[JSC] Compact generator code's bytecode size
https://bugs.webkit.org/show_bug.cgi?id=197822
Reviewed by Michael Saboff.
op_put_to_scope's symbolTableOrScopeDepth is represented as int. This was OK for the old bytecode format since
VirtualRegister / scope depth can be represented by int anyway. But it is problematic now since only int8_t range
will be represented in narrow bytecode. When this field is used for symbol table constant index, it is always
larger than FirstConstantRegisterIndex. So it always exceeds the range of int8_t, and results in wide bytecode.
It makes all generator's op_put_to_scope wide bytecode.
In this patch, we introduce a new (logically) union type SymbolTableOrScopeDepth. It holds unsigned value, and we store the
SymbolTableConstantIndex - FirstConstantRegisterIndex in this unsigned value to make op_put_to_scope narrow bytecode.
* CMakeLists.txt:
* JavaScriptCore.xcodeproj/project.pbxproj:
* bytecode/BytecodeGeneratorification.cpp:
(JSC::BytecodeGeneratorification::run):
* bytecode/BytecodeList.rb:
* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::finishCreation):
* bytecode/Fits.h:
* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::BytecodeGenerator):
(JSC::BytecodeGenerator::emitProfileType):
(JSC::BytecodeGenerator::emitPutToScope):
(JSC::BytecodeGenerator::localScopeDepth const):
* bytecompiler/BytecodeGenerator.h:
* runtime/SymbolTableOrScopeDepth.h: Added.
(JSC::SymbolTableOrScopeDepth::symbolTable):
(JSC::SymbolTableOrScopeDepth::scopeDepth):
(JSC::SymbolTableOrScopeDepth::raw):
(JSC::SymbolTableOrScopeDepth::symbolTable const):
(JSC::SymbolTableOrScopeDepth::scopeDepth const):
(JSC::SymbolTableOrScopeDepth::raw const):
(JSC::SymbolTableOrScopeDepth::dump const):
(JSC::SymbolTableOrScopeDepth::SymbolTableOrScopeDepth):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@245213 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/CMakeLists.txt b/Source/JavaScriptCore/CMakeLists.txt
index fb6210c..fde79e2 100644
--- a/Source/JavaScriptCore/CMakeLists.txt
+++ b/Source/JavaScriptCore/CMakeLists.txt
@@ -963,6 +963,7 @@
runtime/Symbol.h
runtime/SymbolPrototype.h
runtime/SymbolTable.h
+ runtime/SymbolTableOrScopeDepth.h
runtime/TemplateObjectDescriptor.h
runtime/TestRunnerUtils.h
runtime/ThrowScope.h
diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
index b3ecb66..adea1fc 100644
--- a/Source/JavaScriptCore/ChangeLog
+++ b/Source/JavaScriptCore/ChangeLog
@@ -1,3 +1,43 @@
+2019-05-12 Yusuke Suzuki <ysuzuki@apple.com>
+
+ [JSC] Compact generator code's bytecode size
+ https://bugs.webkit.org/show_bug.cgi?id=197822
+
+ Reviewed by Michael Saboff.
+
+ op_put_to_scope's symbolTableOrScopeDepth is represented as int. This was OK for the old bytecode format since
+ VirtualRegister / scope depth can be represented by int anyway. But it is problematic now since only int8_t range
+ will be represented in narrow bytecode. When this field is used for symbol table constant index, it is always
+ larger than FirstConstantRegisterIndex. So it always exceeds the range of int8_t, and results in wide bytecode.
+ It makes all generator's op_put_to_scope wide bytecode.
+
+ In this patch, we introduce a new (logically) union type SymbolTableOrScopeDepth. It holds unsigned value, and we store the
+ SymbolTableConstantIndex - FirstConstantRegisterIndex in this unsigned value to make op_put_to_scope narrow bytecode.
