Fix translation of some cases of mem2reged local variables (#3103)

We should translate null/undef declare records to DebugDeclare with
OpDebugInfoNone instruction referenced in OpVariableId operand.

TODO: currently the specification says, that only OpVariable can be
referenced by this operand. This seem to be a spec bug, we should allow
OpDebugInfoNone there.

Signed-off-by: Sidorov, Dmitry <dmitry.sidorov@intel.com>

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@367ede2461181ae

Author: MrSidims

llvm-spirv/lib/SPIRV/LLVMToSPIRVDbgTran.cpp

@@ -127,8 +127,10 @@ void LLVMToSPIRVDbgTran::finalizeDebugDeclare(
   using namespace SPIRVDebug::Operand::DebugDeclare;
   SPIRVWordVec Ops(OperandCount);
   Ops[DebugLocalVarIdx] = transDbgEntry(DbgDecl->getVariable())->getId();
-  Ops[VariableIdx] = Alloca ? SPIRVWriter->transValue(Alloca, BB)->getId()
-                            : getDebugInfoNoneId();
+  unsigned OpVariableId = getDebugInfoNoneId();
+  if (Alloca && !(isa<ConstantPointerNull>(Alloca) || isa<UndefValue>(Alloca)))
+    OpVariableId = SPIRVWriter->transValue(Alloca, BB)->getId();
+  Ops[VariableIdx] = OpVariableId;
   Ops[ExpressionIdx] = transDbgEntry(DbgDecl->getExpression())->getId();
   DD->setArguments(Ops);
 }

llvm-spirv/lib/SPIRV/SPIRVReader.cpp

@@ -2678,12 +2678,7 @@ Value *SPIRVToLLVM::transValueWithoutDecoration(SPIRVValue *BV, Function *F,
         return mapValue(
             BV, cast<Instruction *>(DbgTran->transDebugIntrinsic(ExtInst, BB)));
       } else {
-        auto MaybeRecord = DbgTran->transDebugIntrinsic(ExtInst, BB);
-        if (!MaybeRecord.isNull()) {
-          auto *Record = cast<DbgRecord *>(MaybeRecord);
-          Record->setDebugLoc(
-              DbgTran->transDebugScope(static_cast<SPIRVInstruction *>(BV)));
-        }
+        DbgTran->transDebugIntrinsic(ExtInst, BB);
         return mapValue(BV, nullptr);
       }
     default:

llvm-spirv/lib/SPIRV/SPIRVToLLVMDbgTran.cpp

@@ -1592,17 +1592,19 @@ SPIRVToLLVMDbgTran::transDebugIntrinsic(const SPIRVExtInst *DebugInst,
       AI->eraseFromParent();
       return DbgDeclare;
     }
+    DebugLoc Loc = transDebugScope(DebugInst);
     return DIB.insertDeclare(GetValue(Ops[VariableIdx]), LocalVar.first,
-                             GetExpression(Ops[ExpressionIdx]), LocalVar.second,
+                             GetExpression(Ops[ExpressionIdx]), Loc,
                              BB);
   }
   case SPIRVDebug::Value: {
     using namespace SPIRVDebug::Operand::DebugValue;
     auto LocalVar = GetLocalVar(Ops[DebugLocalVarIdx]);
     Value *Val = GetValue(Ops[ValueIdx]);
     DIExpression *Expr = GetExpression(Ops[ExpressionIdx]);
+    DebugLoc Loc = transDebugScope(DebugInst);
     DbgInstPtr DbgValIntr = getDIBuilder(DebugInst).insertDbgValueIntrinsic(
-        Val, LocalVar.first, Expr, LocalVar.second, BB);
+        Val, LocalVar.first, Expr, Loc, BB);
 
     std::vector<ValueAsMetadata *> MDs;
     for (size_t I = 0; I != Expr->getNumLocationOperands(); ++I) {

