[cfe-commits] r133621 - in /cfe/trunk: lib/CodeGen/CGObjC.cpp test/CodeGenObjCXX/arc-move.mm
Douglas Gregor
dgregor at apple.com
Wed Jun 22 09:32:26 PDT 2011
Author: dgregor
Date: Wed Jun 22 11:32:26 2011
New Revision: 133621
URL: http://llvm.org/viewvc/llvm-project?rev=133621&view=rev
Log:
Implement the C++0x move optimization for Automatic Reference Counting
objects, so that we steal the retain count of a temporary __strong
pointer (zeroing out that temporary), eliding a retain/release
pair. Addresses <rdar://problem/9364932>.
Added:
cfe/trunk/test/CodeGenObjCXX/arc-move.mm
Modified:
cfe/trunk/lib/CodeGen/CGObjC.cpp
Modified: cfe/trunk/lib/CodeGen/CGObjC.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGObjC.cpp?rev=133621&r1=133620&r2=133621&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGObjC.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGObjC.cpp Wed Jun 22 11:32:26 2011
@@ -2268,6 +2268,31 @@
// ultimate opaque expression.
const llvm::Type *resultType = 0;
+ // If we're loading retained from a __strong xvalue, we can avoid
+ // an extra retain/release pair by zeroing out the source of this
+ // "move" operation.
+ if (e->isXValue() &&
+ e->getType().getObjCLifetime() == Qualifiers::OCL_Strong) {
+ // Emit the lvalue
+ LValue lv = CGF.EmitLValue(e);
+
+ // Load the object pointer and cast it to the appropriate type.
+ QualType exprType = e->getType();
+ llvm::Value *result = CGF.EmitLoadOfLValue(lv, exprType).getScalarVal();
+
+ if (resultType)
+ result = CGF.Builder.CreateBitCast(result, resultType);
+
+ // Set the source pointer to NULL.
+ llvm::Value *null
+ = llvm::ConstantPointerNull::get(
+ cast<llvm::PointerType>(CGF.ConvertType(exprType)));
+ CGF.EmitStoreOfScalar(null, lv.getAddress(), lv.isVolatileQualified(),
+ lv.getAlignment(), exprType);
+
+ return TryEmitResult(result, true);
+ }
+
while (true) {
e = e->IgnoreParens();
Added: cfe/trunk/test/CodeGenObjCXX/arc-move.mm
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjCXX/arc-move.mm?rev=133621&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenObjCXX/arc-move.mm (added)
+++ cfe/trunk/test/CodeGenObjCXX/arc-move.mm Wed Jun 22 11:32:26 2011
@@ -0,0 +1,63 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -fobjc-nonfragile-abi -fblocks -fobjc-arc -O2 -std=c++0x -disable-llvm-optzns -o - %s | FileCheck %s
+
+// define void @_Z11simple_moveRU8__strongP11objc_objectS2_
+void simple_move(__strong id &x, __strong id &y) {
+ // CHECK: = load i8**
+ // CHECK: store i8* null
+ // CHECK: = load i8**
+ // CHECK: store i8*
+ // CHECK-NEXT: call void @objc_release
+ x = static_cast<__strong id&&>(y);
+ // CHECK-NEXT: ret void
+}
+
+template<typename T>
+struct remove_reference {
+ typedef T type;
+};
+
+template<typename T>
+struct remove_reference<T&> {
+ typedef T type;
+};
+
+template<typename T>
+struct remove_reference<T&&> {
+ typedef T type;
+};
+
+template<typename T>
+typename remove_reference<T>::type&& move(T &&x) {
+ return static_cast<typename remove_reference<T>::type&&>(x);
+}
+
+// CHECK: define void @_Z12library_moveRU8__strongP11objc_objectS2_
+void library_move(__strong id &x, __strong id &y) {
+ // CHECK: call i8** @_Z4moveIRU8__strongP11objc_objectEON16remove_referenceIT_E4typeEOS5_
+ // CHECK: load i8**
+ // CHECK: store i8* null, i8**
+ // CHECK: load i8***
+ // CHECK-NEXT: load i8**
+ // CHECK-NEXT: store i8*
+ // CHECK-NEXT: call void @objc_release
+ // CHECK-NEXT: ret void
+ x = move(y);
+}
+
+// CHECK: define void @_Z12library_moveRU8__strongP11objc_object
+void library_move(__strong id &y) {
+ // CHECK: [[Y:%[a-zA-Z0-9]+]] = call i8** @_Z4moveIRU8__strongP11objc_objectEON16remove_referenceIT_E4typeEOS5_
+ // Load the object
+ // CHECK-NEXT: [[OBJ:%[a-zA-Z0-9]+]] = load i8** [[Y]]
+ // Null out y
+ // CHECK-NEXT: store i8* null, i8** [[Y]]
+ // Initialize x with the object
+ // CHECK-NEXT: store i8* [[OBJ]], i8** [[X:%[a-zA-Z0-9]+]]
+ id x = move(y);
+
+ // CHECK-NEXT: store i32 17
+ int i = 17;
+ // CHECK-NEXT: [[OBJ:%[a-zA-Z0-9]+]] = load i8** [[X]]
+ // CHECK-NEXT: call void @objc_release(i8* [[OBJ]])
+ // CHECK-NEXT: ret void
+}
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