When constructing debug information for synthesized variables for the

non-fragile ABI we may not be able to lay out the type and the debugger
would ignore us even if we did put in the offset. Go ahead and just
put any value there and don't look up the offset since it may not exist.

rdar://10210157

llvm-svn: 141261

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -1148,8 +1148,8 @@ llvm::DIType CGDebugInfo::CreateType(const ObjCInterfaceType *Ty,
   unsigned Line = getLineNumber(ID->getLocation());
   unsigned RuntimeLang = TheCU.getLanguage();
 
-  // If this is just a forward declaration, return a special forward-declaration
-  // debug type.
+  // If this is just a forward declaration return a special forward-declaration
+  // debug type since we won't be able to lay out the entire type.
   if (ID->isForwardDecl()) {
     llvm::DIType FwdDecl =
       DBuilder.createStructType(Unit, ID->getName(),
@@ -1223,7 +1223,12 @@ llvm::DIType CGDebugInfo::CreateType(const ObjCInterfaceType *Ty,
       FieldAlign =  CGM.getContext().getTypeAlign(FType);
     }
 
-    uint64_t FieldOffset = RL.getFieldOffset(FieldNo);
+    // We can't know the offset of our ivar in the structure if we're using
+    // the non-fragile abi and the debugger should ignore the value anyways.
+    // Call it the FieldNo+1 due to how debuggers use the information,
+    // e.g. negating the value when it needs a lookup in the dynamic table.
+    uint64_t FieldOffset = CGM.getLangOptions().ObjCNonFragileABI ? FieldNo+1
+      : RL.getFieldOffset(FieldNo);
 
     unsigned Flags = 0;
     if (Field->getAccessControl() == ObjCIvarDecl::Protected)

clang/test/CodeGenObjC/debug-info-crash-2.m

@@ -0,0 +1,15 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin11 -g -S %s -o -
+@class Bar;
+@interface Foo
+@property (strong, nonatomic) Bar *window;
+@end
+
+@interface Foo__ : Foo
+@end
+@implementation Foo__
+@end
+
+@implementation Foo
+@synthesize window = _window;
+@end
+