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runtime: Move String implementation stubs that want need the auto-released return value optimization to an ARC compiled file
String's hashValue function is implemented in terms of Foundation's hash function in a runtime function on darwin platforms. For non-ASCII strings we will call str.decomposedStringWithCanonicalMapping inside this runtime function which will allocate a new NSString and return the result in the current autorelease pool. We implemented this function in a file compiled without ARC. This meant that we would leak said NSString into the current active autorelease pool. This patch moves the implementation to a file compiled with ARC. ARC will insert objc_retainAutoreleasedReturnValue call and on platforms that require it an marker for the hand-off of the autoreleased return value optimization. SR-4889 rdar://32199117
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5 files changed

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‎stdlib/public/stubs/CMakeLists.txt

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@@ -11,6 +11,7 @@ set(swift_stubs_objc_sources
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FoundationHelpers.mm
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OptionalBridgingHelper.mm
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Reflection.mm
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SwiftNativeNSXXXBaseARC.m
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SwiftNativeNSXXXBase.mm.gyb)
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set(swift_stubs_unicode_normalization_sources
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UnicodeNormalization.cpp)
@@ -41,3 +42,5 @@ add_swift_library(swiftStdlibStubs OBJECT_LIBRARY TARGET_LIBRARY
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LINK_FLAGS ${SWIFT_RUNTIME_CORE_LINK_FLAGS}
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INSTALL_IN_COMPONENT stdlib)
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set_property(SOURCE SwiftNativeNSXXXBaseARC.m APPEND_STRING PROPERTY COMPILE_FLAGS
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"-fobjc-arc")

‎stdlib/public/stubs/SwiftNativeNSXXXBase.mm.gyb

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@@ -143,25 +143,6 @@ swift_stdlib_CFStringHashCString(const uint8_t *bytes, CFIndex len) {
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return Result;
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}
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SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
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size_t
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swift_stdlib_NSStringHashValue(NSString *NS_RELEASES_ARGUMENT str,
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bool isASCII) {
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size_t Result =
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isASCII ? str.hash : str.decomposedStringWithCanonicalMapping.hash;
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swift_unknownRelease(str);
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return Result;
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}
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SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
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size_t
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swift_stdlib_NSStringHashValuePointer(void *opaque, bool isASCII) {
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NSString *str = (NSString *)opaque;
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return isASCII ? str.hash : str.decomposedStringWithCanonicalMapping.hash;
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}
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SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
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bool swift_stdlib_NSStringHasPrefixNFD(NSString *theString,
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NSString *prefix) {

‎stdlib/public/stubs/SwiftNativeNSXXXBaseARC.m

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//===--- SwiftNativeNSXXXBaseARC.mm - Runtime stubs that require ARC ------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "swift/Runtime/Config.h"
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#if SWIFT_OBJC_INTEROP
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#import <Foundation/Foundation.h>
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#import <CoreFoundation/CoreFoundation.h>
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#include <objc/NSObject.h>
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#include <objc/runtime.h>
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#include <objc/objc.h>
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/// The following two routines need to be implemented in ARC because
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/// decomposedStringWithCanonicalMapping returns its result autoreleased. And we
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/// want ARC to insert 'objc_retainAutoreleasedReturnValue' and the necessary
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/// markers for the hand-off.
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SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
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size_t swift_stdlib_NSStringHashValue(NSString *NS_RELEASES_ARGUMENT str,
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bool isASCII) {
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return isASCII ? str.hash : str.decomposedStringWithCanonicalMapping.hash;
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}
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SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_INTERFACE
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size_t
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swift_stdlib_NSStringHashValuePointer(void *opaque, bool isASCII) {
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NSString __unsafe_unretained *str =
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(__bridge NSString __unsafe_unretained *)opaque;
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return isASCII ? str.hash : str.decomposedStringWithCanonicalMapping.hash;
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}
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#endif

‎test/stdlib/StringMemoryTest.swift

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// RUN: %empty-directory(%t)
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// RUN: %target-build-swift -O %s -o %t/StringMemoryTest
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// RUN: %target-run %t/StringMemoryTest | %FileCheck %s
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// REQUIRES: optimized_stdlib
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// REQUIRES: executable_test
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// REQUIRES: objc_interop
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import Foundation
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@inline(never)
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func lookup(_ str: String, _ dict: [String: Int]) -> Bool {
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if let _ = dict[str] {
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return true
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}
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return false
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}
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/// Make sure the hash function does not leak.
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let dict = [ "foo" : 1]
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for _ in 0 ..< 10_000_000 {
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if lookup("\u{1F1E7}\u{1F1E7}", dict) {
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print("Found?!")
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}
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}
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// CHECK: Not found
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print("Not found")
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var usage = rusage()
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getrusage(RUSAGE_SELF, &usage)
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// CHECK: success
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// CHECK-NOT: failure
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// We should not need 50MB for this.
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if usage.ru_maxrss > 50 * 1024 * 1024 {
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print("failure - should not need 50MB!")
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} else {
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print("success")
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}

