[llvm-commits] CVS: llvm/lib/Transforms/Scalar/Reassociate.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

Reassociate.cpp updated: 1.14 -> 1.15

---
Log message:

Fix a huge performance problem in reassociate by introducing a
rank map cache for instruction ranks


---
Diffs of the changes:

Index: llvm/lib/Transforms/Scalar/Reassociate.cpp
diff -u llvm/lib/Transforms/Scalar/Reassociate.cpp:1.14 llvm/lib/Transforms/Scalar/Reassociate.cpp:1.15
--- llvm/lib/Transforms/Scalar/Reassociate.cpp:1.14	Sat Dec 14 21:49:50 2002
+++ llvm/lib/Transforms/Scalar/Reassociate.cpp	Sat Dec 14 21:56:00 2002
@@ -36,6 +36,7 @@
 
   class Reassociate : public FunctionPass {
     std::map<BasicBlock*, unsigned> RankMap;
+    std::map<Instruction*, unsigned> InstRankMap;
   public:
     bool runOnFunction(Function &F);
 
@@ -76,12 +77,16 @@
         I->hasSideEffects())
       return RankMap[I->getParent()];
 
+    unsigned &CachedRank = InstRankMap[I];
+    if (CachedRank) return CachedRank;    // Rank already known?
+
+    // If not, compute it!
     unsigned Rank = 0, MaxRank = RankMap[I->getParent()];
     for (unsigned i = 0, e = I->getNumOperands();
          i != e && Rank != MaxRank; ++i)
       Rank = std::max(Rank, getRank(I->getOperand(i)));
 
-    return Rank;
+    return CachedRank = Rank;
   }
 
   // Otherwise it's a global or constant, rank 0.
@@ -267,5 +272,6 @@
 
   // We are done with the rank map...
   RankMap.clear();
+  InstRankMap.clear();
   return Changed;
 }