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Re: gas emits incorrect .debug_line prologue header length for 64-bit DWARF
- From: Alan Modra <amodra at gmail dot com>
- To: Ed Maste <emaste at freebsd dot org>
- Cc: binutils at sourceware dot org
- Date: Fri, 28 Feb 2014 15:08:30 +1030
- Subject: Re: gas emits incorrect .debug_line prologue header length for 64-bit DWARF
- Authentication-results: sourceware.org; auth=none
- References: <CAPyFy2D4WizPNHZcA7syz_ETEasLcC3kCC0hQ74qP=ZnGiBoVw at mail dot gmail dot com>
On Thu, Feb 27, 2014 at 01:03:23PM -0500, Ed Maste wrote:
> The header_length field is supposed to be the number of bytes
> following the field to the first byte of the line number program, but
> dwarf2dbg.c:out_debug_line has hard-coded constants that are correct
> only for 32-bit DWARF.
>
> I've fixed it in FreeBSD here in SVN r256692:
> http://svnweb.freebsd.org/base?view=revision&revision=256692
Thanks for the heads-up. I'm committing the following to mainline
that calculates the length as a simple difference of two symbols.
* dwarf2dbg.c (out_debug_line): Correct .debug_line header_length
field for 64-bit dwarf.
diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index 6d6ee2d..ac6148f 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -1515,7 +1515,7 @@ static void
out_debug_line (segT line_seg)
{
expressionS exp;
- symbolS *prologue_end;
+ symbolS *prologue_start, *prologue_end;
symbolS *line_end;
struct line_seg *s;
int sizeof_offset;
@@ -1527,10 +1527,14 @@ out_debug_line (segT line_seg)
out_two (DWARF2_LINE_VERSION);
/* Length of the prologue following this length. */
+ prologue_start = symbol_temp_make ();
prologue_end = symbol_temp_make ();
+ exp.X_op = O_subtract;
exp.X_add_symbol = prologue_end;
- exp.X_add_number = - (4 + 2 + 4);
+ exp.X_op_symbol = prologue_start;
+ exp.X_add_number = 0;
emit_expr (&exp, sizeof_offset);
+ symbol_set_value_now (prologue_start);
/* Parameters of the state machine. */
out_byte (DWARF2_LINE_MIN_INSN_LENGTH);
--
Alan Modra
Australia Development Lab, IBM