commit c168c6f86f811327488b58f7e2cc9826801a0155
author Reid Kleckner <rnk@google.com> Wed Dec 26 21:52:17 2018 +0000
committer Reid Kleckner <rnk@google.com> Wed Dec 26 21:52:17 2018 +0000
tree 3ec6122b4d1a79b4bb234ea92dc4143d28eb791f
parent a643e6449ba284e345ddd35479b8c4f897eed386

[codeview] Check if this 'this' type of a method is a pointer

Fixes crash reported after r347354 for frontends that don't always emit
'this' pointers for methods. Now we will silently produce debug info
that makes functions like this look like static methods, which seems
reasonable.

llvm-svn: 350073

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 990f0f4..8cabad4 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1838,9 +1838,19 @@
   SmallVector<TypeIndex, 8> ArgTypeIndices;
   TypeIndex ReturnTypeIndex = getTypeIndex(ReturnAndArgs[Index++]);
 
+  // If the first argument is a pointer type and this isn't a static method,
+  // treat it as the special 'this' parameter, which is encoded separately from
+  // the arguments.
   TypeIndex ThisTypeIndex;
-  if (!IsStaticMethod && ReturnAndArgs.size() > 1)
-    ThisTypeIndex = getTypeIndexForThisPtr(ReturnAndArgs[Index++], Ty);
+  if (!IsStaticMethod && ReturnAndArgs.size() > Index) {
+    if (const DIDerivedType *PtrTy =
+            dyn_cast_or_null<DIDerivedType>(ReturnAndArgs[Index].resolve())) {
+      if (PtrTy->getTag() == dwarf::DW_TAG_pointer_type) {
+        ThisTypeIndex = getTypeIndexForThisPtr(PtrTy, Ty);
+        Index++;
+      }
+    }
+  }
 
   while (Index < ReturnAndArgs.size())
     ArgTypeIndices.push_back(getTypeIndex(ReturnAndArgs[Index++]));
@@ -2396,9 +2406,10 @@
 }
 
 codeview::TypeIndex
-CodeViewDebug::getTypeIndexForThisPtr(DITypeRef TypeRef,
+CodeViewDebug::getTypeIndexForThisPtr(const DIDerivedType *PtrTy,
                                       const DISubroutineType *SubroutineTy) {
-  const DIType *Ty = TypeRef.resolve();
+  assert(PtrTy->getTag() == dwarf::DW_TAG_pointer_type &&
+         "this type must be a pointer type");
 
   PointerOptions Options = PointerOptions::None;
   if (SubroutineTy->getFlags() & DINode::DIFlags::FlagLValueReference)
@@ -2411,13 +2422,13 @@
   // so that the TypeIndex for the this pointer can be shared with the type
   // index for other pointers to this class type.  If there is a ref qualifier
   // then we lookup the pointer using the subroutine as the parent type.
-  auto I = TypeIndices.find({Ty, SubroutineTy});
+  auto I = TypeIndices.find({PtrTy, SubroutineTy});
   if (I != TypeIndices.end())
     return I->second;
 
   TypeLoweringScope S(*this);
-  TypeIndex TI = lowerTypePointer(cast<DIDerivedType>(Ty), Options);
-  return recordTypeIndexForDINode(Ty, TI, SubroutineTy);
+  TypeIndex TI = lowerTypePointer(PtrTy, Options);
+  return recordTypeIndexForDINode(PtrTy, TI, SubroutineTy);
 }
 
 TypeIndex CodeViewDebug::getTypeIndexForReferenceTo(DITypeRef TypeRef) {

llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 1c2b9bf..21557ed 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -377,7 +377,7 @@
                                    DITypeRef ClassTyRef = DITypeRef());
 
   codeview::TypeIndex
-  getTypeIndexForThisPtr(DITypeRef TypeRef,
+  getTypeIndexForThisPtr(const DIDerivedType *PtrTy,
                          const DISubroutineType *SubroutineTy);
 
   codeview::TypeIndex getTypeIndexForReferenceTo(DITypeRef TypeRef);