Changeset 223715 in webkit for trunk/Source/JavaScriptCore/runtime/Structure.cpp

Timestamp:

Oct 19, 2017, 3:23:58 PM (8 years ago)

Author:

[email protected]

Message:

We should hard code the poly proto offset
​https://bugs.webkit.org/show_bug.cgi?id=178531

Reviewed by Filip Pizlo.

This patch embraces that the poly proto offset is always zero. It's already
the case that we would always get the inline offset zero for poly proto just
by construction. This just hardcodes this assumption throughout the codebase.
This appears to be a 1% speedometer progression in my testing.

The downside of this patch is that it may require changing how we do
things when we implement poly proto when inheriting from builtin
types. I think we can face this problem when we decide to implement
that.

• bytecode/AccessCase.cpp:

(JSC::AccessCase::generateWithGuard):

• dfg/DFGOperations.cpp:
• dfg/DFGSpeculativeJIT.cpp:

(JSC::DFG::SpeculativeJIT::compileInstanceOfForObject):
(JSC::DFG::SpeculativeJIT::compileGetPrototypeOf):

• ftl/FTLLowerDFGToB3.cpp:

(JSC::FTL::DFG::LowerDFGToB3::compileGetPrototypeOf):
(JSC::FTL::DFG::LowerDFGToB3::compileInstanceOf):

• jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_instanceof):

• jit/JITOpcodes32_64.cpp:

(JSC::JIT::emit_op_instanceof):

• runtime/CommonSlowPaths.cpp:

(JSC::SLOW_PATH_DECL):

• runtime/JSObject.cpp:

(JSC::JSObject::setPrototypeDirect):

• runtime/JSObject.h:

(JSC::JSObject::locationForOffset const):
(JSC::JSObject::locationForOffset):
(JSC::JSObject::getDirect const):

• runtime/PropertyOffset.h:
• runtime/Structure.cpp:

(JSC::Structure::create):
(JSC::Structure::dump const):

• runtime/Structure.h:
• runtime/StructureInlines.h:

(JSC::Structure::storedPrototype const):
(JSC::Structure::storedPrototypeObject const):

File:

• trunk/Source/JavaScriptCore/runtime/Structure.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/runtime/Structure.cpp

@@ -309 +309 @@
         [&] (const GCSafeConcurrentJSLocker&, PropertyOffset offset, PropertyOffset newLastOffset) {
             RELEASE_ASSERT(Structure::outOfLineCapacity(newLastOffset) == oldOutOfLineCapacity);
-            RELEASE_ASSERT(isInlineOffset(offset));
-            result->m_prototype.set(vm, result, jsNumber(offset));
+            RELEASE_ASSERT(offset == knownPolyProtoOffset);
+            RELEASE_ASSERT(isInlineOffset(knownPolyProtoOffset));
+            result->m_prototype.setWithoutWriteBarrier(JSValue());
             result->setLastOffset(newLastOffset);
         });
@@ -1173 +1174 @@
     
     if (hasPolyProto())
-        out.print(", PolyProto offset:", polyProtoOffset());
+        out.print(", PolyProto offset:", knownPolyProtoOffset);
     else if (m_prototype.get().isCell())
         out.print(", Proto:", RawPointer(m_prototype.get().asCell()));