[Bug debug/109487] New: GCC generates redundant DWARF information after DW_OP_stack_value.

[hluaw at connect dot ust.hk via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109487

            Bug ID: 109487
           Summary: GCC generates redundant DWARF information after
                    DW_OP_stack_value.
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hluaw at connect dot ust.hk
  Target Milestone: ---

Given the following code:
#include "stdint.h"
struct S0 {
  signed a : 25;
  const int b;
};
int c, d;
int func_29(uint64_t p1, struct S0 p2, uint16_t p3) {
  d = p2.a;
  p2.a = 0;
}
int main() {
  struct S0 e[] = {{}, {}, {}, {}, {5, 0}, {338810, 4728}};
  func_29(c, e[5], 0);
}

Compiled with GCC 12.2.0 and -O1

GCC generates the following DWARF information on p2.

DW_OP_const4u: 338810; 
DW_OP_stack_value; 
DW_OP_bit_piece: size: 25 offset: 0; 
DW_OP_bit_piece: size: 39 offset: 0

But in DWARFv5, DW_OP_stack_value immediately terminate the evaluation of DWARF
expression.

These redundant information are unnecessary and causes trouble in LLDB, making
it unable to display the value of p2.

I know this case somehow is in the "grey area" of the standard, but it is still
a redundant...