I think gcc produce wrong location information of function argument.
/***** sample source sub.c ******/
int test(int first, int second)
{
return second;
}
/********************************/
The sample source is compiled as follows.
======================================================
tan...@r48:/usr/local/te/bappl/test/$
/usr/local/te/tool/Linux-i686/bin/arm-unknown-elf-gcc -v -Wa,-v -g -c sub.c
Using built-in specs.
Target: arm-unknown-elf
Configured with:
/usr/local/te/tool/build/gnu/gcc-4.4.3-tkernel/gcc-4.4.3/configure
--prefix=/usr/local/te/tool/Linux-i686 --target=arm-unknown-elf --with-gnu-as
--with-gnu-ld --with-gmp-include=/usr/local/te/tool/Linux-i686/include-libs
--with-gmp-lib=/usr/local/te/tool/Linux-i686/lib
--with-mpfr-include=/usr/local/te/tool/Linux-i686/include-libs
--with-mpfr-lib=/usr/local/te/tool/Linux-i686/lib --enable-threads
--enable-languages=c,c++ --enable-version-specific-runtime-libs
--disable-libstdcxx-pch --disable-hosted-libstdcxx --disable-libada
Thread model: single
gcc version 4.4.3 (GCC)
COLLECT_GCC_OPTIONS='-v' '-g' '-c'
/usr/local/te/tool/Linux-i686/libexec/gcc/arm-unknown-elf/4.4.3/cc1 -quiet -v
-D__USES_INITFINI__ sub.c -quiet -dumpbase sub.c -auxbase sub -g -version -o
/tmp/ccqF2DxV.s
ignoring nonexistent directory
"/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/../../../../arm-unknown-elf/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/include
/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/include-fixed
/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/../../../../arm-unknown-elf/sys-include
End of search list.
GNU C (GCC) version 4.4.3 (arm-unknown-elf)
compiled by GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu4), GMP version
4.2.2, MPFR version 2.3.1.
GGC heuristics: --param ggc-min-expand=64 --param ggc-min-heapsize=64255
Compiler executable checksum: 20ebd17b34fa094008992b6e0117d9b5
COLLECT_GCC_OPTIONS='-v' '-g' '-c'
/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/../../../../arm-unknown-elf/bin/as
-v -v -o sub.o /tmp/ccqF2DxV.s
GNU assembler version 2.20.1 (arm-unknown-elf) using BFD version (GNU Binutils)
2.20.1.20100303
COMPILER_PATH=/usr/local/te/tool/Linux-i686/libexec/gcc/arm-unknown-elf/4.4.3/:/usr/local/te/tool/Linux-i686/libexec/gcc/arm-unknown-elf/4.4.3/:/usr/local/te/tool/Linux-i686/libexec/gcc/arm-unknown-elf/:/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/:/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/:/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/../../../../arm-unknown-elf/bin/
LIBRARY_PATH=/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/:/usr/local/te/tool/Linux-i686/lib/gcc/arm-unknown-elf/4.4.3/../../../../arm-unknown-elf/lib/
COLLECT_GCC_OPTIONS='-v' '-g' '-c'
tan...@r48:/usr/local/te/bappl/test/$
======================================================
The complied object file is disassembled as follows.
======================================================
/usr/local/te/tool/Linux-i686/bin/arm-unknown-elf-objdump -S sub.o
sub.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <test>:
int test(int first, int second)
{
0: e52db004 push {fp} ; (str fp, [sp, #-4]!)
4: e28db000 add fp, sp, #0
8: e24dd008 sub sp, sp, #8
c: e50b0004 str r0, [fp, #-4]
10: e50b1008 str r1, [fp, #-8]
return second;
14: e51b3008 ldr r3, [fp, #-8]
}
18: e1a00003 mov r0, r3
1c: e28bd000 add sp, fp, #0
20: e8bd0800 pop {fp}
24: e12fff1e bx lr
======================================================
Next is .debug_info.
DW_AT_location of argument "second" is "(DW_OP_fbreg: -12)".
I think DW_OP_fbreg must be -8.
Gdb shows wrong value for the argument.
Is there a patch for this problem.
======================================================
/usr/local/te/tool/Linux-i686/bin/arm-unknown-elf-readelf --debug-dump=info
sub.o
Contents of the .debug_info section:
Compilation Unit @ offset 0x0:
Length: 0x63 (32-bit)
Version: 2
Abbrev Offset: 0
Pointer Size: 4
<0><b>: Abbrev Number: 1 (DW_TAG_compile_unit)
< c> DW_AT_producer : (indirect string, offset: 0x26): GNU C 4.4.3
<10> DW_AT_language : 1 (ANSI C)
<11> DW_AT_name : (indirect string, offset: 0x37): sub.c
<15> DW_AT_comp_dir : (indirect string, offset: 0xd):
/usr/local/te/bappl/test
<19> DW_AT_low_pc : 0x0
<1d> DW_AT_high_pc : 0x28
<21> DW_AT_stmt_list : 0x0
<1><25>: Abbrev Number: 2 (DW_TAG_subprogram)
<26> DW_AT_external : 1
<27> DW_AT_name : (indirect string, offset: 0x32): test
<2b> DW_AT_decl_file : 1
<2c> DW_AT_decl_line : 1
<2d> DW_AT_prototyped : 1
<2e> DW_AT_type : <0x5f>
<32> DW_AT_low_pc : 0x0
<36> DW_AT_high_pc : 0x28
<3a> DW_AT_frame_base : 0x0 (location list)
<3e> DW_AT_sibling : <0x5f>
<2><42>: Abbrev Number: 3 (DW_TAG_formal_parameter)
<43> DW_AT_name : (indirect string, offset: 0x0): first
<47> DW_AT_decl_file : 1
<48> DW_AT_decl_line : 1
<49> DW_AT_type : <0x5f>
<4d> DW_AT_location : 2 byte block: 91 78 (DW_OP_fbreg: -8)
<2><50>: Abbrev Number: 3 (DW_TAG_formal_parameter)
<51> DW_AT_name : (indirect string, offset: 0x6): second
<55> DW_AT_decl_file : 1
<56> DW_AT_decl_line : 1
<57> DW_AT_type : <0x5f>
<5b> DW_AT_location : 2 byte block: 91 74 (DW_OP_fbreg: -12)
<1><5f>: Abbrev Number: 4 (DW_TAG_base_type)
<60> DW_AT_byte_size : 4
<61> DW_AT_encoding : 5 (signed)
<62> DW_AT_name : int
======================================================
best regards.
--
Summary: Dwarf:Wrong location information of function argument
Product: gcc
Version: 4.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: debug
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tanaka at personal-media dot co dot jp
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: arm-unknown-elf
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43439
