[lldb-dev] How is variable info retrieved in debugging for executables generated by llvm backend?

Greg Clayton gclayton at apple.com
Wed Feb 19 11:03:11 PST 2014


If I had to guess, I would venture to say your problem is one of:
1 - you don't have your registers correctly defined and didn't specify the DWARF register numbers for your register context
2 - your DWARF is incorrect

I am guessing #1 is your issue. 

How are you debugging your program? Are you using the GDB remote protocol? If so, how did you tell LLDB about all of your CPU registers? Did you use the LLDB specific GDB remote extensions? Did you specify a target definition python file? You will need to make sure that you tell LLDB about all of your CPU registers and also tell LLDB the DWARF register number for each register accurately.

Variable "a" has debug info:

0x00000054:         DW_TAG_variable [4]  
                     DW_AT_name( "a" )
                     DW_AT_decl_file( "/home/yangyy/workspace/newlib/test.c" )
                     DW_AT_decl_line( 4 )
                     DW_AT_type( {0x0000007f} ( int ) )
                     DW_AT_location( fbreg +16 )

The location says it is at the frame base register + 16 bytes. The frame base is defined in the parent DIE:

0x00000022:     DW_TAG_subprogram [2] *
                 DW_AT_name( "main" )
                 DW_AT_decl_file( "/home/yangyy/workspace/newlib/test.c" )
                 DW_AT_decl_line( 2 )
                 DW_AT_prototyped( true )
                 DW_AT_type( {0x0000007f} ( int ) )
                 DW_AT_external( true )
                 DW_AT_low_pc( 0x00000028 )
                 DW_AT_high_pc( 0x00000084 )
                 DW_AT_frame_base( regx 0x0000003c )

So it says the frame base register is DWARF register 0x3c. In your target definition you will need to have told us which register has the DWARF register number 0x3c, otherwise we will fail to evaluate the expression.

Greg


On Feb 18, 2014, at 11:10 PM, 杨勇勇 <triple.yang at gmail.com> wrote:

