Re: [patch] Parse DW_AT_ranges into PSYMTABS (for childless CU, for vDSO32)

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Tue, 09 Oct 2007 20:59:31 +0200, Daniel Jacobowitz wrote:
...
> Does that work with the default linker script and without -nostdlib?

Attached the patch with the testcase no longer using its own .lds.


Regards,
Jan

2007-11-24  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2read.c (dwarf2_get_pc_bounds): Moved the `DW_AT_ranges' parsing
	code with its variables OBJFILE, CU_HEADER and OBFD into ...
	(dwarf2_ranges_read): ... a new function.
	(read_partial_die): Implemented the parsing of `DW_AT_ranges'.

2007-11-24  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.dwarf2/dw2-ranges.S, gdb.dwarf2/dw2-ranges.exp: New files.

Index: gdb/dwarf2read.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2read.c,v
retrieving revision 1.236
diff -u -p -r1.236 dwarf2read.c
--- gdb/dwarf2read.c	25 Oct 2007 20:54:27 -0000	1.236
+++ gdb/dwarf2read.c	24 Nov 2007 15:41:32 -0000
@@ -3077,6 +3077,124 @@ read_lexical_block_scope (struct die_inf
   local_symbols = new->locals;
 }
 
+/* Get low and high pc attributes from DW_AT_ranges attribute value OFFSET.
+   Return 1 if the attributes are present and valid, otherwise, return 0.  */
+
+static int
+dwarf2_ranges_read (unsigned offset, CORE_ADDR *low_return,
+		    CORE_ADDR *high_return, struct dwarf2_cu *cu)
+{
+  struct objfile *objfile = cu->objfile;
+  struct comp_unit_head *cu_header = &cu->header;
+  bfd *obfd = objfile->obfd;
+  unsigned int addr_size = cu_header->addr_size;
+  CORE_ADDR mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
+  /* Base address selection entry.  */
+  CORE_ADDR base;
+  int found_base;
+  unsigned int dummy;
+  gdb_byte *buffer;
+  CORE_ADDR marker;
+  int low_set;
+  CORE_ADDR low = 0;
+  CORE_ADDR high = 0;
+
+  found_base = cu_header->base_known;
+  base = cu_header->base_address;
+
+  if (offset >= dwarf2_per_objfile->ranges_size)
+    {
+      complaint (&symfile_complaints,
+		 _("Offset %d out of bounds for DW_AT_ranges attribute"),
+		 offset);
+      return 0;
+    }
+  buffer = dwarf2_per_objfile->ranges_buffer + offset;
+
+  /* Read in the largest possible address.  */
+  marker = read_address (obfd, buffer, cu, &dummy);
+  if ((marker & mask) == mask)
+    {
+      /* If we found the largest possible address, then
+	 read the base address.  */
+      base = read_address (obfd, buffer + addr_size, cu, &dummy);
+      buffer += 2 * addr_size;
+      offset += 2 * addr_size;
+      found_base = 1;
+    }
+
+  low_set = 0;
+
+  while (1)
+    {
+      CORE_ADDR range_beginning, range_end;
+
+      range_beginning = read_address (obfd, buffer, cu, &dummy);
+      buffer += addr_size;
+      range_end = read_address (obfd, buffer, cu, &dummy);
+      buffer += addr_size;
+      offset += 2 * addr_size;
+
+      /* An end of list marker is a pair of zero addresses.  */
+      if (range_beginning == 0 && range_end == 0)
+	/* Found the end of list entry.  */
+	break;
+
+      /* Each base address selection entry is a pair of 2 values.
+	 The first is the largest possible address, the second is
+	 the base address.  Check for a base address here.  */
+      if ((range_beginning & mask) == mask)
+	{
+	  /* If we found the largest possible address, then
+	     read the base address.  */
+	  base = read_address (obfd, buffer + addr_size, cu, &dummy);
+	  found_base = 1;
+	  continue;
+	}
+
+      if (!found_base)
+	{
+	  /* We have no valid base address for the ranges
+	     data.  */
+	  complaint (&symfile_complaints,
+		     _("Invalid .debug_ranges data (no base address)"));
+	  return 0;
+	}
+
+      range_beginning += base;
+      range_end += base;
+