+
+ * CMakeLists.txt:
+ * JavaScriptCore.xcodeproj/project.pbxproj:
+ * bytecode/BytecodeGeneratorification.cpp:
+ (JSC::BytecodeGeneratorification::run):
+ * bytecode/BytecodeList.rb:
+ * bytecode/CodeBlock.cpp:
+ (JSC::CodeBlock::finishCreation):
+ * bytecode/Fits.h:
+ * bytecompiler/BytecodeGenerator.cpp:
+ (JSC::BytecodeGenerator::BytecodeGenerator):
+ (JSC::BytecodeGenerator::emitProfileType):
+ (JSC::BytecodeGenerator::emitPutToScope):
+ (JSC::BytecodeGenerator::localScopeDepth const):
+ * bytecompiler/BytecodeGenerator.h:
+ * runtime/SymbolTableOrScopeDepth.h: Added.
+ (JSC::SymbolTableOrScopeDepth::symbolTable):
+ (JSC::SymbolTableOrScopeDepth::scopeDepth):
+ (JSC::SymbolTableOrScopeDepth::raw):
+ (JSC::SymbolTableOrScopeDepth::symbolTable const):
+ (JSC::SymbolTableOrScopeDepth::scopeDepth const):
+ (JSC::SymbolTableOrScopeDepth::raw const):
+ (JSC::SymbolTableOrScopeDepth::dump const):
+ (JSC::SymbolTableOrScopeDepth::SymbolTableOrScopeDepth):
+
2019-05-10 Saam barati <sbarati@apple.com>
Call to JSToWasmICCallee::createStructure passes in wrong prototype value
diff --git a/Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj b/Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
index e7dc887..fa0c844 100644
--- a/Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
+++ b/Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
@@ -1742,6 +1742,7 @@
DE26E9031CB5DD0500D2BE82 /* BuiltinExecutableCreator.h in Headers */ = {isa = PBXBuildFile; fileRef = DE26E9021CB5DD0500D2BE82 /* BuiltinExecutableCreator.h */; };
DEA7E2451BBC677F00D78440 /* JSTypedArrayViewPrototype.h in Headers */ = {isa = PBXBuildFile; fileRef = 53917E7C1B791106000EBD33 /* JSTypedArrayViewPrototype.h */; settings = {ATTRIBUTES = (Private, ); }; };
E124A8F70E555775003091F1 /* OpaqueJSString.h in Headers */ = {isa = PBXBuildFile; fileRef = E124A8F50E555775003091F1 /* OpaqueJSString.h */; settings = {ATTRIBUTES = (Private, ); }; };
+ E31179AA2288386100514B2C /* SymbolTableOrScopeDepth.h in Headers */ = {isa = PBXBuildFile; fileRef = E31179A92288385D00514B2C /* SymbolTableOrScopeDepth.h */; settings = {ATTRIBUTES = (Private, ); }; };
E31618131EC5FE170006A218 /* DOMAnnotation.h in Headers */ = {isa = PBXBuildFile; fileRef = E31618101EC5FE080006A218 /* DOMAnnotation.h */; settings = {ATTRIBUTES = (Private, ); }; };
E31618151EC5FE270006A218 /* DOMAttributeGetterSetter.h in Headers */ = {isa = PBXBuildFile; fileRef = E31618121EC5FE080006A218 /* DOMAttributeGetterSetter.h */; settings = {ATTRIBUTES = (Private, ); }; };
E318CBC11B8AEF5100A2929D /* JSModuleNamespaceObject.h in Headers */ = {isa = PBXBuildFile; fileRef = E318CBBF1B8AEF5100A2929D /* JSModuleNamespaceObject.h */; settings = {ATTRIBUTES = (Private, ); }; };
@@ -4721,6 +4722,7 @@
E18E3A560DF9278C00D90B34 /* VM.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; lineEnding = 0; path = VM.h; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objcpp; };
E18E3A570DF9278C00D90B34 /* VM.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; lineEnding = 0; path = VM.cpp; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.cpp; };
E30677971B8BC6F5003F87F0 /* ModuleLoader.js */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.javascript; path = ModuleLoader.js; sourceTree = "<group>"; };
+ E31179A92288385D00514B2C /* SymbolTableOrScopeDepth.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = SymbolTableOrScopeDepth.h; sourceTree = "<group>"; };