> Sorry, this is the attachment.
> 
> 
> 2014-02-19 15:08 GMT+08:00 杨勇勇 <triple.yang at gmail.com>:
> Thank you.
> 
> Here is an example and the attchment contains extra files including object file and executable file.
> I want to print for example the value of "a", but lldb command "frame variable a" displays "0" and so does "b", and "c".
> Meanwhile, the value is correct if I directly check registers or memory.
> 
> Following content is composed of three part:
> 1. C program.
> 2. assembly file including directives of dwarf debug info.
> 3. dwarf debug info dumpped from executable file with llvm-dwarfdump.
> 
> ///////////////////////////////////////////////////////////////////////////////////////////
> // C
> int
> main(int argc, char *argv[])
> {
>   int a = 11;
>   int b = 22;
>   int c = a+b;
>   return c;
> }
> 
> ######################################
> # asm including dwarf debugging info
> 	.file	"test.c"
> 	.section	.debug_info,"", at progbits
> Lsection_info:
> 	.section	.debug_abbrev,"", at progbits
> Lsection_abbrev:
> 	.section	.debug_aranges,"", at progbits
> 	.section	.debug_macinfo,"", at progbits
> 	.section	.debug_line,"", at progbits
> Lsection_line:
> 	.section	.debug_loc,"", at progbits
> 	.section	.debug_pubtypes,"", at progbits
> 	.section	.debug_str,"MS", at progbits,1
> Linfo_string:
> 	.section	.debug_ranges,"", at progbits
> Ldebug_range:
> 	.section	.debug_loc,"", at progbits
> Lsection_debug_loc:
> 	.text
> Ltext_begin:
> 	.data
> 	.file	1 "test.c"
> 	.text
> 	.global	main
> 	.type	main, at function
> main:                                   # @main
> Lfunc_begin0:
> 	.loc	1 3 0                   # test.c:3:0
> # BB#0:                                 # %entry
> 	.loc	1 2 0 prologue_end      # test.c:2:0
> 	[SP + -4] = FP;;
> 	[SP + -8] = J30;;
> 	FP = SP;;
> 	J31 = -40;;
> 	SP = SP + J31;;
> 	#DEBUG_VALUE: main:argc <- undef
> 	#DEBUG_VALUE: main:argv <- undef
> 	R2 = 0;;
> 	R3 = 11;;
> 	[FP + -12] = R2;;
> 	[FP + -16] = R0;;
> 	[FP + -20] = R1;;
> 	.loc	1 4 0                   # test.c:4:0
> 	[FP + -24] = R3;;
> 	R2 = 22;;
> 	.loc	1 5 0                   # test.c:5:0
> 	[FP + -28] = R2;;
> 	.loc	1 6 0                   # test.c:6:0
> 	R3 = [FP + -24];;
> 	R2 = R3 + R2 (T);;
> 	[FP + -32] = R2;;
> 	.loc	1 7 0                   # test.c:7:0
> 	[FP + -36] = R0;;
> 	R0 = R2;;
> 	[FP + -40] = R1;;
> 	SP = FP;;
> 	J30 = [SP + -8];;
> 	FP = [SP + -4];;
> 	jump J30;;
> Ltmp0:
> Ltmp1:
> 	.size	main, Ltmp1-main
> Lfunc_end0:
> 
> Ltext_end:
> 	.data
> Ldata_end:
> 	.text
> Lsection_end1:
> 	.section	.debug_info,"", at progbits
> L.debug_info_begin0:
> 	.int	148                     # Length of Compilation Unit Info
> 	.short	2                       # DWARF version number
> 	.int	L.debug_abbrev_begin    # Offset Into Abbrev. Section
> 	.byte	4                       # Address Size (in bytes)
> 	.byte	1                       # Abbrev [1] 0xb:0x8d DW_TAG_compile_unit
> 	.int	Linfo_string0           # DW_AT_producer
> 	.short	12                      # DW_AT_language
> 	.int	Linfo_string1           # DW_AT_name
> 	.int	0                       # DW_AT_low_pc
> 	.int	Lsection_line           # DW_AT_stmt_list
> 	.int	Linfo_string2           # DW_AT_comp_dir
> 	.byte	2                       # Abbrev [2] 0x22:0x5d DW_TAG_subprogram
> 	.int	Linfo_string3           # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	2                       # DW_AT_decl_line
>                                         # DW_AT_prototyped
> 	.int	127                     # DW_AT_type
>                                         # DW_AT_external
> 	.int	Lfunc_begin0            # DW_AT_low_pc
> 	.int	Lfunc_end0              # DW_AT_high_pc
> 	.byte	2                       # DW_AT_frame_base
> 	.byte	144
> 	.byte	60
> 	.byte	3                       # Abbrev [3] 0x38:0xe DW_TAG_formal_parameter
> 	.int	Linfo_string5           # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	2                       # DW_AT_decl_line
> 	.int	127                     # DW_AT_type
