[DirectX] Differentiate between 1 overload and zero in the OpBuilder

DXIL operations that only have one signature behave one of two ways - either
they are always suffixed with a type like `dx.op.ThreadId.i32` and hence have
exactly one overload, or they're never suffixed like `dx.op.CreateHandle` and
hence have zero overloads.

Update DXIL.td for operations that have one overload and remove the hack in the
builder that was adjusting names for unoverloaded ops.

Author: bogner

llvm/lib/Target/DirectX/DXIL.td

@@ -671,26 +671,29 @@ def Dot4 :  DXILOp<56, dot4> {
 def ThreadId :  DXILOp<93, threadId> {
   let Doc = "Reads the thread ID";
   let LLVMIntrinsic = int_dx_thread_id;
-  let arguments = [i32Ty];
-  let result = i32Ty;
+  let arguments = [overloadTy];
+  let result = overloadTy;
+  let overloads = [Overloads<DXIL1_0, [i32Ty]>];
   let stages = [Stages<DXIL1_0, [compute, mesh, amplification, node]>];
   let attributes = [Attributes<DXIL1_0, [ReadNone]>];
 }
 
 def GroupId :  DXILOp<94, groupId> {
   let Doc = "Reads the group ID (SV_GroupID)";
   let LLVMIntrinsic = int_dx_group_id;
-  let arguments = [i32Ty];
-  let result = i32Ty;
+  let arguments = [overloadTy];
+  let result = overloadTy;
+  let overloads = [Overloads<DXIL1_0, [i32Ty]>];
   let stages = [Stages<DXIL1_0, [compute, mesh, amplification, node]>];
   let attributes = [Attributes<DXIL1_0, [ReadNone]>];
 }
 
 def ThreadIdInGroup :  DXILOp<95, threadIdInGroup> {
   let Doc = "Reads the thread ID within the group  (SV_GroupThreadID)";
   let LLVMIntrinsic = int_dx_thread_id_in_group;
-  let arguments = [i32Ty];
-  let result = i32Ty;
+  let arguments = [overloadTy];
+  let result = overloadTy;
+  let overloads = [Overloads<DXIL1_0, [i32Ty]>];
   let stages = [Stages<DXIL1_0, [compute, mesh, amplification, node]>];
   let attributes = [Attributes<DXIL1_0, [ReadNone]>];
 }
@@ -699,7 +702,8 @@ def FlattenedThreadIdInGroup :  DXILOp<96, flattenedThreadIdInGroup> {
   let Doc = "Provides a flattened index for a given thread within a given "
             "group (SV_GroupIndex)";
   let LLVMIntrinsic = int_dx_flattened_thread_id_in_group;
-  let result = i32Ty;
+  let result = overloadTy;
+  let overloads = [Overloads<DXIL1_0, [i32Ty]>];
   let stages = [Stages<DXIL1_0, [compute, mesh, amplification, node]>];
   let attributes = [Attributes<DXIL1_0, [ReadNone]>];
 }

llvm/lib/Target/DirectX/DXILOpBuilder.cpp

@@ -87,6 +87,9 @@ static const char *getOverloadTypeName(OverloadKind Kind) {
 }
 
 static OverloadKind getOverloadKind(Type *Ty) {
+  if (!Ty)
+    return OverloadKind::VOID;
+
   Type::TypeID T = Ty->getTypeID();
   switch (T) {
   case Type::VoidTyID:
@@ -379,11 +382,7 @@ Expected<CallInst *> DXILOpBuilder::tryCreateOp(dxil::OpCode OpCode,
 
   uint16_t ValidTyMask = Prop->Overloads[*OlIndexOrErr].ValidTys;
 
-  // If we don't have an overload type, use the function's return type. This is
-  // a bit of a hack, but it's necessary to get the type suffix on unoverloaded
-  // DXIL ops correct, like `dx.op.threadId.i32`.
-  OverloadKind Kind =
-      getOverloadKind(OverloadTy ? OverloadTy : DXILOpFT->getReturnType());
+  OverloadKind Kind = getOverloadKind(OverloadTy);
 
   // Check if the operation supports overload types and OverloadTy is valid
   // per the specified types for the operation