+      /* FIXME: This is recording everything as a low-high
+	 segment of consecutive addresses.  We should have a
+	 data structure for discontiguous block ranges
+	 instead.  */
+      if (! low_set)
+	{
+	  low = range_beginning;
+	  high = range_end;
+	  low_set = 1;
+	}
+      else
+	{
+	  if (range_beginning < low)
+	    low = range_beginning;
+	  if (range_end > high)
+	    high = range_end;
+	}
+    }
+
+  if (! low_set)
+    /* If the first entry is an end-of-list marker, the range
+       describes an empty scope, i.e. no instructions.  */
+    return 0;
+
+  if (low_return)
+    *low_return = low;
+  if (high_return)
+    *high_return = high;
+  return 1;
+}
+
 /* Get low and high pc attributes from a die.  Return 1 if the attributes
    are present and valid, otherwise, return 0.  Return -1 if the range is
    discontinuous, i.e. derived from DW_AT_ranges information.  */
@@ -3084,10 +3202,7 @@ static int
 dwarf2_get_pc_bounds (struct die_info *die, CORE_ADDR *lowpc,
 		      CORE_ADDR *highpc, struct dwarf2_cu *cu)
 {
-  struct objfile *objfile = cu->objfile;
-  struct comp_unit_head *cu_header = &cu->header;
   struct attribute *attr;
-  bfd *obfd = objfile->obfd;
   CORE_ADDR low = 0;
   CORE_ADDR high = 0;
   int ret = 0;
@@ -3111,108 +3226,11 @@ dwarf2_get_pc_bounds (struct die_info *d
       attr = dwarf2_attr (die, DW_AT_ranges, cu);
       if (attr != NULL)
 	{
-	  unsigned int addr_size = cu_header->addr_size;
-	  CORE_ADDR mask = ~(~(CORE_ADDR)1 << (addr_size * 8 - 1));
 	  /* Value of the DW_AT_ranges attribute is the offset in the
 	     .debug_ranges section.  */
-	  unsigned int offset = DW_UNSND (attr);
-	  /* Base address selection entry.  */
-	  CORE_ADDR base;
-	  int found_base;
-	  unsigned int dummy;
-	  gdb_byte *buffer;
-	  CORE_ADDR marker;
-	  int low_set;
- 
-	  found_base = cu_header->base_known;
-	  base = cu_header->base_address;
-
-	  if (offset >= dwarf2_per_objfile->ranges_size)
-	    {
-	      complaint (&symfile_complaints,
-	                 _("Offset %d out of bounds for DW_AT_ranges attribute"),
-			 offset);
-	      return 0;
-	    }
-	  buffer = dwarf2_per_objfile->ranges_buffer + offset;
-
-	  /* Read in the largest possible address.  */
-	  marker = read_address (obfd, buffer, cu, &dummy);
-	  if ((marker & mask) == mask)
-	    {
-	      /* If we found the largest possible address, then
-		 read the base address.  */
-	      base = read_address (obfd, buffer + addr_size, cu, &dummy);
-	      buffer += 2 * addr_size;
-	      offset += 2 * addr_size;
-	      found_base = 1;
-	    }
-
-	  low_set = 0;
-
-	  while (1)
-	    {
-	      CORE_ADDR range_beginning, range_end;
-
-	      range_beginning = read_address (obfd, buffer, cu, &dummy);
-	      buffer += addr_size;
-	      range_end = read_address (obfd, buffer, cu, &dummy);
-	      buffer += addr_size;
-	      offset += 2 * addr_size;
-
-	      /* An end of list marker is a pair of zero addresses.  */
-	      if (range_beginning == 0 && range_end == 0)
-		/* Found the end of list entry.  */
-		break;
-
-	      /* Each base address selection entry is a pair of 2 values.
-		 The first is the largest possible address, the second is
-		 the base address.  Check for a base address here.  */
-	      if ((range_beginning & mask) == mask)
-		{
-		  /* If we found the largest possible address, then
-		     read the base address.  */
-		  base = read_address (obfd, buffer + addr_size, cu, &dummy);
-		  found_base = 1;
-		  continue;
-		}
-
-	      if (!found_base)
-		{
-		  /* We have no valid base address for the ranges
-		     data.  */
-		  complaint (&symfile_complaints,
-			     _("Invalid .debug_ranges data (no base address)"));
-		  return 0;
-		}
-
-	      range_beginning += base;
