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

[vsk]

Summary

[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.

rdar://23713871

[rjmccall]

You don't need a CodeGenFunction for this; just use llvm::ConstantExpr::getBitCast. Please document the requirement that this returns an i8* in CGObjCRuntime.h.

[vsk]

• Update patch according to John's comments.

[rjmccall]

Thank you, that's great. LGTM.

[vsk]

Thanks for the review. Committed r256185

[vsk]

Closing old review.

lib/CodeGen/CGObjCMac.cpp

       if (auto numStrong = (Result & 0xF00) >> 8)
         printf(", BL_STRONG:%d", (int) numStrong);
       if (auto numByref = (Result & 0x0F0) >> 4)
         printf(", BL_BYREF:%d", (int) numByref);
       if (auto numWeak = (Result & 0x00F) >> 0)
         printf(", BL_WEAK:%d", (int) numWeak);
       printf(", BL_OPERATOR:0\n");
     }
-    return llvm::ConstantInt::get(CGM.IntPtrTy, Result);
+    return llvm::ConstantExpr::getIntToPtr(
+        llvm::ConstantInt::get(CGM.IntPtrTy, Result), CGM.Int8PtrTy);
   }
   
   unsigned char inst = (BLOCK_LAYOUT_OPERATOR << 4) | 0;
   Layout.push_back(inst);
   std::string BitMap;
   for (unsigned i = 0, e = Layout.size(); i != e; i++)
     BitMap += Layout[i];
   

lib/CodeGen/CGObjCRuntime.h

   virtual void EmitGCMemmoveCollectable(CodeGen::CodeGenFunction &CGF,
                                         Address DestPtr,
                                         Address SrcPtr,
                                         llvm::Value *Size) = 0;
   virtual llvm::Constant *BuildGCBlockLayout(CodeGen::CodeGenModule &CGM,
                                   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;
 
   struct MessageSendInfo {
     const CGFunctionInfo &CallInfo;
     llvm::PointerType *MessengerType;
 
     MessageSendInfo(const CGFunctionInfo &callInfo,

test/CodeGenObjCXX/blocks.mm

 }
 
 // PR24780
 class CaptureThisAndAnotherPointer {
   void test(void *ptr) {
     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