Split the sdisel code munging stuff out into its own opt-pass, CodeGenPrepare.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35528 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 556 insertions, 1 deletions

diff --git a/include/llvm/LinkAllPasses.h b/include/llvm/LinkAllPasses.h
index 834fe48..7bf1c16 100644
--- a/include/llvm/LinkAllPasses.h
+++ b/include/llvm/LinkAllPasses.h
@@ -109,6 +109,7 @@ namespace {
       (void) llvm::createIndMemRemPass();
       (void) llvm::createInstCountPass();
       (void) llvm::createPredicateSimplifierPass();
+      (void) llvm::createCodeGenPreparePass();
 
       (void)new llvm::IntervalPartition();
       (void)new llvm::ImmediateDominators();
diff --git a/include/llvm/Transforms/Scalar.h b/include/llvm/Transforms/Scalar.h
index a675730..379ee57 100644
--- a/include/llvm/Transforms/Scalar.h
+++ b/include/llvm/Transforms/Scalar.h
@@ -121,7 +121,7 @@ LoopPass *createLICMPass();
 // optional parameter used to consult the target machine whether certain
 // transformations are profitable.
 //
-LoopPass *createLoopStrengthReducePass(const TargetLowering *TLI = NULL);
+LoopPass *createLoopStrengthReducePass(const TargetLowering *TLI = 0);
 
 //===----------------------------------------------------------------------===//
 //
@@ -309,6 +309,12 @@ extern const PassInfo *LCSSAID;
 //
 FunctionPass *createPredicateSimplifierPass();
 
+//===----------------------------------------------------------------------===//
+//
+// CodeGenPrepare - This pass prepares a function for instruction selection.
+//
+FunctionPass *createCodeGenPreparePass(const TargetLowering *TLI = 0);
+
 } // End llvm namespace
 
 #endif
diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp
new file mode 100644
index 0000000..f80513e
--- /dev/null
+++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp
@@ -0,0 +1,548 @@
+//===- CodeGenPrepare.cpp - Prepare a function for code generation --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Chris Lattner and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass munges the code in the input function to better prepare it for
+// SelectionDAG-based code generation.  This works around limitations in it's
+// basic-block-at-a-time approach.  It should eventually be removed.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "codegenprepare"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Constants.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Target/TargetAsmInfo.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/ADT/SmallSet.h"
+using namespace llvm;
+
+namespace {  
+  class VISIBILITY_HIDDEN CodeGenPrepare : public FunctionPass {
+    /// TLI - Keep a pointer of a TargetLowering to consult for determining
+    /// transformation profitability.
+    const TargetLowering *TLI;
+  public:
+    CodeGenPrepare(const TargetLowering *tli = 0) : TLI(tli) {}
+    bool runOnFunction(Function &F);
+    
+  private:
+    bool OptimizeBlock(BasicBlock &BB);
+    bool OptimizeGEPExpression(GetElementPtrInst *GEPI);
+  };
+}
+static RegisterPass<CodeGenPrepare> X("codegenprepare",
+                                      "Optimize for code generation");
+
+FunctionPass *llvm::createCodeGenPreparePass(const TargetLowering *TLI) {
+  return new CodeGenPrepare(TLI);
+}
+
+
+bool CodeGenPrepare::runOnFunction(Function &F) {
+  bool MadeChange = true;
+  bool EverMadeChange = false;
+  while (MadeChange) {
+    MadeChange = false;
+    for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+      MadeChange |= OptimizeBlock(*BB);
+    EverMadeChange |= MadeChange;
+  }
+  return EverMadeChange;
+}
+
+/// SplitEdgeNicely - Split the critical edge from TI to it's specified
+/// successor if it will improve codegen.  We only do this if the successor has
+/// phi nodes (otherwise critical edges are ok).  If there is already another
+/// predecessor of the succ that is empty (and thus has no phi nodes), use it
+/// instead of introducing a new block.
+static void SplitEdgeNicely(TerminatorInst *TI, unsigned SuccNum, Pass *P) {
+  BasicBlock *TIBB = TI->getParent();
+  BasicBlock *Dest = TI->getSuccessor(SuccNum);
+  assert(isa<PHINode>(Dest->begin()) &&
+         "This should only be called if Dest has a PHI!");
+  
+  /// TIPHIValues - This array is lazily computed to determine the values of
+  /// PHIs in Dest that TI would provide.
