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pjs/js/narcissus/jsssa.js

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JavaScript
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Bug 573569: One-pass SSA builder for Narcissus. (r=gal)
2010-09-24 00:19:05 +04:00
/* vim: set sw=4 ts=4 et tw=78: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is the Narcissus JavaScript engine.
*
* The Initial Developer of the Original Code is
* Brendan Eich <brendan@mozilla.org>.
* Portions created by the Initial Developer are Copyright (C) 2004
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Narcissus - JS implemented in JS.
*
* SSA builder and optimizations.
*/
(function() {
const parser = Narcissus.parser;
const definitions = Narcissus.definitions;
const tokens = definitions.tokens;
const Node = parser.Node;
const hasOwnProperty = Object.prototype.hasOwnProperty;
// Set constants in the local scope.
eval(definitions.consts);
const dash = new Node({ lineno: -1 }, INTERVENED);
/*
* Helper for using native JS objects as hashes.
*/
function GenHash(seed) {
this.seed = seed || 1;
}
GenHash.prototype = {
gen: function(name) {
// | is an illegal JS identifier character, so we don't risk the
// generated hash being an actual identifier.
return name + "|" + this.seed++;
}
}
const genhash = new GenHash();
/*
* FLow analysis helper data structure.
*/
function Upvars(defs, uses, useTuples, intervenes, escapes, flowIUVs,
needsEscape, isEval) {
this.__hash__ = genhash.gen("$upvars");
this.defs = defs || new Map;
this.uses = uses || new Map;
this.useTuples = useTuples || new Map;
this.intervenes = intervenes || new Map;
this.escapes = escapes || new Map;
// For flowing upvars.
this.flowIUVs = flowIUVs || new Map;
this.needsEscape = needsEscape;
this.isEval = isEval;
}
Upvars.prototype = {
clone: function() {
return new Upvars(this.defs.clone(),
this.uses.clone(),
this.useTuples.clone(),
this.intervenes.clone(),
this.escapes.clone(),
this.flowIUVs.clone(),
this.needsEscape,
this.isEval);
},
unionWith: function(r) {
this.defs.unionWith(r.defs);
this.uses.unionWith(r.uses);
this.useTuples.unionWith(r.useTuples);
this.intervenes.unionWith(r.intervenes);
this.escapes.unionWith(r.escapes);
this.flowIUVs.unionWith(r.flowIUVs);
this.needsEscape = this.needsEscape || r.needsEscape;
this.isEval = this.isEval || r.isEval;
},
// Calculates the set of intervened vars transitively. A null means
// "everything", i.e. eval.
transClosureI: function(visited) {
var r = this.defs.clone();
var members = this.intervenes.members;
var uv;
// We can have mutually recursive functions which cause cycles:
//
// function f() {
// var x, h;
// function g() { h(); }
// h = function() { g(); };
// g();
// }
//
// So we need to keep track of all the upvars we've already
// visited.
visited.insert1(this);
var uvs;
for (var i in members) {
uv = members[i];
// If the upvar was intervened, we must give up and consider
// all upvars to have been invalidated.
if (uv.def === dash) {
return null;
}
uvs = uv.upvars;
if (uvs && !visited.lookup(uvs)) {
var tci;
if (tci = uvs.transClosureI(visited/*, d+1*/)) {
r.unionWith(tci);
} else {
return null;
}
}
}
return r;
},
// Calculates the set of escaped vars transitively. A null means
// "everything", i.e. eval.
transClosureE: function(visited) {
var r = this.escapes.clone();
var members = r.members;
var uv;
visited.insert1(this);
// The transitive closure of escapes is all the union of the
// transitive closures of the _interventions_ of those escapes
// _and_ the transitive closures of the escapes of those escapes.
var uvs;
for (var i in members) {
uv = members[i];
// If the upvar was intervened, we must give up and consider
// all upvars to have escaped.
if (uv.def === dash) {
return null;
}
uvs = uv.upvars;
if (uvs && !visited.lookup(uvs)) {
var tci, tce;
if (tci = uvs.transClosureI(visited)) {
r.unionWith(tci);
} else {
return null;
}
if (tce = uvs.transClosureE(visited)) {
r.unionWith(tce);
} else {
return null;
}
}
}
return r;
}
}
// Entry for a variable, includes flow information.
//
// type ::= VAR | CONST | LET
function Current(name, type, def, upvars) {
def = def || mkRawIdentifier({ lineno: -1 }, "undefined", null, true);
this.__hash__ = genhash.gen(name);
this.name = name;
this.type = type;
this._def = def;
this.upvars = upvars;
this.gotIntervened = false;
}
Current.prototype = {
clone: function() {
var c = new Current(this.name,
this.type,
this.def,
this.upvars.clone());
c.gotIntervened = this.gotIntervened;
return c;
},
get def() {
return this.gotIntervened ? dash : this._def;
},
set def(d) {
this._def = d;
}
};
// Map that can be used as a set.
function Map() {
this.members = {};
this.length = 0;
}
function h(k) {
return k.__hash__ ? k.__hash__ : k;
}
Map.prototype = {
clone: function() {
var c = new Map;
c.unionWith(this);
return c;
},
lookup: function(k) {
return this.members[h(k)];
},
insert: function(k, v) {
k = h(k);
if (!hasOwnProperty.call(this.members, k)) {
this.members[k] = v;
this.length++;
}
},
insert1: function(k) {
this.insert(k, k);
},
remove: function(k) {
k = h(k);
if (hasOwnProperty.call(this.members, k)) {
delete this.members[k];
this.length--;
}
},
unionWith: function(r) {
var members = r.members;
var keys = Object.getOwnPropertyNames(members);
for (var i in keys) {
var k = keys[i];
this.insert(k, members[k]);
}
},
clear: function() {
this.members = {};
this.length = 0;
}
}
// Bindings attached to each scope level.
function Bindings(p, isFunction, isWith) {
this.parent = p;
this.isFunction = isFunction;
this.isWith = isWith;
this.currents = {};
this.params = {};
this.possibleHoists = {};
this.dead = false;
this.inRHS = 0;
if (isWith) {
this.withIntervenes = new Map;
}
if (isFunction) {
// frees is a superset of upvars
this.frees = {};
this.upvars = new Upvars;
this.backpatchUpvars = new Map;
// The set of variables that have escaped permanently. Monotonic
// per function.
this.escaped = new Upvars;
// Backup values for upvars that were assigned to.
this.upvarOlds = {};
// Nodes for recursive function calls.
this.backpatchMus = [];
}
// Cache nearest function.
var r = this;
while (!r.isFunction) {
r = r.parent;
}
this.nearestFunction = r;
}
Bindings.prototype = {
escapedVars: function() {
if (this.evalEscaped) {
return null;
}
return this.escaped.transClosureI(new Map);
},
declareParam: function(x) {
this.params[x] = true;
},
declareVar: function(x, tt, isExternal) {
if (this.dead) {
return;
}
var fb = this.nearestFunction;
var c = this.current(x);
if (c) {
if (c.type == LET) {
throw new TypeError("Cannot redeclare a let to a var");
}
if (c.type == CONST && tt == CONST) {
throw new TypeError("redeclaration of const " + x);
}
} else if (!hasOwnProperty.call(fb.params, x)) {
// Don't redeclare vars; just don't error. This is important
// during hoisting to have hoisted functions intervene properly.
//
// We can also shadow upvar clones.
//
// If we don't know of a variable, we need to put it all the
// way at the top (the enclosing function's context) with a value
// of "undefined".
var fb = this.nearestFunction;
fb.currents[x] = c = new Current(x, tt);
c.internal = !isExternal;
return c.def;
}
},
declareLet: function(x, hoisted, isExternal) {
if (this.dead) {
return;
}
var c = this.currents[x];
if (c) {
if (!c.hoisted)
throw new TypeError("Cannot redeclare a let");
// Okay to redeclare a hoisted let once.
c.hoisted = false;
return;
}
c = this.currents[x] = new Current(x, LET);
c.hoisted = hoisted;
c.internal = !isExternal;
return c.def;
},
update: function(x, def, upvars) {
if (this.dead) {
return;
}
var c = this.current(x);
if (!c) {
// Backup upvar assignments.
c = this.upvar(x);
var p = this.nearestFunction;
if (!hasOwnProperty.call(p.upvarOlds, x)) {
p.upvarOlds[x] = { def: c.def,
upvars: c.upvars.clone(),
gotIntervened: c.gotIntervened };
}
}
if (c.type == CONST) {
return;
}
// New assignments clear intervention.
c.gotIntervened = false;
c.def = def;
c.upvars = upvars;
},
hasCurrent: function(x) {
var p = this.isFunction ? null : this.parent;
return hasOwnProperty.call(this.currents, x) ||
(p && p.hasCurrent(x));
},
hasParam: function(x) {
var p = this.nearestFunction;
return hasOwnProperty.call(p.params, x);
},
hasUpParam: function(x) {
var p = this.nearestFunction;
p = p.parent;
if (p) {
var r = p.hasParam(x);
return r || p.hasUpParam(x);
} else {
return null;
}
},
upvar: function(x) {
// Find the closest bindings above the current function toplevel.
