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

1 files changed, 35 insertions, 6 deletions

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index 7a7eb6b682..b53ac13925 100644
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -21,13 +21,41 @@
 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 };
       return ConstantFoldInstOperands(Instruction::And, CLHS->getType(),
                                       Ops, 2, TD);
     }
@@ -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: