MS ABI: Emit HandlerMap entries for C++ catch

The HandlerMap describes, to the runtime, what sort of catches surround
the try.  In principle, this structure has to be emitted by the backend
because only it knows the layout of the stack (the runtime needs to know
where on the stack the destination of a copy lives, etc.) but there is
some C++ specific information that the backend can't reason about.

Stick this information in special LLVM globals with the relevant
"const", "volatile", "reference" info mangled into the name.

llvm-svn: 232538

1 files changed, 55 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/MicrosoftCXXABI.cpp b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
index 7539ad8bdfa..6417b87444d 100644
--- a/clang/lib/CodeGen/MicrosoftCXXABI.cpp
+++ b/clang/lib/CodeGen/MicrosoftCXXABI.cpp
@@ -45,7 +45,7 @@ public:
       : CGCXXABI(CGM), BaseClassDescriptorType(nullptr),
         ClassHierarchyDescriptorType(nullptr),
         CompleteObjectLocatorType(nullptr), CatchableTypeType(nullptr),
-        ThrowInfoType(nullptr) {}
+        ThrowInfoType(nullptr), HandlerMapEntryType(nullptr) {}
 
   bool HasThisReturn(GlobalDecl GD) const override;
   bool hasMostDerivedReturn(GlobalDecl GD) const override;
@@ -84,7 +84,8 @@ public:
                                                    const VPtrInfo *Info);
 
   llvm::Constant *getAddrOfRTTIDescriptor(QualType Ty) override;
-  llvm::Constant *getAddrOfCXXCatchDescriptor(QualType Ty) override;
+  llvm::Constant *
+  getAddrOfCXXHandlerMapEntry(QualType Ty, QualType CatchHandlerType) override;
 
   bool shouldTypeidBeNullChecked(bool IsDeref, QualType SrcRecordTy) override;
   void EmitBadTypeidCall(CodeGenFunction &CGF) override;
@@ -572,6 +573,18 @@ public:
 
   void emitCXXStructor(const CXXMethodDecl *MD, StructorType Type) override;
 
+  llvm::StructType *getHandlerMapEntryType() {
+    if (!HandlerMapEntryType) {
+      llvm::Type *FieldTypes[] = {
+        CGM.IntTy,                           // Flags
+        getImageRelativeType(CGM.Int8PtrTy), // TypeDescriptor
+      };
+      HandlerMapEntryType = llvm::StructType::create(
+          CGM.getLLVMContext(), FieldTypes, "eh.HandlerMapEntry");
+    }
+    return HandlerMapEntryType;
+  }
+
   llvm::StructType *getCatchableTypeType() {
     if (CatchableTypeType)
       return CatchableTypeType;
@@ -685,6 +698,7 @@ private:
   llvm::StructType *CatchableTypeType;
   llvm::DenseMap<uint32_t, llvm::StructType *> CatchableTypeArrayTypeMap;
   llvm::StructType *ThrowInfoType;
+  llvm::StructType *HandlerMapEntryType;
 };
 
 }
@@ -3186,14 +3200,48 @@ static QualType decomposeTypeForEH(ASTContext &Context, QualType T,
   return T;
 }
 
-llvm::Constant *MicrosoftCXXABI::getAddrOfCXXCatchDescriptor(QualType Type) {
-  // TypeDescriptors for exceptions never has qualified pointer types,
+llvm::Constant *
+MicrosoftCXXABI::getAddrOfCXXHandlerMapEntry(QualType Type,
+                                             QualType CatchHandlerType) {
+  // TypeDescriptors for exceptions never have qualified pointer types,
   // qualifiers are stored seperately in order to support qualification
   // conversions.
   bool IsConst, IsVolatile;
   Type = decomposeTypeForEH(getContext(), Type, IsConst, IsVolatile);
 
-  return getAddrOfRTTIDescriptor(Type);
+  bool IsReference = CatchHandlerType->isReferenceType();
+
+  SmallString<256> MangledName;
+  {
+    llvm::raw_svector_ostream Out(MangledName);
+    getMangleContext().mangleCXXHandlerMapEntry(Type, IsConst, IsVolatile,
+                                                IsReference, Out);
+  }
+
+  if (llvm::GlobalVariable *GV = CGM.getModule().getNamedGlobal(MangledName))
+    return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
+
+  uint32_t Flags = 0;
+  if (IsConst)
+    Flags |= 1;
+  if (IsVolatile)
+    Flags |= 2;
+  if (IsReference)
+    Flags |= 8;
+
+  llvm::Constant *Fields[] = {
+      llvm::ConstantInt::get(CGM.IntTy, Flags),                // Flags
+      getImageRelativeConstant(getAddrOfRTTIDescriptor(Type)), // TypeDescriptor
+  };
+  llvm::StructType *HandlerMapEntryType = getHandlerMapEntryType();
+  auto *Var = new llvm::GlobalVariable(
+      CGM.getModule(), HandlerMapEntryType, /*Constant=*/true,
+      llvm::GlobalValue::PrivateLinkage,
+      llvm::ConstantStruct::get(HandlerMapEntryType, Fields),
+      StringRef(MangledName));
+  Var->setUnnamedAddr(true);
+  Var->setSection("llvm.metadata");
+  return Var;
 }
 
 /// \brief Gets a TypeDescriptor.  Returns a llvm::Constant * rather than a
@@ -3201,7 +3249,7 @@ llvm::Constant *MicrosoftCXXABI::getAddrOfCXXCatchDescriptor(QualType Type) {
 /// types, and need to be abstracted.  They are abstracting by casting the
 /// address to an Int8PtrTy.
 llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
-  SmallString<256> MangledName, TypeInfoString;
+  SmallString<256> MangledName;
   {
     llvm::raw_svector_ostream Out(MangledName);
     getMangleContext().mangleCXXRTTI(Type, Out);
@@ -3212,6 +3260,7 @@ llvm::Constant *MicrosoftCXXABI::getAddrOfRTTIDescriptor(QualType Type) {
     return llvm::ConstantExpr::getBitCast(GV, CGM.Int8PtrTy);
 
   // Compute the fields for the TypeDescriptor.
+  SmallString<256> TypeInfoString;
   {
     llvm::raw_svector_ostream Out(TypeInfoString);
     getMangleContext().mangleCXXRTTIName(Type, Out);