Changeset 208404 in webkit for trunk/Source/JavaScriptCore/interpreter/Interpreter.cpp

Timestamp:

Nov 4, 2016, 4:02:19 PM (9 years ago)

Author:

[email protected]

Message:

EvalCodeCache should not give up in strict mode and other cases
​https://bugs.webkit.org/show_bug.cgi?id=164357

Reviewed by Michael Saboff.

JSTests:

• microbenchmarks/eval-cached.js: Added. 45x faster now.
• stress/eval-cached.js: Added. Try running the same eval text in a bunch

of different scopes and verify that we access the right scope.

Source/JavaScriptCore:

EvalCodeCache gives up in non-trivial cases because generated eval code
can't soundly migrate from, for example, a let scope to a non-let scope.
The number of cases has grown over time.

Instead, let's cache eval code based on the location of the call to
eval(). That way, we never relocate the code, and it's sound to make
normal assumptions about our surrounding scope.

• bytecode/EvalCodeCache.h:

(JSC::EvalCodeCache::CacheKey::CacheKey): Use CallSiteIndex to uniquely
identify the location of our call to eval().

(JSC::EvalCodeCache::CacheKey::hash):
(JSC::EvalCodeCache::CacheKey::operator==):
(JSC::EvalCodeCache::CacheKey::Hash::equal): Use CallSiteIndex instead
of lots of other flags.

(JSC::EvalCodeCache::tryGet): No need to include details that are implied
by our CallSiteIndex.

(JSC::EvalCodeCache::getSlow): No need to skip caching in complex
situations. We promise we'll never relocate the cached code.

(JSC::EvalCodeCache::isCacheableScope): Deleted.
(JSC::EvalCodeCache::isCacheable): Deleted.

• interpreter/Interpreter.cpp:

(JSC::eval): Pass through a CallSiteIndex to uniquely identify this call
to eval().

File:

• trunk/Source/JavaScriptCore/interpreter/Interpreter.cpp (modified) (3 diffs)

trunk/Source/JavaScriptCore/interpreter/Interpreter.cpp

@@ -110 +110 @@
     
     CallFrame* callerFrame = callFrame->callerFrame();
+    CallSiteIndex callerCallSiteIndex = callerFrame->callSiteIndex();
     CodeBlock* callerCodeBlock = callerFrame->codeBlock();
     JSScope* callerScopeChain = callerFrame->uncheckedR(callerCodeBlock->scopeRegister().offset()).Register::scope();
@@ -131 +132 @@
         evalContextType = EvalContextType::None;
 
-    EvalExecutable* eval = callerCodeBlock->evalCodeCache().tryGet(callerCodeBlock->isStrictMode(), programSource, derivedContextType, evalContextType, isArrowFunctionContext, callerScopeChain);
+    EvalExecutable* eval = callerCodeBlock->evalCodeCache().tryGet(programSource, callerCallSiteIndex);
     if (!eval) {
         if (!callerCodeBlock->isStrictMode()) {
@@ -148 +149 @@
         ASSERT(!scope.exception());
 
-        eval = callerCodeBlock->evalCodeCache().getSlow(callFrame, callerCodeBlock, callerCodeBlock->isStrictMode(), derivedContextType, evalContextType, isArrowFunctionContext, programSource, callerScopeChain);
+        eval = callerCodeBlock->evalCodeCache().getSlow(callFrame, callerCodeBlock, programSource, callerCallSiteIndex, callerCodeBlock->isStrictMode(), derivedContextType, evalContextType, isArrowFunctionContext, callerScopeChain);
 
         if (!eval)