From f79091e91f984b356f747954ef470951690fdab7 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@apple.com>
Date: Sat, 15 Apr 2017 05:31:35 +0000
Subject: [PATCH] [ObjC] Use empty Objective-C collection literal constants
when available.
Original patch by Douglas Gregor with minor modifications.
rdar://problem/20689633
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@300389 91177308-0d34-0410-b5e6-96231b3b80d8
---
include/clang/Basic/ObjCRuntime.h | 14 ++++++
lib/CodeGen/CGObjC.cpp | 16 +++++-
lib/Sema/SemaExprCXX.cpp | 12 +++++
test/CodeGenObjC/empty-collection-literals.m | 51 ++++++++++++++++++++
4 files changed, 91 insertions(+), 2 deletions(-)
create mode 100644 test/CodeGenObjC/empty-collection-literals.m
diff --git a/include/clang/Basic/ObjCRuntime.h b/include/clang/Basic/ObjCRuntime.h
index 78fc8998824..8dc259c7ab6 100644
--- a/include/clang/Basic/ObjCRuntime.h
+++ b/include/clang/Basic/ObjCRuntime.h
@@ -326,6 +326,20 @@ public:
}
}
+ /// Are the empty collection symbols available?
+ bool hasEmptyCollections() const {
+ switch (getKind()) {
+ default:
+ return false;
+ case MacOSX:
+ return getVersion() >= VersionTuple(10, 11);
+ case iOS:
+ return getVersion() >= VersionTuple(9);
+ case WatchOS:
+ return getVersion() >= VersionTuple(2);
+ }
+ }
+
/// \brief Try to parse an Objective-C runtime specification from the given
/// string.
///
diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index c011ab4dfc9..067718e2b8e 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -117,10 +117,22 @@ llvm::Value *CodeGenFunction::EmitObjCCollectionLiteral(const Expr *E,
const ObjCArrayLiteral *ALE = dyn_cast<ObjCArrayLiteral>(E);
if (!ALE)
DLE = cast<ObjCDictionaryLiteral>(E);
-
- // Compute the type of the array we're initializing.
+
+ // Optimize empty collections by referencing constants, when available.
uint64_t NumElements =
ALE ? ALE->getNumElements() : DLE->getNumElements();
+ if (NumElements == 0 && CGM.getLangOpts().ObjCRuntime.hasEmptyCollections()) {
+ StringRef ConstantName = ALE ? "__NSArray0__" : "__NSDictionary0__";
+ QualType IdTy(CGM.getContext().getObjCIdType());
+ llvm::Constant *Constant =
+ CGM.CreateRuntimeVariable(ConvertType(IdTy), ConstantName);
+ LValue LV = LValue::MakeAddr(Constant, IdTy,
+ Context.getTypeAlignInChars(IdTy), Context);
+ return Builder.CreateBitCast(EmitLoadOfScalar(LV, E->getLocStart()),
+ ConvertType(E->getType()));
+ }
+
+ // Compute the type of the array we're initializing.
llvm::APInt APNumElements(Context.getTypeSize(Context.getSizeType()),
NumElements);
QualType ElementType = Context.getObjCIdType().withConst();
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 485d012b6e6..d65570fcef7 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -5980,9 +5980,21 @@ ExprResult Sema::MaybeBindToTemporary(Expr *E) {
} else if (ObjCBoxedExpr *BoxedExpr = dyn_cast<ObjCBoxedExpr>(E)) {
D = BoxedExpr->getBoxingMethod();
} else if (ObjCArrayLiteral *ArrayLit = dyn_cast<ObjCArrayLiteral>(E)) {
+ // Don't do reclaims if we're using the zero-element array
+ // constant.
