Changeset 249337 in webkit

Timestamp:

Aug 30, 2019 11:53:26 AM (5 years ago)

Author:

ysuzuki@apple.com

Message:

[JSC] Generate new.target register only when it is used
​https://bugs.webkit.org/show_bug.cgi?id=201335

Reviewed by Mark Lam.

JSTests:

• stress/ensure-new-register-allocated.js: Added.

(shouldBe):
(basic):
(arrow):
(Base):
(Derived):
(evaluate):

Source/JavaScriptCore:

Since bytecode generator knows whether new.target register can be used, we should emit and use new.target register
only when it is actually required.

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::BytecodeGenerator):

• bytecompiler/BytecodeGenerator.h:

(JSC::BytecodeGenerator::newTarget):

• parser/Nodes.h:

(JSC::ScopeNode::needsNewTargetRegisterForThisScope const):

Location:

trunk

Files:

• JSTests/ChangeLog (modified) (1 diff)
• JSTests/stress/ensure-new-register-allocated.js (added)
• Source/JavaScriptCore/ChangeLog (modified) (1 diff)
• Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp (modified) (7 diffs)
• Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h (modified) (1 diff)
• Source/JavaScriptCore/parser/Nodes.h (modified) (1 diff)

trunk/JSTests/ChangeLog

@@ +1 @@
+2019-08-30  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        [JSC] Generate new.target register only when it is used
+        https://bugs.webkit.org/show_bug.cgi?id=201335
+
+        Reviewed by Mark Lam.
+
+        * stress/ensure-new-register-allocated.js: Added.
+        (shouldBe):
+        (basic):
+        (arrow):
+        (Base):
+        (Derived):
+        (evaluate):
+
 2019-08-30  Yusuke Suzuki  <ysuzuki@apple.com>
 

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2019-08-30  Yusuke Suzuki  <ysuzuki@apple.com>
+
+        [JSC] Generate new.target register only when it is used
+        https://bugs.webkit.org/show_bug.cgi?id=201335
+
+        Reviewed by Mark Lam.
+
+        Since bytecode generator knows whether new.target register can be used, we should emit and use new.target register
+        only when it is actually required.
+
+        * bytecompiler/BytecodeGenerator.cpp:
+        (JSC::BytecodeGenerator::BytecodeGenerator):
+        * bytecompiler/BytecodeGenerator.h:
+        (JSC::BytecodeGenerator::newTarget):
+        * parser/Nodes.h:
+        (JSC::ScopeNode::needsNewTargetRegisterForThisScope const):
+
 2019-08-30  Yusuke Suzuki  <ysuzuki@apple.com>
 

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

@@ -668 +668 @@
 
 
-    m_newTargetRegister = addVar();
+    if (functionNode->needsNewTargetRegisterForThisScope() || isNewTargetUsedInInnerArrowFunction() || codeBlock->usesEval())
+        m_newTargetRegister = addVar();
+
     switch (parseMode) {
     case SourceParseMode::GeneratorWrapperFunctionMode:
@@ -726 +728 @@
     case SourceParseMode::GeneratorBodyMode: {
         // |this| is already filled correctly before here.
-        emitLoad(m_newTargetRegister, jsUndefined());
+        if (m_newTargetRegister)
+            emitLoad(m_newTargetRegister, jsUndefined());
         break;
     }
@@ -733 +736 @@
         if (SourceParseMode::ArrowFunctionMode != parseMode) {
             if (isConstructor()) {
-                move(m_newTargetRegister, &m_thisRegister);
+                if (m_newTargetRegister)
+                    move(m_newTargetRegister, &m_thisRegister);
                 if (constructorKind() == ConstructorKind::Extends) {
                     moveEmptyValue(&m_thisRegister);
@@ -773 +777 @@
             emitLoadThisFromArrowFunctionLexicalEnvironment();
 
-        if (m_scopeNode->usesNewTarget() || m_scopeNode->usesSuperCall())
+        if (m_scopeNode->needsNewTargetRegisterForThisScope())
             emitLoadNewTargetFromArrowFunctionLexicalEnvironment();
     }
@@ -830 +834 @@
             emitLoadThisFromArrowFunctionLexicalEnvironment();
     
-        if (m_scopeNode->usesNewTarget() || m_scopeNode->usesSuperCall())
+        if (m_scopeNode->needsNewTargetRegisterForThisScope())
             emitLoadNewTargetFromArrowFunctionLexicalEnvironment();
     }
@@ -900 +904 @@
     codeBlock->adoptFunctionHoistingCandidates(WTFMove(hoistedFunctions));
     
-    if (evalNode->usesSuperCall() || evalNode->usesNewTarget())
+    if (evalNode->needsNewTargetRegisterForThisScope())
         m_newTargetRegister = addVar();
 
@@ -906 +910 @@
         emitLoadThisFromArrowFunctionLexicalEnvironment();
 
-    if (evalNode->usesSuperCall() || evalNode->usesNewTarget())
+    if (evalNode->needsNewTargetRegisterForThisScope())
         emitLoadNewTargetFromArrowFunctionLexicalEnvironment();
 

trunk/Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h

@@ -424 +424 @@
         RegisterID* newTarget()
         {
+            ASSERT(m_newTargetRegister);
             return m_newTargetRegister;
         }

trunk/Source/JavaScriptCore/parser/Nodes.h

@@ -1800 +1800 @@
         bool hasSloppyModeHoistedFunction(UniquedStringImpl* uid) const { return m_sloppyModeHoistedFunctions.contains(uid); }
 
+        bool needsNewTargetRegisterForThisScope() const
+        {
+            return usesSuperCall() || usesNewTarget();
+        }
+
         VariableEnvironment& varDeclarations() { return m_varDeclarations; }