From 05cfdb0eac37eb5571518e1ef2ade9f0397dbc80 Mon Sep 17 00:00:00 2001 From: Raphael Isemann Date: Fri, 26 Apr 2019 07:21:36 +0000 Subject: [PATCH] Allow direct comparison of ConstString against StringRef Summary: When we want to compare a ConstString against a string literal (or any other non-ConstString), we currently have to explicitly turn the other string into a ConstString. This makes sense as comparing ConstStrings against each other is only a fast pointer comparison. However, currently we (rather incorrectly) use in several places in LLDB temporary ConstStrings when we just want to compare a given ConstString against a hardcoded value, for example like this: ``` if (extension != ConstString(".oat") && extension != ConstString(".odex")) ``` Obviously this kind of defeats the point of ConstStrings. In the comparison above we would construct two temporary ConstStrings every time we hit the given code. Constructing a ConstString is relatively expensive: we need to go to the StringPool, take a read and possibly an exclusive write-lock and then look up our temporary string in the string map of the pool. So we do a lot of heavy work for essentially just comparing a <6 characters in two strings. I initially wanted to just fix these issues by turning the temporary ConstString in static variables/ members, but that made the code much less readable. Instead I propose to add a new overload for the ConstString comparison operator that takes a StringRef. This comparison operator directly compares the ConstString content against the given StringRef without turning the StringRef into a ConstString. This means that the example above can look like this now: ``` if (extension != ".oat" && extension != ".odex") ``` It also no longer has to unlock/lock two locks and call multiple functions in other TUs for constructing the temporary ConstString instances. Instead this should end up just being a direct string comparison of the two given strings on most compilers. This patch also directly updates all uses of temporary and short ConstStrings in LLDB to use this new comparison operator. It also adds a some unit tests for the new and old comparison operator. Reviewers: #lldb, JDevlieghere, espindola, amccarth Reviewed By: JDevlieghere, amccarth Subscribers: amccarth, clayborg, JDevlieghere, emaste, arichardson, MaskRay, lldb-commits Tags: #lldb Differential Revision: https://reviews.llvm.org/D60667 llvm-svn: 359281 --- lldb/include/lldb/Utility/ConstString.h | 39 +++++++++++++++ .../MacOSX-DYLD/DynamicLoaderDarwin.cpp | 2 +- .../MacOSX-DYLD/DynamicLoaderMacOS.cpp | 2 +- .../MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp | 4 +- .../Clang/ClangExpressionSourceCode.cpp | 3 +- .../Clang/ClangUserExpression.cpp | 2 +- .../Plugins/Language/CPlusPlus/LibCxx.cpp | 10 ++-- .../Language/CPlusPlus/LibCxxVector.cpp | 2 +- .../Plugins/Language/CPlusPlus/LibStdcpp.cpp | 8 ++-- .../CPlusPlus/LibStdcppUniquePointer.cpp | 7 ++- lldb/source/Plugins/Language/ObjC/CF.cpp | 6 +-- .../AppleObjCRuntime/AppleObjCRuntime.cpp | 3 +- .../Plugins/ObjectFile/ELF/ObjectFileELF.cpp | 4 +- .../Platform/Android/PlatformAndroid.cpp | 2 +- .../MacOSX/SystemRuntimeMacOSX.cpp | 5 +- lldb/unittests/Utility/ConstStringTest.cpp | 48 +++++++++++++++++++ 16 files changed, 115 insertions(+), 32 deletions(-) diff --git a/lldb/include/lldb/Utility/ConstString.h b/lldb/include/lldb/Utility/ConstString.h index c707082e2ad37..8576c18ddcd81 100644 --- a/lldb/include/lldb/Utility/ConstString.h +++ b/lldb/include/lldb/Utility/ConstString.h @@ -154,6 +154,30 @@ class ConstString { return m_string == rhs.m_string; } + /// Equal to operator against a non-ConstString value. + /// + /// Returns true if this string is equal to the string in \a rhs. This + /// overload is usually slower than comparing against a ConstString value. + /// However, if the rhs string not already a ConstString and it is impractical + /// to turn it into a non-temporary variable, then this overload is faster. + /// + /// \param[in] rhs + /// Another string object to compare this object to. + /// + /// \return + /// \li \b true if this object is equal to \a rhs. + /// \li \b false if this object is not equal to \a rhs. + bool operator==(const char *rhs) const { + // ConstString differentiates between empty strings and nullptr strings, but + // StringRef doesn't. Therefore we have to do this check manually now. + if (m_string == nullptr && rhs != nullptr) + return false; + if (m_string != nullptr && rhs == nullptr) + return