factor some logic out of instcombine into a new SimplifyAddInst method.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90011 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/InstructionSimplify.h b/include/llvm/Analysis/InstructionSimplify.h
index 1cd7e565563728ee60bd9dad016b7cebf67174a9..13314e6ea0e5e129b38a19882bf880e3bc2c5bdd 100644 (file)
--- a/include/llvm/Analysis/InstructionSimplify.h
+++ b/include/llvm/Analysis/InstructionSimplify.h
@@ -20,6 +20,11 @@ namespace llvm {
   class Instruction;
   class Value;
   class TargetData;
+
+  /// SimplifyAddInst - Given operands for an Add, see if we can
+  /// fold the result.  If not, this returns null.
+  Value *SimplifyAddInst(Value *LHS, Value *RHS, bool isNSW, bool isNUW,
+                         const TargetData *TD = 0);
   
   /// SimplifyAndInst - Given operands for an And, see if we can
   /// fold the result.  If not, this returns null.

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 7a7eb6b6829331aa77ccb346798d6c129d877603..b53ac13925b17a7930f7c32cf103a419278831a8 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -21,10 +21,38 @@
 using namespace llvm;
 using namespace llvm::PatternMatch;
 
-/// SimplifyAndInst - Given operands for an And, see if we can
+/// SimplifyAddInst - Given operands for an Add, see if we can
 /// fold the result.  If not, this returns null.
-Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1,
+Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
                              const TargetData *TD) {
+  if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+    if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+      Constant *Ops[] = { CLHS, CRHS };
+      return ConstantFoldInstOperands(Instruction::Add, CLHS->getType(),
+                                      Ops, 2, TD);
+    }
+    
+    // Canonicalize the constant to the RHS.
+    std::swap(Op0, Op1);
+  }
+  
+  if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
+    // X + undef -> undef
+    if (isa<UndefValue>(Op1C))
+      return Op1C;
+    
+    // X + 0 --> X
+    if (Op1C->isNullValue())
+      return Op0;
+  }
+  
+  // FIXME: Could pull several more out of instcombine.
+  return 0;
+}
+
+/// SimplifyAndInst - Given operands for an And, see if we can
+/// fold the result.  If not, this returns null.
+Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD) {
   if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
     if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
       Constant *Ops[] = { CLHS, CRHS };
@@ -83,8 +111,7 @@ Value *llvm::SimplifyAndInst(Value *Op0, Value *Op1,
 
 /// SimplifyOrInst - Given operands for an Or, see if we can
 /// fold the result.  If not, this returns null.
-Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1,
-                            const TargetData *TD) {
+Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1, const TargetData *TD) {
   if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
     if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
       Constant *Ops[] = { CLHS, CRHS };
@@ -142,8 +169,6 @@ Value *llvm::SimplifyOrInst(Value *Op0, Value *Op1,
 }
 
 
-
-
 static const Type *GetCompareTy(Value *Op) {
   return CmpInst::makeCmpResultType(Op->getType());
 }
@@ -327,6 +352,10 @@ Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD) {
   switch (I->getOpcode()) {
   default:
     return ConstantFoldInstruction(I, TD);
+  case Instruction::Add:
+    return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+                           cast<BinaryOperator>(I)->hasNoSignedWrap(),
+                           cast<BinaryOperator>(I)->hasNoUnsignedWrap(), TD);
   case Instruction::And:
     return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD);
   case Instruction::Or:

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 95563b0493bc074d73a9474d975b2cc6028551be..c591ef841c0d7fcb9aaed3c0d95a0735c7a0b847 100644 (file)
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -2163,8 +2163,8 @@ bool InstCombiner::WillNotOverflowSignedAdd(Value *LHS, Value *RHS) {
   
   // Add has the property that adding any two 2's complement numbers can only 
   // have one carry bit which can change a sign.  As such, if LHS and RHS each
-  // have at least two sign bits, we know that the addition of the two values will
-  // sign extend fine.
+  // have at least two sign bits, we know that the addition of the two values
+  // will sign extend fine.
   if (ComputeNumSignBits(LHS) > 1 && ComputeNumSignBits(RHS) > 1)
     return true;
   
@@ -2184,15 +2184,12 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
   bool Changed = SimplifyCommutative(I);
   Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
 
-  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
-    // X + undef -> undef
-    if (isa<UndefValue>(RHS))
-      return ReplaceInstUsesWith(I, RHS);
-
-    // X + 0 --> X
-    if (RHSC->isNullValue())
-      return ReplaceInstUsesWith(I, LHS);
+  if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
+                                 I.hasNoUnsignedWrap(), TD))
+    return ReplaceInstUsesWith(I, V);
 
+  
+  if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
     if (ConstantInt *CI = dyn_cast<ConstantInt>(RHSC)) {
       // X + (signbit) --> X ^ signbit
       const APInt& Val = CI->getValue();
@@ -4322,7 +4319,6 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
 
   if (Value *V = SimplifyAndInst(Op0, Op1, TD))
     return ReplaceInstUsesWith(I, V);
-    
 
   // See if we can simplify any instructions used by the instruction whose sole 
   // purpose is to compute bits we don't care about.