//
// We don't consider upvars to be current, or SSA-able,
// immediately at parse time inside an inner function. We'd have
// to prove a lot to get that property, i.e. the set of all inner
// functions whose upvar-set include the current upvar in question
// don't escape.
var p = this.nearestFunction;
p = p.parent;
if (p) {
var c = p.current(x);
// Don't return clones, only originals.
return c || p.upvar(x);
} else {
return null;
}
},
addUpvar: function(tt, uv) {
this.nearestFunction.upvars[tt].insert1(uv);
},
pushUpvarUse: function(uv, n) {
var useTuples = this.nearestFunction.upvars.useTuples;
if (!useTuples.lookup(uv)) {
useTuples.insert(uv, { cdef: undefined, nodes: [] });
}
useTuples.lookup(uv).nodes.push(n);
},
pushMuUse: function(n) {
this.nearestFunction.backpatchMus.push(n);
},
removeMuUse: function(n) {
var nodes = this.nearestFunction.backpatchMus;
for (var i in nodes) {
if (n === nodes[i]) {
nodes[i] = nodes[nodes.length-1];
nodes.pop();
return;
}
}
},
removeUpvarUse: function(uv, n) {
// XXX Can we do better than linear?
var useTuples = this.nearestFunction.upvars.useTuples;
var nodes = useTuples.lookup(uv).nodes;
for (var i in nodes) {
if (n === nodes[i]) {
// Since ordering doesn't matter here, swap it with the
// last element and pop.
nodes[i] = nodes[nodes.length-1];
nodes.pop();
return;
}
}
},
addBackpatchUpvars: function(upvars) {
this.nearestFunction.backpatchUpvars.insert1(upvars);
},
closureIsEval: function() {
// This is to signal that if the current function becomes a
// closure, when it is called, it invalidates everything in the
// current scope chain like an eval.
this.nearestFunction.isEval = true;
},
closureNeedsEscape: function() {
// This is to signal that if the current function becomes a
// closure, when it is called, it also needs to invalidate the set
// of all escaped variables because some unknown identifier was
// called inside the function.
this.nearestFunction.needsEscape = true;
},
addToFrees: function(x) {
this.nearestFunction.frees[x] = true;
},
declareFunction: function(x, f, frees, upvars) {
var fb = this.nearestFunction;
if (!fb.currents[x]) {
fb.currents[x] = new Current(f.name, VAR, f, upvars);
}
},
mu: function(x) {
// Is x a recursive call to a function in the current function
// stack?
var r = this;
while (r) {
var fb = r.nearestFunction;
if (fb.name == x) {
return fb;
} else {
r = r.parent;
}
}
return null;
},
current: function(x) {
var r = undefined;
if (hasOwnProperty.call(this.currents, x)) {
r = this.currents[x];
} else if (!this.isFunction && this.parent) {
// Only look up in parent if we don't cross function
// boundaries.
r = this.parent.current(x);
}
return r;
},
unionUpTo: function(upTo) {
var vars = new Map;
var p = this;
while (p) {
var currents = p.currents;
var cs = Object.getOwnPropertyNames(currents);
var c;
for (var i in cs) {
c = currents[cs[i]];
// Consts don't need to be intervened.
if (c.type != CONST) {
vars.insert1(c);
}
}
if (p === upTo)
return vars;
else
p = p.parent;
}
// If upto were null, i.e. "everything".
return vars;
},
intervene: function(vars) {
// If we're to intervene everything, we do it recursively, even
// across function boundaries.
if (!vars) {
vars = this.unionUpTo(null);
}
var uv, intervened = [];
var members = vars.members;
for (var i in members) {
uv = members[i];
// If we intervened an upvar, be sure to save the old value to
// restore when the function finishes parsing.
if (!this.hasCurrent(uv.name)) {
var p = this.nearestFunction;
var x = uv.name;
if (uv.upvars) {
// At this point any flow upvars have escaped.
var fiuvs = uv.upvars.flowIUVs.members;
for (var j in fiuvs) {
this.addUpvar("escapes", fiuvs[j]);
}
}
if (!hasOwnProperty.call(p.upvarOlds, x)) {
p.upvarOlds[x] = { def: uv.def,
upvars: uv.upvars,
gotIntervened: uv.gotIntervened };
}
}
// Save the original definition along with the pointer of the
// upvar it belongs to.
intervened.push({ ptr: uv,
def: uv.def,
upvars: uv.upvars, });
uv.def = undefined;
uv.upvars = undefined;
// Intervening 2+ times in a row can cause old to be
// improperly defined in phis.
uv.gotIntervened = true;
}
return intervened;
},
rememberPossibleHoist: function(x) {
//
// Taxonomy of hoists:
//
// If we don't know anything about it, it's a var hoist.
// If we are in a non-toplevel block, it's also a let hoist.
// Else
// If we are in a non-toplevel block, it's a let hoist.
//
// Hoists propagate backwards when blocks finish, i.e.
//
// { 1
// { 2
// x;
// }
// }
//
// When we finish parsing block 2, x needs to be propagated as a let
// hoist to block 1 as well.
//
this.possibleHoists[x] = true;
},
isPossibleHoist: function(x) {
return hasOwnProperty.call(this.possibleHoists, x) &&
!hasOwnProperty.call(this.params, x);
},
propagatePossibleHoists: function() {
var p = this.inFunction ? this.parent.nearestFunction
: this.parent;
if (!p)
return;
var hoists = Object.getOwnPropertyNames(this.possibleHoists);
var x;
for (var i in hoists) {
x = hoists[i];
if (!hasOwnProperty.call(p.currents, x)) {
p.rememberPossibleHoist(x);
}
}
},
};
function SSAJoin(p, b, before) {
this.parent = p;
this.binds = b;
this.hasJoinBefore = before;
this.branch = 0;
this.phis = {};
this.uses = {};
// this.binds is the _parent_ bindings for this join. Each branch will
// have a different set of bindings!
}
SSAJoin.mkJoin = function(ps, parent, branches, propagate) {
// No point in doing phi if no branches branch.
if (branches < 1) {
return null;
}
var e, e2, rhs;
function phiAssignment(x, operands) {
var e, lhs, rhs;
var ft = { lineno: -1 };
lhs = new Node(ft, IDENTIFIER);
lhs.value = x;
// Set local to help decomp do value numbering.
lhs.local = operands.type;
rhs = new Node(ft, PHI);
rhs.__hash__ = genhash.gen("$phi");
// Optimize away phi nodes where every branch has been intervened, we
// don't even need to propagate.
var allDashes = true;
var os, o = null;
for (var i = branches - 1; i >= 0; i--) {
o = operands[i] ? operands[i].def : operands.old.def;
if (o.type != INTERVENED)
allDashes = false;
rhs.push(o);
}
if (allDashes) {
return null;
}
rhs.reverse();
e = new Node(ft, ASSIGN);
e.push(lhs);
e.push(rhs);
return e;
}
e = new Node({ lineno: -1 }, COMMA);
for (var x in ps) {
if (!(e2 = phiAssignment(x, ps[x]))) {
continue;
}
rhs = e2[1];
// Optimize away phis that are only one branch, but we still need
// to propagate them!
if (branches == 1) {
rhs = rhs[0];
} else {
// Push a phi use for each operand so the phis can be filled
// in during exec.
for (var i = 0, j = rhs.length; i < j; i++) {
if (rhs[i].type == INTERVENED) {
rhs.intervened = true;
}
rhs[i].pushPhiUse(rhs);
}
e.push(e2);
}
propagate(x, rhs);
}
return e.length > 0 ? e : null;
}
SSAJoin.prototype = {
nearestTryJoin: function() {
if (this.isTry) {
return this;
} else if (this.parent) {
return this.parent.nearestTryJoin();
} else {
return null;
}
},
unionPhisUpTo: function(joinUpTo) {
var ps = {}, join = this, binds = join.binds;
var bindsUpTo = joinUpTo.binds;
while (join) {
for (var x in join.phis) {
//
// Only insert phis for which the pointer for x in the up-to
// environment is the same as the pointer for it in the
// current environment. This is to prevent cases like the
// following:
//
// var x = 0;
// while (e1) {
// x = 1;
// {
// let x = 0;
// if (e2) {
// x = 2;
// break;
// } else {
// x = 3;
// break;
// }
// }
// }
//
// Even though in the join for the if x has a phi, it
// shouldn't be counted for the break since it's a phi for the
// let x. Only the x = 1 phi at the while level should be
// counted.
//
if (bindsUpTo.current(x) === binds.current(x)) {
ps[x] = join.phis[x];
}
}
if (join === joinUpTo) {
break;
}
join = join.parent;
binds = join.binds;
}
return ps;
},
shiftPhis: function() {
var ps = this.phis;
for (var x in ps) {
ps[x].shift();
}
this.branch--;
},
killBranch: function(currentBinds, killJoin, isThrow) {
// killJoin is null for return.
currentBinds.dead = true;
// If we are inside of a try block and we are not a throw, then we
// create a new branch in the finally join node.
var tryJoin = this.nearestTryJoin();
if (tryJoin && tryJoin&& !isThrow) {
var oldKillJoin = killJoin;
killJoin = tryJoin.isFinally ? tryJoin : tryJoin.parent;
}
if (!killJoin) {
this.dead = true;
return;
}
var killBinds = killJoin.binds;
// Need to manually calculate the union of all phi nodes between here
// and killJoin.
var ps = this.unionPhisUpTo(killJoin);
// Propagate the phis up to the break environment.
var c, old;
for (var x in ps) {
//
// For breaks we _only_ insert a phi branch; we do _not_ remember
// it as the current value.
