[clang] [HLSL] add support for HLSLAggregateSplatCast and HLSLElementwiseCast to constant expression evaluator (PR #164700)

[Joshua Batista via cfe-commits]

================
@@ -3829,6 +3829,330 @@ static bool CheckArraySize(EvalInfo &Info, const ConstantArrayType *CAT,
       /*Diag=*/true);
 }
 
+static bool handleScalarCast(EvalInfo &Info, const FPOptions FPO, const Expr *E,
+                             QualType SourceTy, QualType DestTy,
+                             APValue const &Original, APValue &Result) {
+  // boolean must be checked before integer
+  // since IsIntegerType() is true for bool
+  if (SourceTy->isBooleanType()) {
+    if (DestTy->isBooleanType()) {
+      Result = Original;
+      return true;
+    }
+    if (DestTy->isIntegerType() || DestTy->isRealFloatingType()) {
+      bool BoolResult;
+      if (!HandleConversionToBool(Original, BoolResult))
+        return false;
+      uint64_t IntResult = BoolResult;
+      QualType IntType = DestTy->isIntegerType()
+                             ? DestTy
+                             : Info.Ctx.getIntTypeForBitwidth(64, false);
+      Result = APValue(Info.Ctx.MakeIntValue(IntResult, IntType));
+    }
+    if (DestTy->isFloatingType()) {
----------------
bob80905 wrote:

I think complex types would fall into this if condition. Though I think it should be impossible to come across that type in HLSL, it makes me wonder why the distinction between isrealfloating vs isfloating. Is this if condition meant to handle complex types correctly?

https://github.com/llvm/llvm-project/pull/164700