Changeset 262083 in webkit for trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp

Timestamp:

May 22, 2020, 3:31:13 PM (5 years ago)

Author:

[email protected]

Message:

in_by_val inside structure property for-in loop should use an opcode like has_structure_property but for "in"
​https://bugs.webkit.org/show_bug.cgi?id=212239

Reviewed by Tadeu Zagallo.

JSTests:

• microbenchmarks/in-by-val-inside-for-in-loop.js: Added.

(assert):
(count):

• stress/in-by-val-inside-for-in-loop.js: Added.

(assert):
(test1.count):
(test1):
(test2.count):
(test2):
(test3.count):
(test3):
(test4.count):
(test4):
(test5.count):
(test5):
(test6.count):
(test6):
(test7.count):
(test7):
(test8.count):
(test8):

Source/JavaScriptCore:

There is code inside Speedometer 2 that is like:

`
for (let p in o) {

if (p in o2)

...

}
`

Where o and o2 frequently share the same structure. Elm does this when it's
diffing two objects. We already optimize o2[p] (get_by_val) in the above loop
for structure properties. This patch adds that same optimization for in_by_val.
Because we already emit a "structure" loop for for-in, where we iterate structure
properties, the fast path for the above, where o and o2 have the same
structure is simply a structure check followed by return true.

This patch introduces the new opcode: op_in_structure_property. Its fast path is identical
to op_has_structure_property. Its slow path, however, behaves like "in", which
uses the HasProperty internal method, unlike op_has_structure_property,
which uses the GetOwnProperty internal method. This behavior difference is
observable using Proxy.

This a 5% perf improvement in the Elm subtest in Speedometer 2.

• bytecode/BytecodeList.rb:
• bytecode/BytecodeUseDef.cpp:

(JSC::computeUsesForBytecodeIndexImpl):
(JSC::computeDefsForBytecodeIndexImpl):

• bytecompiler/BytecodeGenerator.cpp:

(JSC::BytecodeGenerator::emitInByVal):
(JSC::rewriteOp):
(JSC::StructureForInContext::finalize):

• bytecompiler/BytecodeGenerator.h:

(JSC::StructureForInContext::addInInst):

• dfg/DFGAbstractInterpreterInlines.h:

(JSC::DFG::AbstractInterpreter<AbstractStateType>::executeEffects):

• dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::parseBlock):

• dfg/DFGCapabilities.cpp:

(JSC::DFG::capabilityLevel):

• dfg/DFGClobberize.h:

(JSC::DFG::clobberize):

• dfg/DFGDoesGC.cpp:

(JSC::DFG::doesGC):

• dfg/DFGFixupPhase.cpp:

(JSC::DFG::FixupPhase::fixupNode):

• dfg/DFGNodeType.h:
• dfg/DFGOperations.cpp:
• dfg/DFGOperations.h:
• dfg/DFGPredictionPropagationPhase.cpp:
• dfg/DFGSafeToExecute.h:

(JSC::DFG::safeToExecute):

• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::compileInStructureProperty):

• dfg/DFGSpeculativeJIT.h:
• dfg/DFGSpeculativeJIT32_64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• dfg/DFGSpeculativeJIT64.cpp:

(JSC::DFG::SpeculativeJIT::compile):

• ftl/FTLCapabilities.cpp:

(JSC::FTL::canCompile):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::compileNode):
(JSC::FTL::DFG::LowerDFGToB3::compileHasStructurePropertyImpl):
(JSC::FTL::DFG::LowerDFGToB3::compileHasStructureProperty):
(JSC::FTL::DFG::LowerDFGToB3::compileInStructureProperty):

• jit/JIT.cpp:

(JSC::JIT::privateCompileMainPass):
(JSC::JIT::privateCompileSlowCases):

• jit/JIT.h:
• jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_in_structure_property):

• jit/JITOpcodes32_64.cpp:

(JSC::JIT::emit_op_in_structure_property):

• llint/LLIntOffsetsExtractor.cpp:
• llint/LowLevelInterpreter.asm:
• llint/LowLevelInterpreter64.asm:
• runtime/CommonSlowPaths.cpp:

(JSC::SLOW_PATH_DECL):

• runtime/CommonSlowPaths.h:
• runtime/JSObject.cpp:

(JSC::JSObject::hasPropertyGeneric const):

• runtime/JSPropertyNameEnumerator.h:

File:

• trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/ftl/FTLLowerDFGToB3.cpp

@@ -1478 +1478 @@
             compileHasStructureProperty();
             break;
+        case InStructureProperty:
+            compileInStructureProperty();
+            break;
         case GetDirectPname:
             compileGetDirectPname();
@@ -12242 +12245 @@
     }
 
-    void compileHasStructureProperty()
+    template <typename SlowPathCall>
+    void compileHasStructurePropertyImpl(LValue base, SlowPathCall slowPathCall)
     {
         JSGlobalObject* globalObject = m_graph.globalObjectFor(m_node->origin.semantic);
-        LValue base = lowJSValue(m_node->child1());
         LValue property = lowString(m_node->child2());
         LValue enumerator = lowCell(m_node->child3());
 
+        LBasicBlock isCellCase = m_out.newBlock();
         LBasicBlock correctStructure = m_out.newBlock();
-        LBasicBlock wrongStructure = m_out.newBlock();
+        LBasicBlock slowPath = m_out.newBlock();
         LBasicBlock continuation = m_out.newBlock();
+
+        m_out.branch(isCell(base, provenType(m_node->child1())),
+            usually(isCellCase), rarely(slowPath));
+
+        LBasicBlock lastNext = m_out.appendTo(isCellCase, correctStructure);
 
         m_out.branch(m_out.notEqual(
             m_out.load32(base, m_heaps.JSCell_structureID),
             m_out.load32(enumerator, m_heaps.JSPropertyNameEnumerator_cachedStructureID)),
-            rarely(wrongStructure), usually(correctStructure));
-
-        LBasicBlock lastNext = m_out.appendTo(correctStructure, wrongStructure);
+            rarely(slowPath), usually(correctStructure));
+
+        m_out.appendTo(correctStructure, slowPath);
         ValueFromBlock correctStructureResult = m_out.anchor(m_out.booleanTrue);
         m_out.jump(continuation);
 
-        m_out.appendTo(wrongStructure, continuation);
-        ValueFromBlock wrongStructureResult = m_out.anchor(
+        m_out.appendTo(slowPath, continuation);
+        ValueFromBlock slowPathResult = m_out.anchor(
             m_out.equal(
                 m_out.constInt64(JSValue::encode(jsBoolean(true))), 
-                vmCall(Int64, operationHasGenericProperty, weakPointer(globalObject), base, property)));
+                vmCall(Int64, slowPathCall, weakPointer(globalObject), base, property)));
         m_out.jump(continuation);
 
         m_out.appendTo(continuation, lastNext);
-        setBoolean(m_out.phi(Int32, correctStructureResult, wrongStructureResult));
+        setBoolean(m_out.phi(Int32, correctStructureResult, slowPathResult));
+    }
+
+    void compileHasStructureProperty()
+    {
+        compileHasStructurePropertyImpl(lowJSValue(m_node->child1()), operationHasGenericProperty);
+    }
+
+    void compileInStructureProperty()
+    {
+        compileHasStructurePropertyImpl(lowCell(m_node->child1()), operationInStructureProperty);
     }