Templated structs have invalid debug info.

Description

The debug value mapping for templated structs map to the pointer of the struct, instead of the value of the struct.

Steps to Reproduce

Compile the following shader:

// /T ps_6_0 /Zi /Od
template<typename T>
struct S {
  T a, b;
  T Get() {
    return a + b;
  }
};


[RootSignature("")]
float main(float x : X, float y : Y, float z : Z, float w : W) : SV_Target {
  S<float> s;
  s.a = x;
  s.b = y;
  return s.Get();
}

Actual Behavior

You will see that the member b of variable s has the following mapping:

call void @llvm.dbg.value(metadata float %0, i64 0, metadata !53, metadata !58), !dbg !55 ; var:"this" !DIExpression(DW_OP_bit_piece, 32, 32) func:"Get"
!53 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "this", arg: 1, scope: !8, type: !54)
!54 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 32, align: 32)
!9 = !DICompositeType(tag: DW_TAG_structure_type, name: "S<float>", file: !1, line: 4, size: 64, align: 32, elements: !10, templateParams: !17)

The expected behaviour should be that this variable should be a value type, like so:

call void @llvm.dbg.value(metadata float %0, i64 0, metadata !51, metadata !55), !dbg !52 ; var:"this" !DIExpression(DW_OP_bit_piece, 32, 32) func:"Get"
!51 = !DILocalVariable(tag: DW_TAG_arg_variable, name: "this", arg: 1, scope: !8, type: !9)
!9 = !DICompositeType(tag: DW_TAG_structure_type, name: "S", file: !1, line: 11, size: 64, align: 32, elements: !10)

(This was done by compiling a non-templated version of struct S)

Environment

• DXC version: Nightly
• Host Operating System: Windows 11

Start by compiling the provided HLSL shader with DXC using /T ps_6_0 /Zi /Od and inspect the emitted LLVM debug metadata for the templated struct. Compare it with the non-templated struct output; done means the this debug variable uses the structure value type rather than a pointer type.