Don't use JSFunction's allocation profile when getting the prototype can be effectful
https://bugs.webkit.org/show_bug.cgi?id=182942
<rdar://problem/37584764>
Reviewed by Mark Lam.
JSTests:
- stress/get-prototype-create-this-effectful.js: Added.
Source/JavaScriptCore:
Prior to this patch, the create_this implementation assumed that anything
that is a JSFunction can use the object allocation profile and go down the
fast path to allocate the |this| object. Implied by this approach is that
accessing the 'prototype' property of the incoming function is not an
effectful operation. This is inherent to the ObjectAllocationProfile
data structure: it caches the prototype field. However, getting the
'prototype' property might be an effectful operation, e.g, it could
be a getter. Many variants of functions in JS have the 'prototype' property
as non-configurable. However, some functions, like bound functions, do not
have the 'prototype' field with these attributes.
This patch adds the notion of 'canUseAllocationProfile' to JSFunction
and threads it through so that we only go down the fast path and use
the allocation profile when the prototype property is non-configurable.
- bytecompiler/NodesCodegen.cpp:
(JSC::ClassExprNode::emitBytecode):
- dfg/DFGOperations.cpp:
- runtime/CommonSlowPaths.cpp:
(JSC::SLOW_PATH_DECL):
(JSC::JSFunction::prototypeForConstruction):
(JSC::JSFunction::allocateAndInitializeRareData):
(JSC::JSFunction::initializeRareData):
(JSC::JSFunction::getOwnPropertySlot):
(JSC::JSFunction::canUseAllocationProfileNonInline):
(JSC::JSFunction::ensureRareDataAndAllocationProfile):
- runtime/JSFunctionInlines.h:
(JSC::JSFunction::canUseAllocationProfile):
