From a3c27d36bc019788a969fb4dfcf21a22b227cb95 Mon Sep 17 00:00:00 2001
From: Evan Cheng <evan.cheng@apple.com>
Date: Sun, 17 Aug 2008 08:07:31 +0000
Subject: [PATCH] Revert 54821. It's miscompiling 252.eon and 447.dealII

llvm-svn: 54878
---
 lib/Transforms/Scalar/LoopStrengthReduce.cpp | 119 +------------------
 1 file changed, 1 insertion(+), 118 deletions(-)

diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 40bbe95f7e9..04faa0aa508 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -45,7 +45,6 @@ STATISTIC(NumReduced ,    "Number of GEPs strength reduced");
 STATISTIC(NumInserted,    "Number of PHIs inserted");
 STATISTIC(NumVariable,    "Number of PHIs with variable strides");
 STATISTIC(NumEliminated , "Number of strides eliminated");
-STATISTIC(NumShadow , "Number of Shadow IVs optimized");
 
 namespace {
 
@@ -178,13 +177,8 @@ private:
                                   IVStrideUse* &CondUse,
                                   const SCEVHandle* &CondStride);
     void OptimizeIndvars(Loop *L);
-
-    /// OptimizeShadowIV - If IV is used in a int-to-float cast
-    /// inside the loop then try to eliminate the cast opeation.
-    void OptimizeShadowIV(Loop *L, ICmpInst *Cond,
-                          const SCEVHandle *&CondStride);
     bool FindIVUserForCond(ICmpInst *Cond, IVStrideUse *&CondUse,
-                           const SCEVHandle *&CondStride);
+                       const SCEVHandle *&CondStride);
     bool RequiresTypeConversion(const Type *Ty, const Type *NewTy);
     unsigned CheckForIVReuse(bool, bool, const SCEVHandle&,
                              IVExpr&, const Type*,
@@ -1695,115 +1689,6 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
   return Cond;
 }
 
-/// OptimizeShadowIV - If IV is used in a int-to-float cast
-/// inside the loop then try to eliminate the cast opeation.
-void LoopStrengthReduce::OptimizeShadowIV(Loop *L, ICmpInst *Cond,
-                                          const SCEVHandle *&CondStride) {
-
-  const SCEVConstant *SC = dyn_cast<SCEVConstant>(*CondStride);
-  if (!SC) return;
-
-  SCEVHandle IterationCount = SE->getIterationCount(L);
-  if (isa<SCEVCouldNotCompute>(IterationCount))
-    return;
-
-  for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e;
-       ++Stride) {
-    std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI = 
-      IVUsesByStride.find(StrideOrder[Stride]);
-    assert(SI != IVUsesByStride.end() && "Stride doesn't exist!");
-
-    for (std::vector<IVStrideUse>::iterator UI = SI->second.Users.begin(),
-           E = SI->second.Users.end(); UI != E; /* empty */) {
-      std::vector<IVStrideUse>::iterator CandidateUI = UI;
-      UI++;
-      Instruction *ShadowUse = CandidateUI->User;
-      const Type *DestTy = NULL;
-
-      /* If shadow use is a int->float cast then insert a second IV
-         to elminate this cast.
-
-           for (unsigned i = 0; i < n; ++i) 
-             foo((double)i);
-
-         is trnasformed into
-
-           double d = 0.0;
-           for (unsigned i = 0; i < n; ++i, ++d) 
-             foo(d);
-      */
-      UIToFPInst *UCast = dyn_cast<UIToFPInst>(CandidateUI->User);
-      if (UCast) 
-        DestTy = UCast->getDestTy();
-      else {
-        SIToFPInst *SCast = dyn_cast<SIToFPInst>(CandidateUI->User);
-        if (!SCast) continue;
-        DestTy = SCast->getDestTy();
-      }
-      
-      PHINode *PH = dyn_cast<PHINode>(ShadowUse->getOperand(0));
-      if (!PH) continue;
-      if (PH->getNumIncomingValues() != 2) continue;
-
-      const Type *SrcTy = PH->getType();
-      int Mantissa = DestTy->getFPMantissaWidth();
-      if (Mantissa == -1) continue; 
-      if ((int)TD->getTypeSizeInBits(SrcTy) > Mantissa)
-        continue;
-
-      unsigned Entry, Latch;
-      if (PH->getIncomingBlock(0) == L->getLoopPreheader()) {
-        Entry = 0;
-        Latch = 1;
-      } else {
-        Entry = 1;
-        Latch = 0;
-      }
-        
-      ConstantInt *Init = dyn_cast<ConstantInt>(PH->getIncomingValue(Entry));
-      if (!Init) continue;
-      ConstantFP *NewInit = ConstantFP::get(DestTy, Init->getZExtValue());
-
-      BinaryOperator *Incr = 
-        dyn_cast<BinaryOperator>(PH->getIncomingValue(Latch));
-      if (!Incr) continue;
-      if (Incr->getOpcode() != Instruction::Add
-          && Incr->getOpcode() != Instruction::Sub)
-        continue;
-
-      /* Initialize new IV, double d = 0.0 in above example. */
-      ConstantInt *C = NULL;
-      if (Incr->getOperand(0) == PH)
-        C = dyn_cast<ConstantInt>(Incr->getOperand(1));
-      else if (Incr->getOperand(1) == PH)
-        C = dyn_cast<ConstantInt>(Incr->getOperand(0));
-      else
-        continue;
-
-      if (!C) continue;
-
-      /* Add new PHINode. */
-      PHINode *NewPH = PHINode::Create(DestTy, "IV.S.", PH);
-
-      /* create new icnrement. '++d' in above example. */
-      ConstantFP *CFP = ConstantFP::get(DestTy, C->getZExtValue());
-      BinaryOperator *NewIncr = 
-        BinaryOperator::Create(Incr->getOpcode(),
-                               NewPH, CFP, "IV.S.next.", Incr);
-
-      NewPH->addIncoming(NewInit, PH->getIncomingBlock(Entry));
-      NewPH->addIncoming(NewIncr, PH->getIncomingBlock(Latch));
-
-      /* Remove cast operation */
-      ShadowUse->replaceAllUsesWith(NewPH);
-      ShadowUse->eraseFromParent();
-      SI->second.Users.erase(CandidateUI);
-      NumShadow++;
-      break;
-    }
-  }
-}
-
 // OptimizeIndvars - Now that IVUsesByStride is set up with all of the indvar
 // uses in the loop, look to see if we can eliminate some, in favor of using
 // common indvars for the different uses.
@@ -1831,8 +1716,6 @@ void LoopStrengthReduce::OptimizeIndvars(Loop *L) {
   if (!FindIVUserForCond(Cond, CondUse, CondStride))
     return; // setcc doesn't use the IV.
 
-  OptimizeShadowIV(L, Cond, CondStride);
-
   // If possible, change stride and operands of the compare instruction to
   // eliminate one stride.
   Cond = ChangeCompareStride(L, Cond, CondUse, CondStride);