[clang] [HLSL] Implement support for HLSL intrinsic - select (PR #107129)

[Farzon Lotfi via cfe-commits]

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@@ -1512,6 +1512,83 @@ void SetElementTypeAsReturnType(Sema *S, CallExpr *TheCall,
   TheCall->setType(ReturnType);
 }
 
+static bool CheckScalarOrVector(Sema *S, CallExpr *TheCall, QualType Scalar,
+				unsigned ArgIndex) {
+  assert(TheCall->getNumArgs() >= ArgIndex);
+  QualType ArgType = TheCall->getArg(ArgIndex)->getType();
+  auto *VTy = ArgType->getAs<VectorType>();
+  // not the scalar or vector<scalar>
+  if (!(S->Context.hasSameUnqualifiedType(ArgType, Scalar) ||
+	(VTy && S->Context.hasSameUnqualifiedType(VTy->getElementType(),
+						  Scalar)))) {
+    S->Diag(TheCall->getArg(0)->getBeginLoc(),
+		   diag::err_typecheck_expect_scalar_or_vector)
+	<< ArgType << Scalar;
+    return true;
+  }
+  return false;
+}
+
+static bool CheckBoolSelect(Sema *S, CallExpr *TheCall) {
+  assert(TheCall->getNumArgs() == 3);
+  Expr *Arg1 = TheCall->getArg(1);
+  Expr *Arg2 = TheCall->getArg(2);
+  if(!S->Context.hasSameUnqualifiedType(Arg1->getType(),
+					Arg2->getType())) {
+    S->Diag(TheCall->getBeginLoc(),
+	    diag::err_typecheck_call_different_arg_types)
+      << Arg1->getType() << Arg2->getType()
+      << Arg1->getSourceRange() << Arg2->getSourceRange();
+    return true;
+  }
+
+  TheCall->setType(Arg1->getType());
+  return false;
+}
+
+static bool CheckVectorSelect(Sema *S, CallExpr *TheCall) {
+  assert(TheCall->getNumArgs() == 3);
+  Expr *Arg1 = TheCall->getArg(1);
+  Expr *Arg2 = TheCall->getArg(2);
+  if (!Arg1->getType()->isVectorType()) {
+    S->Diag(Arg1->getBeginLoc(),
+	    diag::err_builtin_non_vector_type)
+      << "Second" << "__builtin_hlsl_select" << Arg1->getType()
+      << Arg1->getSourceRange();
+    return true;
+  }
+  
+  if (!Arg2->getType()->isVectorType()) {
+    S->Diag(Arg2->getBeginLoc(),
+	    diag::err_builtin_non_vector_type)
+      << "Third" << "__builtin_hlsl_select" << Arg2->getType()
+      << Arg2->getSourceRange();
+    return true;
+  }
+
+  if (!S->Context.hasSameUnqualifiedType(Arg1->getType(),
+					 Arg2->getType())) {
+    S->Diag(TheCall->getBeginLoc(),
+	    diag::err_typecheck_call_different_arg_types)
+      << Arg1->getType() << Arg2->getType()
+      << Arg1->getSourceRange() << Arg2->getSourceRange();
+    return true;
+  }
+
+  // caller has checked that Arg0 is a vector.
+  // check all three args have the same length.
+  if (TheCall->getArg(0)->getType()->getAs<VectorType>()->getNumElements() !=
----------------
farzonl wrote:

Fair enough no change needed. I did I mean the length check. 

i thought  maybe there is something we  could do to generalize this or maybe there is something that does length checks already in `Sema`\ `SemaChecking`. 

https://github.com/llvm/llvm-project/pull/107129