Performance: Improve efficiency of source file lookup in cmMakefile

This reintroduces the change from commit v3.10.0-rc1~69^2 (Performance:
Improve efficiency of source file lookup in cmMakefile, 2017-08-17) with
some corrections.  The original was rolled back by commit
v3.10.0-rc1~52^2~1 (Revert "Performance: ...", 2017-09-25) due to
incompatibilities found.  The rollback was followed-up by addition of a
test for the offending case, and this revision passes the test.

1 files changed, 4 insertions, 16 deletions

diff --git a/Source/cmSourceFileLocation.cxx b/Source/cmSourceFileLocation.cxx
index 4f337f2..6add7b3 100644
--- a/Source/cmSourceFileLocation.cxx
+++ b/Source/cmSourceFileLocation.cxx
@@ -8,9 +8,7 @@
 #include "cmSystemTools.h"
 #include "cmake.h"
 
-#include <algorithm>
 #include <assert.h>
-#include <vector>
 
 cmSourceFileLocation::cmSourceFileLocation()
   : Makefile(nullptr)
@@ -86,13 +84,9 @@ void cmSourceFileLocation::UpdateExtension(const std::string& name)
   // The global generator checks extensions of enabled languages.
   cmGlobalGenerator* gg = this->Makefile->GetGlobalGenerator();
   cmMakefile const* mf = this->Makefile;
-  const std::vector<std::string>& srcExts =
-    mf->GetCMakeInstance()->GetSourceExtensions();
-  const std::vector<std::string>& hdrExts =
-    mf->GetCMakeInstance()->GetHeaderExtensions();
+  auto cm = mf->GetCMakeInstance();
   if (!gg->GetLanguageFromExtension(ext.c_str()).empty() ||
-      std::find(srcExts.begin(), srcExts.end(), ext) != srcExts.end() ||
-      std::find(hdrExts.begin(), hdrExts.end(), ext) != hdrExts.end()) {
+      cm->IsSourceExtension(ext) || cm->IsHeaderExtension(ext)) {
     // This is a known extension.  Use the given filename with extension.
     this->Name = cmSystemTools::GetFilenameName(name);
     this->AmbiguousExtension = false;
@@ -149,14 +143,8 @@ bool cmSourceFileLocation::MatchesAmbiguousExtension(
   // disk.  One of these must match if loc refers to this source file.
   std::string const& ext = this->Name.substr(loc.Name.size() + 1);
   cmMakefile const* mf = this->Makefile;
-  const std::vector<std::string>& srcExts =
-    mf->GetCMakeInstance()->GetSourceExtensions();
-  if (std::find(srcExts.begin(), srcExts.end(), ext) != srcExts.end()) {
-    return true;
-  }
-  std::vector<std::string> hdrExts =
-    mf->GetCMakeInstance()->GetHeaderExtensions();
-  return std::find(hdrExts.begin(), hdrExts.end(), ext) != hdrExts.end();
+  auto cm = mf->GetCMakeInstance();
+  return cm->IsSourceExtension(ext) || cm->IsHeaderExtension(ext);
 }
 
 bool cmSourceFileLocation::Matches(cmSourceFileLocation const& loc)