E31618101EC5FE080006A218 /* DOMAnnotation.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DOMAnnotation.h; sourceTree = "<group>"; };
E31618111EC5FE080006A218 /* DOMAttributeGetterSetter.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = DOMAttributeGetterSetter.cpp; sourceTree = "<group>"; };
E31618121EC5FE080006A218 /* DOMAttributeGetterSetter.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = DOMAttributeGetterSetter.h; sourceTree = "<group>"; };
@@ -7299,6 +7301,7 @@
705B41AA1A6E501E00716757 /* SymbolPrototype.h */,
0F919D2715856770004A4E7D /* SymbolTable.cpp */,
14A396A60CD2933100B5B4FF /* SymbolTable.h */,
+ E31179A92288385D00514B2C /* SymbolTableOrScopeDepth.h */,
BDB4B5E099CD4C1BB3C1CF05 /* TemplateObjectDescriptor.cpp */,
70ECA6041AFDBEA200449739 /* TemplateObjectDescriptor.h */,
0FA2C17917D7CF84009D015F /* TestRunnerUtils.cpp */,
@@ -9857,6 +9860,7 @@
705B41B21A6E501E00716757 /* SymbolPrototype.h in Headers */,
996B73281BDA08EF00331B84 /* SymbolPrototype.lut.h in Headers */,
BC18C46B0E16F5CD00B34460 /* SymbolTable.h in Headers */,
+ E31179AA2288386100514B2C /* SymbolTableOrScopeDepth.h in Headers */,
0FD79A2D1EBBBDBB00DA88D3 /* Synchronousness.h in Headers */,
0F1FB38F1E173A6700A9BE50 /* SynchronousStopTheWorldMutatorScheduler.h in Headers */,
A784A26411D16622005776AC /* SyntaxChecker.h in Headers */,
diff --git a/Source/JavaScriptCore/bytecode/BytecodeGeneratorification.cpp b/Source/JavaScriptCore/bytecode/BytecodeGeneratorification.cpp
index 2e6dcc8..81ab758 100644
--- a/Source/JavaScriptCore/bytecode/BytecodeGeneratorification.cpp
+++ b/Source/JavaScriptCore/bytecode/BytecodeGeneratorification.cpp
@@ -252,7 +252,7 @@
storage.identifierIndex, // identifier
operand, // value
GetPutInfo(DoNotThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization), // info
- m_generatorFrameSymbolTableIndex, // symbol table constant index
+ SymbolTableOrScopeDepth::symbolTable(VirtualRegister { m_generatorFrameSymbolTableIndex }), // symbol table constant index
storage.scopeOffset.offset() // scope offset
);
});
diff --git a/Source/JavaScriptCore/bytecode/BytecodeList.rb b/Source/JavaScriptCore/bytecode/BytecodeList.rb
index 8ca0da9..0695a25 100644
--- a/Source/JavaScriptCore/bytecode/BytecodeList.rb
+++ b/Source/JavaScriptCore/bytecode/BytecodeList.rb
@@ -50,6 +50,7 @@
:StructureID,
:StructureChain,
:SymbolTable,
+ :SymbolTableOrScopeDepth,
:ToThisStatus,
:TypeLocation,
:WatchpointSet,
@@ -881,7 +882,7 @@
value: VirtualRegister, # offset 3
# $begin: :private,
getPutInfo: GetPutInfo,
- symbolTableOrScopeDepth: int,
+ symbolTableOrScopeDepth: SymbolTableOrScopeDepth,
offset: unsigned,
},
metadata: {
@@ -977,7 +978,7 @@
op :profile_type,
args: {
targetVirtualRegister: VirtualRegister,
- symbolTableOrScopeDepth: int,
+ symbolTableOrScopeDepth: SymbolTableOrScopeDepth,
flag: ProfileTypeBytecodeFlag,
identifier?: unsigned,
resolveType: ResolveType,
diff --git a/Source/JavaScriptCore/bytecode/CodeBlock.cpp b/Source/JavaScriptCore/bytecode/CodeBlock.cpp
index db28f67..ecc1a95 100644
--- a/Source/JavaScriptCore/bytecode/CodeBlock.cpp
+++ b/Source/JavaScriptCore/bytecode/CodeBlock.cpp
@@ -643,7 +643,7 @@
if (bytecode.m_getPutInfo.resolveType() == LocalClosureVar) {
// Only do watching if the property we're putting to is not anonymous.
