[binutils-gdb] Use a std::vector instead of a std::map to hold Input_merge_map.

[Rafael "थ�vila" de "Espथऐndola" <espindola at sourceware dot org>]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=400f89447b72cbd48a2fc8b016a09cbc4e590d81

commit 400f89447b72cbd48a2fc8b016a09cbc4e590d81
Author: Rafael �vila de Espíndola <rafael.espindola@gmail.com>
Date:   Mon Jun 1 22:47:20 2015 -0400

    Use a std::vector instead of a std::map to hold Input_merge_map.
    
    A std::map is hardly the best data structure for a small map from small
    integers.

Diff:
---
 gold/ChangeLog |  7 +++++++
 gold/merge.cc  | 31 +++++++++----------------------
 gold/merge.h   | 16 +++-------------
 3 files changed, 19 insertions(+), 35 deletions(-)

diff --git a/gold/ChangeLog b/gold/ChangeLog
index 64ce33f..8e08d3b 100644
--- a/gold/ChangeLog
+++ b/gold/ChangeLog
@@ -1,3 +1,10 @@
+2015-06-01  Rafael �vila de Espíndola <rafael.espindola@gmail.com>
+
+	* merge.cc (get_input_merge_map): Update for data structure change.
+	(get_or_make_input_merge_map): Update for data structure change.
+	* merge.h (Object_merge_map): Use a std::vector<std::pair>> instead of
+	a std::map. Remove first_shnum_, first_map_, second_shnum_, second_map_.
+
 2015-05-16  Alan Modra  <amodra@gmail.com>
 
 	* reloc.cc (Sized_relobj_file::find_functions): Use function_location.
diff --git a/gold/merge.cc b/gold/merge.cc
index d395312..50d13af 100644
--- a/gold/merge.cc
+++ b/gold/merge.cc
@@ -49,13 +49,13 @@ const Object_merge_map::Input_merge_map*
 Object_merge_map::get_input_merge_map(unsigned int shndx) const
 {
   gold_assert(shndx != -1U);
-  if (shndx == this->first_shnum_)
-    return &this->first_map_;
-  if (shndx == this->second_shnum_)
-    return &this->second_map_;
-  Section_merge_maps::const_iterator p = this->section_merge_maps_.find(shndx);
-  if (p != this->section_merge_maps_.end())
-    return p->second;
+  const Section_merge_maps &maps = this->section_merge_maps_;
+  for (Section_merge_maps::const_iterator i = maps.begin(), e = maps.end();
+       i != e; ++i)
+    {
+      if (i->first == shndx)
+	return i->second;
+    }
   return NULL;
 }
 
@@ -73,23 +73,10 @@ Object_merge_map::get_or_make_input_merge_map(
       return map;
     }
 
-  // We need to create a new entry.
-  if (this->first_shnum_ == -1U)
-    {
-      this->first_shnum_ = shndx;
-      this->first_map_.output_data = output_data;
-      return &this->first_map_;
-    }
-  if (this->second_shnum_ == -1U)
-    {
-      this->second_shnum_ = shndx;
-      this->second_map_.output_data = output_data;
-      return &this->second_map_;
-    }
-
   Input_merge_map* new_map = new Input_merge_map;
   new_map->output_data = output_data;
-  this->section_merge_maps_[shndx] = new_map;
+  Section_merge_maps &maps = this->section_merge_maps_;
+  maps.push_back(std::make_pair(shndx, new_map));
   return new_map;
 }
 
diff --git a/gold/merge.h b/gold/merge.h
index 54caed8..53846ee 100644
--- a/gold/merge.h
+++ b/gold/merge.h
@@ -42,9 +42,7 @@ class Object_merge_map
 {
  public:
   Object_merge_map()
-    : first_shnum_(-1U), first_map_(),
-      second_shnum_(-1U), second_map_(),
-      section_merge_maps_()
+    : section_merge_maps_()
   { }
 
   ~Object_merge_map();
@@ -152,7 +150,8 @@ class Object_merge_map
   };
 
   // Map input section indices to merge maps.
-  typedef std::map<unsigned int, Input_merge_map*> Section_merge_maps;
+  typedef std::vector<std::pair<unsigned int, Input_merge_map*> >
+      Section_merge_maps;
 
   // Return a pointer to the Input_merge_map to use for the input
   // section SHNDX, or NULL.
@@ -165,15 +164,6 @@ class Object_merge_map
                                              this)->get_input_merge_map(shndx));
   }
 
-  // Any given object file will normally only have a couple of input
-  // sections with mergeable contents.  So we keep the first two input
-  // section numbers inline, and push any further ones into a map.  A
-  // value of -1U in first_shnum_ or second_shnum_ means that we don't
-  // have a corresponding entry.
-  unsigned int first_shnum_;
-  Input_merge_map first_map_;
-  unsigned int second_shnum_;
-  Input_merge_map second_map_;
   Section_merge_maps section_merge_maps_;
 };