[Bug debug/112582] Inconsistent Variable Values: Discrepancy between Source-Level and Instruction-Level Debugging

["iamanonymous.cs at gmail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112582

--- Comment #2 from Anonymous <iamanonymous.cs at gmail dot com> ---
(In reply to Andrew Pinski from comment #1)
>         .cfi_def_cfa_offset 32
>         .loc 1 27 5 view .LVU27
>         movl    $-5, %eax
>         .loc 1 28 5 view .LVU28
>         movl    $-10, %edx
>         .loc 1 29 3 view .LVU29 // point where after `si`'s is located
>         leaq    14(%rsp), %rsi
>         leaq    12(%rsp), %rdi
>         .loc 1 27 5 view .LVU30
>         movw    %ax, 12(%rsp)
>         .loc 1 28 3 is_stmt 1 view .LVU31
>         .loc 1 28 5 is_stmt 0 view .LVU32
>         movw    %dx, 14(%rsp)
>         .loc 1 29 3 is_stmt 1 view .LVU33 // point where step is 
>         call    foo
> ...
>        .ascii "x\0"    # DW_AT_name
>                         # DW_AT_decl_file (1, /app/example.c)
>                         # DW_AT_decl_line (0x1a)
>         .byte   0x16  # DW_AT_decl_column
>         .long   0x9e  # DW_AT_type
>         .uleb128 0x2    # DW_AT_location
>         .byte   0x91  # DW_OP_fbreg
>         .sleb128 -20
>         .uleb128 0x3    # (DIE (0x78) DW_TAG_variable)
>         .ascii "y\0"    # DW_AT_name
>                         # DW_AT_decl_file (1, /app/example.c)
>                         # DW_AT_decl_line (0x1a)
>         .byte   0x19  # DW_AT_decl_column
>         .long   0x9e  # DW_AT_type
>         .uleb128 0x2    # DW_AT_location
>         .byte   0x91  # DW_OP_fbreg
>         .sleb128 -18
> 
> Not a bug.

Thank you, Andrew, for your response. I have concerns regarding the information
provided by the debugger, as it may be somewhat misleading. Although the
debugger indicates that lines 27 and 28 have been executed, a closer
examination reveals that the assigned values of the x and y variables do not
align with expected results. From the user's perspective, it appears that lines
27 and 28 have indeed been executed, yet the variable values remain unchanged.
Therefore, I was wondering whether there are any guarantees from the compiler
or debugger.