//
// The variable also could've gotten intervened on the way:
// var x = 0;
// try {
// if (cond) {
// eval(foo);
// }
// } catch (e) {
// }
//
c = killBinds.current(x) || killBinds.upvar(x);
old = ps[x].old;
killJoin.insertPhi(c.type, x, c.def, c.upvars,
old.def, old.upvars);
}
killJoin.finishBranch();
killJoin.upkill = oldKillJoin;
// Don't set this.dead until the end else insertPhi and finishBranch
// won't work properly.
this.dead = true;
},
finishBranch: function() {
if (!this.dead) {
this.branch++;
}
},
commit: function() {
// Output assignments and push phi nodes to parent?
var r, e;
var ps = this.phis, us = this.uses
var parent = this.parent;
var binds = this.binds;
var ft = { lineno: -1 };
var intervened = false;
function go(x, rhs) {
var u = us[x], uu;
var old = ps[x].old;
var prop = ps[x].prop;
if (u) {
for (var i = 0, j = u.length; i < j; i++) {
//
// If the use pointed to the old value (before the loop)
// or it didn't point to anything before and is on the
// rhs, update it to use the phi node.
//
// NB: An identifier on the lhs would have had its forward
// pointer set to null instead of undefined.
//
uu = u[i];
// Phi nodes might have stale branches.
if (uu.type == PHI) {
for (var k = 0, l = uu.length; k < l; k++) {
if (uu[k] === old.def) {
uu[k] = rhs;
rhs.pushPhiUse(uu);
}
}
} else if (uu.forward === old.def) {
uu.forward = rhs;
}
}
}
var upvars = unionPhiUpvars(ps[x]);
// If we explicitly set a value to propagate, propagate that.
if (prop) {
rhs = prop.def;
upvars = prop.upvars;
}
// Propagate to parent if it's bound there.
var type = ps[x].type;
if (parent && (type == VAR || !binds.currents[x])) {
parent.insertPhi(ps[x].type, x, rhs, upvars,
old.def, old.upvars);
//
// The phi node might be using stale values that need to be
// replaced if it's contained in a loop.
//
// function f() {
// var x = 0;
// while (x < 10) {
// if (false) {
// x = x + 1;
// }
// // The phi for the if will contain a
// // stale forward pointer to x.
// x = 1;
// }
// }
//
parent.rememberUse(x, rhs);
}
binds.update(x, rhs, upvars);
}
e = SSAJoin.mkJoin(ps, parent, this.branch, go);
if (!e) {
// If every branch was killed, we need to restore, or we're going
// to be left with the last branch's values as the currents.
if (this.branch < 1) {
this.restore(binds);
}
return null;
}
r = new Node(ft, SEMICOLON);
r.expression = e;
return r;
},
// Record a use if we need to.
rememberUse: function(x, v) {
if (this.hasJoinBefore) {
var uses = this.uses;
if (!hasOwnProperty.call(uses, x)) {
uses[x] = [];
}
uses[x].push(v);
} else {
// Recur to the nearest enclosing parent with hasJoinBefore.
this.parent && this.parent.rememberUse(x, v);
}
},
insertDashes: function(binds, intervened) {
var iv, uv, c, name;
for (var x in intervened) {
iv = intervened[x];
uv = iv.ptr;
name = uv.name;
c = binds.current(name);
// If we intervened the current copy, we need to insert a phi.
// This will also allow us to restore.
if (uv === c && !c.internal &&
(uv.type == VAR || !binds.currents[name])) {
this.insertPhi(c.type, name, dash, new Upvars,
iv.def, iv.upvars);
}
}
},
intervene: function(binds, vars) {
var intervened = this.intervened = binds.intervene(vars);
this.insertDashes(binds, intervened);
return intervened;
},
// Restore the backups.
restore: function(binds) {
binds.dead = false;
this.dead = false;
var intervened = this.intervened;
if (intervened) {
var iv;
for (var x in intervened) {
iv = intervened[x];
iv.ptr.def = iv.def;
iv.ptr.upvars = iv.upvars;
}
}
var ps = this.phis;
var old;
for (var x in ps) {
old = ps[x].old;
binds.update(x, old.def, old.upvars);
}
},
// old need only be passed in if the insertPhi is possibly a first phi for
// a join.
insertPhi: function(type, x, def, upvars,
oldDef, oldUpvars,
propDef, propUpvars) {
var n, ps = this.phis;
var psx;
if (!ps || this.dead) {
return;
}
if (!ps[x]) {
psx = ps[x] = [];
psx.use = [];
} else {
psx = ps[x];
}
psx[this.branch] = { def: def, upvars: upvars };
// Assignments in loop conditions.
if (propDef) {
psx.prop = { def: propDef, upvars: propUpvars };
}
if (!psx.old) {
psx.old = { def: oldDef, upvars: oldUpvars };
}
if (!psx.type) {
psx.type = type;
}
}
};
/*
* SSA builder.
*/
function extendBuilder(child, super) {
var childProto = child.prototype,
superProto = super.prototype;
for (var ns in super.prototype) {
var childNS = childProto[ns];
var superNS = superProto[ns];
var childNSType = typeof childNS;
if (childNSType === "undefined") {
childProto[ns] = superNS;
} else if (childNSType === "object") {
for (var m in superNS) {
let childMethod = childNS[m];
let superMethod = superNS[m];
if (typeof childMethod === "undefined") {
childNS[m] = superMethod;
} else {
childNS[m] = function() {
if (this.binds)
return childMethod.apply(this, arguments);
else
return superMethod.apply(this, arguments);
};
}
}
}
}
}
function SSABuilder() {
parser.bindSubBuilders(this, SSABuilder.prototype);
this.binds = null;
this.join = null;
this.hoists = {};
this.inJoinPostDom = [false];
this.finallyKills = [];
this.joinStack = [];
this.destructuringTmpFresh = 0;
this.postfixTmpFresh = 0;
}
//
// These methods are guarded to only execute if we're inside a function.
//
SSABuilder.prototype = {
IF: {
setCondition: function(n, e) {
n.condition = e;
// We parsed the condition in the parent context because the
// join for if comes after.
this.join = new SSAJoin(this.join, this.binds, false);
},
setThenPart: function(n, s) {
var join = this.join;
n.thenPart = s;
join.finishBranch();
join.restore(this.binds);
},
finish: function(n) {
var join = this.join;
this.join = join.parent;
join.finishBranch();
n.ssaJoin = join.commit();
}
},
SWITCH: {
setDiscriminant: function(n, e) {
var join = this.join = new SSAJoin(this.join, this.binds, false);
n.discriminant = e;
n.breakJoin = join;
n.continueJoin = join;
this.fallthrough = false;
},
addCase: function(n, n2) {
var join = this.join;
if (join.dead) {
//
// The previous branch is dead (i.e. we had a break on the
// current case so it was killed and added a new branch to
// the switch)
//
join.restore(this.binds);
this.fallthrough = false;
} else {
// Is fallthrough, mark next branch as needing a join.
this.fallthrough = true;
}
n.cases.push(n2);
},
finish: function(n) {
var join = this.join;
this.join = join.parent;
if (this.fallthrough)
join.finishBranch();
n.ssaJoin = join.commit();
}
},
CASE: {
initializeStatements: function(n, t) {
n.statements = new Node(t, BLOCK);
// Do we need to generate phi nodes due to fallthrough?
if (this.fallthrough) {
n.ssaJoin = fallthroughJoin(n, this.join, this.binds);
}
}
},
DEFAULT: {
initializeStatements: function(n, t) {
n.statements = new Node(t, BLOCK);
// Do we need to generate phi nodes due to fallthrough?
if (this.fallthrough) {
n.ssaJoin = fallthroughJoin(n, this.join, this.binds);
}
}
},
FOR: {
build: function(t) {
var n = new Node(t, FOR);
//
// scB serves as the parent context so we can remember the old
// values of variables if we're parsing a `for in' statement.
// for in's are weird because we don't parse things in
// dominator order.
//
// In `for (e1 in e2)', e1 doesn't dominate e2. i.e. in
//
// for (var i in is.concat([i]))
//
// the i on the right hand of the `in' gets evaluated once to
// its value before the for statement.
//
var breakJoin = new SSAJoin(this.join, this.binds, false);
var continueJoin = new SSAJoin(breakJoin, this.binds, true);
n.isLoop = true;
n.breakJoin = breakJoin;
n.continueJoin = continueJoin;
continueJoin.finishBranch();
breakJoin.finishBranch();
this.join = breakJoin;
return n;
},
setObject: function(n, e) {
var t = n.tokenizer;
var itrhs = mkCall("iterator", e);
// This may be changed later.
n.setup = mkDecl(this, "LET", t, "$it", itrhs, false);
n.condition = mkCall("hasNext", mkIdentifier(this, t, "$it"));
},
setSetup: function(n, e) {
n.setup = e || null;
this.join = n.continueJoin;
this.inJoinPostDom.push(true);
},
setCondition: function(n, e) {
n.condition = e;
this.inJoinPostDom.pop();
},
setIterator: function(n, e, e2, s) {
var setup = n.setup;
//
// For `for in' loops, we also parse the right of the `in'
// expression in the parent (break) bindings.
