revert r149184

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149205 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 58 insertions, 17 deletions

diff --git a/lib/CodeGen/CGObjCMac.cpp b/lib/CodeGen/CGObjCMac.cpp
index 8bd96382c9..ecf6181b1c 100644
--- a/lib/CodeGen/CGObjCMac.cpp
+++ b/lib/CodeGen/CGObjCMac.cpp
@@ -1392,6 +1392,63 @@ public:
                                       const ObjCInterfaceDecl *Interface,
                                       const ObjCIvarDecl *Ivar);
 };
+
+/// A helper class for performing the null-initialization of a return
+/// value.
+struct NullReturnState {
+  llvm::BasicBlock *NullBB;
+  llvm::BasicBlock *callBB;
+  NullReturnState() : NullBB(0), callBB(0) {}
+
+  void init(CodeGenFunction &CGF, llvm::Value *receiver) {
+    // Make blocks for the null-init and call edges.
+    NullBB = CGF.createBasicBlock("msgSend.nullinit");
+    callBB = CGF.createBasicBlock("msgSend.call");
+
+    // Check for a null receiver and, if there is one, jump to the
+    // null-init test.
+    llvm::Value *isNull = CGF.Builder.CreateIsNull(receiver);
+    CGF.Builder.CreateCondBr(isNull, NullBB, callBB);
+
+    // Otherwise, start performing the call.
+    CGF.EmitBlock(callBB);
+  }
+
+  RValue complete(CodeGenFunction &CGF, RValue result, QualType resultType) {
+    if (!NullBB) return result;
+
+    // Finish the call path.
+    llvm::BasicBlock *contBB = CGF.createBasicBlock("msgSend.cont");
+    if (CGF.HaveInsertPoint()) CGF.Builder.CreateBr(contBB);
+
+    // Emit the null-init block and perform the null-initialization there.
+    CGF.EmitBlock(NullBB);
+    if (!resultType->isAnyComplexType()) {
+      assert(result.isAggregate() && "null init of non-aggregate result?");
+      CGF.EmitNullInitialization(result.getAggregateAddr(), resultType);
+      // Jump to the continuation block.
+      CGF.EmitBlock(contBB);
+      return result;
+    }
+
+    // _Complex type
+    // FIXME. Now easy to handle any other scalar type whose result is returned
+    // in memory due to ABI limitations.
+    CGF.EmitBlock(contBB);
+    CodeGenFunction::ComplexPairTy CallCV = result.getComplexVal();
+    llvm::Type *MemberType = CallCV.first->getType();
+    llvm::Constant *ZeroCV = llvm::Constant::getNullValue(MemberType);
+    // Create phi instruction for scalar complex value.
+    llvm::PHINode *PHIReal = CGF.Builder.CreatePHI(MemberType, 2);
+    PHIReal->addIncoming(ZeroCV, NullBB);
+    PHIReal->addIncoming(CallCV.first, callBB);
+    llvm::PHINode *PHIImag = CGF.Builder.CreatePHI(MemberType, 2);
+    PHIImag->addIncoming(ZeroCV, NullBB);
+    PHIImag->addIncoming(CallCV.second, callBB);
+    return RValue::getComplex(PHIReal, PHIImag);
+  }
+};
+
 } // end anonymous namespace
 
 /* *** Helper Functions *** */
@@ -1598,23 +1655,7 @@ CGObjCCommonMac::EmitMessageSend(CodeGen::CodeGenFunction &CGF,
 
   llvm::Constant *Fn = NULL;
   if (CGM.ReturnTypeUsesSRet(FnInfo)) {
-    if (!IsSuper) {
-      bool nullCheckAlreadyDone = false;
-      // We have already done this computation once and flag could have been
-      // passed down. But such cases are extremely rare and we do this lazily,
-      // instead of absorbing cost of passing down a flag for all cases.
-      if (CGM.getLangOptions().ObjCAutoRefCount && Method)
-        for (ObjCMethodDecl::param_const_iterator i = Method->param_begin(), 
-             e = Method->param_end(); i != e; ++i) {
-          if ((*i)->hasAttr<NSConsumedAttr>()) {
-            nullCheckAlreadyDone = true;
-            break;
-          } 
-        }
-      if (!nullCheckAlreadyDone)
-        nullReturn.init(CGF, Arg0);
-    }
-    
+    if (!IsSuper) nullReturn.init(CGF, Arg0);
     Fn = (ObjCABI == 2) ?  ObjCTypes.getSendStretFn2(IsSuper)
       : ObjCTypes.getSendStretFn(IsSuper);
   } else if (CGM.ReturnTypeUsesFPRet(ResultType)) {