[PATCH] gdb: dwarf2read.c handle DW_AT_high_pc constant form for DWARF 4+.

[PATCH] gdb: dwarf2read.c handle DW_AT_high_pc constant form for DWARF 4+.

[Mark Wielaard]

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Hi,

This goes together with the first binutils patch described here:
http://sourceware.org/ml/binutils/2012-04/msg00423.html

That together with the following patch will make gdb handle
DW_AT_high_pc constant form following DWARF 4+.

Tested on x86_64-unknown-linux-gnu against both a patched and unpatched
gcc from git trunk (to output the new form for DW_AT_high_pc).

Cheers,

Mark

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From 6a0cbea1b863226fa22e786e69aee9d01cb8a25f Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mjw@redhat.com>
Date: Fri, 27 Apr 2012 15:09:46 +0200
Subject: [PATCH] gdb: dwarf2read.c handle DW_AT_high_pc constant form for
 DWARF 4+.

        * dwarf2read.c (dwarf2_get_pc_bounds): Check DW_AT_high_pc form to
        see whether it is an address or a constant offset from DW_AT_low_pc.
        (dwarf2_record_block_ranges): Likewise.
        (read_partial_die): Likewise.
---
 gdb/ChangeLog    |    7 +++++++
 gdb/dwarf2read.c |   38 +++++++++++++++++++++++++++++---------
 2 files changed, 36 insertions(+), 9 deletions(-)

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 31b207f..ee659f3 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,10 @@
+2012-04-27  Mark Wielaard  <mjw@redhat.com>
+
+	* dwarf2read.c (dwarf2_get_pc_bounds): Check DW_AT_high_pc form to
+	see whether it is an address or a constant offset from DW_AT_low_pc.
+	(dwarf2_record_block_ranges): Likewise.
+	(read_partial_die): Likewise.
+
 2012-04-26  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	Fix DW_AT_lower_bound defaults for DWARF-4+.
diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index 99bba9f..7ae3b86 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -6706,17 +6706,23 @@ dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
 		      struct partial_symtab *pst)
 {
   struct attribute *attr;
+  struct attribute *attr_high;
   CORE_ADDR low = 0;
   CORE_ADDR high = 0;
   int ret = 0;
 
-  attr = dwarf2_attr (die, DW_AT_high_pc, cu);
-  if (attr)
+  attr_high = dwarf2_attr (die, DW_AT_high_pc, cu);
+  if (attr_high)
     {
-      high = DW_ADDR (attr);
       attr = dwarf2_attr (die, DW_AT_low_pc, cu);
       if (attr)
-	low = DW_ADDR (attr);
+        {
+	  low = DW_ADDR (attr);
+	  if (attr_high->form == DW_FORM_addr)
+	    high = DW_ADDR (attr_high);
+	  else
+	    high = low + DW_UNSND (attr_high);
+	}
       else
 	/* Found high w/o low attribute.  */
 	return 0;
@@ -6864,16 +6870,20 @@ dwarf2_record_block_ranges (struct die_info *die, struct block *block,
 {
   struct objfile *objfile = cu->objfile;
   struct attribute *attr;
+  struct attribute *attr_high;
 
-  attr = dwarf2_attr (die, DW_AT_high_pc, cu);
-  if (attr)
+  attr_high = dwarf2_attr (die, DW_AT_high_pc, cu);
+  if (attr_high)
     {
-      CORE_ADDR high = DW_ADDR (attr);
-
       attr = dwarf2_attr (die, DW_AT_low_pc, cu);
       if (attr)
         {
           CORE_ADDR low = DW_ADDR (attr);
+	  CORE_ADDR high;
+	  if (attr_high->form == DW_FORM_addr)
+	    high = DW_ADDR (attr_high);
+	  else
+	    high = low + DW_UNSND (attr_high);
 
           record_block_range (block, baseaddr + low, baseaddr + high - 1);
         }
@@ -9925,6 +9935,7 @@ read_partial_die (struct partial_die_info *part_die,
   struct attribute attr;
   int has_low_pc_attr = 0;
   int has_high_pc_attr = 0;
+  int high_pc_relative = 0;
 
   memset (part_die, 0, sizeof (struct partial_die_info));
 
@@ -9981,7 +9992,13 @@ read_partial_die (struct partial_die_info *part_die,
 	  break;
 	case DW_AT_high_pc:
 	  has_high_pc_attr = 1;
-	  part_die->highpc = DW_ADDR (&attr);
+	  if (attr.form == DW_FORM_addr)
+	    part_die->highpc = DW_ADDR (&attr);
+	  else
+	    {
+	      high_pc_relative = 1;
+	      part_die->highpc = DW_UNSND (&attr);
+	    }
 	  break;
 	case DW_AT_location:
           /* Support the .debug_loc offsets.  */
@@ -10061,6 +10078,9 @@ read_partial_die (struct partial_die_info *part_die,
 	}
     }
 
+  if (high_pc_relative)
+    part_die->highpc += part_die->lowpc;
+
   if (has_low_pc_attr && has_high_pc_attr)
     {
       /* When using the GNU linker, .gnu.linkonce. sections are used to
-- 
1.7.7.6

Re: [PATCH] gdb: dwarf2read.c handle DW_AT_high_pc constant form for DWARF 4+.

[Tom Tromey]

>>>>> "Mark" == Mark Wielaard <mjw@redhat.com> writes:

Mark>         * dwarf2read.c (dwarf2_get_pc_bounds): Check DW_AT_high_pc form to
Mark>         see whether it is an address or a constant offset from DW_AT_low_pc.
Mark>         (dwarf2_record_block_ranges): Likewise.
Mark>         (read_partial_die): Likewise.

Thanks, Mark.
This is ok.

Tom