implement @hekota suggestion, add warning to test, add comments

Author: spall

clang/lib/Sema/SemaHLSL.cpp

@@ -2048,16 +2048,14 @@ static bool CheckAllArgTypesAreCorrect(
 static bool CheckFloatOrHalfVecRepresentation(Sema *S, SourceLocation Loc,
                                               int ArgOrdinal,
                                               clang::QualType PassedType) {
-  QualType EltTy = PassedType;
-  if (auto *VecTy = EltTy->getAs<VectorType>())
-    EltTy = VecTy->getElementType();
+  if (auto *VecTy = PassedType->getAs<VectorType>())
+    if (VecTy->getElementType()->isHalfType() ||
+        VecTy->getElementType()->isFloat32Type())
+      return false;
 
-  if (!PassedType->getAs<VectorType>() ||
-      !(EltTy->isHalfType() || EltTy->isFloat32Type()))
-    return S->Diag(Loc, diag::err_builtin_invalid_arg_type)
-           << ArgOrdinal << /* vector of */ 4 << /* no int */ 0
-           << /* half or float */ 2 << PassedType;
-  return false;
+  return S->Diag(Loc, diag::err_builtin_invalid_arg_type)
+         << ArgOrdinal << /* vector of */ 4 << /* no int */ 0
+         << /* half or float */ 2 << PassedType;
 }
 
 static bool CheckFloatOrHalfRepresentation(Sema *S, SourceLocation Loc,
@@ -2109,17 +2107,16 @@ static bool CheckFloatingOrIntRepresentation(Sema *S, SourceLocation Loc,
 static bool CheckUnsignedIntVecRepresentation(Sema *S, SourceLocation Loc,
                                               int ArgOrdinal,
                                               clang::QualType PassedType) {
-  QualType EltTy = PassedType;
-  if (auto *VecTy = EltTy->getAs<VectorType>())
-    EltTy = VecTy->getElementType();
+  if (auto *VecTy = PassedType->getAs<VectorType>())
+    if (VecTy->getElementType()->isUnsignedIntegerType())
+      return false;
 
-  if (!PassedType->getAs<VectorType>() || !EltTy->isUnsignedIntegerType())
-    return S->Diag(Loc, diag::err_builtin_invalid_arg_type)
-           << ArgOrdinal << /* vector of */ 4 << /* uint */ 3 << /* no fp */ 0
-           << PassedType;
-  return false;
+  return S->Diag(Loc, diag::err_builtin_invalid_arg_type)
+         << ArgOrdinal << /* vector of */ 4 << /* uint */ 3 << /* no fp */ 0
+         << PassedType;
 }
 
+// checks for unsigned ints of all sizes
 static bool CheckUnsignedIntRepresentation(Sema *S, SourceLocation Loc,
                                            int ArgOrdinal,
                                            clang::QualType PassedType) {
@@ -2387,10 +2384,10 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
     if (SemaRef.checkArgCount(TheCall, 2))
       return true;
     if (CheckScalarOrVector(&SemaRef, TheCall, SemaRef.Context.UnsignedIntTy,
-                            0))
+                            0)) // only check for uint
       return true;
     if (CheckScalarOrVector(&SemaRef, TheCall, SemaRef.Context.UnsignedIntTy,
-                            1))
+                            1)) // only check for uint
       return true;
     if (CheckAllArgsHaveSameType(&SemaRef, TheCall))
       return true;

clang/test/SemaHLSL/BuiltIns/mad-errors.hlsl

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify -verify-ignore-unexpected=note,warning
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify -verify-ignore-unexpected=note
 
 float2 test_no_second_arg(float2 p0) {
   return __builtin_hlsl_mad(p0);
@@ -23,6 +23,7 @@ float2 test_mad_no_second_arg(float2 p0) {
 float2 test_mad_vector_size_mismatch(float3 p0, float2 p1) {
   return mad(p0, p0, p1);
   // expected-warning@-1 {{implicit conversion truncates vector: 'float3' (aka 'vector<float, 3>') to 'vector<float, 2>' (vector of 2 'float' values)}}
+  // expected-warning@-2 {{implicit conversion truncates vector: 'float3' (aka 'vector<float, 3>') to 'vector<float, 2>' (vector of 2 'float' values)}}
 }
 
 float2 test_mad_builtin_vector_size_mismatch(float3 p0, float2 p1) {