llvm-spirv/test/DebugInfo/DebugDeclareUnused.cl

@@ -14,6 +14,6 @@ void foo() {
   int a;
 }
 
-// CHECK-SPIRV: Undef [[#]] [[#Undef:]]
-// CHECK-SPIRV: ExtInst [[#]] [[#]] [[#]] DebugDeclare [[#]] [[#Undef]] [[#]]
-// CHECK-LLVM:  #dbg_declare(ptr undef, ![[#]], !DIExpression(DW_OP_constu, 0, DW_OP_swap, DW_OP_xderef), ![[#]])
+// CHECK-SPIRV: ExtInst [[#]] [[#InfoNone:]] [[#]] DebugInfoNone
+// CHECK-SPIRV: ExtInst [[#]] [[#]] [[#]] DebugDeclare [[#]] [[#InfoNone]] [[#]]
+// CHECK-LLVM:  #dbg_declare(ptr poison, ![[#]], !DIExpression(DW_OP_constu, 0, DW_OP_swap, DW_OP_xderef), ![[#]])

llvm-spirv/test/DebugInfo/mem2reged_local_var.ll

@@ -0,0 +1,59 @@
+; Check if the translator handles #dbg_declare(ptr null ...) correctly
+
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: llvm-spirv %t.spv -to-text -o %t.spt
+; RUN: FileCheck < %t.spt %s --check-prefixes=CHECK-SPIRV
+; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
+; RUN: llvm-dis < %t.rev.bc | FileCheck %s --check-prefix=CHECK-LLVM
+
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -o %t.spv --spirv-debug-info-version=nonsemantic-shader-100
+; RUN: llvm-spirv %t.spv -to-text -o %t.spt
+; RUN: FileCheck < %t.spt %s --check-prefixes=CHECK-SPIRV
+; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
+; RUN: llvm-dis < %t.rev.bc | FileCheck %s --check-prefix=CHECK-LLVM
+
+; RUN: llvm-as %s -o %t.bc
+; RUN: llvm-spirv %t.bc -o %t.spv --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv %t.spv -to-text -o %t.spt
+; RUN: FileCheck < %t.spt %s --check-prefixes=CHECK-SPIRV
+; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
+; RUN: llvm-dis < %t.rev.bc | FileCheck %s --check-prefix=CHECK-LLVM
+
+; CHECK-SPIRV: ExtInst [[#]] [[#None:]] [[#]] DebugInfoNone
+; CHECK-SPIRV: ExtInst [[#]] [[#LocalVar:]] [[#]] DebugLocalVariable
+; CHECK-SPIRV: ExtInst [[#]] [[#]] [[#]] DebugDeclare [[#LocalVar]] [[#None]] [[#]]
+
+; CHECK-LLVM: #dbg_declare(ptr poison, ![[#LocalVar:]], !DIExpression(DW_OP_constu, 4, DW_OP_swap, DW_OP_xderef), ![[#Loc:]])
+; CHECK-LLVM-DAG: ![[#LocalVar]] = !DILocalVariable(name: "bar"
+; CHECK-LLVM-DAG: ![[#Loc]] = !DILocation(line: 23
+
+; ModuleID = 'test.bc'
+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-G1"
+target triple = "spir64"
+
+define spir_kernel void @__omp_offloading_811_29c0007__Z4main_l28() {
+newFuncRoot:
+  %0 = alloca i32, i32 0, align 4, !dbg !4
+  store i32 0, ptr null, align 4
+  %four.ascast.fpriv = alloca i32, align 4, !dbg !4
+    #dbg_declare(ptr null, !8, !DIExpression(DW_OP_constu, 4, DW_OP_swap, DW_OP_xderef), !10)
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, imports: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/path/to")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !DILocation(line: 28, column: 1, scope: !5)
+!5 = distinct !DILexicalBlock(scope: !6, file: !1, line: 28, column: 1)
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 28, type: !7, scopeLine: 28, flags: DIFlagArtificial, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition, unit: !0)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocalVariable(name: "bar", scope: !5, file: !1, line: 23, type: !9)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !DILocation(line: 23, column: 7, scope: !5)
+