-	      range_end += base;
-
-	      /* FIXME: This is recording everything as a low-high
-		 segment of consecutive addresses.  We should have a
-		 data structure for discontiguous block ranges
-		 instead.  */
-	      if (! low_set)
-		{
-		  low = range_beginning;
-		  high = range_end;
-		  low_set = 1;
-		}
-	      else
-		{
-		  if (range_beginning < low)
-		    low = range_beginning;
-		  if (range_end > high)
-		    high = range_end;
-		}
-	    }
-
-	  if (! low_set)
-	    /* If the first entry is an end-of-list marker, the range
-	       describes an empty scope, i.e. no instructions.  */
+	  if (!dwarf2_ranges_read (DW_UNSND (attr), &low, &high, cu))
 	    return 0;
-
+	  /* Found discontinuous range of addresses.  */
 	  ret = -1;
 	}
     }
@@ -5569,6 +5587,11 @@ read_partial_die (struct partial_die_inf
 	  has_high_pc_attr = 1;
 	  part_die->highpc = DW_ADDR (&attr);
 	  break;
+	case DW_AT_ranges:
+	  if (dwarf2_ranges_read (DW_UNSND (&attr), &part_die->lowpc,
+				  &part_die->highpc, cu))
+	    has_low_pc_attr = has_high_pc_attr = 1;
+	  break;
 	case DW_AT_location:
           /* Support the .debug_loc offsets */
           if (attr_form_is_block (&attr))
Index: gdb/testsuite/gdb.dwarf2/dw2-ranges.S
===================================================================
RCS file: gdb/testsuite/gdb.dwarf2/dw2-ranges.S
diff -N gdb/testsuite/gdb.dwarf2/dw2-ranges.S
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.dwarf2/dw2-ranges.S	24 Nov 2007 15:41:33 -0000
@@ -0,0 +1,40 @@
+/*
+   Copyright 2007 Free Software Foundation, Inc.
+   
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+   
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+   
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Despite the sections below will be adjacent the assembler has to produce
+   DW_AT_ranges as the linker could place both sections at arbitrary locations.
+   */
+
+	/* Without this directive GAS will not emit DWARF2 unless we provide an
+	   instruction to assemble.  We want to avoid any instructions to
+	   remain architecture independent.  */
+	.loc_mark_labels	1
+
+	.text
+
+	.globl	main
+	.func	main
+main:	.int	0
+	.endfunc
+	.size	main, . - main
+
+	.section	.text.func, "ax", @progbits
+	.globl	func
+	.func	func
+func:	.int	0
+	.endfunc
+	.size	func, . - func
Index: gdb/testsuite/gdb.dwarf2/dw2-ranges.exp
===================================================================
RCS file: gdb/testsuite/gdb.dwarf2/dw2-ranges.exp
diff -N gdb/testsuite/gdb.dwarf2/dw2-ranges.exp
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gdb/testsuite/gdb.dwarf2/dw2-ranges.exp	24 Nov 2007 15:41:33 -0000
@@ -0,0 +1,49 @@
+# Copyright 2007 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test DW_TAG_compile_unit with no children and with neither DW_AT_low_pc nor
+# DW_AT_high_pc but with DW_AT_ranges instead.
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+# For now pick a sampling of likely targets.
+if {![istarget *-*-linux*]
+    && ![istarget *-*-gnu*]
+    && ![istarget *-*-elf*]
+    && ![istarget *-*-openbsd*]
+    && ![istarget arm-*-eabi*]
+    && ![istarget powerpc-*-eabi*]} {
+    verbose "Skipping DW_AT_ranges test."
+    return 0  
+}
+
+set testfile "dw2-ranges"
+set srcfile ${testfile}.S
+set binfile ${objdir}/${subdir}/${testfile}.o
+
+if {[gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" object debug] != "" } {
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+gdb_load ${binfile}
+
+# Correct output:
+# 	Line 39 of "../.././gdb/testsuite/gdb.dwarf2/dw2-ranges.S" starts at address 0x4 and ends at 0x8.
+# Wrong output:
+# 	No line number information available for address 0x4
+
+gdb_test "info line func" "Line \[0-9\]* of .* starts at address .* and ends at .*"