‎test/stdlib/runtime_autorelease_optimization.txt

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// UNSUPPORTED: linux
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// RUN: otool -tvV %platform-module-dir/libswiftCore.dylib | %FileCheck %s --check-prefix=CHECK-%target-cpu
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// Verify the autorelease return optimization sequence.
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/// Test x86-64:
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// CHECK-x86_64-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-x86_64-NOT: ret
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// CHECK-x86_64: movq {{.*}}(%rip), %rsi ## Objc selector ref: decomposedStringWithCanonicalMapping
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// CHECK-x86_64: movq {{.*}}(%rip), [[MSG:%.*]] ## Objc message: -[%rdi decomposedStringWithCanonicalMapping]
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// CHECK-x86_64: callq *[[MSG]]
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// CHECK-x86_64: movq %rax, %rdi
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// CHECK-x86_64: callq {{.*}} ## symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-x86_64: ret
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// CHECK-x86_64-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-x86_64-NOT: ret
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// CHECK-x86_64: movq {{.*}}(%rip), %rsi ## Objc selector ref: decomposedStringWithCanonicalMapping
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// CHECK-x86_64: movq {{.*}}(%rip), [[MSG:%.*]] ## Objc message: -[%rdi decomposedStringWithCanonicalMapping]
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// CHECK-x86_64: callq *[[MSG]]
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// CHECK-x86_64: movq %rax, %rdi
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// CHECK-x86_64: callq {{.*}} ## symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-x86_64: ret
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/// Test i386:
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// CHECK-i386-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-i386-NOT: ret
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// CHECK-i386: calll {{.*}} ## symbol stub for: _objc_msgSend
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// CHECK-i386: movl %ebp, %ebp
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// CHECK-i386: calll {{.*}} ## symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-i386: ret
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// CHECK-i386-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-i386-NOT: ret
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// CHECK-i386: calll {{.*}} ## symbol stub for: _objc_msgSend
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// CHECK-i386: movl %ebp, %ebp
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// CHECK-i386: calll {{.*}} ## symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-i386: ret
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/// Test armv7:
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// CHECK-armv7-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-armv7-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7: mov r7, r7
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// CHECK-armv7: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7: pop {{.*}}pc{{.*}}
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// CHECK-armv7-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-armv7-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7: mov r7, r7
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// CHECK-armv7: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7: pop {{.*}}pc{{.*}}
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/// Test armv7s:
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// CHECK-armv7s-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-armv7s-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7s: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7s: mov r7, r7
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// CHECK-armv7s: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7s: pop {{.*}}pc{{.*}}
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// CHECK-armv7s-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-armv7s-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7s: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7s: mov r7, r7
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// CHECK-armv7s: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7s: pop {{.*}}pc{{.*}}
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/// Test armv7k:
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// CHECK-armv7k-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-armv7k-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7k: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7k: mov r7, r7
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// CHECK-armv7k: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7k: pop {{.*}}pc{{.*}}
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// CHECK-armv7k-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-armv7k-NOT: pop {{.*}}pc{{.*}}
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// CHECK-armv7k: blx {{.*}} @ symbol stub for: _objc_msgSend
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// CHECK-armv7k: mov r7, r7
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// CHECK-armv7k: blx {{.*}} @ symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-armv7k: pop {{.*}}pc{{.*}}
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/// Test arm64:
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// CHECK-arm64-LABEL: _swift_stdlib_NSStringHashValue:
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// CHECK-arm64-NOT: ret
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// CHECK-arm64: bl {{.*}} ; Objc message: -[x0 decomposedStringWithCanonicalMapping]
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// CHECK-arm64: mov x29, x29
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// CHECK-arm64: bl {{.*}} ; symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-arm64: ret
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// CHECK-arm64-LABEL: _swift_stdlib_NSStringHashValuePointer:
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// CHECK-arm64-NOT: ret
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// CHECK-arm64: bl {{.*}} ; Objc message: -[x0 decomposedStringWithCanonicalMapping]
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// CHECK-arm64: mov x29, x29
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// CHECK-arm64: bl {{.*}} ; symbol stub for: _objc_retainAutoreleasedReturnValue
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// CHECK-arm64: ret

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