From 3b95ab569345028a1a8fe521d5ecd81fa97f2653 Mon Sep 17 00:00:00 2001
From: Aaron Orenstein <aorenste@fb.com>
Date: Thu, 17 Aug 2017 18:27:03 -0700
Subject: Performance: Improve efficiency of source file lookup in cmMakefile

Add an unordered map to cmMakefile to speed up GetSource() lookups.
---
 Source/cmMakefile.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'Source/cmMakefile.h')

diff --git a/Source/cmMakefile.h b/Source/cmMakefile.h
index 272522c9ec..2cae659b65 100644
--- a/Source/cmMakefile.h
+++ b/Source/cmMakefile.h
@@ -13,6 +13,7 @@
 #include <stddef.h>
 #include <string>
 #include <unordered_map>
+#include <unordered_set>
 #include <vector>
 
 #include "cmAlgorithms.h"
@@ -808,7 +809,17 @@ protected:
   // libraries, classes, and executables
   mutable cmTargets Targets;
   std::map<std::string, std::string> AliasTargets;
+
   std::vector<cmSourceFile*> SourceFiles;
+  // Because cmSourceFile names are compared in a fuzzy way (see
+  // cmSourceFileLocation::Match()) we can't have a straight mapping from
+  // filename to cmSourceFile.  To make lookups more efficient we store the
+  // Name portion of the cmSourceFileLocation and then compare on the list of
+  // cmSourceFiles that might match that name.  Note that on platforms which
+  // have a case-insensitive filesystem we store the key in all lowercase.
+  typedef std::unordered_set<cmSourceFile*> SourceFileSet;
+  typedef std::unordered_map<std::string, SourceFileSet> SourceFileMap;
+  SourceFileMap SourceFileSearchIndex;
 
   // Tests
   std::map<std::string, cmTest*> Tests;
-- 
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