diff mbox series

[1/4] Improve performance of Ada name searches

Message ID 20231121-ada-lookup-perf-v1-1-1efd2d1dbf65@adacore.com
State New
Headers
Series Improve Ada name lookup performance |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gdb_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_build--master-aarch64 success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gdb_check--master-aarch64 fail Testing failed

Commit Message

Tom Tromey Nov. 21, 2023, 9:09 p.m. UTC 
  A user reported that certain operations -- like printing a large
structure -- could be slow.  I tracked this down to
ada-lang.c:map_matching_symbols taking an inordinate amount of time.
Specifically, calls like the one to look for a parallel "__XVZ"
variable, in ada_to_fixed_type_1, could result in gdb walking over all
the entries in the cooked index over and over.

Looking into this reveals that
cooked_index_functions::expand_matching_symbols is not written
efficiently -- it ignores its "ordered_compare" parameter.  While
fixing this would be good, it turns out that this entire method isn't
needed; so this series removes it.

However, the deletion is not done in this patch.  This one, instead,
fixes the immediate cause of the slowdown, by using
objfile::expand_symtabs_matching when possible.  This approach is
faster because it is more selective about which index entries to
examine.
---
 gdb/ada-lang.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
index ff7222c7eed..8c5ab93f3ca 100644
--- a/gdb/ada-lang.c
+++ b/gdb/ada-lang.c
@@ -5572,8 +5572,16 @@  map_matching_symbols (struct objfile *objfile,
 		      match_data &data)
 {
   data.objfile = objfile;
-  objfile->expand_matching_symbols (lookup_name, domain, global,
-				    is_wild_match ? nullptr : compare_names);
+  if (is_wild_match || lookup_name.ada ().standard_p ())
+    objfile->expand_matching_symbols (lookup_name, domain, global,
+				      is_wild_match ? nullptr : compare_names);
+  else
+    objfile->expand_symtabs_matching (nullptr, &lookup_name,
+				      nullptr, nullptr,
+				      global
+				      ? SEARCH_GLOBAL_BLOCK
+				      : SEARCH_STATIC_BLOCK,
+				      domain, ALL_DOMAIN);
 
   const int block_kind = global ? GLOBAL_BLOCK : STATIC_BLOCK;
   for (compunit_symtab *symtab : objfile->compunits ())