//
// We do the following online transform of for in loops:
//
// for (e1 in e2) {
// body;
// }
//
// If e1 is "var x":
//
// for (let it = e2; hasNext(it); ) {
// var x = next(it);
// body;
// }
//
// If e1 is "let x":
//
// for (let it = e2, x; hasNext(it); ) {
// x = next(it);
// body;
// }
//
// Else,
//
// for (var it = e2; hasNext(it); ) {
// e1 = next(it);
// body;
// }
//
var dexp = e.exp;
var decl = e.decl;
var t = dexp ? dexp.tokenizer : e.tokenizer;
var rhs = mkCall("next", mkIdentifier(this, t, "$it"));
if (e2) {
if (dexp) {
if (e2.type == LET) {
// We need to manually increment localUses and
// uses due to this weird desugaring to assignment
// but leaving the let decl in for head that we
// do.
var bComma = this.COMMA;
e2.push(n.setup[0]);
n.setup = e2;
var comma = bComma.build(t);
desugarDestructuringAssign(this, comma, dexp, rhs);
bComma.finish(comma);
n.update = comma;
} else /* if (e2.type == VAR) */ {
var bVar = this.VAR;
var bDecl = this.DECL;
bDecl.setInitializer(decl, rhs);
bDecl.finish(decl);
bVar.finish(e2);
n.update = e2;
}
} else if (e2.type == VAR) {
var bDecl = this.DECL;
bDecl.setInitializer(e, rhs);
n.update = e2;
} else if (e2.type == LET) {
n.setup.unshift(e);
n.update = mkAssign(this, t, e, rhs);
}
} else {
n.update = mkAssign(this, t, e, rhs);
}
this.join = n.continueJoin;
},
setBody: function(n, s) {
n.body = s;
this.join.finishBranch();
},
finish: function(n) {
var continueJoin = this.join, breakJoin = continueJoin.parent;
this.join = breakJoin.parent;
// Add update to the top if we were a for-in
if (n.type == FOR_IN) {
n.body.unshift(n.update);
n.update = null;
n.type = FOR;
}
n.ssaJoin = continueJoin.commit();
if (n.ssaJoin) {
//
// Make a branch for the committed phis from scC and shift
// the first branch out to avoid duplicate branches.
//
breakJoin.shiftPhis();
breakJoin.finishBranch();
}
n.ssaBreakJoin = breakJoin.commit();
}
},
WHILE: {
build: function(t) {
var n = new Node(t, WHILE);
var breakJoin = new SSAJoin(this.join, this.binds, false);
var continueJoin = new SSAJoin(breakJoin, this.binds, true);
n.isLoop = true;
n.breakJoin = breakJoin;
n.continueJoin = continueJoin;
// Start off in the second branch since the branch entering
// into the loop is the first branch.
continueJoin.finishBranch();
breakJoin.finishBranch();
this.join = continueJoin;
// Any assignments encounted in the while condition causes the
// second branch to be overriding for continueJoin.
this.inJoinPostDom.push(true);
return n;
},
setCondition: function(n, e) {
n.condition = e;
this.inJoinPostDom.pop();
},
setBody: function(n, s) {
n.body = s;
this.join.finishBranch();
},
finish: function(n) {
var continueJoin = this.join, breakJoin = continueJoin.parent;
this.join = breakJoin.parent;
n.ssaJoin = continueJoin.commit();
if (n.ssaJoin) {
// Make a branch for the committed phis from scC and shift
// the first branch out to avoid duplicate branches.
breakJoin.shiftPhis();
breakJoin.finishBranch();
}
n.ssaBreakJoin = breakJoin.commit();
}
},
DO: {
build: function(t) {
var n = new Node(t, DO);
var breakJoin = new SSAJoin(this.join, this.binds, true);
var continueJoin = new SSAJoin(breakJoin, this.binds, true);
n.isLoop = true;
n.breakJoin = breakJoin;
n.continueJoin = continueJoin;
// Start off in the second branch since the branch entering
// into the loop is the first branch.
continueJoin.finishBranch();
breakJoin.finishBranch();
this.join = continueJoin;
// The body and the condition both post-dominate the join.
this.inJoinPostDom.push(true);
return n;
},
setBody: function(n, s) {
n.body = s;
this.join.finishBranch();
},
setCondition: function(n, e) {
n.condition = e;
this.inJoinPostDom.pop();
},
finish: function(n) {
var continueJoin = this.join, breakJoin = continueJoin.parent;
this.join = breakJoin.parent;
n.ssaJoin = continueJoin.commit();
if (n.ssaJoin) {
//
// Make a branch for the committed phis from scC and shift
// the first branch out to avoid duplicate branches.
//
breakJoin.shiftPhis();
breakJoin.finishBranch();
}
//
// Commit the break phi nodes with the line of the loop
// condition.
//
// Control leaves via the condition and not the join node, so
// we should make the second operand of all phis the current
// values.
//
n.ssaBreakJoin = breakJoin.commit();
}
},
BREAK: {
finish: function(n) {
//
// Have to kill the current branch.
//
// A new branch is added to the join of the break context,
// which is emitted _after_ the break environment.
//
this.join.killBranch(this.binds, n.target.breakJoin);
}
},
CONTINUE: {
finish: function(n) {
//
// Have to kill the current branch.
//
// A new branch is added to the join of the continue context,
// which is usually the normal context of the node.
//
this.join.killBranch(this.binds, n.target.continueJoin);
}
},
TRY: {
build: function(t) {
var n = new Node(t, TRY);
var finallyJoin = new SSAJoin(this.join, this.binds, false);
var tryJoin = new SSAJoin(finallyJoin, this.binds, false);
tryJoin.isTry = true;
n.catchClauses = [];
this.join = tryJoin;
return n;
},
setTryBlock: function(n, s) {
var tryJoin = this.join, finallyJoin = tryJoin.parent;
var binds = this.binds;
this.join = finallyJoin;
// Set isTry here since we can throw from inside the try block
// from function calls as well.
finallyJoin.isTry = finallyJoin.isFinally = true;
n.tryBlock = s;
// Add the current value at the end of the try block to the
// first branch of the finally block's phi nodes if the branch
// is still live.
if (!tryJoin.dead) {
var c, old;
for (var x in tryJoin.phis) {
c = binds.current(x) || binds.upvar(x);
old = tryJoin.phis[x].old;
finallyJoin.insertPhi(c.type, x, c.def, c.upvars,
old.def, old.upvars);
}
finallyJoin.finishBranch();
}
this.tryPhis = tryJoin.commit();
// Manually set old values because we want branch restoration
// across branches to actually restore the phi nodes we just
// committed.
for (var x in tryJoin.phis) {
var c = binds.current(x) || binds.upvar(x);
finallyJoin.phis[x].old = { def: c.def, upvars: c.upvars };
}
},
finishCatches: function(n) {
var finallyJoin = this.join;
this.join = finallyJoin.parent;
// Speculate that we have a finally.
n.ssaFinallyJoin = finallyJoin.commit();
this.finallyKills.push(finallyJoin.upkill);
},
finish: function(n) {
// Crazy upkill magical logic.
var upkill = this.finallyKills.pop();
if (upkill && !this.join.dead) {
var killBinds = upkill.binds;
var ps = this.join.unionPhisUpTo(upkill);
for (var x in ps) {
c = killBinds.current(x), old = ps[x].old;
upkill.insertPhi(c.type, x, c.def, c.upvars,
old.def, old.upvars);
}
upkill.finishBranch();
this.join.dead = true;
}
if (!n.finallyBlock) {
// Move the join if we don't have a finally block since
// the finally block post-dominates.
n.ssaJoin = n.ssaFinallyJoin;
n.ssaFinallyJoin = undefined;
}
}
},
CATCH: {
build: function(t) {
// The var name of a catch is actually a let so we need to
// make a new bindings now.
this.binds = new Bindings(this.binds, false, false);
this.noBindingsOnNextBlock = true;
var n = new Node(t, CATCH);
n.guard = null;
return n;
},
setVarName: function(n, v) {
var binds = this.binds;
if (v.type == ARRAY_INIT || v.type == OBJECT_INIT) {
// Desugar destructuring catch var name
var t = n.tokenizer;
var bLet = this.LET;
var bDecl = this.DECL;
var name = this.genDestructuringSym();
var lets = bLet.build(t);
var decl = bDecl.build(t);
bDecl.setName(decl, v);
bLet.addDestructuringDecl(lets, decl);
var rhs = mkRawIdentifier(t, name, null, false);
decl.initializer = rhs;
bDecl.finish(decl);
bLet.finish(lets);
v = name;
n.destructuredLets = lets;
}
binds.declareLet(v);
// The initial value can't be undefined because it's bound
// depending on the throw. If it gets reassigned we can
// forward it though.
binds.update(v, null);
binds.current(v).catchLet = true;
n.varName = v;
},
finish: function(n) {
var p;
var join = this.join;
if (n.destructuredLets) {
n.block.unshift(n.destructuredLets);
}
n.ssaJoin = this.tryPhis;
join.restore(this.binds);
// Finish branch only if we possibly had a throw
if (join.maybeThrows) {
join.finishBranch();
}
}
},
THROW: {
finish: function(n) {
// Have to kill the current branch. Throw adds a new branch
// only when the current join chain has a try somewhere
// upstream.