if (bytecode.m_var != UINT_MAX) {
- SymbolTable* symbolTable = jsCast<SymbolTable*>(getConstant(bytecode.m_symbolTableOrScopeDepth));
+ SymbolTable* symbolTable = jsCast<SymbolTable*>(getConstant(bytecode.m_symbolTableOrScopeDepth.symbolTable().offset()));
const Identifier& ident = identifier(bytecode.m_var);
ConcurrentJSLocker locker(symbolTable->m_lock);
auto iter = symbolTable->find(locker, ident.impl());
@@ -657,7 +657,7 @@
const Identifier& ident = identifier(bytecode.m_var);
metadata.m_watchpointSet = nullptr;
- ResolveOp op = JSScope::abstractResolve(m_globalObject->globalExec(), bytecode.m_symbolTableOrScopeDepth, scope, ident, Put, bytecode.m_getPutInfo.resolveType(), bytecode.m_getPutInfo.initializationMode());
+ ResolveOp op = JSScope::abstractResolve(m_globalObject->globalExec(), bytecode.m_symbolTableOrScopeDepth.scopeDepth(), scope, ident, Put, bytecode.m_getPutInfo.resolveType(), bytecode.m_getPutInfo.initializationMode());
RETURN_IF_EXCEPTION(throwScope, false);
metadata.m_getPutInfo = GetPutInfo(bytecode.m_getPutInfo.resolveMode(), op.type, bytecode.m_getPutInfo.initializationMode());
@@ -687,7 +687,7 @@
switch (bytecode.m_flag) {
case ProfileTypeBytecodeClosureVar: {
const Identifier& ident = identifier(bytecode.m_identifier);
- unsigned localScopeDepth = bytecode.m_symbolTableOrScopeDepth;
+ unsigned localScopeDepth = bytecode.m_symbolTableOrScopeDepth.scopeDepth();
// Even though type profiling may be profiling either a Get or a Put, we can always claim a Get because
// we're abstractly "read"ing from a JSScope.
ResolveOp op = JSScope::abstractResolve(m_globalObject->globalExec(), localScopeDepth, scope, ident, Get, bytecode.m_resolveType, InitializationMode::NotInitialization);
@@ -711,7 +711,7 @@
break;
}
case ProfileTypeBytecodeLocallyResolved: {
- int symbolTableIndex = bytecode.m_symbolTableOrScopeDepth;
+ int symbolTableIndex = bytecode.m_symbolTableOrScopeDepth.symbolTable().offset();
SymbolTable* symbolTable = jsCast<SymbolTable*>(getConstant(symbolTableIndex));
const Identifier& ident = identifier(bytecode.m_identifier);
ConcurrentJSLocker locker(symbolTable->m_lock);
diff --git a/Source/JavaScriptCore/bytecode/Fits.h b/Source/JavaScriptCore/bytecode/Fits.h
index 207e885..24d7757 100644
--- a/Source/JavaScriptCore/bytecode/Fits.h
+++ b/Source/JavaScriptCore/bytecode/Fits.h
@@ -33,6 +33,7 @@
#include "PutByIdFlags.h"
#include "ResultType.h"
#include "SpecialPointer.h"
+#include "SymbolTableOrScopeDepth.h"
#include "VirtualRegister.h"
#include <type_traits>
@@ -133,6 +134,25 @@
};
template<>
+struct Fits<SymbolTableOrScopeDepth, OpcodeSize::Narrow> {
+ static bool check(SymbolTableOrScopeDepth u)
+ {
+ return u.raw() <= UINT8_MAX;
+ }
+
+ static uint8_t convert(SymbolTableOrScopeDepth u)
+ {
+ ASSERT(check(u));
+ return static_cast<uint8_t>(u.raw());
+ }
+
+ static SymbolTableOrScopeDepth convert(uint8_t u)
+ {
+ return SymbolTableOrScopeDepth::raw(u);
+ }
+};
+
+template<>
struct Fits<Special::Pointer, OpcodeSize::Narrow> : Fits<int, OpcodeSize::Narrow> {
using Base = Fits<int, OpcodeSize::Narrow>;
static bool check(Special::Pointer sp) { return Base::check(static_cast<int>(sp)); }
