[Debug Info] Work graph node input/output objects have no usable debug info

[hbystuff]

Version: dxcompiler.dll 1.9(5402-0d3ee6b5)(1.9.0.5402) - 1.9.0.5402 (0d3ee6b55-dirty)

work_graph_repros.zip

dxc -T lib_6_8 -Zi -Qembed_debug -Od -Fc <name>.ll <name>.hlsl

(a) Node object parameters get no debug info at all

Every node object parameter is absent from the emitted metadata. No
DILocalVariable, no dbg.value. Only ordinary locals and system values
survive.

repro	node object parameter	emitted DILocalVariables
24-DispatchNodeInputRecord.hlsl	DispatchNodeInputRecord<MyRecord> input	DTid, idx, val
25-GroupNodeInputRecords.hlsl	GroupNodeInputRecords<MyRecord> input	groupIndex, count, record
26-ThreadNodeInputRecord.hlsl	ThreadNodeInputRecord<MyRecord> input	rec
27-EmptyNodeInput.hlsl	EmptyNodeInput input_records	groupIndex, recordCount
28-NodeOutput.hlsl	NodeOutput<MyOutputRecord> output	val, outputRec
29-NodeOutputArray.hlsl	NodeOutputArray<MyOutputRecord> outputs	selector, outputRec
30-EmptyNodeOutput.hlsl	EmptyNodeOutput output	val

The node object parameter is missing from the right column in every row. Rows
28-30 also drop their input record parameter.

(b) Record handle locals get a zeroinitializer and an empty type

GroupNodeOutputRecords<T> and ThreadNodeOutputRecords<T> locals do get a
DILocalVariable, but it carries no information:

; 31-GroupNodeOutputRecords.ll
call void @llvm.dbg.value(metadata %"struct.GroupNodeOutputRecords<MyOutputRecord>" zeroinitializer, i64 0, metadata !65, metadata !54)   ; var:"outputRec" !DIExpression()

!65 = !DILocalVariable(tag: DW_TAG_auto_variable, name: "outputRec", scope: !6, file: !1, line: 21, type: !66)
!66 = !DICompositeType(tag: DW_TAG_structure_type, name: "GroupNodeOutputRecords<MyOutputRecord>", file: !1, line: 21, size: 32, align: 32, elements: !2, templateParams: !67)

; 32-ThreadNodeOutputRecords.ll
call void @llvm.dbg.value(metadata %"struct.ThreadNodeOutputRecords<MyOutputRecord>" zeroinitializer, i64 0, metadata !67, metadata !53)   ; var:"outputRec" !DIExpression()

!68 = !DICompositeType(tag: DW_TAG_structure_type, name: "ThreadNodeOutputRecords<MyOutputRecord>", file: !1, line: 20, size: 32, align: 32, elements: !2, templateParams: !69)

The value is a constant zeroinitializer and elements: !2 is the empty tuple.
The handle reports as 0 and the type exposes no members. The shader writes
outputRec.Get(0).result immediately afterwards.

Expected

A DILocalVariable for each node input/output parameter, with a location that
reaches the underlying record. The record payload type is already present in
templateParams:. At minimum it should be reachable and its fields addressable.