var join = this.join, tryJoin = join && join.nearestTryJoin();
join && join.killBranch(this.binds, tryJoin, true);
if (tryJoin && tryJoin.parent) {
tryJoin.parent.maybeThrows = true;
}
}
},
RETURN: {
finish: function(n) {
// Have to kill the current branch. Unlike break and continue,
// return does not add any new branches.
var join = this.join;
join && join.killBranch(this.binds, null);
}
},
YIELD: {
build: function(t) {
this.binds.inRHS++;
return new Node(t, YIELD);
},
setValue: function(n, e) {
// Yields can cause escapes.
var join = this.join;
var binds = this.binds;
escapeVars(join, binds, e.upvars || new Upvars);
n.value = e;
--binds.inRHS;
},
finish: function(n) {
// Yields don't kill the current branch, but it does yield
// control. So we need to intervene against all escaped
// variables thus far.
var join = this.join;
var binds = this.binds;
var fb = binds.nearestFunction;
var escaped = fb.escapedVars();
binds.closureNeedsEscape();
if (join) {
join.intervene(binds, escaped);
} else {
binds.intervene(escaped);
}
}
},
FUNCTION: {
setName: function(n, v) {
n.name = v;
// Need to do recursive function names. This can be shadowed
// by params, vars, and inner functions.
//
// You can't assign to it, assigning to the function name
// assigns to either the thing that shadowed it or to a look
// up the scope chain.
this.binds.name = v;
},
addParam: function(n, v) {
n.params.push(v);
this.binds.declareParam(v);
},
hoistVars: function(id, toplevel) {
var binds = this.binds;
var vds = this.hoists[id];
if (toplevel) {
// Rip out the existing bindings and put in a new one.
binds = this.binds = new Bindings(binds.parent, true, false);
binds.noPop = true;
this.noBindingsOnNextBlock = true;
}
if (!vds)
return;
var name, init;
var vd;
for (var i = 0, j = vds.length; i < j; i++) {
vd = vds[i];
name = vd.name;
if (vd.type == FUNCTION) {
// All function hoists are guaranteed to come after
// var hoists (or at least the code in jsparse.js
// does).
//
// We need to check if any of the names in frees have
// been bound, and if so, add it to upvars.
var frees = vd.frees;
var upvars = vd.upvars = new Upvars;
var c;
for (var x in frees) {
c = binds.current(x) || binds.upvar(x);
if (c) {
upvars.defs.insert1(c);
delete frees[x];
}
}
binds.declareFunction(name, vd, frees, upvars);
} else {
binds.declareVar(name, vd.readOnly ? CONST : VAR);
}
}
this.hoists[id] = undefined;
},
finish: function(n, x) {
var binds = this.binds;
this.binds.propagatePossibleHoists();
var p = this.binds = binds.parent;
n.frees = binds.frees;
n.upvars = binds.upvars;
n.upvars.needsEscape = binds.needsEscape;
n.upvars.isEval = binds.isEval;
this.join = this.joinStack.pop();
if (p) {
var name = n.name;
if (name) {
var c = p.current(name);
var ff = n.functionForm;
var pfb = p.nearestFunction;
if (ff == parser.DECLARED_FORM) {
if (pfb.isPossibleHoist(name)) {
x.needsHoisting = true;
}
// DECLARED_FORM functions hoist _above_ vars, so
// if there's a existent var it won't shadow its
// binding.
if (!c) {
pfb.declareFunction(name, n, n.frees, n.upvars);
}
} else if (n.functionForm == parser.STATEMENT_FORM) {
// STATEMENT_FORM functions (i.e. in a block) are
// kind of like assignment because of "dynamic
// scope".
pfb.declareVar(name, VAR);
mkAssignSimple(this, n.tokenizer, name, n, true);
}
}
var uvs = Object.getOwnPropertyNames(binds.upvarOlds);
var old, c, x;
var upvarOlds = binds.upvarOlds;
var p2;
for (var i in uvs) {
x = uvs[i];
old = upvarOlds[x];
// Update in the bindings that has x.
//
// Because of the way intervention propagation works,
// however, the upvar might already be gone, so if we
// don't find it just ignore it.
p2 = p;
while (p2 && !p2.hasCurrent(x)) {
p2 = p2.parent;
}
if (p2) {
p2.update(x, old.def, old.upvars);
c = p2.current(x);
c.gotIntervened = old.gotIntervened;
}
}
}
// Do backpatching for recursive calls
var mus = binds.backpatchMus;
for (var i in mus) {
mus[i].setForward(n);
}
// Backpatch upvars for the ones that we proved to not escape
// and were only written once.
var backpatches = binds.backpatchUpvars.members;
for (var i in backpatches) {
var bp = backpatches[i];
var uvuses = bp.uses.members;
for (var j in uvuses) {
var use = uvuses[j];
var useTuple = bp.useTuples.lookup(use);
var cdef = useTuple.cdef;
if (cdef === undefined)
continue;
var unodes = useTuple.nodes;
for (var k in unodes) {
// All of these are upvar forwards.
unodes[k].setForward(cdef, true);
}
}
}
}
},
VAR: {
addDestructuringDecl: mkAddDestructuringDecl(VAR, false),
addDecl: function(n, n2, x) {
var name = n2.name;
var binds = this.binds;
n2.initializer = binds.declareVar(name, VAR, !n2.internal);
if (binds.nearestFunction.isPossibleHoist(name)) {
x.needsHoisting = true;
}
n.push(n2);
x && x.varDecls.push(mkHoistDecl(this, n2));
}
},
CONST: {
addDestructuringDecl: mkAddDestructuringDecl(CONST, true),
addDecl: function(n, n2, x) {
var name = n2.name;
var binds = this.binds;
n2.initializer = binds.declareVar(name, CONST, !n2.internal);
if (binds.nearestFunction.isPossibleHoist(name)) {
x.needsHoisting = true;
}
n.push(n2);
x && x.varDecls.push(mkHoistDecl(this, n2));
}
},
LET: {
addDestructuringDecl: mkAddDestructuringDecl(LET, false),
addDecl: function(n, n2, s) {
var name = n2.name;
var binds = this.binds;
n2.initializer = binds.declareLet(name, false, !n2.internal);
if (binds.isPossibleHoist(name)) {
s.needsHoisting = true;
}
n.push(n2);
s && s.varDecls.push(mkHoistDecl(this, n2));
}
},
DECL: {
build: function(t) {
this.binds.inRHS++;
return new Node(t, IDENTIFIER);
},
setInitializer: function(n, e) {
if (!n.destructuredDecls) {
var name = n.name;
var c = this.binds.current(name);
// Treat the init as a normal assignment.
//
// c could be null because we might be trying to redeclare
// a param as a variable.
if (c) {
if (c.type == CONST) {
// Also allow initializers to update consts since
// they can't be redeclared anyways.
c.type = VAR;
mkAssignSimple(this, e.tokenizer,
n.name, e, !n.internal);
c.type = CONST;
} else {
mkAssignSimple(this, e.tokenizer,
n.name, e, !n.internal);
}
}
n.initializer = e;
return;
}
desugarDestructuringInit(this, n, e);
},
finish: function(n) {
--this.binds.inRHS;
}
},
LET_BLOCK: {
build: function(t) {
this.binds = new Bindings(this.binds, false, false);
this.binds.noPop = true;
this.noBindingsOnNextBlock = true;
var n = new Node(t, LET_BLOCK);
n.varDecls = [];
return n;
},
finish: function(n) {
this.binds.propagatePossibleHoists();
this.binds = this.binds.parent;
}
},
BLOCK: {
build: function(t, id) {
//
// It's not worth it to create bindings lazily due to
// hoisting. That is, any identifier in an inner block that
// isn't let-bound at the same level (even if it's bound in
// the parent scope!) is a possible let hoist.
//
// To keep this information then we need a bindings-like thing
// for each block anyways, so we might as well just eagerly
// create bindings per block.
