[PATCH] Switch a std::map to a DenseMap in CodeGenRegisters

[Owen Anderson]

Added checking of uniqueness to one loop that would potentially change iteration order here.  I'd prefer *not* to add checking to computeSubRegs() in CodeGenRegisters.cpp because the checking would be quite heavyweight, the method is very hot, and I am explicitly trying to improve LLVM build times in Release+Asserts configs here.


REPOSITORY
  rL LLVM

http://reviews.llvm.org/D7544

Files:
  utils/TableGen/CodeGenRegisters.h
  utils/TableGen/RegisterInfoEmitter.cpp

Index: utils/TableGen/CodeGenRegisters.h
===================================================================
--- utils/TableGen/CodeGenRegisters.h
+++ utils/TableGen/CodeGenRegisters.h
@@ -74,8 +74,7 @@
     std::string getQualifiedName() const;
 
     // Map of composite subreg indices.
-    typedef std::map<CodeGenSubRegIndex *, CodeGenSubRegIndex *,
-                     deref<llvm::less>> CompMap;
+    typedef DenseMap<CodeGenSubRegIndex *, CodeGenSubRegIndex *> CompMap;
 
     // Returns the subreg index that results from composing this with Idx.
     // Returns NULL if this and Idx don't compose.
Index: utils/TableGen/RegisterInfoEmitter.cpp
===================================================================
--- utils/TableGen/RegisterInfoEmitter.cpp
+++ utils/TableGen/RegisterInfoEmitter.cpp
@@ -610,17 +610,19 @@
 static bool combine(const CodeGenSubRegIndex *Idx,
                     SmallVectorImpl<CodeGenSubRegIndex*> &Vec) {
   const CodeGenSubRegIndex::CompMap &Map = Idx->getComposites();
-  for (CodeGenSubRegIndex::CompMap::const_iterator
-       I = Map.begin(), E = Map.end(); I != E; ++I) {
-    CodeGenSubRegIndex *&Entry = Vec[I->first->EnumValue - 1];
-    if (Entry && Entry != I->second)
+  for (const auto &I : Map) {
+    CodeGenSubRegIndex *&Entry = Vec[I.first->EnumValue - 1];
+    if (Entry && Entry != I.second)
       return false;
   }
 
   // All entries are compatible. Make it so.
-  for (CodeGenSubRegIndex::CompMap::const_iterator
-       I = Map.begin(), E = Map.end(); I != E; ++I)
-    Vec[I->first->EnumValue - 1] = I->second;
+  for (const auto &I : Map) {
+    auto *&Entry = Vec[I.first->EnumValue - 1];
+    assert((!Entry || Entry == I.second) &&
+           "Expected EnumValue to be unique");
+    Entry = I.second;
+  }
   return true;
 }

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D7544.20095.patch
Type: text/x-patch
Size: 1804 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150217/639fcccd/attachment.bin>