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Re: Wrong mappin of registers in location lists
- From: Josef Zlomek <zlomekj at suse dot cz>
- To: Michal Ludvig <mludvig at suse dot cz>
- Cc: Daniel Berlin <dberlin at dberlin dot org>, GCC list <gcc at gcc dot gnu dot org>
- Date: Fri, 14 Feb 2003 17:10:20 +0100
- Subject: Re: Wrong mappin of registers in location lists
- References: <3E4D1382.4020008@suse.cz>
> as far as I can see gcc outputs wrong information to .debug_loc on
> x86-64. This is the assembler output:
>
> main:
> .LVL22:
> pushq %rbx
> movl %edi, %ebx
> .LVL23:
> leal 1(%rbx), %edi
> subq $416, %rsp
> [...]
>
> This is DIE of argc:
> .uleb128 0x3 # (DIE (0xef) DW_TAG_formal_parameter)
> .long .LASF4 # DW_AT_name: "argc"
> .byte 0x1 # DW_AT_decl_file
> .byte 0x17 # DW_AT_decl_line
> .long 0x8f # DW_AT_type
> .long .LLST3-.Ldebug_loc0 # DW_AT_location
>
> And finally location list of argc:
> .LLST3:
> .quad .LVL22-.text # Location list begin address (*.LLST3)
> .quad .LVL23-.text # Location list end address (*.LLST3)
> .value 0x1 # Location expression size
> .byte 0x55 # DW_OP_reg5
> .quad .LVL23-.text # Location list begin address (*.LLST3)
> .quad .LFE7-.text # Location list end address (*.LLST3)
> .value 0x1 # Location expression size
> .byte 0x53 # DW_OP_reg3
> .quad 0x0 # Location list terminator begin (*.LLST3)
> .quad 0x0 # Location list terminator end (*.LLST3)
>
> At the entry of the function (.LVL22), argc is dwarf2 register 5
> (DW_OP_reg5), ie %rdi on x86-64. From .LVL23 on it is saved in %rbx, ie.
> DW_OP_reg1. However debug information says it's in DW_OP_reg3, ie. %rdx.
I do not know the register numbers for dwarf, but in gcc core the numbering is this:
(from gcc/gcc/config/i386/i386.h:)
#define ADDITIONAL_REGISTER_NAMES \
{ { "eax", 0 }, { "edx", 1 }, { "ecx", 2 }, { "ebx", 3 }, \
{ "esi", 4 }, { "edi", 5 }, { "ebp", 6 }, { "esp", 7 }, \
Josef