//
var n = new Node(t, BLOCK);
n.varDecls = [];
n.id = id;
if (this.noBindingsOnNextBlock) {
this.binds.block = n;
this.binds.id = id;
this.noBindingsOnNextBlock = false;
return n;
}
this.binds = new Bindings(this.binds, false, false);
this.binds.block = n;
this.binds.id = id;
return n;
},
hoistLets: function(n) {
var lds = this.hoists[n.id];
if (!lds)
return;
var binds = this.binds;
var name, init;
binds = this.binds = new Bindings(binds, false, false);
n.seenLet = true;
for (var i = 0, j = lds.length; i < j; i++) {
name = lds[i].name;
binds.declareLet(name, true);
}
this.hoists[n.id] = undefined;
},
finish: function(n) {
if (this.binds.noPop)
return;
this.binds.propagatePossibleHoists();
this.binds = this.binds.parent;
}
},
ASSIGN: {
addOperand: function(n, n2) {
if (n.length == 0) {
this.binds.inRHS++;
}
n.push(n2);
},
finish: function(n) {
if (n.length == 0) {
return;
}
var join = this.join;
var binds = this.binds;
var fb = binds.nearestFunction;
var lhs = n[0];
var init = n[1];
var upvars = init.upvars || new Upvars;
if (--binds.inRHS > 0) {
n.upvars = init.upvars;
}
// Desugar destructuring.
if (lhs.type == ARRAY_INIT || lhs.type == OBJECT_INIT) {
var t = n.tokenizer;
// Rebuild as COMMA.
n.type = COMMA;
n.length = 0;
desugarDestructuringAssign(this, n, lhs, init);
return;
}
if (lhs.type != IDENTIFIER) {
escapeVars(join, binds, upvars);
return;
}
// Only push phi nodes for identifiers for now, array/object
// SSA is really hard.
var name = lhs.value;
var c = binds.current(name);
var uv = binds.upvar(name);
var hp = binds.hasParam(name);
var hup = binds.hasUpParam(name);
var mb = fb.mu(name);
// Don't count lefthand side identifiers as a use.
if (mb && (!c && !uv && !hup && !hp)) {
binds.removeMuUse(lhs);
}
// Don't trust vars inside of withs.
if (c && binds.isWith && c.type == VAR) {
binds.withIntervenes.insert1(c);
c = null;
uv = null;
}
if (uv && !c) {
// Record name in the closest function binding's
// upvar-set.
binds.addToFrees(name);
binds.addUpvar("defs", uv);
// Since we're not doing flow analysis here, we assume
// conservatively that all upvars have escaped in the
// current function.
var suv = new Upvars;
suv.defs.insert1(uv);
escapeVars(join, binds, suv);
c = uv;
}
if (c) {
if (n.assignOp) {
// Transform op= into a normal assignment only if the
// lhs is an identifier we _know_ to be from a var.
var nt = n.tokenizer;
var lhs = n[0];
var n2 = mkRawIdentifier(nt, name, null, true);
this.PRIMARY.finish(n2);
var o = n.assignOp;
n.assignOp = undefined;
n.length = 0;
n.push(lhs);
n.push(new Node(nt, o, n2, init));
n2.setForward(c.def);
return this.ASSIGN.finish(n);
}
// Clear the forward pointer and upvars on lefthand side.
if (n[0].forward) {
n[0].forward = null;
n[0].upvars = null;
}
// Set local to help decomp to do value numbering.
n[0].local = c.type;
// Get the rightmost expression in case of compound
// assignment.
while (init.type == ASSIGN)
init = init[1];
if (join) {
// If the name is not a local let, we need a phi.
if (c.type == VAR) {
var propInit = null;
var propUpvars = null;
if (this.inJoinPostDom.top()) {
propInit = init;
propUpvars = upvars.clone();
}
join.insertPhi(VAR, name, init,
upvars.clone(),
c.def, c.upvars,
propInit, propUpvars);
} else if (!binds.currents[name]) {
join.insertPhi(LET, name, init,
upvars.clone(),
c.def, c.upvars);
}
}
// Flow the upvars of escaped functions to the names. If
// the init is a lambda, it'll have upvars set on itself.
binds.update(name, init, upvars.clone());
} else {
binds.addToFrees(name);
// At this point all mayEscapes in fact flowed into
// something we don't know about (a property, global,
// etc), which means they have all actually escaped.
escapeVars(join, binds, upvars);
}
}
},
HOOK: {
/*
* Basically the same thing as if, except an expression.
*/
build: function(t) {
var n = new Node(t, HOOK);
n.rhsNewUpvars(this.binds);
return n;
},
setCondition: function(n, e) {
n[0] = e;
n.rhsUnionUpvars(e);
this.join = new SSAJoin(this.join, this.binds, false);
},
setThenPart: function(n, n2) {
var join = this.join;
n[1] = n2;
n.rhsUnionUpvars(n2);
join.finishBranch();
join.restore(this.binds);
},
setElsePart: function(n, n2) {
n[2] = n2;
n.rhsUnionUpvars(n2);
},
finish: function(n) {
var join = this.join;
this.join = join.parent;
join.finishBranch();
n.ssaJoin = join.commit();
}
},
OR: {
build: function(t) {
var n = new Node(t, OR);
n.rhsNewUpvars(this.binds);
return n;
},
addOperand: function(n, n2) {
if (n.length == 0) {
// Short circuiting means the right hand expression needs
// to be parsed in a new context.
var join = this.join = new SSAJoin(this.join, this.binds, false);
// Start in the second branch since the first operand of a
// conditional is executed no matter what.
join.finishBranch();
}
n.rhsUnionUpvars(n2);
n.push(n2);
},
finish: function(n) {
var join = this.join;
this.join = join.parent;
join.finishBranch();
n.ssaJoin = join.commit();
}
},
AND: {
build: function(t) {
var n = new Node(t, AND);
n.rhsNewUpvars(this.binds);
return n;
},
addOperand: function(n, n2) {
if (n.length == 0) {
// Short circuiting means the right hand expression needs
// to be parsed in a new context.
var join = this.join = new SSAJoin(this.join, this.binds, false);
// Start in the second branch since the first operand of a
// conditional is executed no matter what.
join.finishBranch();
}
n.push(n2);
},
finish: function(n) {
var join = this.join;
this.join = join.parent;
join.finishBranch();
n.ssaJoin = join.commit();
}
},
UNARY: {
finish: function(n) {
var op = n.type;
if (n.type != INCREMENT && n.type != DECREMENT)
return;
var join = this.join;
var binds = this.binds;
if (!(n[0].type == IDENTIFIER && binds.hasCurrent(n[0].value)))
return;
//
// Transform
// ++x into (x = x + 1)
// --x into (x = x - 1)
// x++ into (t = x, x = x + 1, t) for t fresh
// x-- into (t = x, x = x - 1, t) for t fresh
//
// _only_ if x is an identifier that we know to be from a var
// or a let.
//
// In this case x cannot be a setter or an arbitrary side
// effect, so we do not duplicate side effects in an unsafe
// fashion.
//
var name = n[0].value;
var c = binds.current(name);
// Don't transform vars inside of withs
if (binds.isWith && c.type == VAR)
return;
var t = n.tokenizer;
var ptmp = this.genPostfixSym();
if (n.postfix) {
binds.block.push(mkDecl(this, "VAR", t, ptmp));
}
var n2 = mkRawIdentifier(t, name, null, true);
if (c) {
n2.setForward(c.def);
}
if (join) {
join.rememberUse(name, n2);
}
if (n.postfix) {
n.parenthesized = true;
n.type = COMMA;
n.length = 0;
n.push(mkAssignSimple(this, t, ptmp,
mkIdentifier(this, t, name)));
}
var aop = op == INCREMENT ? PLUS : MINUS;
var assign = mkAssignSimple(this, t, name,
new Node(t, aop, n2,
mkNumber(t, 1, true)));
if (n.postfix) {
n.push(assign);
n.push(mkIdentifier(this, t, ptmp));
} else {
n.type = ASSIGN;
n.length = 0;
n.push(assign[0]);
n.push(assign[1]);
}
}
},
MEMBER: {
build: function(t, tt) {
this.binds.inRHS++;
return new Node(t, tt);
},
finish: function(n) {
//
// By fortune of the expression grammar the left side of a
// call is never going to call MEMBER.build, and thus not
// considered a mayEscape.
//
// So, anything reported to mayEscape here is going to be an
// argument to new, called with new, or an argument to a
// function.
//
var join = this.join;
var binds = this.binds;
var fb = binds.nearestFunction;
if (--binds.inRHS > 0) {
if (unionOnRight) {
n.upvars = n[1].upvars;
} else {
n.upvars = n[0].upvars;
}
}
if (n.type != CALL)
return;
function processUpvars(upvars) {
var upvarInts = upvars.transClosureI(new Map);
var fiuvs = upvars.flowIUVs.members;
for (var i in fiuvs) {
binds.addUpvar("intervenes", fiuvs[i]);
}
// Inner function calls can cause things to escape.
//
// We might also need the existing escaped set to be
// invalidated.
//
// But if it's an eval, we need to escape everything
// anyways, so don't do extra work.
if (upvars.isEval) {
escapeEval(join, binds);
} else {
var escs;
if (escs = upvars.transClosureE(new Map)) {
if (escs.length > 0 || upvars.needsEscape) {
escapeVars0(join, binds, escs, new Map);
}
}
}
var escaped = fb.escapedVars();
if (escaped && upvarInts && upvars.needsEscape) {
upvarInts.unionWith(escaped);
}
// Inner functions that are called also cause its set
// of upvars to be merged with the parent function's.
fb.upvars.unionWith(upvars);
if (join) {
join.intervene(binds, upvarInts);
} else {
binds.intervene(upvarInts);
}
return escaped;
}
//
// Locally, direct evals can intervene between def and use,
// i.e. it can change existing bindings and introduce new
// local ones, so blast away context.