diff --git a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
index 661cb49..667dac0 100644
--- a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
+++ b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
@@ -551,7 +551,7 @@
entry.disableWatching(*m_vm);
functionSymbolTable->set(NoLockingNecessary, name, entry);
}
- OpPutToScope::emit(this, m_lexicalEnvironmentRegister, UINT_MAX, virtualRegisterForArgument(1 + i), GetPutInfo(ThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization), symbolTableConstantIndex, offset.offset());
+ OpPutToScope::emit(this, m_lexicalEnvironmentRegister, UINT_MAX, virtualRegisterForArgument(1 + i), GetPutInfo(ThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization), SymbolTableOrScopeDepth::symbolTable(VirtualRegister { symbolTableConstantIndex }), offset.offset());
}
// This creates a scoped arguments object and copies the overflow arguments into the
@@ -589,7 +589,7 @@
static_cast<const BindingNode*>(parameters.at(i).first)->boundProperty();
functionSymbolTable->set(NoLockingNecessary, name, SymbolTableEntry(VarOffset(offset)));
- OpPutToScope::emit(this, m_lexicalEnvironmentRegister, addConstant(ident), virtualRegisterForArgument(1 + i), GetPutInfo(ThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization), symbolTableConstantIndex, offset.offset());
+ OpPutToScope::emit(this, m_lexicalEnvironmentRegister, addConstant(ident), virtualRegisterForArgument(1 + i), GetPutInfo(ThrowIfNotFound, LocalClosureVar, InitializationMode::NotInitialization), SymbolTableOrScopeDepth::symbolTable(VirtualRegister { symbolTableConstantIndex }), offset.offset());
}
}
@@ -1803,7 +1803,7 @@
if (!registerToProfile)
return;
- OpProfileType::emit(this, registerToProfile, 0, flag, { }, resolveType());
+ OpProfileType::emit(this, registerToProfile, { }, flag, { }, resolveType());
// Don't emit expression info for this version of profile type. This generally means
// we're profiling information for something that isn't in the actual text of a JavaScript
@@ -1823,7 +1823,7 @@
if (!registerToProfile)
return;
- OpProfileType::emit(this, registerToProfile, 0, flag, { }, resolveType());
+ OpProfileType::emit(this, registerToProfile, { }, flag, { }, resolveType());
emitTypeProfilerExpressionInfo(startDivot, endDivot);
}
@@ -1836,14 +1836,14 @@
return;
ProfileTypeBytecodeFlag flag;
- int symbolTableOrScopeDepth;
+ SymbolTableOrScopeDepth symbolTableOrScopeDepth;
if (var.local() || var.offset().isScope()) {
flag = ProfileTypeBytecodeLocallyResolved;
ASSERT(var.symbolTableConstantIndex());
- symbolTableOrScopeDepth = var.symbolTableConstantIndex();
+ symbolTableOrScopeDepth = SymbolTableOrScopeDepth::symbolTable(VirtualRegister { var.symbolTableConstantIndex() });
} else {
flag = ProfileTypeBytecodeClosureVar;
- symbolTableOrScopeDepth = localScopeDepth();
+ symbolTableOrScopeDepth = SymbolTableOrScopeDepth::scopeDepth(localScopeDepth());
}
OpProfileType::emit(this, registerToProfile, symbolTableOrScopeDepth, flag, addConstant(var.ident()), resolveType());
@@ -2512,18 +2512,18 @@
case VarKind::Scope:
case VarKind::Invalid: {
