[4/4] RFC: refactor partial symbol tables

[Tom Tromey <tromey at redhat dot com>]

This patch removes some dead code from the DWARF reader.

After my various experiments, I have concluded that we will never use
the aranges or pubnames sections.

pubnames (and likewise pubtypes) is simply not useful -- not just to
gdb, I think, but to any debugger.  IMO, gcc should not even generate
it.

aranges is useful, but I think we don't want to bother.  Reading aranges
was the basis of my earlier patch for lazy psymtab reading.  However,
this only fixes part of the problem: it makes by-address lookups work
lazily (nice) but at the expense of very long user-visible delays the
first time a by-name lookup is done.  After some experience with this, I
think it is a bad tradeoff; if there must be a big delay, it is nicer
for users to have it all up front.

Tom

2010-01-14  Tom Tromey  <tromey@redhat.com>

	* dwarf2read.c (struct pubnames_header): Remove.
	(_PUBNAMES_HEADER): Remove.
	(_ACTUAL_PUBNAMES_HEADER_SIZE): Remove.
	(struct aranges_header): Remove.
	(_ARANGES_HEADER, _ACTUAL_ARANGES_HEADER_SIZE): Remove.
	(struct dwarf2_per_objfile) <pubnames, aranges>: Remove.
	(PUBNAMES_SECTION): Remove.
	(ARANGES_SECTION): Remove.
	(dwarf2_locate_sections): Don't handle pubnames or aranges.
	(dwarf2_build_psymtabs): Remove dead code.
	(dwarf2_build_psymtabs_easy): Remove.

>From 3b2fcc7ff7847264d8055e4f1f28dcb1d99c4841 Mon Sep 17 00:00:00 2001
From: Tom Tromey <tromey@redhat.com>
Date: Thu, 14 Jan 2010 14:59:45 -0700
Subject: [PATCH 4/4] Remove dead code from DWARF reader

---
 gdb/ChangeLog    |   14 +++++++
 gdb/dwarf2read.c |  101 +-----------------------------------------------------
 2 files changed, 15 insertions(+), 100 deletions(-)

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index d6adf80..4cdb87a 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -81,38 +81,6 @@ _COMP_UNIT_HEADER;
 #define _ACTUAL_COMP_UNIT_HEADER_SIZE 11
 #endif
 
-/* .debug_pubnames header
-   Because of alignment constraints, this structure has padding and cannot
-   be mapped directly onto the beginning of the .debug_info section.  */
-typedef struct pubnames_header
-  {
-    unsigned int length;	/* length of the .debug_pubnames
-				   contribution  */
-    unsigned char version;	/* version number -- 2 for DWARF
-				   version 2 */
-    unsigned int info_offset;	/* offset into .debug_info section */
-    unsigned int info_size;	/* byte size of .debug_info section
-				   portion */
-  }
-_PUBNAMES_HEADER;
-#define _ACTUAL_PUBNAMES_HEADER_SIZE 13
-
-/* .debug_pubnames header
-   Because of alignment constraints, this structure has padding and cannot
-   be mapped directly onto the beginning of the .debug_info section.  */
-typedef struct aranges_header
-  {
-    unsigned int length;	/* byte len of the .debug_aranges
-				   contribution */
-    unsigned short version;	/* version number -- 2 for DWARF
-				   version 2 */
-    unsigned int info_offset;	/* offset into .debug_info section */
-    unsigned char addr_size;	/* byte size of an address */
-    unsigned char seg_size;	/* byte size of segment descriptor */
-  }
-_ARANGES_HEADER;
-#define _ACTUAL_ARANGES_HEADER_SIZE 12
-
 /* .debug_line statement program prologue
    Because of alignment constraints, this structure has padding and cannot
    be mapped directly onto the beginning of the .debug_info section.  */
@@ -164,8 +132,6 @@ struct dwarf2_per_objfile
   struct dwarf2_section_info info;
   struct dwarf2_section_info abbrev;
   struct dwarf2_section_info line;
-  struct dwarf2_section_info pubnames;
-  struct dwarf2_section_info aranges;
   struct dwarf2_section_info loc;
   struct dwarf2_section_info macinfo;
   struct dwarf2_section_info str;
@@ -207,8 +173,6 @@ static struct dwarf2_per_objfile *dwarf2_per_objfile;
 #define INFO_SECTION     "debug_info"
 #define ABBREV_SECTION   "debug_abbrev"
 #define LINE_SECTION     "debug_line"
-#define PUBNAMES_SECTION "debug_pubnames"
-#define ARANGES_SECTION  "debug_aranges"
 #define LOC_SECTION      "debug_loc"
 #define MACINFO_SECTION  "debug_macinfo"
 #define STR_SECTION      "debug_str"
@@ -774,10 +738,6 @@ dwarf2_invalid_attrib_class_complaint (const char *arg1, const char *arg2)
 
