Don't insert nearly as many redundant phi nodes.

[oota-llvm.git] / lib / Transforms / Scalar / LICM.cpp

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 77ac5634bd9365743ceea998a855b14daaeb1f92..ede3bd9dde630acb39c3ca052605664eac27bfc1 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -42,6 +42,7 @@
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/AliasSetTracker.h"
 #include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ScalarEvolution.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/Compiler.h"
@@ -78,6 +79,8 @@ namespace {
       AU.addRequired<DominatorTree>();
       AU.addRequired<DominanceFrontier>();  // For scalar promotion (mem2reg)
       AU.addRequired<AliasAnalysis>();
+      AU.addPreserved<ScalarEvolution>();
+      AU.addPreserved<DominanceFrontier>();
     }
 
     bool doFinalization() {
@@ -99,6 +102,13 @@ namespace {
     AliasSetTracker *CurAST; // AliasSet information for the current loop...
     std::map<Loop *, AliasSetTracker *> LoopToAliasMap;
 
+    /// cloneBasicBlockAnalysis - Simple Analysis hook. Clone alias set info.
+    void cloneBasicBlockAnalysis(BasicBlock *From, BasicBlock *To, Loop *L);
+
+    /// deleteAnalysisValue - Simple Analysis hook. Delete value V from alias
+    /// set.
+    void deleteAnalysisValue(Value *V, Loop *L);
+
     /// SinkRegion - Walk the specified region of the CFG (defined by all blocks
     /// dominated by the specified block, and that are in the current loop) in
     /// reverse depth first order w.r.t the DominatorTree.  This allows us to
@@ -208,7 +218,9 @@ namespace {
 
 LoopPass *llvm::createLICMPass() { return new LICM(); }
 
-/// Hoist expressions out of the specified loop...
+/// Hoist expressions out of the specified loop. Note, alias info for inner
+/// loop is not preserved so it is not a good idea to run LICM multiple 
+/// times on one loop.
 ///
 bool LICM::runOnLoop(Loop *L, LPPassManager &LPM) {
   Changed = false;
@@ -795,3 +807,22 @@ void LICM::FindPromotableValuesInLoop(
     }
   }
 }
+
+/// cloneBasicBlockAnalysis - Simple Analysis hook. Clone alias set info.
+void LICM::cloneBasicBlockAnalysis(BasicBlock *From, BasicBlock *To, Loop *L) {
+  AliasSetTracker *AST = LoopToAliasMap[L];
+  if (!AST)
+    return;
+
+  AST->copyValue(From, To);
+}
+
+/// deleteAnalysisValue - Simple Analysis hook. Delete value V from alias
+/// set.
+void LICM::deleteAnalysisValue(Value *V, Loop *L) {
+  AliasSetTracker *AST = LoopToAliasMap[L];
+  if (!AST)
+    return;
+
+  AST->deleteValue(V);
+}