//
var inners = this.binds.inners;
var base = baseOfCall(n[0]);
var target = targetOfCall(n[0], IDENTIFIER);
if (target == "eval") {
escapeEval(join, binds);
} else if (base.type == IDENTIFIER) {
var name = base.value;
var c = binds.current(name);
var uv;
if (!c && (uv = binds.upvar(name))) {
c = uv;
// We check for forward because if it's an upvar
// that's been forwarded, it got some immediate
// assignment like:
//
// function f() {
// var x, z, h;
// function g() {
// z = h;
// z();
// }
// }
//
// Here we really only need to intervene on h, not z
// as well.
if (!base.forward) {
binds.addUpvar("intervenes", uv);
}
}
if (c) {
var upvars = c.upvars || new Upvars;
var escaped = processUpvars(upvars);
// Check its list of upvar uses to see if the same
// value has been maintained. This optimization is
// used for write-once upvar resolution:
//
// function f() {
// var x;
// function g() {
// x; // should be forwarded to 0.
// }
//
// x = 0;
// g();
// }
var uvuses = upvars.uses.members;
if (upvars.uses.length > 0) {
binds.addBackpatchUpvars(upvars);
}
for (var i in uvuses) {
var use = uvuses[i];
var name = use.name;
// If the upvar escaped, invalidate it.
if (fb.evalEscaped ||
(escaped && escaped.lookup(use))) {
upvars.uses.remove(use);
upvars.useTuples.remove(use);
continue;
}
if (binds.current(name) === use) {
// If the upvar is current, check if its value
// has changed since last invocation.
var useTuple = upvars.useTuples.lookup(use);
if (useTuple.cdef === undefined) {
// If it's the first time, record the value.
useTuple.cdef = use.def;
} else if (useTuple.cdef !== use.def) {
// If it's changed, invalidate the use.
upvars.uses.remove(use);
upvars.useTuples.remove(use);
}
} else if (binds.upvar(name) === use) {
// If the upvar is still an upvar in the current
// scope and but hasn't been touched, we don't do
// anything. Otherwise we remove it from the list
// of uses to check.
if (hasOwnProperty.call(fb.upvarOlds, use.name)) {
upvars.uses.remove(use);
upvars.useTuples.remove(use);
}
}
}
}
} else if (base.upvars) {
processUpvars(base.upvars);
}
var unionOnRight = n.type == CALL || n.type == NEW_WITH_ARGS ||
n.type == INDEX;
if (unionOnRight) {
escapeVars(join, binds, n[1].upvars || new Upvars);
}
}
},
PRIMARY: {
finish: function(n) {
if (n.type != IDENTIFIER)
return;
var binds = this.binds, join = this.join;
var fb = binds.nearestFunction;
var name = n.value;
var c = binds.current(name);
var uv = binds.upvar(name);
var hp = binds.hasParam(name);
var hup = binds.hasUpParam(name);
var mb = fb.mu(name);
// Don't trust vars inside of withs.
if (binds.isWith && c && c.type == VAR)
return;
c = upvarTreatedAsLocal(binds, name, c, uv);
if (c) {
n.setForward(c.def, uv === c);
} else if (mb && (!uv && !hup && !hp)) {
// In the case where we're recursively calling ourself,
// remember the node for backpatching.
mb.pushMuUse(n);
}
/*
* Any identifier used in an inner block that is not already
* bound by a let _at the same block level_ is a possible let
* hoist.
*/
if (!this.secondPass && !binds.isFunction &&
!n.internal && !binds.currents[name]) {
binds.rememberPossibleHoist(name);
}
if (join) {
join.rememberUse(name, n);
}
//
// If by flow the current node has upvars and is on the RHS
// (either of an assignment or as an argument to new with
// arguments or a call), we need to mark it as possibly
// escaping.
//
if (binds.inRHS > 0) {
if (c && !uv) {
n.upvars = c.upvars;
} else if (uv) {
n.upvars = new Upvars;
n.upvars.flowIUVs.insert1(uv);
}
}
if (!c && !uv) {
if (!this.secondPass && !n.internal &&
!uv && !hp && !hup) {
//
// Any identifier that we don't know anything about is
// always at least a possible var hoist.
//
fb.rememberPossibleHoist(name);
}
binds.closureNeedsEscape();
var escaped = fb.escapedVars();
if (join) {
//
// This is annoying: we don't know if something is a
// direct eval until we finish parsing the MEMBER
// expression, so we can't insert a dash in the
// tryJoin here and have to do it there.
//
// Is this heuristic good enough?
//
var tryJoin = join.nearestTryJoin();
if (tryJoin && name != "eval") {
//
// We can be in a try, in which case throws modify
// the control flow. We don't kill the branch
// because we don't know if we're going to throw.
// We however need to propagate phis up to the try
// context and add a new branch.
//
var ps = join.unionPhisUpTo(tryJoin);
var tryBinds = tryJoin.binds;
var old;
for (var x in ps) {
c = tryBinds.current(x);
old = ps[x].old;
tryJoin.insertPhi(c.type, x, c.def, c.upvars,
old.def, old.upvars);
}
binds.closureNeedsEscape();
var intervened = join.intervene(binds, escaped);
tryJoin.insertDashes(binds, intervened);
tryJoin.finishBranch();
if (!tryJoin.isFinally) {
tryJoin.parent.maybeThrows = true;
}
} else {
join.intervene(binds, escaped);
}
} else {
binds.intervene(escaped);
}
}
}
},
PROPERTY_INIT: {
build: function(t) {
var n = new Node(t, PROPERTY_INIT);
n.rhsNewUpvars(this.binds);
return n;
},
finish: function(n) {
n.rhsUnionUpvars(n[1]);
}
},
COMMA: {
build: function(t) {
var n = new Node(t, COMMA);
n.rhsNewUpvars(this.binds);
return n;
},
addOperand: function(n, n2) {
n.rhsUnionUpvars(n2);
n.push(n2);
}
},
LIST: {
build: function(t) {
var n = new Node(t, LIST);
n.rhsNewUpvars(this.binds);
return n;
},
addOperand: function(n, n2) {
n.rhsUnionUpvars(n2);
n.push(n2);
}
},
ARRAY_INIT: {
build: function(t) {
var n = new Node(t, ARRAY_INIT);
n.rhsNewUpvars(this.binds);
return n;
},
addElement: function(n, n2) {
n.rhsUnionUpvars(n2);
n.push(n2);
}
},
OBJECT_INIT: {
build: function(t) {
var n = new Node(t, OBJECT_INIT);
n.rhsNewUpvars(this.binds);
return n;
},
addProperty: function(n, n2) {
n.rhsUnionUpvars(n2);
n.push(n2);
}
},
WITH: {
setObject: function(n, e) {
// We need to record interventions for assignments
n.object = e;
// Clearing binds will kick the guard in and effectively
// switch us back to the vanilla builder inside the eval. We
// can't just intervene once and resume analysis on the next
// assignment like for eval.
this.binds = new Bindings(this.binds, false, true);
this.binds.noPop = true;
this.noBindingsOnNextBlock = true;
},
finish: function(n) {
var binds = this.binds;
var join = this.join;
if (join) {
join.intervene(binds, binds.withIntervenes);
} else {
binds.intervene(binds.withIntervenes);
}
this.binds = this.binds.parent;
}
},
genDestructuringSym: function() {
return "$dtmp" + this.destructuringTmpFresh++;
},
genPostfixSym: function() {
return "$ptmp" + this.postfixTmpFresh++;
},
setHoists: function(id, vds) {
this.hoists[id] = vds;
}
};
extendBuilder(SSABuilder, parser.DefaultBuilder);
/*
* These methods are unguarded.
*/
var Sbp = SSABuilder.prototype;
Sbp.FUNCTION.build = function(t) {
var binds = this.binds;
var n = new Node(t);
if (n.type != FUNCTION)
n.type = (n.value == "get") ? GETTER : SETTER;
n.params = [];
// Save the current join, since we could be declaring an inner
// function inside a branch.
this.joinStack.push(this.join);
this.join = null;
this.binds = new Bindings(binds, true, false);
this.binds.noPop = true;
this.noBindingsOnNextBlock = true;
return n;
};
/*
* Utility functions.
*/
function escapeEval(join, binds) {
if (join) {
var intervened = join.intervene(binds);
var tryJoin = join.nearestTryJoin();
if (tryJoin) {
tryJoin.insertDashes(binds, intervened);
tryJoin.finishBranch();
}
} else {
binds.intervene();
}
// evals can make everything escape, all the time.
binds.nearestFunction.evalEscaped = true;
binds.closureIsEval();
}
function escapeVars0(join, binds, mayEscape, escapedIntervenes) {
var fb = binds.nearestFunction;
var escaped = fb.evalEscaped ? null : fb.escaped;
binds.closureNeedsEscape();
// We also need to remember if the function that
// escaped calls other upvars:
//
// function f() {
// var x, y, h;
// function g() {
// h();
// }
// h = function () {
// x = 1;
// }
// globalCode(g);
// h = function () {
// y = 1;
// }
// otherGlobalCode() // should invalidate y
if (escaped) {
escaped.defs.unionWith(mayEscape);
escaped.intervenes.unionWith(escapedIntervenes);
etci = escaped.transClosureI(new Map);
} else {
etci = null;
}
if (join) {
join.intervene(binds, etci);
} else {
binds.intervene(etci);
}
}
function escapeVars(join, binds, upvars) {
// Inner functions that escape cause its set of upvars to be unioned
// with that of its parent.
var fb = binds.nearestFunction;
fb.upvars.unionWith(upvars);
// Invalidate all upvar uses because the inner function escaped.
upvars.uses.clear();
upvars.useTuples.clear();
if (upvars.isEval) {
escapeEval(join, binds);
} else {
var tci;
if (tci = upvars.transClosureI(new Map)) {
escapeVars0(join, binds, tci, upvars.intervenes);
} else {
escapeEval(join, binds);
}
}
var fiuvs = upvars.flowIUVs.members;
for (var i in fiuvs) {
binds.addUpvar("escapes", fiuvs[i])
}
}
function unionPhiUpvars(operands) {
var upvars = new Upvars;
var puv, os;
for (var i = 0, j = operands.length; i < j; i++) {
os = operands[i];
if (os) {
if (puv = os.upvars) {
upvars.unionWith(puv);
}
}
}
return upvars;
}
function fallthroughJoin(n, join, binds) {
var ps = join.phis, ps2 = {}, e, r;
function go(x, rhs) {
var upvars = unionPhiUpvars(ps[x]);
binds.update(x, rhs, upvars);
}
//
// Construct a new set of phis that have only two branches.
