1 files changed, 134 insertions, 15 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index c6d60d6f00..7595da08d3 100644
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -44,7 +44,7 @@ namespace {
     }
   
     void set(const APFloat& C);
-  
+
     void negate();
   
     bool isZero() const { return isInt() ? !IntVal : getFpVal().isZero(); }
@@ -79,6 +79,14 @@ namespace {
   
     bool isInt() const { return !IsFp; }
 
+    // If the coefficient is represented by an integer, promote it to a
+    // floating point. 
+    void convertToFpType(const fltSemantics &Sem);
+
+    // Construct an APFloat from a signed integer.
+    // TODO: We should get rid of this function when APFloat can be constructed
+    //       from an *SIGNED* integer. 
+    APFloat createAPFloatFromInt(const fltSemantics &Sem, int Val);
   private:
 
     bool IsFp;
@@ -150,7 +158,9 @@ namespace {
     typedef SmallVector<const FAddend*, 4> AddendVect;
   
     Value *simplifyFAdd(AddendVect& V, unsigned InstrQuota);
-  
+
+    Value *performFactorization(Instruction *I);
+
     /// Convert given addend to a Value
     Value *createAddendVal(const FAddend &A, bool& NeedNeg);
     
@@ -159,6 +169,7 @@ namespace {
     Value *createFSub(Value *Opnd0, Value *Opnd1);
     Value *createFAdd(Value *Opnd0, Value *Opnd1);
     Value *createFMul(Value *Opnd0, Value *Opnd1);
+    Value *createFDiv(Value *Opnd0, Value *Opnd1);
     Value *createFNeg(Value *V);
     Value *createNaryFAdd(const AddendVect& Opnds, unsigned InstrQuota);
     void createInstPostProc(Instruction *NewInst);
@@ -203,7 +214,31 @@ void FAddendCoef::set(const APFloat& C) {
   IsFp = BufHasFpVal = true; 
 }
 
-void FAddendCoef::operator=(const FAddendCoef& That) {
+void FAddendCoef::convertToFpType(const fltSemantics &Sem) {
+  if (!isInt())
+    return;
+
+  APFloat *P = getFpValPtr();
+  if (IntVal > 0)
+    new(P) APFloat(Sem, IntVal);
+  else {
+    new(P) APFloat(Sem, 0 - IntVal);
+    P->changeSign();
+  }
+  IsFp = BufHasFpVal = true; 
+}
+
+APFloat FAddendCoef::createAPFloatFromInt(const fltSemantics &Sem, int Val) {
+  if (Val >= 0)
+    return APFloat(Sem, Val);
+
+  APFloat T(Sem, 0 - Val);
+  T.changeSign();
+
+  return T;
+}
+
+void FAddendCoef::operator=(const FAddendCoef &That) {
   if (That.isInt())
     set(That.IntVal);
   else
@@ -222,13 +257,13 @@ void FAddendCoef::operator+=(const FAddendCoef &That) {
   
   if (isInt()) {
     const APFloat &T = That.getFpVal();
-    set(T);
-    getFpVal().add(APFloat(T.getSemantics(), IntVal), RndMode);
+    convertToFpType(T.getSemantics());
+    getFpVal().add(T, RndMode);
     return;
   }
   
   APFloat &T = getFpVal();
-  T.add(APFloat(T.getSemantics(), That.IntVal), RndMode);
+  T.add(createAPFloatFromInt(T.getSemantics(), That.IntVal), RndMode);
 }
 
 void FAddendCoef::operator-=(const FAddendCoef &That) {
@@ -243,13 +278,13 @@ void FAddendCoef::operator-=(const FAddendCoef &That) {
   
   if (isInt()) {
     const APFloat &T = That.getFpVal();
-    set(T);
-    getFpVal().subtract(APFloat(T.getSemantics(), IntVal), RndMode);
+    convertToFpType(T.getSemantics());
+    getFpVal().subtract(T, RndMode);
     return;
   }
 
   APFloat &T = getFpVal();
-  T.subtract(APFloat(T.getSemantics(), IntVal), RndMode);
+  T.subtract(createAPFloatFromInt(T.getSemantics(), IntVal), RndMode);
 }
 
 void FAddendCoef::operator*=(const FAddendCoef &That) {
@@ -272,11 +307,12 @@ void FAddendCoef::operator*=(const FAddendCoef &That) {
     isInt() ? That.getFpVal().getSemantics() : getFpVal().getSemantics();
 
   if (isInt())
-    set(APFloat(Semantic, IntVal));
+    convertToFpType(Semantic);
   APFloat &F0 = getFpVal();
 
   if (That.isInt())
-    F0.multiply(APFloat(Semantic, That.IntVal), APFloat::rmNearestTiesToEven);
+    F0.multiply(createAPFloatFromInt(Semantic, That.IntVal),
+                APFloat::rmNearestTiesToEven);
   else
     F0.multiply(That.getFpVal(), APFloat::rmNearestTiesToEven);
 
@@ -388,6 +424,78 @@ unsigned FAddend::drillAddendDownOneStep
   return BreakNum;
 }
 
