teemperor created this revision.
teemperor added a reviewer: LLDB.
Herald added subscribers: lldb-commits, MaskRay, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLDB.
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.
Repository:
rLLDB LLDB
https://reviews.llvm.org/D60667
Files:
lldb/include/lldb/Utility/ConstString.h
lldb/source/Core/Disassembler.cpp
lldb/source/Interpreter/OptionGroupPlatform.cpp
lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp
lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp
lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
lldb/source/Plugins/Language/ObjC/CF.cpp
lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptRuntime.cpp
lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
lldb/unittests/Utility/ConstStringTest.cpp
Index: lldb/unittests/Utility/ConstStringTest.cpp
===================================================================
--- lldb/unittests/Utility/ConstStringTest.cpp
+++ lldb/unittests/Utility/ConstStringTest.cpp
@@ -89,3 +89,51 @@
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<const char *>(nullptr));
+ EXPECT_TRUE(foo != "bar");
+
+ ConstString empty("");
+ EXPECT_FALSE(empty == "foo");
+ EXPECT_FALSE(empty != "");
+ EXPECT_FALSE(empty == static_cast<const char *>(nullptr));
+ EXPECT_TRUE(empty != "bar");
+
+ ConstString null;
+ EXPECT_FALSE(null == "foo");
+ EXPECT_TRUE(null != "");
+ EXPECT_TRUE(null == static_cast<const char *>(nullptr));
+ EXPECT_TRUE(null != "bar");
+}
Index: lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
===================================================================
--- lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
+++ lldb/source/Plugins/SystemRuntime/MacOSX/SystemRuntimeMacOSX.cpp
@@ -454,8 +454,7 @@
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 @@
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;
Index: lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
===================================================================
--- lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
+++ lldb/source/Plugins/Platform/Android/PlatformAndroid.cpp
@@ -302,7 +302,7 @@
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");
Index: lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
===================================================================
--- lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1668,7 +1668,7 @@
if (!name || !name[0] || !ParseSectionHeaders())
return 0;
for (size_t i = 1; i < m_section_headers.size(); ++i)
- if (m_section_headers[i].section_name == ConstString(name))
+ if (m_section_headers[i].section_name == name)
return i;
return 0;
}
@@ -1996,8 +1996,8 @@
// 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());
Index: lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptRuntime.cpp
===================================================================
--- lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptRuntime.cpp
+++ lldb/source/Plugins/LanguageRuntime/RenderScript/RenderScriptRuntime/RenderScriptRuntime.cpp
@@ -1685,7 +1685,7 @@
continue;
// Only proceed if the module that has loaded corresponds to this script.
- if (file.GetFilename() != ConstString(shared_lib.c_str()))
+ if (file.GetFilename() != shared_lib)
continue;
// Obtain the script address which we use as a key.
Index: lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
===================================================================
--- lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
+++ lldb/source/Plugins/LanguageRuntime/ObjC/AppleObjCRuntime/AppleObjCRuntime.cpp
@@ -472,7 +472,8 @@
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();
}
Index: lldb/source/Plugins/Language/ObjC/CF.cpp
===================================================================
--- lldb/source/Plugins/Language/ObjC/CF.cpp
+++ lldb/source/Plugins/Language/ObjC/CF.cpp
@@ -139,10 +139,8 @@
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;
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp
@@ -130,12 +130,11 @@
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;
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibStdcpp.cpp
@@ -142,9 +142,9 @@
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 @@
size_t VectorIteratorSyntheticFrontEnd::GetIndexOfChildWithName(
ConstString name) {
- if (name == ConstString("item"))
+ if (name == "item")
return 0;
return UINT32_MAX;
}
@@ -374,7 +374,7 @@
size_t LibStdcppSharedPtrSyntheticFrontEnd::GetIndexOfChildWithName(
ConstString name) {
- if (name == ConstString("_M_ptr"))
+ if (name == "_M_ptr")
return 0;
return UINT32_MAX;
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibCxxVector.cpp
@@ -290,7 +290,7 @@
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);
}
Index: lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
===================================================================
--- lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
+++ lldb/source/Plugins/Language/CPlusPlus/LibCxx.cpp
@@ -300,9 +300,9 @@
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 @@
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;
}
Index: lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
===================================================================
--- lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.cpp
@@ -489,7 +489,7 @@
// 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 {};
Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
===================================================================
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionSourceCode.cpp
@@ -167,8 +167,7 @@
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());
Index: lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
===================================================================
--- lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
+++ lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionDeclMap.cpp
@@ -1170,7 +1170,7 @@
return;
}
- if (name == ConstString(g_lldb_local_vars_namespace_cstr)) {
+ if (name == g_lldb_local_vars_namespace_cstr) {
CompilerDeclContext frame_decl_context =
sym_ctx.block != nullptr ? sym_ctx.block->GetDeclContext()
: CompilerDeclContext();
Index: lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp
===================================================================
--- lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp
+++ lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOSXDYLD.cpp
@@ -136,7 +136,7 @@
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 @@
// 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;
Index: lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp
===================================================================
--- lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp
+++ lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderMacOS.cpp
@@ -111,7 +111,7 @@
const Symbol *symbol =
frame_sp->GetSymbolContext(eSymbolContextSymbol).symbol;
if (symbol) {
- if (symbol->GetName() == ConstString("_dyld_start"))
+ if (symbol->GetName() == "_dyld_start")
did_exec = true;
}
}
Index: lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
===================================================================
--- lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
+++ lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp
@@ -474,7 +474,7 @@
// 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.
Index: lldb/source/Interpreter/OptionGroupPlatform.cpp
===================================================================
--- lldb/source/Interpreter/OptionGroupPlatform.cpp
+++ lldb/source/Interpreter/OptionGroupPlatform.cpp
@@ -123,7 +123,7 @@
const lldb::PlatformSP &platform_sp) const {
if (platform_sp) {
if (!m_platform_name.empty()) {
- if (platform_sp->GetName() != ConstString(m_platform_name.c_str()))
+ if (platform_sp->GetName() != m_platform_name)
return false;
}
Index: lldb/source/Core/Disassembler.cpp
===================================================================
--- lldb/source/Core/Disassembler.cpp
+++ lldb/source/Core/Disassembler.cpp
@@ -1404,8 +1404,7 @@
lldb_private::OperandMatchers::MatchRegOp(const RegisterInfo &info) {
return [&info](const Instruction::Operand &op) {
return (op.m_type == Instruction::Operand::Type::Register &&
- (op.m_register == ConstString(info.name) ||
- op.m_register == ConstString(info.alt_name)));
+ (op.m_register == info.name || op.m_register == info.alt_name));
};
}
Index: lldb/include/lldb/Utility/ConstString.h
===================================================================
--- lldb/include/lldb/Utility/ConstString.h
+++ lldb/include/lldb/Utility/ConstString.h
@@ -154,6 +154,28 @@
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 is short and not already a ConstString, 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==(llvm::StringRef 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 ^ !rhs.data())
+ 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 +192,21 @@
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 is short and not already a ConstString, 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!=(llvm::StringRef rhs) const { return !(*this == rhs); }
+
bool operator<(ConstString rhs) const;
/// Get the string value as a C string.
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