+  std::vector<Value*> TIPHIValues;
+  
+  // Check to see if Dest has any blocks that can be used as a split edge for
+  // this terminator.
+  for (pred_iterator PI = pred_begin(Dest), E = pred_end(Dest); PI != E; ++PI) {
+    BasicBlock *Pred = *PI;
+    // To be usable, the pred has to end with an uncond branch to the dest.
+    BranchInst *PredBr = dyn_cast<BranchInst>(Pred->getTerminator());
+    if (!PredBr || !PredBr->isUnconditional() ||
+        // Must be empty other than the branch.
+        &Pred->front() != PredBr)
+      continue;
+    
+    // Finally, since we know that Dest has phi nodes in it, we have to make
+    // sure that jumping to Pred will have the same affect as going to Dest in
+    // terms of PHI values.
+    PHINode *PN;
+    unsigned PHINo = 0;
+    bool FoundMatch = true;
+    for (BasicBlock::iterator I = Dest->begin();
+         (PN = dyn_cast<PHINode>(I)); ++I, ++PHINo) {
+      if (PHINo == TIPHIValues.size())
+        TIPHIValues.push_back(PN->getIncomingValueForBlock(TIBB));
+      
+      // If the PHI entry doesn't work, we can't use this pred.
+      if (TIPHIValues[PHINo] != PN->getIncomingValueForBlock(Pred)) {
+        FoundMatch = false;
+        break;
+      }
+    }
+    
+    // If we found a workable predecessor, change TI to branch to Succ.
+    if (FoundMatch) {
+      Dest->removePredecessor(TIBB);
+      TI->setSuccessor(SuccNum, Pred);
+      return;
+    }
+  }
+  
+  SplitCriticalEdge(TI, SuccNum, P, true);  
+}
+
+
+/// InsertGEPComputeCode - Insert code into BB to compute Ptr+PtrOffset,
+/// casting to the type of GEPI.
+static Instruction *InsertGEPComputeCode(Instruction *&V, BasicBlock *BB,
+                                         Instruction *GEPI, Value *Ptr,
+                                         Value *PtrOffset) {
+  if (V) return V;   // Already computed.
+  
+  // Figure out the insertion point
+  BasicBlock::iterator InsertPt;
+  if (BB == GEPI->getParent()) {
+    // If GEP is already inserted into BB, insert right after the GEP.
+    InsertPt = GEPI;
+    ++InsertPt;
+  } else {
+    // Otherwise, insert at the top of BB, after any PHI nodes
+    InsertPt = BB->begin();
+    while (isa<PHINode>(InsertPt)) ++InsertPt;
+  }
+  
+  // If Ptr is itself a cast, but in some other BB, emit a copy of the cast into
+  // BB so that there is only one value live across basic blocks (the cast 
+  // operand).
+  if (CastInst *CI = dyn_cast<CastInst>(Ptr))
+    if (CI->getParent() != BB && isa<PointerType>(CI->getOperand(0)->getType()))
+      Ptr = CastInst::create(CI->getOpcode(), CI->getOperand(0), CI->getType(),
+                             "", InsertPt);
+  
+  // Add the offset, cast it to the right type.
+  Ptr = BinaryOperator::createAdd(Ptr, PtrOffset, "", InsertPt);
+  // Ptr is an integer type, GEPI is pointer type ==> IntToPtr
+  return V = CastInst::create(Instruction::IntToPtr, Ptr, GEPI->getType(), 
+                              "", InsertPt);
+}
+
+/// ReplaceUsesOfGEPInst - Replace all uses of RepPtr with inserted code to
+/// compute its value.  The RepPtr value can be computed with Ptr+PtrOffset. One
+/// trivial way of doing this would be to evaluate Ptr+PtrOffset in RepPtr's
+/// block, then ReplaceAllUsesWith'ing everything.  However, we would prefer to
+/// sink PtrOffset into user blocks where doing so will likely allow us to fold
+/// the constant add into a load or store instruction.  Additionally, if a user
+/// is a pointer-pointer cast, we look through it to find its users.