> 	.byte	2                       # DW_AT_location
> 	.byte	145
> 	.byte	24
> 	.byte	3                       # Abbrev [3] 0x46:0xe DW_TAG_formal_parameter
> 	.int	Linfo_string6           # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	2                       # DW_AT_decl_line
> 	.int	146                     # DW_AT_type
> 	.byte	2                       # DW_AT_location
> 	.byte	145
> 	.byte	20
> 	.byte	4                       # Abbrev [4] 0x54:0xe DW_TAG_variable
> 	.int	Linfo_string8           # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	4                       # DW_AT_decl_line
> 	.int	127                     # DW_AT_type
> 	.byte	2                       # DW_AT_location
> 	.byte	145
> 	.byte	16
> 	.byte	4                       # Abbrev [4] 0x62:0xe DW_TAG_variable
> 	.int	Linfo_string9           # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	5                       # DW_AT_decl_line
> 	.int	127                     # DW_AT_type
> 	.byte	2                       # DW_AT_location
> 	.byte	145
> 	.byte	12
> 	.byte	4                       # Abbrev [4] 0x70:0xe DW_TAG_variable
> 	.int	Linfo_string10          # DW_AT_name
> 	.byte	1                       # DW_AT_decl_file
> 	.byte	6                       # DW_AT_decl_line
> 	.int	127                     # DW_AT_type
> 	.byte	2                       # DW_AT_location
> 	.byte	145
> 	.byte	8
> 	.byte	0                       # End Of Children Mark
> 	.byte	5                       # Abbrev [5] 0x7f:0x7 DW_TAG_base_type
> 	.int	Linfo_string4           # DW_AT_name
> 	.byte	5                       # DW_AT_encoding
> 	.byte	4                       # DW_AT_byte_size
> 	.byte	5                       # Abbrev [5] 0x86:0x7 DW_TAG_base_type
> 	.int	Linfo_string7           # DW_AT_name
> 	.byte	6                       # DW_AT_encoding
> 	.byte	1                       # DW_AT_byte_size
> 	.byte	6                       # Abbrev [6] 0x8d:0x5 DW_TAG_pointer_type
> 	.int	134                     # DW_AT_type
> 	.byte	6                       # Abbrev [6] 0x92:0x5 DW_TAG_pointer_type
> 	.int	141                     # DW_AT_type
> 	.byte	0                       # End Of Children Mark
> L.debug_info_end0:
> 	.section	.debug_abbrev,"", at progbits
> L.debug_abbrev_begin:
> 	.byte	1                       # Abbreviation Code
> 	.byte	17                      # DW_TAG_compile_unit
> 	.byte	1                       # DW_CHILDREN_yes
> 	.byte	37                      # DW_AT_producer
> 	.byte	14                      # DW_FORM_strp
> 	.byte	19                      # DW_AT_language
> 	.byte	5                       # DW_FORM_data2
> 	.byte	3                       # DW_AT_name
> 	.byte	14                      # DW_FORM_strp
> 	.byte	17                      # DW_AT_low_pc
> 	.byte	1                       # DW_FORM_addr
> 	.byte	16                      # DW_AT_stmt_list
> 	.byte	6                       # DW_FORM_data4
> 	.byte	27                      # DW_AT_comp_dir
> 	.byte	14                      # DW_FORM_strp
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	2                       # Abbreviation Code
> 	.byte	46                      # DW_TAG_subprogram
> 	.byte	1                       # DW_CHILDREN_yes
> 	.byte	3                       # DW_AT_name
> 	.byte	14                      # DW_FORM_strp
> 	.byte	58                      # DW_AT_decl_file
> 	.byte	11                      # DW_FORM_data1
> 	.byte	59                      # DW_AT_decl_line
> 	.byte	11                      # DW_FORM_data1
> 	.byte	39                      # DW_AT_prototyped
> 	.byte	25                      # DW_FORM_flag_present
> 	.byte	73                      # DW_AT_type
> 	.byte	19                      # DW_FORM_ref4
> 	.byte	63                      # DW_AT_external
> 	.byte	25                      # DW_FORM_flag_present
> 	.byte	17                      # DW_AT_low_pc
> 	.byte	1                       # DW_FORM_addr
> 	.byte	18                      # DW_AT_high_pc
> 	.byte	1                       # DW_FORM_addr
> 	.byte	64                      # DW_AT_frame_base