//
// The first branch is kept undefined and will be filled in with the
// parent value (i.e. entering the branch via the case label and not by
// falling through).
//
// The second branch copies over the current values (i.e. entering
// the branch by falling through the previous case).
//
var c;
for (var px in ps) {
c = binds.current(px);
ps2[px] = [];
ps2[px][1] = { def: c.def, upvars: c.upvars };
ps2[px].old = ps[px].old;
}
e = SSAJoin.mkJoin(ps2, join.parent, 2, go);
r = new Node({ lineno: n.lineno }, SEMICOLON);
r.expression = e;
return r;
}
function baseOfCall(n) {
switch (n.type) {
case DOT:
return baseOfCall(n[0]);
case INDEX:
return baseOfCall(n[0]);
default:
return n;
}
}
function targetOfCall(n, ident) {
switch (n.type) {
case ident:
return n.value;
case DOT:
return targetOfCall(n[1], IDENTIFIER);
case INDEX:
return targetOfCall(n[1], STRING);
default:
return null;
}
}
function mkHoistDecl(builder, n) {
var bDecl = builder.DECL;
var hoistDecl = bDecl.build(n.tokenizer, n.type);
bDecl.setName(hoistDecl, n.name);
// Don't do another ASSIGN.
hoistDecl.initializer = n.initializer;
bDecl.setReadOnly(n, n.readOnly);
bDecl.finish(hoistDecl);
return hoistDecl;
}
function mkIndex(builder, t, rhs, x) {
var bMember = builder.MEMBER;
var bPrimary = builder.PRIMARY;
var idx, idxLit;
idxLit = bPrimary.build(t, STRING)
idxLit.value = x;
bPrimary.finish(idxLit);
idx = bMember.build(t, INDEX);
bMember.addOperand(idx, rhs);
bMember.addOperand(idx, idxLit);
bMember.finish(idx);
return idx;
}
function mkIdentifier(builder, t, name, isExternal) {
var bPrimary = builder.PRIMARY;
var n = bPrimary.build(t, IDENTIFIER);
n.name = n.value = name;
n.internal = !isExternal;
bPrimary.finish(n);
return n;
}
function mkAssign(builder, t, lhs, initializer) {
var bAssign = builder.ASSIGN;
var n = bAssign.build(t);
bAssign.addOperand(n, lhs);
bAssign.addOperand(n, initializer);
bAssign.finish(n);
return n;
}
function mkAssignSimple(builder, t, name, initializer, isExternal) {
var bPrimary = builder.PRIMARY;
var id = bPrimary.build(t, IDENTIFIER);
id.name = id.value = name;
id.internal = !isExternal;
bPrimary.finish(id);
return mkAssign(builder, t, id, initializer);
}
function desugarDestructuringAssign(builder, comma, n, e) {
var t = n.tokenizer;
var binds = builder.binds;
var bComma = builder.COMMA;
function go(lhss, rhs) {
var lhs, lhsType, idx;
for (var x in lhss) {
lhs = lhss[x];
lhsType = lhs.type;
idx = mkIndex(builder, t, rhs, x);
if (lhsType == IDENTIFIER) {
var name = lhs.value;
var a = mkAssignSimple(builder, t, name, idx, true);
bComma.addOperand(comma, a);
} else if (lhsType == ARRAY_INIT || lhsType == OBJECT_INIT) {
// We are not guaranteed simple names unlike in
// declarations.
go(lhs, idx);
} else {
var a = mkAssign(builder, t, lhs, idx);
bComma.addOperand(comma, a);
}
}
}
// We need to the init to be linear.
var decl = mkDecl(builder, "LET", n.tokenizer,
builder.genDestructuringSym(),
e, false);
builder.binds.block.push(decl);
decl[0].setForward(e);
go(n.destructuredNames, decl[0]);
}
function desugarDestructuringInit(builder, n, e) {
var t = n.tokenizer;
var binds = builder.binds;
var ddecls = n.destructuredDecls;
var bDecl = builder.DECL;
function go(ddecls, rhs) {
var n2, n3, id, idxLit, idx;
for (var x in ddecls) {
n2 = ddecls[x];
// Desugar to an index operation.
idx = mkIndex(builder, t, rhs, x);
if (n2.type == IDENTIFIER) {
bDecl.setInitializer(n2, idx);
bDecl.finish(n2);
} else {
go(n2, idx);
}
}
}
// We need the right hand side of the destructuring assignment
// to be linear after the transform, so we first need to
// assign the right hand side to a separate decl.
var block = builder.binds.block;
if (block) {
var dtmp = builder.genDestructuringSym();
var decl = mkDecl(builder, "LET", t, dtmp, e, false);
block.push(decl);
decl[0].setForward(e);
go(ddecls, decl[0]);
} else {
// This only happens when we have destructuring for a catch var,
// in which case that catch var already has let-scoping, so we
// don't need to make a new let decl.
go(ddecls, e);
}
}
function mkAddDestructuringDecl(type, ro) {
return function(n, n2, x) {
var t = n2.tokenizer;
var binds = this.binds;
var bDecl = this.DECL;
var numDecls = 0;
var b;
if (type == VAR) {
b = this.VAR;
} else if (type == CONST) {
b = this.CONST;
} else {
b = this.LET;
}
function go(lhss) {
var ddecls = {};
for (var idx in lhss) {
var lhs = lhss[idx];
if (lhs.type == IDENTIFIER) {
var decl = bDecl.build(t);
var name = lhs.value;
decl.forward = lhs.forward;
// In declarations we're guaranteed that the
// pattern contains only simple names.
bDecl.setName(decl, name);
bDecl.setReadOnly(decl, ro);
// For decrementing localUses in
// desugarDestructuringInit.
decl.wasLocal = binds.hasCurrent(name);
b.addDecl(n, decl, x);
ddecls[idx] = decl;
numDecls++;
} else {
ddecls[idx] = go(lhs);
}
}
return ddecls;
}
n2.destructuredDecls = go(n2.name.destructuredNames);
n2.numDecls = numDecls;
}
}
function mkDecl(builder, tt, t, name, initializer, isExternal) {
var b = builder[tt];
var bDecl = builder.DECL;
var decl = bDecl.build(t);
bDecl.setName(decl, name);
decl.internal = !isExternal;
var lt = b.build(t);
b.addDecl(lt, decl);
if (initializer) {
bDecl.setInitializer(decl, initializer);
}
bDecl.finish(decl);
b.finish(lt);
return lt;
}
function mkCall(f, n, isExternal) {
var ident = new Node(n.tokenizer, IDENTIFIER);
ident.value = f;
ident.internal = !isExternal;
return new Node(n.tokenizer, CALL, ident,
new Node(n.tokenizer, LIST, n));
}
function mkRawIdentifier(t, name, init, isExternal) {
var n = new Node(t, IDENTIFIER);
n.name = n.value = name;
n.internal = !isExternal;
n.initializer = init;
return n;
}
function mkNumber(t, i, isExternal) {
var n = new Node(t, NUMBER);
n.value = i;
n.internal = !isExternal;
return n;
}
var Np = Node.prototype;
Np.rhsNewUpvars = function(binds) {
if (binds.inRHS > 0) {
this.upvars = new Upvars;
}
};
Np.rhsUnionUpvars = function(n) {
if (this.upvars && n.upvars) {
this.upvars.unionWith(n.upvars)
}
};
function upvarTreatedAsLocal(binds, name, c, uv) {
var fb = binds.nearestFunction;
// If we have a backup, then we've assigned to this upvar
// in the current function and treat it as a local.
return hasOwnProperty.call(fb.upvarOlds, name) ? uv : c;
}
Np.setForward = function(fwd, isUpvar) {
// Don't link to intervened.
if (fwd === dash)
return;
this.forward = fwd;
if (fwd) {
if (!fwd.backwards)
fwd.backwards = [];
fwd.backwards.push(this);
}
};
Np.resolve = function() {
var f = this.forward;
if (f) {
this.forward = f.resolve();
return this.forward;
}
return this;
};
// Push a pointer to a phi node to a node so that the latter fill in phi
// node's value when it itself is computed.
Np.pushPhiUse = function(p) {
if (!this.phiUses)
this.phiUses = [];
this.phiUses.push(p);
};
parser.SSABuilder = SSABuilder;
}());