+static void ReplaceUsesOfGEPInst(Instruction *RepPtr, Value *Ptr, 
+                                 Constant *PtrOffset, BasicBlock *DefBB,
+                                 GetElementPtrInst *GEPI,
+                           std::map<BasicBlock*,Instruction*> &InsertedExprs) {
+  while (!RepPtr->use_empty()) {
+    Instruction *User = cast<Instruction>(RepPtr->use_back());
+    
+    // If the user is a Pointer-Pointer cast, recurse. Only BitCast can be
+    // used for a Pointer-Pointer cast.
+    if (isa<BitCastInst>(User)) {
+      ReplaceUsesOfGEPInst(User, Ptr, PtrOffset, DefBB, GEPI, InsertedExprs);
+      
+      // Drop the use of RepPtr. The cast is dead.  Don't delete it now, else we
+      // could invalidate an iterator.
+      User->setOperand(0, UndefValue::get(RepPtr->getType()));
+      continue;
+    }
+    
+    // If this is a load of the pointer, or a store through the pointer, emit
+    // the increment into the load/store block.
+    Instruction *NewVal;
+    if (isa<LoadInst>(User) ||
+        (isa<StoreInst>(User) && User->getOperand(0) != RepPtr)) {
+      NewVal = InsertGEPComputeCode(InsertedExprs[User->getParent()], 
+                                    User->getParent(), GEPI,
+                                    Ptr, PtrOffset);
+    } else {
+      // If this use is not foldable into the addressing mode, use a version 
+      // emitted in the GEP block.
+      NewVal = InsertGEPComputeCode(InsertedExprs[DefBB], DefBB, GEPI, 
+                                    Ptr, PtrOffset);
+    }
+    
+    if (GEPI->getType() != RepPtr->getType()) {
+      BasicBlock::iterator IP = NewVal;
+      ++IP;
+      // NewVal must be a GEP which must be pointer type, so BitCast
+      NewVal = new BitCastInst(NewVal, RepPtr->getType(), "", IP);
+    }
+    User->replaceUsesOfWith(RepPtr, NewVal);
+  }
+}
+
+/// OptimizeGEPExpression - Since we are doing basic-block-at-a-time instruction
+/// selection, we want to be a bit careful about some things.  In particular, if
+/// we have a GEP instruction that is used in a different block than it is
+/// defined, the addressing expression of the GEP cannot be folded into loads or
+/// stores that use it.  In this case, decompose the GEP and move constant
+/// indices into blocks that use it.
+bool CodeGenPrepare::OptimizeGEPExpression(GetElementPtrInst *GEPI) {
+  // If this GEP is only used inside the block it is defined in, there is no
+  // need to rewrite it.
+  bool isUsedOutsideDefBB = false;
+  BasicBlock *DefBB = GEPI->getParent();
+  for (Value::use_iterator UI = GEPI->use_begin(), E = GEPI->use_end(); 
+       UI != E; ++UI) {
+    if (cast<Instruction>(*UI)->getParent() != DefBB) {
+      isUsedOutsideDefBB = true;
+      break;
+    }
+  }
+  if (!isUsedOutsideDefBB) return false;
+
+  // If this GEP has no non-zero constant indices, there is nothing we can do,
+  // ignore it.
+  bool hasConstantIndex = false;
+  bool hasVariableIndex = false;
+  for (GetElementPtrInst::op_iterator OI = GEPI->op_begin()+1,
+       E = GEPI->op_end(); OI != E; ++OI) {
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(*OI)) {
+      if (!CI->isZero()) {
+        hasConstantIndex = true;
+        break;
+      }
+    } else {
+      hasVariableIndex = true;
+    }
+  }
+  
+  // If this is a "GEP X, 0, 0, 0", turn this into a cast.
+  if (!hasConstantIndex && !hasVariableIndex) {
+    /// The GEP operand must be a pointer, so must its result -> BitCast
+    Value *NC = new BitCastInst(GEPI->getOperand(0), GEPI->getType(), 
+                                GEPI->getName(), GEPI);
+    GEPI->replaceAllUsesWith(NC);
+    GEPI->eraseFromParent();
+    return true;
+  }
+  
+  // If this is a GEP &Alloca, 0, 0, forward subst the frame index into uses.
+  if (!hasConstantIndex && !isa<AllocaInst>(GEPI->getOperand(0)))
+    return false;
+
+  // If we don't have target lowering info, we can't lower the GEP.
+  if (!TLI) return false;
+  const TargetData *TD = TLI->getTargetData();
+
+  // Otherwise, decompose the GEP instruction into multiplies and adds.  Sum the
+  // constant offset (which we now know is non-zero) and deal with it later.
