[InstCombine] Avoid some uses of ConstantExpr::getZExt() (NFC)

Let the IRBuilder constant fold instead.

Author: nikic

llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp

@@ -830,15 +830,15 @@ static Instruction *foldNoWrapAdd(BinaryOperator &Add,
   // (sext (X +nsw NarrowC)) + C --> (sext X) + (sext(NarrowC) + C)
   Constant *NarrowC;
   if (match(Op0, m_OneUse(m_SExt(m_NSWAdd(m_Value(X), m_Constant(NarrowC)))))) {
-    Constant *WideC = ConstantExpr::getSExt(NarrowC, Ty);
-    Constant *NewC = ConstantExpr::getAdd(WideC, Op1C);
+    Value *WideC = Builder.CreateSExt(NarrowC, Ty);
+    Value *NewC = Builder.CreateAdd(WideC, Op1C);
     Value *WideX = Builder.CreateSExt(X, Ty);
     return BinaryOperator::CreateAdd(WideX, NewC);
   }
   // (zext (X +nuw NarrowC)) + C --> (zext X) + (zext(NarrowC) + C)
   if (match(Op0, m_OneUse(m_ZExt(m_NUWAdd(m_Value(X), m_Constant(NarrowC)))))) {
-    Constant *WideC = ConstantExpr::getZExt(NarrowC, Ty);
-    Constant *NewC = ConstantExpr::getAdd(WideC, Op1C);
+    Value *WideC = Builder.CreateZExt(NarrowC, Ty);
+    Value *NewC = Builder.CreateAdd(WideC, Op1C);
     Value *WideX = Builder.CreateZExt(X, Ty);
     return BinaryOperator::CreateAdd(WideX, NewC);
   }

llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp

@@ -1184,14 +1184,14 @@ Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
   Value *X;
   if (match(Src, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Constant(C)))) &&
       X->getType() == DestTy)
-    return BinaryOperator::CreateAnd(X, ConstantExpr::getZExt(C, DestTy));
+    return BinaryOperator::CreateAnd(X, Builder.CreateZExt(C, DestTy));
 
   // zext((trunc(X) & C) ^ C) -> ((X & zext(C)) ^ zext(C)).
   Value *And;
   if (match(Src, m_OneUse(m_Xor(m_Value(And), m_Constant(C)))) &&
       match(And, m_OneUse(m_And(m_Trunc(m_Value(X)), m_Specific(C)))) &&
       X->getType() == DestTy) {
-    Constant *ZC = ConstantExpr::getZExt(C, DestTy);
+    Value *ZC = Builder.CreateZExt(C, DestTy);
     return BinaryOperator::CreateXor(Builder.CreateAnd(X, ZC), ZC);
   }
 
@@ -1202,7 +1202,7 @@ Instruction *InstCombinerImpl::visitZExt(ZExtInst &Zext) {
   // zext (and (trunc X), C) --> and X, (zext C)
   if (match(Src, m_And(m_Trunc(m_Value(X)), m_Constant(C))) &&
       X->getType() == DestTy) {
-    Constant *ZextC = ConstantExpr::getZExt(C, DestTy);
+    Value *ZextC = Builder.CreateZExt(C, DestTy);
     return BinaryOperator::CreateAnd(X, ZextC);
   }