> 	.byte	10                      # DW_FORM_block1
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	3                       # Abbreviation Code
> 	.byte	5                       # DW_TAG_formal_parameter
> 	.byte	0                       # DW_CHILDREN_no
> 	.byte	3                       # DW_AT_name
> 	.byte	14                      # DW_FORM_strp
> 	.byte	58                      # DW_AT_decl_file
> 	.byte	11                      # DW_FORM_data1
> 	.byte	59                      # DW_AT_decl_line
> 	.byte	11                      # DW_FORM_data1
> 	.byte	73                      # DW_AT_type
> 	.byte	19                      # DW_FORM_ref4
> 	.byte	2                       # DW_AT_location
> 	.byte	10                      # DW_FORM_block1
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	4                       # Abbreviation Code
> 	.byte	52                      # DW_TAG_variable
> 	.byte	0                       # DW_CHILDREN_no
> 	.byte	3                       # DW_AT_name
> 	.byte	14                      # DW_FORM_strp
> 	.byte	58                      # DW_AT_decl_file
> 	.byte	11                      # DW_FORM_data1
> 	.byte	59                      # DW_AT_decl_line
> 	.byte	11                      # DW_FORM_data1
> 	.byte	73                      # DW_AT_type
> 	.byte	19                      # DW_FORM_ref4
> 	.byte	2                       # DW_AT_location
> 	.byte	10                      # DW_FORM_block1
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	5                       # Abbreviation Code
> 	.byte	36                      # DW_TAG_base_type
> 	.byte	0                       # DW_CHILDREN_no
> 	.byte	3                       # DW_AT_name
> 	.byte	14                      # DW_FORM_strp
> 	.byte	62                      # DW_AT_encoding
> 	.byte	11                      # DW_FORM_data1
> 	.byte	11                      # DW_AT_byte_size
> 	.byte	11                      # DW_FORM_data1
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	6                       # Abbreviation Code
> 	.byte	15                      # DW_TAG_pointer_type
> 	.byte	0                       # DW_CHILDREN_no
> 	.byte	73                      # DW_AT_type
> 	.byte	19                      # DW_FORM_ref4
> 	.byte	0                       # EOM(1)
> 	.byte	0                       # EOM(2)
> 	.byte	0                       # EOM(3)
> L.debug_abbrev_end:
> 	.section	.debug_aranges,"", at progbits
> 	.section	.debug_ranges,"", at progbits
> 	.section	.debug_macinfo,"", at progbits
> 	.section	.debug_str,"MS", at progbits,1
> Linfo_string0:
> 	.asciz	 "clang version 3.3 (/opt/git.repo/clang.git/ b422d20530588813b09057b45d5b383f0b175ced) (/opt/git.repo/llvm.git/ 57b428f0a6be7b81bc364b0088992b1f820b516e)"
> Linfo_string1:
> 	.asciz	 "test.c"
> Linfo_string2:
> 	.asciz	 "/home/yangyy/workspace/newlib"
> Linfo_string3:
> 	.asciz	 "main"
> Linfo_string4:
> 	.asciz	 "int"
> Linfo_string5:
> 	.asciz	 "argc"
> Linfo_string6:
> 	.asciz	 "argv"
> Linfo_string7:
> 	.asciz	 "char"
> Linfo_string8:
> 	.asciz	 "a"
> Linfo_string9:
> 	.asciz	 "b"
> Linfo_string10:
> 	.asciz	 "c"
> 
> #########################################
> # dwarf debug info dumpped from its executable file with llvm-dwarfdump
> mspu.out:	file format ELF32-mspu
> 
> .debug_abbrev contents:
> Abbrev table for offset: 0x00000000
> [1] DW_TAG_compile_unit	DW_CHILDREN_yes
> 	DW_AT_producer	DW_FORM_strp
> 	DW_AT_language	DW_FORM_data2
> 	DW_AT_name	DW_FORM_strp
> 	DW_AT_low_pc	DW_FORM_addr
> 	DW_AT_stmt_list	DW_FORM_data4
> 	DW_AT_comp_dir	DW_FORM_strp
> 
> [2] DW_TAG_subprogram	DW_CHILDREN_yes
> 	DW_AT_name	DW_FORM_strp
> 	DW_AT_decl_file	DW_FORM_data1
> 	DW_AT_decl_line	DW_FORM_data1
> 	DW_AT_prototyped	DW_FORM_flag_present
> 	DW_AT_type	DW_FORM_ref4
> 	DW_AT_external	DW_FORM_flag_present
> 	DW_AT_low_pc	DW_FORM_addr
> 	DW_AT_high_pc	DW_FORM_addr
> 	DW_AT_frame_base	DW_FORM_block1
> 
> [3] DW_TAG_formal_parameter	DW_CHILDREN_no
> 	DW_AT_name	DW_FORM_strp
> 	DW_AT_decl_file	DW_FORM_data1
> 	DW_AT_decl_line	DW_FORM_data1
> 	DW_AT_type	DW_FORM_ref4