+  uint64_t ConstantOffset = 0;
+  const Type *UIntPtrTy = TD->getIntPtrType();
+  Value *Ptr = new PtrToIntInst(GEPI->getOperand(0), UIntPtrTy, "", GEPI);
+  const Type *Ty = GEPI->getOperand(0)->getType();
+
+  for (GetElementPtrInst::op_iterator OI = GEPI->op_begin()+1,
+       E = GEPI->op_end(); OI != E; ++OI) {
+    Value *Idx = *OI;
+    if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
+      unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
+      if (Field)
+        ConstantOffset += TD->getStructLayout(StTy)->getElementOffset(Field);
+      Ty = StTy->getElementType(Field);
+    } else {
+      Ty = cast<SequentialType>(Ty)->getElementType();
+
+      // Handle constant subscripts.
+      if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
+        if (CI->getZExtValue() == 0) continue;
+        ConstantOffset += (int64_t)TD->getTypeSize(Ty)*CI->getSExtValue();
+        continue;
+      }
+      
+      // Ptr = Ptr + Idx * ElementSize;
+      
+      // Cast Idx to UIntPtrTy if needed.
+      Idx = CastInst::createIntegerCast(Idx, UIntPtrTy, true/*SExt*/, "", GEPI);
+      
+      uint64_t ElementSize = TD->getTypeSize(Ty);
+      // Mask off bits that should not be set.
+      ElementSize &= ~0ULL >> (64-UIntPtrTy->getPrimitiveSizeInBits());
+      Constant *SizeCst = ConstantInt::get(UIntPtrTy, ElementSize);
+
+      // Multiply by the element size and add to the base.
+      Idx = BinaryOperator::createMul(Idx, SizeCst, "", GEPI);
+      Ptr = BinaryOperator::createAdd(Ptr, Idx, "", GEPI);
+    }
+  }
+  
+  // Make sure that the offset fits in uintptr_t.
+  ConstantOffset &= ~0ULL >> (64-UIntPtrTy->getPrimitiveSizeInBits());
+  Constant *PtrOffset = ConstantInt::get(UIntPtrTy, ConstantOffset);
+  
+  // Okay, we have now emitted all of the variable index parts to the BB that
+  // the GEP is defined in.  Loop over all of the using instructions, inserting
+  // an "add Ptr, ConstantOffset" into each block that uses it and update the
+  // instruction to use the newly computed value, making GEPI dead.  When the
+  // user is a load or store instruction address, we emit the add into the user
+  // block, otherwise we use a canonical version right next to the gep (these 
+  // won't be foldable as addresses, so we might as well share the computation).
+  
+  std::map<BasicBlock*,Instruction*> InsertedExprs;
+  ReplaceUsesOfGEPInst(GEPI, Ptr, PtrOffset, DefBB, GEPI, InsertedExprs);
+  
+  // Finally, the GEP is dead, remove it.
+  GEPI->eraseFromParent();
+  
+  return true;
+}
+
+/// SinkInvariantGEPIndex - If a GEP instruction has a variable index that has
+/// been hoisted out of the loop by LICM pass, sink it back into the use BB
+/// if it can be determined that the index computation can be folded into the
+/// addressing mode of the load / store uses.
+static bool SinkInvariantGEPIndex(BinaryOperator *BinOp,
+                                  const TargetLowering &TLI) {
+  // Only look at Add.
+  if (BinOp->getOpcode() != Instruction::Add)
+    return false;
+
+  // DestBBs - These are the blocks where a copy of BinOp will be inserted.
+  SmallSet<BasicBlock*, 8> DestBBs;
+  BasicBlock *DefBB = BinOp->getParent();
+  bool MadeChange = false;
+  for (Value::use_iterator UI = BinOp->use_begin(), E = BinOp->use_end(); 
+       UI != E; ++UI) {
+    Instruction *GEPI = cast<Instruction>(*UI);
+    // Only look for GEP use in another block.
+    if (GEPI->getParent() == DefBB) continue;
+
+    if (isa<GetElementPtrInst>(GEPI)) {
+      // If the GEP has another variable index, abondon.
