Reviewers: Dan Ehrenberg, Michael Starzinger, Yang,
Description:
[es6] Parameter scopes for sloppy eval
This CL is a nightmare! For the utterly irrelevant edge case of a sloppy
function with non-simple parameters and a call to direct eval, like here,
let x = 1;
function f(g = () => x) {
var y
eval("var x = 2")
return g() + x // f() = 3
}
we have to do all of the following, on top of the declaration block
("varblock")
contexts we already introduce around the body:
- Introduce the ability for varblock contexts to have both a ScopeInfo and
an
extension object (e.g., the body varblock in the example will contain both a
static var y and a dynamic var x). No other scope needs that. Since there
are no
context slots left, a special new struct is introduced that pairs up scope
info
and extension object.
- When declaring lookup slots in the runtime, this new struct is allocated
in
the case where an extension object has to be added to a block scope (at
which
point the block's extension slot still contains a plain ScopeInfo).
- While at it, introduce some abstraction to access context extension slots
in a
more controlled manner, in order to keep special-casing to a minimum.
- Make sure that even empty varblock contexts do not get optimised away when
they contain a sloppy eval, so that they can host the potential extension
object.
- Extend dynamic search for declaration contexts (used by sloppy direct
eval) to
recognize varblock contexts.
- In the parser, if a function has a sloppy direct eval, introduce an
additional
varblock scope around each non-simple (desugared) parameter, as required by
the
spec to contain possible dynamic var bindings.
- In the pattern rewriter, add the ability to hoist the named variables the
pattern declares to an outer scope. That is required because the actual
destructuring has to be evaluated inside the protecting varblock scope, but
the
bindings that the desugaring introduces are in the outer scope.
- ScopeInfos need to save the information whether a block is a varblock, to
make
sloppy eval calls work correctly that deserialise them as part of the scope
chain.
- Add the ability to materialize block scopes with extension objects in the
debugger. Likewise, enable setting extension variables in block scopes via
the
debugger interface.
- While at it, refactor and unify some respective code in the debugger.
Sorry, this CL is large. I could try to split it up, but everything is
rather
entangled.
@mstarzinger: Please review the changes to contexts.
@yangguo: Please have a look at the debugger stuff.
[email protected], [email protected], [email protected]
BUG=v8:811,v8:2160
LOG=N
Please review this at https://codereview.chromium.org/1292753007/
Base URL: https://chromium.googlesource.com/v8/v8.git@master
Affected files (+448, -116 lines):
M include/v8.h
M src/bootstrapper.cc
M src/compiler/ast-graph-builder.cc
M src/contexts.h
M src/contexts.cc
M src/debug/debug-scopes.h
M src/debug/debug-scopes.cc
M src/factory.h
M src/factory.cc
M src/full-codegen/full-codegen.cc
M src/hydrogen.cc
M src/objects.h
M src/objects.cc
M src/objects-debug.cc
M src/objects-inl.h
M src/objects-printer.cc
M src/parser.h
M src/parser.cc
M src/pattern-rewriter.cc
M src/runtime/runtime-object.cc
M src/runtime/runtime-scopes.cc
M src/scopeinfo.cc
M src/scopes.h
M src/scopes.cc
M test/mjsunit/harmony/default-parameters.js
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