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| -rw-r--r-- | gdb/ChangeLog | 4 | ||||
| -rw-r--r-- | gdb/dwarf2read.c | 28 |
2 files changed, 32 insertions, 0 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 22b4f02..e33de3b 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,7 @@ +2001-07-30 Jim Blandy <jimb@redhat.com> + + * dwarf2read.c (dwarf2_build_psymtabs_hard): Doc fix. + 2001-07-27 Daniel Jacobowitz <drow@mvista.com> * configure.in: Only invoke AC_FUNC_SETPGRP if not cross-compiling. diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c index a3ca771..bc559b0 100644 --- a/gdb/dwarf2read.c +++ b/gdb/dwarf2read.c @@ -977,6 +977,34 @@ 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); |