From f69a113fe54e7d272f9e9f9a43c5cd0eedaf006b Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Thu, 2 Jun 2016 06:21:37 +0000
Subject: [PATCH] [codeview] Return type indices for typedefs

Use the type index of the underlying type unless we have a typedef from
long to HRESULT; HRESULT typedefs are translated to T_HRESULT.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271494 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/AsmPrinter/CodeViewDebug.cpp | 12 ++++++++++
 lib/CodeGen/AsmPrinter/CodeViewDebug.h   |  1 +
 test/DebugInfo/COFF/typedef.ll           | 38 ++++++++++++++++++++++++++++++++
 3 files changed, 51 insertions(+)
 create mode 100644 test/DebugInfo/COFF/typedef.ll

diff --git a/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index dec6770537e..7c167ba0c43 100644
--- a/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -731,6 +731,8 @@ void CodeViewDebug::beginFunction(const MachineFunction *MF) {
 TypeIndex CodeViewDebug::lowerType(const DIType *Ty) {
   // Generic dispatch for lowering an unknown type.
   switch (Ty->getTag()) {
+  case dwarf::DW_TAG_typedef:
+    return lowerTypeAlias(cast<DIDerivedType>(Ty));
   case dwarf::DW_TAG_base_type:
     return lowerTypeBasic(cast<DIBasicType>(Ty));
   case dwarf::DW_TAG_pointer_type:
@@ -748,6 +750,16 @@ TypeIndex CodeViewDebug::lowerType(const DIType *Ty) {
   }
 }
 
+TypeIndex CodeViewDebug::lowerTypeAlias(const DIDerivedType *Ty) {
+  // TODO: MSVC emits a S_UDT record.
+  DITypeRef UnderlyingTypeRef = Ty->getBaseType();
+  TypeIndex UnderlyingTypeIndex = getTypeIndex(UnderlyingTypeRef);
+  if (UnderlyingTypeIndex == TypeIndex(SimpleTypeKind::Int32Long) &&
+      Ty->getName() == "HRESULT")
+    return TypeIndex(SimpleTypeKind::HResult);
+  return UnderlyingTypeIndex;
+}
+
 TypeIndex CodeViewDebug::lowerTypeBasic(const DIBasicType *Ty) {
   TypeIndex Index;
   dwarf::TypeKind Kind;
diff --git a/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 41350d42f7e..24d785b8d4b 100644
--- a/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -190,6 +190,7 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   codeview::TypeIndex getTypeIndex(DITypeRef Ty);
 
   codeview::TypeIndex lowerType(const DIType *Ty);
+  codeview::TypeIndex lowerTypeAlias(const DIDerivedType *Ty);
   codeview::TypeIndex lowerTypeBasic(const DIBasicType *Ty);
   codeview::TypeIndex lowerTypePointer(const DIDerivedType *Ty);
   codeview::TypeIndex lowerTypeMemberPointer(const DIDerivedType *Ty);
diff --git a/test/DebugInfo/COFF/typedef.ll b/test/DebugInfo/COFF/typedef.ll
new file mode 100644
index 00000000000..a38080a6bfb
--- /dev/null
+++ b/test/DebugInfo/COFF/typedef.ll
@@ -0,0 +1,38 @@
+; RUN: llc < %s -filetype=obj | llvm-readobj - -codeview | FileCheck %s
+
+; CHECK: CodeViewDebugInfo [
+; CHECK:   Subsection [
+; CHECK:     Local {
+; CHECK:       Type: wchar_t (0x71)
+; CHECK:       Flags [ (0x0)
+; CHECK:       ]
+; CHECK:       VarName: foo
+; CHECK:     }
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-pc-windows-msvc18.0.0"
+
+define void @test1() !dbg !5 {
+entry:
+  %foo = alloca i16, align 2
+  call void @llvm.dbg.declare(metadata i16* %foo, metadata !8, metadata !11), !dbg !12
+  ret void, !dbg !12
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1)
+!1 = !DIFile(filename: "-", directory: "/usr/local/google/home/majnemer/llvm/src")
+!3 = !{i32 2, !"CodeView", i32 1}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "test1", linkageName: "test1", scope: !6, file: !6, type: !7, unit: !0, variables: !{})
+!6 = !DIFile(filename: "<stdin>", directory: ".")
+!7 = !DISubroutineType(types: !{})
+!8 = !DILocalVariable(name: "foo", scope: !5, file: !6, line: 3, type: !9)
+!9 = !DIDerivedType(tag: DW_TAG_typedef, name: "XYZ", file: !6, line: 2, baseType: !10)
+!10 = !DIBasicType(name: "wchar_t", size: 16, align: 16, encoding: DW_ATE_unsigned)
+!11 = !DIExpression()
+!12 = !DILocation(line: 3, column: 16, scope: !5)
-- 
2.11.0