GetPutInfo getPutInfo(0);
- int scopeDepth;
+ SymbolTableOrScopeDepth symbolTableOrScopeDepth;
ScopeOffset offset;
if (variable.offset().isScope()) {
offset = variable.offset().scopeOffset();
getPutInfo = GetPutInfo(resolveMode, LocalClosureVar, initializationMode);
- scopeDepth = variable.symbolTableConstantIndex();
+ symbolTableOrScopeDepth = SymbolTableOrScopeDepth::symbolTable(VirtualRegister { variable.symbolTableConstantIndex() });
} else {
ASSERT(resolveType() != LocalClosureVar);
getPutInfo = GetPutInfo(resolveMode, resolveType(), initializationMode);
- scopeDepth = localScopeDepth();
+ symbolTableOrScopeDepth = SymbolTableOrScopeDepth::scopeDepth(localScopeDepth());
}
- OpPutToScope::emit(this, scope, addConstant(variable.ident()), value, getPutInfo, scopeDepth, !!offset ? offset.offset() : 0);
+ OpPutToScope::emit(this, scope, addConstant(variable.ident()), value, getPutInfo, symbolTableOrScopeDepth, !!offset ? offset.offset() : 0);
m_codeBlock->addPropertyAccessInstruction(m_lastInstruction.offset());
return value;
} }
@@ -3743,7 +3743,7 @@
return dst;
}
-int BytecodeGenerator::localScopeDepth() const
+unsigned BytecodeGenerator::localScopeDepth() const
{
return m_localScopeDepth;
}
diff --git a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
index 95341a9..1c90313 100644
--- a/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
+++ b/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
@@ -1235,10 +1235,10 @@
SegmentedVector<Label, 32> m_labels;
SegmentedVector<LabelScope, 32> m_labelScopes;
unsigned m_finallyDepth { 0 };
- int m_localScopeDepth { 0 };
+ unsigned m_localScopeDepth { 0 };
const CodeType m_codeType;
- int localScopeDepth() const;
+ unsigned localScopeDepth() const;
void pushLocalControlFlowScope();
void popLocalControlFlowScope();
diff --git a/Source/JavaScriptCore/runtime/SymbolTableOrScopeDepth.h b/Source/JavaScriptCore/runtime/SymbolTableOrScopeDepth.h
new file mode 100644
index 0000000..91f5e8f
--- /dev/null
+++ b/Source/JavaScriptCore/runtime/SymbolTableOrScopeDepth.h
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2019 Apple Inc. All Rights Reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include "VirtualRegister.h"
+#include <wtf/PrintStream.h>
+
+namespace JSC {
+
+class SymbolTableOrScopeDepth {
+public:
+ SymbolTableOrScopeDepth() = default;
+
+ static SymbolTableOrScopeDepth symbolTable(VirtualRegister reg)
+ {
+ ASSERT(reg.isConstant());
+ return SymbolTableOrScopeDepth(reg.offset() - FirstConstantRegisterIndex);
+ }
+
+ static SymbolTableOrScopeDepth scopeDepth(unsigned scopeDepth)
+ {
+ return SymbolTableOrScopeDepth(scopeDepth);
+ }
+
+ static SymbolTableOrScopeDepth raw(unsigned value)
+ {
+ return SymbolTableOrScopeDepth(value);
+ }
+
+ VirtualRegister symbolTable() const
+ {
+ return VirtualRegister(m_raw + FirstConstantRegisterIndex);
+ }
+
+ unsigned scopeDepth() const
+ {
+ return m_raw;
+ }
+
+ unsigned raw() const { return m_raw; }
+
+ void dump(PrintStream& out) const
+ {
+ out.print(m_raw);
+ }
+
+private:
+ SymbolTableOrScopeDepth(unsigned value)
+ : m_raw(value)
+ { }
+
+ unsigned m_raw { 0 };
+};
+
+} // namespace JSC
