:6:24] b.1_2 = b;
  [/app/example.cpp:6:24] _3 = b.1_2 + 1;
  [/app/example.cpp:6:24] b = _3;
  [/app/example.cpp:6:18] if (_3 <= 0)
    goto <bb 3>; [94.50%]
  else
    goto <bb 6>; [5.50%]

  <bb 5> [local count: 55807731]:
  d_6 = .ASAN_POISON ();

  <bb 6> [local count: 114863531]:
  # d_22 = PHI <[0:0] d_6(5), [0:0] d_9(4)>
  [/app/example.cpp:12:13] _5 = d_22;

The location of the load is missing and now is always a direct poison call
without any location info left over.

I am not sure how this would work out really ...