+ if (ArrayLit->getNumElements() == 0 &&
+ Context.getLangOpts().ObjCRuntime.hasEmptyCollections())
+ return E;
+
D = ArrayLit->getArrayWithObjectsMethod();
} else if (ObjCDictionaryLiteral *DictLit
= dyn_cast<ObjCDictionaryLiteral>(E)) {
+ // Don't do reclaims if we're using the zero-element dictionary
+ // constant.
+ if (DictLit->getNumElements() == 0 &&
+ Context.getLangOpts().ObjCRuntime.hasEmptyCollections())
+ return E;
+
D = DictLit->getDictWithObjectsMethod();
}
diff --git a/test/CodeGenObjC/empty-collection-literals.m b/test/CodeGenObjC/empty-collection-literals.m
new file mode 100644
index 00000000000..0f9715f521f
--- /dev/null
+++ b/test/CodeGenObjC/empty-collection-literals.m
@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -I %S/Inputs -triple x86_64-apple-macosx10.10.0 -fobjc-runtime=macosx-10.10.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITHOUT-EMPTY-COLLECTIONS %s
+// RUN: %clang_cc1 -I %S/Inputs -triple x86_64-apple-macosx10.11.0 -fobjc-runtime=macosx-10.11.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITH-EMPTY-COLLECTIONS %s
+
+// RUN: %clang_cc1 -I %S/Inputs -triple arm64-apple-ios8.0 -fobjc-runtime=ios-8.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITHOUT-EMPTY-COLLECTIONS %s
+// RUN: %clang_cc1 -I %S/Inputs -triple arm64-apple-ios9.0 -fobjc-runtime=ios-9.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITH-EMPTY-COLLECTIONS %s
+
+// RUN: %clang_cc1 -I %S/Inputs -triple armv7k-apple-watchos2.0 -fobjc-runtime=watchos-1.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITHOUT-EMPTY-COLLECTIONS %s
+// RUN: %clang_cc1 -I %S/Inputs -triple armv7k-apple-watchos2.0 -fobjc-runtime=watchos-2.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITH-EMPTY-COLLECTIONS %s
+
+// RUN: %clang_cc1 -I %S/Inputs -triple arm64-apple-tvos8.0 -fobjc-runtime=ios-8.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITHOUT-EMPTY-COLLECTIONS %s
+// RUN: %clang_cc1 -I %S/Inputs -triple arm64-apple-tvos9.0 -fobjc-runtime=ios-9.0 -emit-llvm -fblocks -fobjc-arc -fobjc-runtime-has-weak -o - %s | FileCheck -check-prefix=CHECK-WITH-EMPTY-COLLECTIONS %s
+
+#include "literal-support.h"
+
+void test_empty_array() {
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-LABEL: define void @test_empty_array
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: {{call.*objc_msgSend}}
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: {{call.*objc_retainAutoreleasedReturnValue}}
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: ret void
+
+ // CHECK-WITH-EMPTY-COLLECTIONS-LABEL: define void @test_empty_array
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: load {{.*}} @__NSArray0__
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: {{call.*objc_retain\(}}
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: call void @objc_storeStrong
+ // CHECK-WITH-EMPTY-COLLECTIONS-NEXT: ret void
+ NSArray *arr = @[];
+}
+
+void test_empty_dictionary() {
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-LABEL: define void @test_empty_dictionary
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: {{call.*objc_msgSend}}
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: {{call.*objc_retainAutoreleasedReturnValue}}
+ // CHECK-WITHOUT-EMPTY-COLLECTIONS: ret void
+
+ // CHECK-WITH-EMPTY-COLLECTIONS-LABEL: define void @test_empty_dictionary
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: load {{.*}} @__NSDictionary0__
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: {{call.*objc_retain\(}}
+ // CHECK-WITH-EMPTY-COLLECTIONS-NOT: ret void
+ // CHECK-WITH-EMPTY-COLLECTIONS: call void @objc_storeStrong
+ // CHECK-WITH-EMPTY-COLLECTIONS-NEXT: ret void
+ NSDictionary *dict = @{};
+}
--
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