> 	DW_AT_location	DW_FORM_block1
> 
> [4] DW_TAG_variable	DW_CHILDREN_no
> 	DW_AT_name	DW_FORM_strp
> 	DW_AT_decl_file	DW_FORM_data1
> 	DW_AT_decl_line	DW_FORM_data1
> 	DW_AT_type	DW_FORM_ref4
> 	DW_AT_location	DW_FORM_block1
> 
> [5] DW_TAG_base_type	DW_CHILDREN_no
> 	DW_AT_name	DW_FORM_strp
> 	DW_AT_encoding	DW_FORM_data1
> 	DW_AT_byte_size	DW_FORM_data1
> 
> [6] DW_TAG_pointer_type	DW_CHILDREN_no
> 	DW_AT_type	DW_FORM_ref4
> 
> 
> .debug_info contents:
> 0x00000000: Compile Unit: length = 0x00000094 version = 0x0002 abbr_offset = 0x0000 addr_size = 0x04 (next CU at 0x00000098)
> 
> 0x0000000b: DW_TAG_compile_unit [1] *
> 0x0000000c:   DW_AT_producer [DW_FORM_strp]	( .debug_str[0x00000000] = "clang version 3.3 (/opt/git.repo/clang.git/ b422d20530588813b09057b45d5b383f0b175ced) (/opt/git.repo/llvm.git/ 57b428f0a6be7b81bc364b0088992b1f820b516e)")
> 0x00000010:   DW_AT_language [DW_FORM_data2]	(0x000c)
> 0x00000012:   DW_AT_name [DW_FORM_strp]	( .debug_str[0x00000099] = "test.c")
> 0x00000016:   DW_AT_low_pc [DW_FORM_addr]	(0x0000000000000000)
> 0x0000001a:   DW_AT_stmt_list [DW_FORM_data4]	(0x00000000)
> 0x0000001e:   DW_AT_comp_dir [DW_FORM_strp]	( .debug_str[0x000000a0] = "/home/yangyy/workspace/newlib")
> 
> 0x00000022:   DW_TAG_subprogram [2] *
> 0x00000023:     DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000be] = "main")
> 0x00000027:     DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x00000028:     DW_AT_decl_line [DW_FORM_data1]	(0x02)
> 0x00000029:     DW_AT_prototyped [DW_FORM_flag_present]	(true)
> 0x00000029:     DW_AT_type [DW_FORM_ref4]	(cu + 0x007f => {0x0000007f})
> 0x0000002d:     DW_AT_external [DW_FORM_flag_present]	(true)
> 0x0000002d:     DW_AT_low_pc [DW_FORM_addr]	(0x0000000000000028)
> 0x00000031:     DW_AT_high_pc [DW_FORM_addr]	(0x0000000000000084)
> 0x00000035:     DW_AT_frame_base [DW_FORM_block1]	(<0x02> 90 3c )
> 
> 0x00000038:     DW_TAG_formal_parameter [3]  
> 0x00000039:       DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000c7] = "argc")
> 0x0000003d:       DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x0000003e:       DW_AT_decl_line [DW_FORM_data1]	(0x02)
> 0x0000003f:       DW_AT_type [DW_FORM_ref4]	(cu + 0x007f => {0x0000007f})
> 0x00000043:       DW_AT_location [DW_FORM_block1]	(<0x02> 91 18 )
> 
> 0x00000046:     DW_TAG_formal_parameter [3]  
> 0x00000047:       DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000cc] = "argv")
> 0x0000004b:       DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x0000004c:       DW_AT_decl_line [DW_FORM_data1]	(0x02)
> 0x0000004d:       DW_AT_type [DW_FORM_ref4]	(cu + 0x0092 => {0x00000092})
> 0x00000051:       DW_AT_location [DW_FORM_block1]	(<0x02> 91 14 )
> 
> 0x00000054:     DW_TAG_variable [4]  
> 0x00000055:       DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000d6] = "a")
> 0x00000059:       DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x0000005a:       DW_AT_decl_line [DW_FORM_data1]	(0x04)
> 0x0000005b:       DW_AT_type [DW_FORM_ref4]	(cu + 0x007f => {0x0000007f})
> 0x0000005f:       DW_AT_location [DW_FORM_block1]	(<0x02> 91 10 )
> 
> 0x00000062:     DW_TAG_variable [4]  
> 0x00000063:       DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000d8] = "b")
> 0x00000067:       DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x00000068:       DW_AT_decl_line [DW_FORM_data1]	(0x05)
> 0x00000069:       DW_AT_type [DW_FORM_ref4]	(cu + 0x007f => {0x0000007f})
> 0x0000006d:       DW_AT_location [DW_FORM_block1]	(<0x02> 91 0c )
> 
> 0x00000070:     DW_TAG_variable [4]  
> 0x00000071:       DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000da] = "c")
> 0x00000075:       DW_AT_decl_file [DW_FORM_data1]	(0x01)
> 0x00000076:       DW_AT_decl_line [DW_FORM_data1]	(0x06)
> 0x00000077:       DW_AT_type [DW_FORM_ref4]	(cu + 0x007f => {0x0000007f})
> 0x0000007b:       DW_AT_location [DW_FORM_block1]	(<0x02> 91 08 )
> 
> 0x0000007e:     NULL
> 
> 0x0000007f:   DW_TAG_base_type [5]  
> 0x00000080:     DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000c3] = "int")
> 0x00000084:     DW_AT_encoding [DW_FORM_data1]	(0x05)
> 0x00000085:     DW_AT_byte_size [DW_FORM_data1]	(0x04)
> 
> 0x00000086:   DW_TAG_base_type [5]  
> 0x00000087:     DW_AT_name [DW_FORM_strp]	( .debug_str[0x000000d1] = "char")
> 0x0000008b:     DW_AT_encoding [DW_FORM_data1]	(0x06)
> 0x0000008c:     DW_AT_byte_size [DW_FORM_data1]	(0x01)
> 
> 0x0000008d:   DW_TAG_pointer_type [6]  
> 0x0000008e:     DW_AT_type [DW_FORM_ref4]	(cu + 0x0086 => {0x00000086})
> 
> 0x00000092:   DW_TAG_pointer_type [6]  
> 0x00000093:     DW_AT_type [DW_FORM_ref4]	(cu + 0x008d => {0x0000008d})
> 
> 0x00000097:   NULL
> 
> .debug_frame contents:
> 
> 
> .debug_aranges contents:
> 
> .debug_line contents:
> Line table prologue:
>    total_length: 0x00000037
>         version: 2
> prologue_length: 0x0000001d
> min_inst_length: 1
> default_is_stmt: 1
>       line_base: -5
>      line_range: 14
>     opcode_base: 13
> standard_opcode_lengths[DW_LNS_copy] = 0
> standard_opcode_lengths[DW_LNS_advance_pc] = 1
> standard_opcode_lengths[DW_LNS_advance_line] = 1
> standard_opcode_lengths[DW_LNS_set_file] = 1
> standard_opcode_lengths[DW_LNS_set_column] = 1
> standard_opcode_lengths[DW_LNS_negate_stmt] = 0
> standard_opcode_lengths[DW_LNS_set_basic_block] = 0
> standard_opcode_lengths[DW_LNS_const_add_pc] = 0
> standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
> standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
> standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
> standard_opcode_lengths[DW_LNS_set_isa] = 1
>                 Dir  Mod Time   File Len   File Name
>                 ---- ---------- ---------- ---------------------------
> file_names[  1]    0 0x00000000 0x00000000 test.c
> 
> Address            Line   Column File   ISA Flags
> ------------------ ------ ------ ------ --- -------------
> 0x0000000000000028      2      0      1   0  is_stmt prologue_end
> 0x0000000000000050      4      0      1   0  is_stmt
> 0x0000000000000058      5      0      1   0  is_stmt
> 0x000000000000005c      6      0      1   0  is_stmt
> 0x0000000000000068      7      0      1   0  is_stmt
> 0x0000000000000084      7      0      1   0  is_stmt end_sequence
> 
> .debug_str contents:
> 0x00000000: "clang version 3.3 (/opt/git.repo/clang.git/ b422d20530588813b09057b45d5b383f0b175ced) (/opt/git.repo/llvm.git/ 57b428f0a6be7b81bc364b0088992b1f820b516e)"
> 0x00000099: "test.c"
> 0x000000a0: "/home/yangyy/workspace/newlib"
> 0x000000be: "main"
> 0x000000c3: "int"
> 0x000000c7: "argc"
> 0x000000cc: "argv"
> 0x000000d1: "char"
> 0x000000d6: "a"
> 0x000000d8: "b"
> 0x000000da: "c"
> 
> .debug_ranges contents:
> 
> .debug_pubnames contents:
> Length:                0
> Version:               0
> Offset in .debug_info: 0
> Size:                  0
> 
>   Offset    Name
> 
> .debug_abbrev.dwo contents:
> < EMPTY >
> 
> 
> 
> 2014-02-19 2:28 GMT+08:00 Greg Clayton <gclayton at apple.com>:
> 
> All of this information is contained in the DWARF debug info that you must generate. Are you generating DWARF? If not, you will need to. If so, please attach an example program that contains DWARF and specify which function you are having trouble getting variable information for.
> 
> Greg Clayton
> 
> On Feb 18, 2014, at 12:44 AM, 杨勇勇 <triple.yang at gmail.com> wrote:
> 
> > Hi, all
> >
> > I ported llvm backend and lldb recently. Both tools can basically work.
> > lldb is able to debug programs in asm style and frame unwinding is OK.
> >
> > But "frame variable XX" does not work because lldb is not able to determine the address of
> > XX from debug info.
> >
> > Can someone give any clue?
> > Thanks in advance.
> >
> > --
> > 杨勇勇 (Yang Yong-Yong)
> > _______________________________________________
> > lldb-dev mailing list
> > lldb-dev at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/lldb-dev
> 
> 
> 
> 
> -- 
> 杨勇勇 (Yang Yong-Yong)
> 
> 
> 
> -- 
> 杨勇勇 (Yang Yong-Yong)
> <example.tar.bz2>





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