+// Try to perform following optimization on the input instruction I. Return the
+// simplified expression if was successful; otherwise, return 0.
+//
+//   Instruction "I" is                Simplified into
+// -------------------------------------------------------
+//   (x * y) +/- (x * z)               x * (y +/- z)
+//   (y / x) +/- (z / x)               (y +/- z) / x
+//
+Value *FAddCombine::performFactorization(Instruction *I) {
+  assert((I->getOpcode() == Instruction::FAdd ||
+          I->getOpcode() == Instruction::FSub) && "Expect add/sub");
+  
+  Instruction *I0 = dyn_cast<Instruction>(I->getOperand(0));
+  Instruction *I1 = dyn_cast<Instruction>(I->getOperand(1));
+  
+  if (!I0 || !I1 || I0->getOpcode() != I1->getOpcode())
+    return 0;
+
+  bool isMpy = false;
+  if (I0->getOpcode() == Instruction::FMul)
+    isMpy = true;
+  else if (I0->getOpcode() != Instruction::FDiv)
+    return 0;
+
+  Value *Opnd0_0 = I0->getOperand(0);
+  Value *Opnd0_1 = I0->getOperand(1);
+  Value *Opnd1_0 = I1->getOperand(0);
+  Value *Opnd1_1 = I1->getOperand(1);
+
+  //  Input Instr I       Factor   AddSub0  AddSub1 
+  //  ----------------------------------------------
+  // (x*y) +/- (x*z)        x        y         z
+  // (y/x) +/- (z/x)        x        y         z
+  //
+  Value *Factor = 0;
+  Value *AddSub0 = 0, *AddSub1 = 0;
+  
+  if (isMpy) {
+    if (Opnd0_0 == Opnd1_0 || Opnd0_0 == Opnd1_1)
+      Factor = Opnd0_0;
+    else if (Opnd0_1 == Opnd1_0 || Opnd0_1 == Opnd1_1)
+      Factor = Opnd0_1;
+
+    if (Factor) {
+      AddSub0 = (Factor == Opnd0_0) ? Opnd0_1 : Opnd0_0;
+      AddSub1 = (Factor == Opnd1_0) ? Opnd1_1 : Opnd1_0;
+    }
+  } else if (Opnd0_1 == Opnd1_1) {
+    Factor = Opnd0_1;
+    AddSub0 = Opnd0_0;
+    AddSub1 = Opnd1_0;
+  }
+
+  if (!Factor)
+    return 0;
+
+  // Create expression "NewAddSub = AddSub0 +/- AddsSub1"
+  Value *NewAddSub = (I->getOpcode() == Instruction::FAdd) ?
+                      createFAdd(AddSub0, AddSub1) :
+                      createFSub(AddSub0, AddSub1);
+  if (ConstantFP *CFP = dyn_cast<ConstantFP>(NewAddSub)) {
+    const APFloat &F = CFP->getValueAPF();
+    if (!F.isNormal() || F.isDenormal())
+      return 0;
+  }
+
+  if (isMpy)
+    return createFMul(Factor, NewAddSub);
+ 
+  return createFDiv(NewAddSub, Factor);
+}
+
 Value *FAddCombine::simplify(Instruction *I) {
   assert(I->hasUnsafeAlgebra() && "Should be in unsafe mode");
 
@@ -471,7 +579,8 @@ Value *FAddCombine::simplify(Instruction *I) {
       return R;
   }
 
-  return 0;
+  // step 6: Try factorization as the last resort, 
+  return performFactorization(I);
 }
 
 Value *FAddCombine::simplifyFAdd(AddendVect& Addends, unsigned InstrQuota) {
@@ -627,7 +736,8 @@ Value *FAddCombine::createNaryFAdd
 Value *FAddCombine::createFSub
   (Value *Opnd0, Value *Opnd1) {
   Value *V = Builder->CreateFSub(Opnd0, Opnd1);
-  createInstPostProc(cast<Instruction>(V));
+  if (Instruction *I = dyn_cast<Instruction>(V))
+    createInstPostProc(I);
   return V;
 }
 
@@ -639,13 +749,22 @@ Value *FAddCombine::createFNeg(Value *V) {
 Value *FAddCombine::createFAdd
   (Value *Opnd0, Value *Opnd1) {
   Value *V = Builder->CreateFAdd(Opnd0, Opnd1);
-  createInstPostProc(cast<Instruction>(V));
+  if (Instruction *I = dyn_cast<Instruction>(V))
+    createInstPostProc(I);
   return V;
 }
 
 Value *FAddCombine::createFMul(Value *Opnd0, Value *Opnd1) {
   Value *V = Builder->CreateFMul(Opnd0, Opnd1);
-  createInstPostProc(cast<Instruction>(V));
+  if (Instruction *I = dyn_cast<Instruction>(V))
+    createInstPostProc(I);
+  return V;
+}
+
+Value *FAddCombine::createFDiv(Value *Opnd0, Value *Opnd1) {
+  Value *V = Builder->CreateFDiv(Opnd0, Opnd1);
+  if (Instruction *I = dyn_cast<Instruction>(V))
+    createInstPostProc(I);
   return V;
 }