false; + + return GetStringRef() == rhs; + } + /// Not equal to operator /// /// Returns true if this string is not equal to the string in \a rhs. This @@ -170,6 +194,21 @@ class ConstString { return m_string != rhs.m_string; } + /// Not equal to operator against a non-ConstString value. + /// + /// Returns true if this string is not equal to the string in \a rhs. This + /// overload is usually slower than comparing against a ConstString value. + /// However, if the rhs string not already a ConstString and it is impractical + /// to turn it into a non-temporary variable, then this overload is faster. + /// + /// \param[in] rhs + /// Another string object to compare this object to. + /// + /// \return + /// \li \b true if this object is not equal to \a rhs. + /// \li \b false if this object is equal to \a rhs. + bool operator!=(const char *rhs) const { return !(*this == rhs); } + bool operator<(ConstString rhs) const; /// Get the string value as a C string. diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp index 39440fdcb63b8..7475b1a87aad5 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp @@ -474,7 +474,7 @@ bool DynamicLoaderDarwin::JSONImageInformationIntoImageInfo( // that starts of file offset zero and that has bytes in the file... if ((image_infos[i].segments[k].fileoff == 0 && image_infos[i].segments[k].filesize > 0) || - (image_infos[i].segments[k].name == ConstString("__TEXT"))) { + (image_infos[i].segments[k].name == "__TEXT")) { image_infos[i].slide = image_infos[i].address - image_infos[i].segments[k].vmaddr; // We have found the slide amount, so we can exit this for loop. diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp index 53a9371696ce2..29e4ac0654ab0 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp @@ -111,7 +111,7 @@ bool DynamicLoaderMacOS::ProcessDidExec() { const Symbol *symbol = frame_sp->GetSymbolContext(eSymbolContextSymbol).symbol; if (symbol) { - if (symbol->GetName() == ConstString("_dyld_start")) + if (symbol->GetName() == "_dyld_start") did_exec = true; } } diff --git a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp index f4c50b888d4fa..9c0125a6db045 100644 --- a/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp +++ b/lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp @@ -136,7 +136,7 @@ bool DynamicLoaderMacOSXDYLD::ProcessDidExec() { const Symbol *symbol = frame_sp->GetSymbolContext(eSymbolContextSymbol).symbol; if (symbol) { - if (symbol->GetName() == ConstString("_dyld_start")) + if (symbol->GetName() == "_dyld_start") did_exec = true; } } @@ -898,7 +898,7 @@ uint32_t DynamicLoaderMacOSXDYLD::ParseLoadCommands(const DataExtractor &data, // starts of file offset zero and that has bytes in the file... if ((dylib_info.segments[i].fileoff == 0 && dylib_info.segments[i].filesize > 0) || - (dylib_info.segments[i].name == ConstString("__TEXT"))) { + (dylib_info.segments[i].name == "__TEXT")) { dylib_info.slide = dylib_info.address - dylib_info.segments[i].vmaddr; // We have found the slide amount, so we can exit this for loop. break; diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp index 5be376ea3faf6..2fc690e3d5ba3 100644 --- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp +++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp @@ -167,8 +167,7 @@ static void AddLocalVariableDecls(const lldb::VariableListSP &var_list_sp, lldb::VariableSP var_sp = var_list_sp->GetVariableAtIndex(i); ConstString var_name = var_sp->GetName(); - if (!var_name || var_name == ConstString("this") || - var_name == ConstString(".block_descriptor")) + if (!var_name || var_name == "this" || var_name == ".block_descriptor") continue; stream.Printf("using $__lldb_local_vars::%s;\n", var_name.AsCString()); diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp index 34cfb8951be55..2e64b08853946 100644 --- a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp +++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp @@ -488,7 +488,7 @@ ClangUserExpression::GetModulesToImport(ExecutionContext &exe_ctx) { // We currently don't support importing any other modules in the expression // parser. for (const SourceModule &m : sc.comp_unit->GetImportedModules()) - if (!m.path.empty() && m.path.front() == ConstString("std")) + if (!m.path.empty() && m.path.front() == "std") return {"std"}; return {}; diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp index e63452eb95eae..9dceca6123f31 100644 --- a/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp +++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp @@ -300,9 +300,9 @@ bool lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd:: size_t lldb_private::formatters::LibCxxMapIteratorSyntheticFrontEnd:: GetIndexOfChildWithName(ConstString name) { - if (name == ConstString("first")) + if (name == "first") return 0; - if (name == ConstString("second")) + if (name == "second") return 1; return UINT32_MAX; } @@ -430,11 +430,11 @@ bool lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd:: size_t lldb_private::formatters::LibcxxSharedPtrSyntheticFrontEnd:: GetIndexOfChildWithName(ConstString name) { - if (name == ConstString("__ptr_")) + if (name == "__ptr_") return 0; - if (name == ConstString("count")) + if (name == "count") return 1; - if (name == ConstString("weak_count")) + if (name == "weak_count") return 2; return UINT32_MAX; } diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp index b7ed597d48a5b..bcd7442bc6693 100644 --- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp +++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp @@ -290,7 +290,7 @@ lldb_private::formatters::LibcxxStdVectorSyntheticFrontEndCreator( if (!type.IsValid() || type.GetNumTemplateArguments() == 0) return nullptr; CompilerType arg_type = type.GetTypeTemplateArgument(0); - if (arg_type.GetTypeName() == ConstString("bool")) + if (arg_type.GetTypeName() == "bool") return new LibcxxVectorBoolSyntheticFrontEnd(valobj_sp); return new LibcxxStdVectorSyntheticFrontEnd(valobj_sp); } diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp index 0aac93c3c7696..0e0f6663c924b 100644 --- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp +++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp @@ -142,9 +142,9 @@ bool LibstdcppMapIteratorSyntheticFrontEnd::MightHaveChildren() { return true; } size_t LibstdcppMapIteratorSyntheticFrontEnd::GetIndexOfChildWithName( ConstString name) { - if (name == ConstString("first")) + if (name == "first") return 0; - if (name == ConstString("second")) + if (name == "second") return 1; return UINT32_MAX; } @@ -224,7 +224,7 @@ bool VectorIteratorSyntheticFrontEnd::MightHaveChildren() { return true; } size_t VectorIteratorSyntheticFrontEnd::GetIndexOfChildWithName( ConstString name) { - if (name == ConstString("item")) + if (name == "item") return 0; return UINT32_MAX; } @@ -374,7 +374,7 @@ bool LibStdcppSharedPtrSyntheticFrontEnd::MightHaveChildren() { return true; } size_t LibStdcppSharedPtrSyntheticFrontEnd::GetIndexOfChildWithName( ConstString name) { - if (name == ConstString("_M_ptr")) + if (name == "_M_ptr") return 0; return UINT32_MAX; } diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp index 451e58f779665..3860f960cb3de 100644 --- a/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp +++ b/lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp @@ -130,12 +130,11 @@ size_t LibStdcppUniquePtrSyntheticFrontEnd::CalculateNumChildren() { size_t LibStdcppUniquePtrSyntheticFrontEnd::GetIndexOfChildWithName( ConstString name) { - if (name == ConstString("ptr") || name == ConstString("pointer")) + if (name == "ptr" || name == "pointer") return 0; - if (name == ConstString("del") || name == ConstString("deleter")) + if (name == "del" || name == "deleter") return 1; - if (name == ConstString("obj") || name == ConstString("object") || - name == ConstString("$$dereference$$")) + if (name == "obj" || name == "object" || name == "$$dereference$$") return 2; return UINT32_MAX; } diff --git a/lldb/source/Plugins/Language/ObjC/CF.cpp b/lldb/source/Plugins/Language/ObjC/CF.cpp index 99a880f3fe692..7db55e15b5c17 100644 --- a/lldb/source/Plugins/Language/ObjC/CF.cpp +++ b/lldb/source/Plugins/Language/ObjC/CF.cpp @@ -139,10 +139,8 @@ bool lldb_private::formatters::CFBitVectorSummaryProvider( bool is_type_ok = false; // check to see if this is a CFBag we know about if (descriptor->IsCFType()) { ConstString type_name(valobj.GetTypeName()); - if (type_name == ConstString("__CFMutableBitVector") || - type_name == ConstString("__CFBitVector") || - type_name == ConstString("CFMutableBitVectorRef") || - type_name == ConstString("CFBitVectorRef")) { + if (type_name == "__CFMutableBitVector" || type_name == "__CFBitVector" || + type_name == "CFMutableBitVectorRef" || type_name == "CFBitVectorRef") { if (valobj.IsPointerType()) is_type_ok = true; } diff --git a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp index 419f209068d99..8e7014dcd6118 100644 --- a/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp +++ b/lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp @@ -472,7 +472,8 @@ ValueObjectSP AppleObjCRuntime::GetExceptionObjectForThread( while (descriptor) { ConstString class_name(descriptor->GetClassName()); - if (class_name == ConstString("NSException")) return cpp_exception; + if (class_name == "NSException") + return cpp_exception; descriptor = descriptor->GetSuperclass(); } diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp index ac9642b2968d1..d41d9722fa2cc 100644 --- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp +++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp @@ -1996,8 +1996,8 @@ unsigned ObjectFileELF::ParseSymbols(Symtab *symtab, user_id_t start_id, // custom extension and file name makes it highly unlikely that this will // collide with anything else. ConstString file_extension = m_file.GetFileNameExtension(); - bool skip_oatdata_oatexec = file_extension == ConstString(".oat") || - file_extension == ConstString(".odex"); + bool skip_oatdata_oatexec = + file_extension == ".oat" || file_extension == ".odex"; ArchSpec arch = GetArchitecture(); ModuleSP module_sp(GetModule()); diff --git a/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp b/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp index 1e9c840a24180..3b8c9206ca329 100644 --- a/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp +++ b/lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp @@ -302,7 +302,7 @@ Status PlatformAndroid::DownloadSymbolFile(const lldb::ModuleSP &module_sp, const FileSpec &dst_file_spec) { // For oat file we can try to fetch additional debug info from the device ConstString extension = module_sp->GetFileSpec().GetFileNameExtension(); - if (extension != ConstString(".oat") && extension != ConstString(".odex")) + if (extension != ".oat" && extension != ".odex") return Status( "Symbol file downloading only supported for oat and odex files"); diff --git a/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp b/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp index 6b81ec8d3a7c6..82be85699b2c3 100644 --- a/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp +++ b/lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp @@ -454,8 +454,7 @@ void SystemRuntimeMacOSX::ReadLibdispatchTSDIndexes() { ThreadSP SystemRuntimeMacOSX::GetExtendedBacktraceThread(ThreadSP real_thread, ConstString type) { ThreadSP originating_thread_sp; - if (BacktraceRecordingHeadersInitialized() && - type == ConstString("libdispatch")) { + if (BacktraceRecordingHeadersInitialized() && type == "libdispatch") { Status error; // real_thread is either an actual, live thread (in which case we need to @@ -554,7 +553,7 @@ ThreadSP SystemRuntimeMacOSX::GetExtendedBacktraceForQueueItem(QueueItemSP queue_item_sp, ConstString type) { ThreadSP extended_thread_sp; - if (type != ConstString("libdispatch")) + if (type != "libdispatch") return extended_thread_sp; bool stop_id_is_valid = true; diff --git a/lldb/unittests/Utility/ConstStringTest.cpp b/lldb/unittests/Utility/ConstStringTest.cpp index 9c2f2cf369bdc..74753b903171d 100644 --- a/lldb/unittests/Utility/ConstStringTest.cpp +++ b/lldb/unittests/Utility/ConstStringTest.cpp @@ -89,3 +89,51 @@ TEST(ConstStringTest, NullAndEmptyStates) { EXPECT_TRUE(null.IsEmpty()); EXPECT_TRUE(null.IsNull()); } + +TEST(ConstStringTest, CompareConstString) { + ConstString foo("foo"); + ConstString foo2("foo"); + ConstString bar("bar"); + + EXPECT_TRUE(foo == foo2); + EXPECT_TRUE(foo2 == foo); + EXPECT_TRUE(foo == ConstString("foo")); + + EXPECT_FALSE(foo == bar); + EXPECT_FALSE(foo2 == bar); + EXPECT_FALSE(foo == ConstString("bar")); + EXPECT_FALSE(foo == ConstString("different")); + EXPECT_FALSE(foo == ConstString("")); + EXPECT_FALSE(foo == ConstString()); + + ConstString empty(""); + EXPECT_FALSE(empty == ConstString("bar")); + EXPECT_FALSE(empty == ConstString()); + EXPECT_TRUE(empty == ConstString("")); + + ConstString null; + EXPECT_FALSE(null == ConstString("bar")); + EXPECT_TRUE(null == ConstString()); + EXPECT_FALSE(null == ConstString("")); +} + +TEST(ConstStringTest, CompareStringRef) { + ConstString foo("foo"); + + EXPECT_TRUE(foo == "foo"); + EXPECT_TRUE(foo != ""); + EXPECT_FALSE(foo == static_cast(nullptr)); + EXPECT_TRUE(foo != "bar"); + + ConstString empty(""); + EXPECT_FALSE(empty == "foo"); + EXPECT_FALSE(empty != ""); + EXPECT_FALSE(empty == static_cast(nullptr)); + EXPECT_TRUE(empty != "bar"); + + ConstString null; + EXPECT_FALSE(null == "foo"); + EXPECT_TRUE(null != ""); + EXPECT_TRUE(null == static_cast(nullptr)); + EXPECT_TRUE(null != "bar"); +}