Cache CU value translated outside of usual flow (#2072)

Compilation unit can be translated earlier, e.g. in `transEntryPoint()`.
We should save the translated LLVM value to be used further.

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@803e528

Author: vmaksimo

llvm-spirv/lib/SPIRV/SPIRVToLLVMDbgTran.cpp

@@ -1052,8 +1052,8 @@ MDNode *SPIRVToLLVMDbgTran::transEntryPoint(const SPIRVExtInst *DebugInst) {
   std::string Producer = getString(Ops[CompilerSignatureIdx]);
   std::string CLArgs = getString(Ops[CommandLineArgsIdx]);
 
-  [[maybe_unused]] DICompileUnit *C =
-      transCompilationUnit(CU, Producer, CLArgs);
+  DICompileUnit *C = transCompilationUnit(CU, Producer, CLArgs); // NOLINT
+  DebugInstCache[CU] = C;
 
   return transFunction(EP, true /*IsMainSubprogram*/);
 }

llvm-spirv/test/DebugInfo/NonSemantic/Shader200/DebugTypeDef.ll

@@ -0,0 +1,52 @@
+; This test covers assertion "Typedef should have a parent scope"
+
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -spirv-text --spirv-debug-info-version=nonsemantic-shader-200 -o %t.spt
+; RUN: FileCheck < %t.spt %s --check-prefix=CHECK-SPIRV
+; RUN: llvm-spirv %t.bc -o %t.spv --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv -r -emit-opaque-pointers %t.spv -o %t.rev.bc
+; RUN: llvm-dis %t.rev.bc 
+; RUN: FileCheck < %t.rev.ll %s --check-prefix=CHECK-LLVM
+
+; CHECK-SPIRV: String [[#TestStr:]] "test.cpp"
+; CHECK-SPIRV: String [[#StdStr:]] "stddef.h"
+; CHECK-SPIRV: [[#SourceCpp:]] [[#]] DebugSource [[#TestStr]]
+; CHECK-SPIRV: [[#Scope:]] [[#]] DebugCompilationUnit [[#]] [[#]] [[#SourceCpp]]
+; CHECK-SPIRV: [[#SourceHeader:]] [[#]] DebugSource [[#StdStr]]
+; CHECK-SPIRV: DebugTypedef [[#]] [[#]] [[#SourceHeader]] [[#]] [[#]] [[#Scope]]
+; CHECK-SPIRV: DebugEntryPoint [[#]] [[#Scope]]
+
+; CHECK-LLVM: DW_TAG_typedef
+target datalayout = "e-i64:64-v16:16-v24:32-v32:32-v48:64-v96:128-v192:256-v256:256-v512:512-v1024:1024-n8:16:32:64"
+target triple = "spir64"
+
+$_ZTSZ4mainEUlvE_ = comdat any
+
+; Function Attrs: convergent mustprogress norecurse nounwind
+define weak_odr dso_local spir_kernel void @_ZTSZ4mainEUlvE_() #0 comdat !dbg !14 {
+entry:
+  ret void
+}
+
+attributes #0 = { convergent mustprogress norecurse nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!10, !11, !12, !13}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang based compiler", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, imports: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression(DW_OP_constu, 175, DW_OP_stack_value))
+!5 = distinct !DIGlobalVariable(name: "N", scope: !0, file: !1, line: 7, type: !6, isLocal: true, isDefinition: true)
+!6 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !7)
+!7 = !DIDerivedType(tag: DW_TAG_typedef, name: "size_t", file: !8, line: 62, baseType: !9)
+!8 = !DIFile(filename: "stddef.h", directory: "")
+!9 = !DIBasicType(name: "unsigned long", size: 64, encoding: DW_ATE_unsigned)
+!10 = !{i32 7, !"Dwarf Version", i32 4}
+!11 = !{i32 2, !"Debug Info Version", i32 3}
+!12 = !{i32 1, !"wchar_size", i32 4}
+!13 = !{i32 7, !"frame-pointer", i32 2}
+!14 = distinct !DISubprogram(name: "_ZTSZ4mainEUlvE_", scope: !1, file: !1, line: 24, type: !15, flags: DIFlagArtificial | DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!15 = !DISubroutineType(cc: DW_CC_nocall, types: !16)
+!16 = !{null}