Reapply "[CodeGen] Fix assignments of inline layouts into the byref structure"

When using blocks, a byref structure is created to represent the
closure. The "byref.layout" field of this structure is an i8*. However,
some 'inline' layouts are represented as i64's, not i8*'s.

Prior to r246985 we cast the i64 'inline' layout to an i8* before
assigning it into the byref structure. This patch brings the cast back
and adds a regression test.

The original version of this patch was too invasive. This version only adds the
cast to BuildByrefLayout.

Differential Revision: http://reviews.llvm.org/D15674

rdar://23713871

llvm-svn: 256190

clang/lib/CodeGen/CGObjCMac.cpp

@@ -2640,6 +2640,8 @@ llvm::Constant *CGObjCCommonMac::BuildByrefLayout(CodeGen::CodeGenModule &CGM,
   if (const RecordType *record = T->getAs<RecordType>()) {
     BuildRCBlockVarRecordLayout(record, fieldOffset, hasUnion, true /*ByrefLayout */);
     llvm::Constant *Result = getBitmapBlockLayout(true);
+    if (isa<llvm::ConstantInt>(Result))
+      Result = llvm::ConstantExpr::getIntToPtr(Result, CGM.Int8PtrTy);
     return Result;
   }
   llvm::Constant *nullPtr = llvm::Constant::getNullValue(CGM.Int8PtrTy);

clang/lib/CodeGen/CGObjCRuntime.h

@@ -275,8 +275,11 @@ public:
                                   const CodeGen::CGBlockInfo &blockInfo) = 0;
   virtual llvm::Constant *BuildRCBlockLayout(CodeGen::CodeGenModule &CGM,
                                   const CodeGen::CGBlockInfo &blockInfo) = 0;
+
+  /// Returns an i8* which points to the byref layout information.
   virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,
                                            QualType T) = 0;
+
   virtual llvm::GlobalVariable *GetClassGlobal(const std::string &Name,
                                                bool Weak = false) = 0;
 

clang/test/CodeGenObjCXX/blocks.mm

@@ -68,3 +68,18 @@ class CaptureThisAndAnotherPointer {
     takeBlock(^{ useValues(ptr, this); });
   }
 };
+
+// rdar://problem/23713871
+// Check that we don't crash when using BLOCK_LAYOUT_STRONG.
+#pragma clang assume_nonnull begin
+@interface NSUUID @end
+#pragma clang assume_nonnull end
+
+struct Wrapper1 { NSUUID *Ref; };
+struct Wrapper2 { Wrapper1 W1; };
+
+@implementation B
+- (void) captureStrongRef {
+  __block Wrapper2 W2;
+}
+@end