Add utility routines for creating integer negation operators with NSW set.

Integer negation only overflows with INT_MIN, but that's an important case.

llvm-svn: 91662

2 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/VMCore/Constants.cpp b/llvm/lib/VMCore/Constants.cpp
index a62f75b1c80..2507402f899 100644
--- a/llvm/lib/VMCore/Constants.cpp
+++ b/llvm/lib/VMCore/Constants.cpp
@@ -627,6 +627,12 @@ Constant* ConstantVector::get(Constant* const* Vals, unsigned NumVals) {
   return get(std::vector<Constant*>(Vals, Vals+NumVals));
 }
 
+Constant* ConstantExpr::getNSWNeg(Constant* C) {
+  assert(C->getType()->isIntOrIntVector() &&
+         "Cannot NEG a nonintegral value!");
+  return getNSWSub(ConstantFP::getZeroValueForNegation(C->getType()), C);
+}
+
 Constant* ConstantExpr::getNSWAdd(Constant* C1, Constant* C2) {
   return getTy(C1->getType(), Instruction::Add, C1, C2,
                OverflowingBinaryOperator::NoSignedWrap);
diff --git a/llvm/lib/VMCore/Instructions.cpp b/llvm/lib/VMCore/Instructions.cpp
index b03ee93dbe7..97fec399e48 100644
--- a/llvm/lib/VMCore/Instructions.cpp
+++ b/llvm/lib/VMCore/Instructions.cpp
@@ -1772,6 +1772,18 @@ BinaryOperator *BinaryOperator::CreateNeg(Value *Op, const Twine &Name,
                             Op->getType(), Name, InsertAtEnd);
 }
 
+BinaryOperator *BinaryOperator::CreateNSWNeg(Value *Op, const Twine &Name,
+                                             Instruction *InsertBefore) {
+  Value *zero = ConstantFP::getZeroValueForNegation(Op->getType());
+  return BinaryOperator::CreateNSWSub(zero, Op, Name, InsertBefore);
+}
+
+BinaryOperator *BinaryOperator::CreateNSWNeg(Value *Op, const Twine &Name,
+                                             BasicBlock *InsertAtEnd) {
+  Value *zero = ConstantFP::getZeroValueForNegation(Op->getType());
+  return BinaryOperator::CreateNSWSub(zero, Op, Name, InsertAtEnd);
+}
+
 BinaryOperator *BinaryOperator::CreateFNeg(Value *Op, const Twine &Name,
                                            Instruction *InsertBefore) {
   Value *zero = ConstantFP::getZeroValueForNegation(Op->getType());