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RE: Compiler emitting .debug_line versus binutils
- From: "Will Newton" <will dot newton at imgtec dot com>
- To: "Dave Korn" <dave dot korn at artimi dot com>, <binutils at sourceware dot org>
- Date: Fri, 29 Jun 2007 15:58:42 +0100
- Subject: RE: Compiler emitting .debug_line versus binutils
> On 29 June 2007 15:35, Will Newton wrote:
>
> > Hi all, I have a binutils 2.17 port and a gcc 2.95.3 port for an
> > embedded DSP type chip. The compiler spits out a
> .debug_line section in the
> > assembler code like this: .section
> .debug_line
> > .4byte 0xab .2byte 0x2 .4byte 0x1b
> .byte 0x4
> > .byte 0x1 .byte -10 .byte 245
> .byte 10
> > ... This seems to be done by dwarf2out_finish() in
> dwarf2out.c inside gcc.
> > I assemble the result with gas, which then outputs another
> .debug_line
> > section in dwarf2_finish() in dwarf2dbg.c. This results in
> a rather
> > strabge looking .debug_line section in the final executable.
>
> What's strange-looking about it? That's exactly what
> they're supposed to look like.
What is strange (to me at least) is that I get two chunks of debug_line
data output, so if I do readelf --debug-dump=line I get some valid debug
data followed by an empty chunk of debug_line data. Is that expected?
e.g.
Dump of debug contents of section .debug_line:
Length: 171
DWARF Version: 2
Prologue Length: 27
Minimum Instruction Length: 4
Initial value of 'is_stmt': 1
Line Base: -10
Line Range: 245
Opcode Base: 10
(debug line data...)
Length: 25
DWARF Version: 2
Prologue Length: 19
Minimum Instruction Length: 1
Initial value of 'is_stmt': 1
Line Base: -5
Line Range: 14
Opcode Base: 13
Opcodes:
Opcode 1 has 0 args
Opcode 2 has 1 args
Opcode 3 has 1 args
Opcode 4 has 1 args
Opcode 5 has 1 args
Opcode 6 has 0 args
Opcode 7 has 0 args
Opcode 8 has 0 args
Opcode 9 has 1 args
Opcode 10 has 0 args
Opcode 11 has 0 args
Opcode 12 has 1 args
The Directory Table is empty.
The File Name Table is empty.
Line Number Statements:
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