+      bool hasVariableIndex = false;
+      for (GetElementPtrInst::op_iterator OI = GEPI->op_begin()+1,
+             OE = GEPI->op_end(); OI != OE; ++OI)
+        if (*OI != BinOp && !isa<ConstantInt>(*OI)) {
+          hasVariableIndex = true;
+          break;
+        }
+      if (hasVariableIndex)
+        break;
+
+      BasicBlock *GEPIBB = GEPI->getParent();
+      for (Value::use_iterator UUI = GEPI->use_begin(), UE = GEPI->use_end(); 
+           UUI != UE; ++UUI) {
+        Instruction *GEPIUser = cast<Instruction>(*UUI);
+        const Type *UseTy = NULL;
+        if (LoadInst *Load = dyn_cast<LoadInst>(GEPIUser))
+          UseTy = Load->getType();
+        else if (StoreInst *Store = dyn_cast<StoreInst>(GEPIUser))
+          UseTy = Store->getOperand(0)->getType();
+
+        // Check if it is possible to fold the expression to address mode.
+        if (UseTy && isa<ConstantInt>(BinOp->getOperand(1))) {
+          uint64_t Scale = TLI.getTargetData()->getTypeSize(UseTy);
+          int64_t Cst = cast<ConstantInt>(BinOp->getOperand(1))->getSExtValue();
+          // e.g. load (gep i32 * %P, (X+42)) => load (%P + X*4 + 168).
+          if (TLI.isLegalAddressImmediate(Cst*Scale, UseTy) &&
+              (Scale == 1 || TLI.isLegalAddressScale(Scale, UseTy))) {
+            DestBBs.insert(GEPIBB);
+            MadeChange = true;
+            break;
+          }
+        }
+      }
+    }
+  }
+
+  // Nothing to do.
+  if (!MadeChange)
+    return false;
+
+  /// InsertedOps - Only insert a duplicate in each block once.
+  std::map<BasicBlock*, BinaryOperator*> InsertedOps;
+  for (Value::use_iterator UI = BinOp->use_begin(), E = BinOp->use_end(); 
+       UI != E; ) {
+    Instruction *User = cast<Instruction>(*UI);
+    BasicBlock *UserBB = User->getParent();
+
+    // Preincrement use iterator so we don't invalidate it.
+    ++UI;
+
+    // If any user in this BB wants it, replace all the uses in the BB.
+    if (DestBBs.count(UserBB)) {
+      // Sink it into user block.
+      BinaryOperator *&InsertedOp = InsertedOps[UserBB];
+      if (!InsertedOp) {
+        BasicBlock::iterator InsertPt = UserBB->begin();
+        while (isa<PHINode>(InsertPt)) ++InsertPt;
+      
+        InsertedOp =
+          BinaryOperator::create(BinOp->getOpcode(), BinOp->getOperand(0),
+                                 BinOp->getOperand(1), "", InsertPt);
+      }
+
+      User->replaceUsesOfWith(BinOp, InsertedOp);
+    }
+  }
+
+  if (BinOp->use_empty())
+      BinOp->eraseFromParent();
+
+  return true;
+}
+
+/// OptimizeNoopCopyExpression - We have determined that the specified cast
+/// instruction is a noop copy (e.g. it's casting from one pointer type to
+/// another, int->uint, or int->sbyte on PPC.
+///
+/// Return true if any changes are made.
+static bool OptimizeNoopCopyExpression(CastInst *CI) {
+  BasicBlock *DefBB = CI->getParent();
+  
+  /// InsertedCasts - Only insert a cast in each block once.
+  std::map<BasicBlock*, CastInst*> InsertedCasts;
+  
+  bool MadeChange = false;
+  for (Value::use_iterator UI = CI->use_begin(), E = CI->use_end(); 
+       UI != E; ) {
+    Use &TheUse = UI.getUse();
+    Instruction *User = cast<Instruction>(*UI);
+    
+    // Figure out which BB this cast is used in.  For PHI's this is the
+    // appropriate predecessor block.
+    BasicBlock *UserBB = User->getParent();
+    if (PHINode *PN = dyn_cast<PHINode>(User)) {
+      unsigned OpVal = UI.getOperandNo()/2;
+      UserBB = PN->getIncomingBlock(OpVal);
+    }
+    
+    // Preincrement use iterator so we don't invalidate it.
+    ++UI;
+    
+    // If this user is in the same block as the cast, don't change the cast.
