From 596dc4adfff347b4d8dc1f7e4eb57b8f2f342281 Mon Sep 17 00:00:00 2001
From: Tom Tromey <tom@tromey.com>
Date: Fri, 8 May 2020 14:14:05 -0600
Subject: Speed up psymbol reading by removing a copy

I noticed that cp_canonicalize_string and friends copy a
unique_xmalloc_ptr to a std::string.  However, this copy isn't
genuinely needed anywhere, and it serves to slow down DWARF psymbol
reading.

This patch removes the copy and updates the callers to adapt.

This speeds up the reader from 1.906 seconds (mean of 10 runs, of gdb
on a copy of itself) to 1.888 seconds (mean of 10 runs, on the same
copy as the first trial).

gdb/ChangeLog
2020-05-08  Tom Tromey  <tom@tromey.com>

	* symtab.h (class demangle_result_storage) <set_malloc_ptr>: New
	overload.
	<swap_string, m_string>: Remove.
	* symtab.c (demangle_for_lookup, completion_list_add_symbol):
	Update.
	* stabsread.c (define_symbol, read_type): Update.
	* linespec.c (find_linespec_symbols): Update.
	* gnu-v3-abi.c (gnuv3_get_typeid): Update.
	* dwarf2/read.c (dwarf2_canonicalize_name): Update.
	* dbxread.c (read_dbx_symtab): Update.
	* cp-support.h (cp_canonicalize_string_full)
	(cp_canonicalize_string, cp_canonicalize_string_no_typedefs):
	Return unique_xmalloc_ptr.
	* cp-support.c (inspect_type): Update.
	(cp_canonicalize_string_full): Return unique_xmalloc_ptr.
	(cp_canonicalize_string_no_typedefs, cp_canonicalize_string):
	Likewise.
	* c-typeprint.c (print_name_maybe_canonical): Update.
	* break-catch-throw.c (check_status_exception_catchpoint):
	Update.
---
 gdb/break-catch-throw.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

(limited to 'gdb/break-catch-throw.c')

diff --git a/gdb/break-catch-throw.c b/gdb/break-catch-throw.c
index 07dcc7d..59293c4 100644
--- a/gdb/break-catch-throw.c
+++ b/gdb/break-catch-throw.c
@@ -156,26 +156,28 @@ check_status_exception_catchpoint (struct bpstats *bs)
   if (self->pattern == NULL)
     return;
 
+  const char *name = nullptr;
+  gdb::unique_xmalloc_ptr<char> canon;
   try
     {
       struct value *typeinfo_arg;
-      std::string canon;
 
       fetch_probe_arguments (NULL, &typeinfo_arg);
       type_name = cplus_typename_from_type_info (typeinfo_arg);
 
       canon = cp_canonicalize_string (type_name.c_str ());
-      if (!canon.empty ())
-	std::swap (type_name, canon);
+      name = (canon == nullptr
+	      ? canon.get ()
+	      : type_name.c_str ());
     }
   catch (const gdb_exception_error &e)
     {
       exception_print (gdb_stderr, e);
     }
 
-  if (!type_name.empty ())
+  if (name != nullptr)
     {
-      if (self->pattern->exec (type_name.c_str (), 0, NULL, 0) != 0)
+      if (self->pattern->exec (name, 0, NULL, 0) != 0)
 	bs->stop = 0;
     }
 }
-- 
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