[review] Only clear the minsym array when necessary

[Christian Biesinger (Code Review)]

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/442
......................................................................

Only clear the minsym array when necessary

The array starts out initialized to zero:
  minimal_symbol *msymbol_hash[MINIMAL_SYMBOL_HASH_SIZE] {};

So we only need to explicitly clear it if there were previous minsyms
added to it. This patch does that.

gdb/ChangeLog:

2019-10-29  Christian Biesinger  <cbiesinger@google.com>

	* minsyms.c (clear_minimal_symbol_hash_tables): New function.
	(build_minimal_symbol_hash_tables): Code to clear the table moved
	to clear_minimal_symbol_hash_tables.
	(minimal_symbol_reader::install): Call clear_minimal_symbol_hash_tables
	when needed.

Change-Id: I7da994fe6747f67714e7efe9fdbb0dbc4d6ea532
---
M gdb/minsyms.c
1 file changed, 14 insertions(+), 8 deletions(-)



diff --git a/gdb/minsyms.c b/gdb/minsyms.c
index db3e546..10f02bb 100644
--- a/gdb/minsyms.c
+++ b/gdb/minsyms.c
@@ -1238,6 +1238,16 @@
   return (mcount);
 }
 
+static void
+clear_minimal_symbol_hash_tables (struct objfile *objfile)
+{
+  for (size_t i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++)
+    {
+      objfile->per_bfd->msymbol_hash[i] = 0;
+      objfile->per_bfd->msymbol_demangled_hash[i] = 0;
+    }
+}
+
 /* Build (or rebuild) the minimal symbol hash tables.  This is necessary
    after compacting or sorting the table since the entries move around
    thus causing the internal minimal_symbol pointers to become jumbled.  */
@@ -1248,14 +1258,7 @@
   int i;
   struct minimal_symbol *msym;
 
-  /* Clear the hash tables.  */
-  for (i = 0; i < MINIMAL_SYMBOL_HASH_SIZE; i++)
-    {
-      objfile->per_bfd->msymbol_hash[i] = 0;
-      objfile->per_bfd->msymbol_demangled_hash[i] = 0;
-    }
-
-  /* Now, (re)insert the actual entries.  */
+  /* (Re)insert the actual entries.  */
   for ((i = objfile->per_bfd->minimal_symbol_count,
 	msym = objfile->per_bfd->msymbols.get ());
        i > 0;
@@ -1345,6 +1348,9 @@
          The strings themselves are also located in the storage_obstack
          of this objfile.  */
 
+      if (m_objfile->per_bfd->minimal_symbol_count)
+	clear_minimal_symbol_hash_tables (m_objfile);
+
       m_objfile->per_bfd->minimal_symbol_count = mcount;
       m_objfile->per_bfd->msymbols = std::move (msym_holder);
 

-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: I7da994fe6747f67714e7efe9fdbb0dbc4d6ea532
Gerrit-Change-Number: 442
Gerrit-PatchSet: 1
Gerrit-Owner: Christian Biesinger <cbiesinger@google.com>
Gerrit-MessageType: newchange