[CodeGen] Remove an unnecessary cast (NFC) (#146380)

E is already of Expr * and shares the same declaration among all these
cases.

Author: kazutakahirata

clang/lib/CodeGen/CGExprScalar.cpp

@@ -2440,7 +2440,7 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
   case CK_BlockPointerToObjCPointerCast:
   case CK_AnyPointerToBlockPointerCast:
   case CK_BitCast: {
-    Value *Src = Visit(const_cast<Expr*>(E));
+    Value *Src = Visit(E);
     llvm::Type *SrcTy = Src->getType();
     llvm::Type *DstTy = ConvertType(DestTy);
 
@@ -2606,11 +2606,10 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
   case CK_AtomicToNonAtomic:
   case CK_NonAtomicToAtomic:
   case CK_UserDefinedConversion:
-    return Visit(const_cast<Expr*>(E));
+    return Visit(E);
 
   case CK_NoOp: {
-    return CE->changesVolatileQualification() ? EmitLoadOfLValue(CE)
-                                              : Visit(const_cast<Expr *>(E));
+    return CE->changesVolatileQualification() ? EmitLoadOfLValue(CE) : Visit(E);
   }
 
   case CK_BaseToDerived: {
@@ -2712,10 +2711,10 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
   case CK_LValueToRValue:
     assert(CGF.getContext().hasSameUnqualifiedType(E->getType(), DestTy));
     assert(E->isGLValue() && "lvalue-to-rvalue applied to r-value!");
-    return Visit(const_cast<Expr*>(E));
+    return Visit(E);
 
   case CK_IntegralToPointer: {
-    Value *Src = Visit(const_cast<Expr*>(E));
+    Value *Src = Visit(E);
 
     // First, convert to the correct width so that we control the kind of
     // extension.
@@ -2768,7 +2767,7 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
   case CK_HLSLAggregateSplatCast:
   case CK_VectorSplat: {
     llvm::Type *DstTy = ConvertType(DestTy);
-    Value *Elt = Visit(const_cast<Expr *>(E));
+    Value *Elt = Visit(E);
     // Splat the element across to all elements
     llvm::ElementCount NumElements =
         cast<llvm::VectorType>(DstTy)->getElementCount();
@@ -2906,7 +2905,7 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
   case CK_HLSLVectorTruncation: {
     assert((DestTy->isVectorType() || DestTy->isBuiltinType()) &&
            "Destination type must be a vector or builtin type.");
-    Value *Vec = Visit(const_cast<Expr *>(E));
+    Value *Vec = Visit(E);
     if (auto *VecTy = DestTy->getAs<VectorType>()) {
       SmallVector<int> Mask;
       unsigned NumElts = VecTy->getNumElements();