Whoops, forgot to commit this yesterday:

[deliverable/binutils-gdb.git] / gdb / dwarf2read.c

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index a3ca771eef537f48285aec38246431c15e61dfd4..16a3e23080e608f033e7272c42820e0f70dadf2c 100644 (file)
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -554,9 +554,6 @@ static struct complaint dwarf2_unsupported_const_value_attr =
   "unsupported const value attribute form: '%s'", 0, 0
 };
 
-/* Externals references.  */
-extern int info_verbose;       /* From main.c; nonzero => verbose */
-
 /* local function prototypes */
 
 static void dwarf2_locate_sections (bfd *, asection *, PTR);
@@ -869,8 +866,9 @@ dwarf2_build_psymtabs (struct objfile *objfile, int mainline)
                                           dwarf_line_offset,
                                           dwarf_line_size);
 
-  if (mainline || objfile->global_psymbols.size == 0 ||
-      objfile->static_psymbols.size == 0)
+  if (mainline
+      || (objfile->global_psymbols.size == 0
+         && objfile->static_psymbols.size == 0))
     {
       init_psymbol_list (objfile, 1024);
     }
@@ -977,6 +975,34 @@ dwarf2_build_psymtabs_hard (struct objfile *objfile, int mainline)
   info_ptr = dwarf_info_buffer;
   abbrev_ptr = dwarf_abbrev_buffer;
 
+  /* We use dwarf2_tmp_obstack for objects that don't need to survive
+     the partial symbol scan, like attribute values.
+
+     We could reduce our peak memory consumption during partial symbol
+     table construction by freeing stuff from this obstack more often
+     --- say, after processing each compilation unit, or each die ---
+     but it turns out that this saves almost nothing.  For an
+     executable with 11Mb of Dwarf 2 data, I found about 64k allocated
+     on dwarf2_tmp_obstack.  Some investigation showed:
+
+     1) 69% of the attributes used forms DW_FORM_addr, DW_FORM_data*,
+        DW_FORM_flag, DW_FORM_[su]data, and DW_FORM_ref*.  These are
+        all fixed-length values not requiring dynamic allocation.
+
+     2) 30% of the attributes used the form DW_FORM_string.  For
+        DW_FORM_string, read_attribute simply hands back a pointer to
+        the null-terminated string in dwarf_info_buffer, so no dynamic
+        allocation is needed there either.
+
+     3) The remaining 1% of the attributes all used DW_FORM_block1.
+        75% of those were DW_AT_frame_base location lists for
+        functions; the rest were DW_AT_location attributes, probably
+        for the global variables.
+
+     Anyway, what this all means is that the memory the dwarf2
+     reader uses as temporary space reading partial symbols is about
+     0.5% as much as we use for dwarf_*_buffer.  That's noise.  */
+
   obstack_init (&dwarf2_tmp_obstack);
   back_to = make_cleanup (dwarf2_free_tmp_obstack, NULL);
 
@@ -3001,7 +3027,7 @@ dwarf2_read_section (struct objfile *objfile, file_ptr offset,
 
   buf = (char *) obstack_alloc (&objfile->psymbol_obstack, size);
   if ((bfd_seek (abfd, offset, SEEK_SET) != 0) ||
-      (bfd_read (buf, size, 1, abfd) != size))
+      (bfd_bread (buf, size, abfd) != size))
     {
       buf = NULL;
       error ("Dwarf Error: Can't read DWARF data from '%s'",