+    if (UserBB == DefBB) continue;
+    
+    // If we have already inserted a cast into this block, use it.
+    CastInst *&InsertedCast = InsertedCasts[UserBB];
+
+    if (!InsertedCast) {
+      BasicBlock::iterator InsertPt = UserBB->begin();
+      while (isa<PHINode>(InsertPt)) ++InsertPt;
+      
+      InsertedCast = 
+        CastInst::create(CI->getOpcode(), CI->getOperand(0), CI->getType(), "", 
+                         InsertPt);
+      MadeChange = true;
+    }
+    
+    // Replace a use of the cast with a use of the new casat.
+    TheUse = InsertedCast;
+  }
+  
+  // If we removed all uses, nuke the cast.
+  if (CI->use_empty())
+    CI->eraseFromParent();
+  
+  return MadeChange;
+}
+
+
+
+// In this pass we look for GEP and cast instructions that are used
+// across basic blocks and rewrite them to improve basic-block-at-a-time
+// selection.
+bool CodeGenPrepare::OptimizeBlock(BasicBlock &BB) {
+  bool MadeChange = false;
+  
+  // Split all critical edges where the dest block has a PHI and where the phi
+  // has shared immediate operands.
+  TerminatorInst *BBTI = BB.getTerminator();
+  if (BBTI->getNumSuccessors() > 1) {
+    for (unsigned i = 0, e = BBTI->getNumSuccessors(); i != e; ++i)
+      if (isa<PHINode>(BBTI->getSuccessor(i)->begin()) &&
+          isCriticalEdge(BBTI, i, true))
+        SplitEdgeNicely(BBTI, i, this);
+  }
+  
+  
+  for (BasicBlock::iterator BBI = BB.begin(), E = BB.end(); BBI != E; ) {
+    Instruction *I = BBI++;
+    
+    if (CallInst *CI = dyn_cast<CallInst>(I)) {
+      // If we found an inline asm expession, and if the target knows how to
+      // lower it to normal LLVM code, do so now.
+      if (TLI && isa<InlineAsm>(CI->getCalledValue()))
+        if (const TargetAsmInfo *TAI = 
+            TLI->getTargetMachine().getTargetAsmInfo()) {
+          if (TAI->ExpandInlineAsm(CI))
+            BBI = BB.begin();
+        }
+    } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
+      MadeChange |= OptimizeGEPExpression(GEPI);
+    } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
+      // If the source of the cast is a constant, then this should have
+      // already been constant folded.  The only reason NOT to constant fold
+      // it is if something (e.g. LSR) was careful to place the constant
+      // evaluation in a block other than then one that uses it (e.g. to hoist
+      // the address of globals out of a loop).  If this is the case, we don't
+      // want to forward-subst the cast.
+      if (isa<Constant>(CI->getOperand(0)))
+        continue;
+      
+      if (!TLI) continue;
+      
+      // If this is a noop copy, sink it into user blocks to reduce the number
+      // of virtual registers that must be created and coallesced.
+      MVT::ValueType SrcVT = TLI->getValueType(CI->getOperand(0)->getType());
+      MVT::ValueType DstVT = TLI->getValueType(CI->getType());
+      
+      // This is an fp<->int conversion?
+      if (MVT::isInteger(SrcVT) != MVT::isInteger(DstVT))
+        continue;
+      
+      // If this is an extension, it will be a zero or sign extension, which
+      // isn't a noop.
+      if (SrcVT < DstVT) continue;
+      
+      // If these values will be promoted, find out what they will be promoted
+      // to.  This helps us consider truncates on PPC as noop copies when they
+      // are.
+      if (TLI->getTypeAction(SrcVT) == TargetLowering::Promote)
+        SrcVT = TLI->getTypeToTransformTo(SrcVT);
+      if (TLI->getTypeAction(DstVT) == TargetLowering::Promote)
+        DstVT = TLI->getTypeToTransformTo(DstVT);
+      
+      // If, after promotion, these are the same types, this is a noop copy.
+      if (SrcVT == DstVT)
+        MadeChange |= OptimizeNoopCopyExpression(CI);
+    } else if (BinaryOperator *BinOp = dyn_cast<BinaryOperator>(I)) {
+      if (TLI)
+        MadeChange |= SinkInvariantGEPIndex(BinOp, *TLI);
+    }
+  }
+  return MadeChange;
+}
+