Address a large chunk of this FIXME by accumulating the cost for

[oota-llvm.git] / lib / Transforms / Utils / LCSSA.cpp

diff --git a/lib/Transforms/Utils/LCSSA.cpp b/lib/Transforms/Utils/LCSSA.cpp
index 885da337cf3ef6b5ee14e907923ce1fd1e8f2e55..2d1b166c21011ae3cf836e712ce50a1831a9b34e 100644 (file)
--- a/lib/Transforms/Utils/LCSSA.cpp
+++ b/lib/Transforms/Utils/LCSSA.cpp
@@ -29,18 +29,17 @@
 
 #define DEBUG_TYPE "lcssa"
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/Pass.h"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/Statistic.h"
 #include "llvm/Analysis/Dominators.h"
 #include "llvm/Analysis/LoopPass.h"
 #include "llvm/Analysis/ScalarEvolution.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/SSAUpdater.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Pass.h"
 #include "llvm/Support/PredIteratorCache.h"
+#include "llvm/Transforms/Utils/SSAUpdater.h"
 using namespace llvm;
 
 STATISTIC(NumLCSSA, "Number of live out of a loop variables");
@@ -54,6 +53,8 @@ namespace {
 
     // Cached analysis information for the current function.
     DominatorTree *DT;
+    LoopInfo *LI;
+    ScalarEvolution *SE;
     std::vector<BasicBlock*> LoopBlocks;
     PredIteratorCache PredCache;
     Loop *L;
@@ -118,6 +119,8 @@ bool LCSSA::runOnLoop(Loop *TheLoop, LPPassManager &LPM) {
   L = TheLoop;
   
   DT = &getAnalysis<DominatorTree>();
+  LI = &getAnalysis<LoopInfo>();
+  SE = getAnalysisIfAvailable<ScalarEvolution>();
 
   // Get the set of exiting blocks.
   SmallVector<BasicBlock*, 8> ExitBlocks;
@@ -157,6 +160,12 @@ bool LCSSA::runOnLoop(Loop *TheLoop, LPPassManager &LPM) {
       MadeChange |= ProcessInstruction(I, ExitBlocks);
     }
   }
+
+  // If we modified the code, remove any caches about the loop from SCEV to
+  // avoid dangling entries.
+  // FIXME: This is a big hammer, can we clear the cache more selectively?
+  if (SE && MadeChange)
+    SE->forgetLoop(L);
   
   assert(L->isLCSSAForm(*DT));
   PredCache.clear();
@@ -227,7 +236,6 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
                                   PredCache.GetNumPreds(ExitBB),
                                   Inst->getName()+".lcssa",
                                   ExitBB->begin());
-    PN->setDebugLoc(GetFirstDebugLocInBasicBlock(ExitBB));
 
     // Add inputs from inside the loop for this PHI.
     for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI) {
@@ -247,7 +255,7 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
     // Remember that this phi makes the value alive in this block.
     SSAUpdate.AddAvailableValue(ExitBB, PN);
   }
-  
+
   // Rewrite all uses outside the loop in terms of the new PHIs we just
   // inserted.
   for (unsigned i = 0, e = UsesToRewrite.size(); i != e; ++i) {
@@ -262,6 +270,9 @@ bool LCSSA::ProcessInstruction(Instruction *Inst,
 
     if (isa<PHINode>(UserBB->begin()) &&
         isExitBlock(UserBB, ExitBlocks)) {
+      // Tell the VHs that the uses changed. This updates SCEV's caches.
+      if (UsesToRewrite[i]->get()->hasValueHandle())
+        ValueHandleBase::ValueIsRAUWd(*UsesToRewrite[i], UserBB->begin());
       UsesToRewrite[i]->set(UserBB->begin());
       continue;
     }