 static void dwarf2_locate_sections (bfd *, asection *, void *);
 
-#if 0
-static void dwarf2_build_psymtabs_easy (struct objfile *);
-#endif
-
 static void dwarf2_create_include_psymtab (char *, struct partial_symtab *,
                                            struct objfile *);
 
@@ -1226,16 +1186,6 @@ dwarf2_locate_sections (bfd *abfd, asection *sectp, void *ignore_ptr)
       dwarf2_per_objfile->line.asection = sectp;
       dwarf2_per_objfile->line.size = bfd_get_section_size (sectp);
     }
-  else if (section_is_p (sectp->name, PUBNAMES_SECTION))
-    {
-      dwarf2_per_objfile->pubnames.asection = sectp;
-      dwarf2_per_objfile->pubnames.size = bfd_get_section_size (sectp);
-    }
-  else if (section_is_p (sectp->name, ARANGES_SECTION))
-    {
-      dwarf2_per_objfile->aranges.asection = sectp;
-      dwarf2_per_objfile->aranges.size = bfd_get_section_size (sectp);
-    }
   else if (section_is_p (sectp->name, LOC_SECTION))
     {
       dwarf2_per_objfile->loc.asection = sectp;
@@ -1479,57 +1429,8 @@ dwarf2_build_psymtabs (struct objfile *objfile)
       init_psymbol_list (objfile, 1024);
     }
 
-#if 0
-  if (dwarf_aranges_offset && dwarf_pubnames_offset)
-    {
-      /* Things are significantly easier if we have .debug_aranges and
-         .debug_pubnames sections */
-
-      dwarf2_build_psymtabs_easy (objfile);
-    }
-  else
-#endif
-    /* only test this case for now */
-    {
-      /* In this case we have to work a bit harder */
-      dwarf2_build_psymtabs_hard (objfile);
-    }
-}
-
-#if 0
-/* Build the partial symbol table from the information in the
-   .debug_pubnames and .debug_aranges sections.  */
-
-static void
-dwarf2_build_psymtabs_easy (struct objfile *objfile)
-{
-  bfd *abfd = objfile->obfd;
-  char *aranges_buffer, *pubnames_buffer;
-  char *aranges_ptr, *pubnames_ptr;
-  unsigned int entry_length, version, info_offset, info_size;
-
-  pubnames_buffer = dwarf2_read_section (objfile,
-					 dwarf_pubnames_section);
-  pubnames_ptr = pubnames_buffer;
-  while ((pubnames_ptr - pubnames_buffer) < dwarf2_per_objfile->pubnames.size)
-    {
-      unsigned int bytes_read;
-
-      entry_length = read_initial_length (abfd, pubnames_ptr, &bytes_read);
-      pubnames_ptr += bytes_read;
-      version = read_1_byte (abfd, pubnames_ptr);
-      pubnames_ptr += 1;
-      info_offset = read_4_bytes (abfd, pubnames_ptr);
-      pubnames_ptr += 4;
-      info_size = read_4_bytes (abfd, pubnames_ptr);
-      pubnames_ptr += 4;
-    }
-
-  aranges_buffer = dwarf2_read_section (objfile,
-					dwarf_aranges_section);
-
+  dwarf2_build_psymtabs_hard (objfile);
 }
-#endif
 
 /* Return TRUE if OFFSET is within CU_HEADER.  */
 
-- 
1.6.2.5