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Bug 553778: Don't orphan placeholder definition nodes when a real definition is found. r=brendan

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When we incorporate an inner function's lexdeps into our own lexdeps and
decls tables, always create a fresh definition node for an identifier we
don't have an entry for yet, and turn the inner definition node into a use
of that definition, to ensure that references to those definitions from
TOK_UPVARS nodes properly resolve to the outer definitions that capture
them.

This patch also changes MakePlaceholder to initialize the new node's type
and op. Normally, JSParseNode::create initializes them from the current
token, but that creates a fragile dependency of placeholder construction on
lexing state, and is not actually what two out of (now) three call sites
want.
This commit is contained in:
Jim Blandy 2010-11-10 13:18:15 -08:00
parent 6d8362bfc5
commit 15430ee67a
3 changed files with 78 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

113
js/src/jsparse.cpp
View File

@ -1428,6 +1428,8 @@ MakePlaceholder(JSParseNode *pn, JSTreeContext *tc)
return NULL;
ALE_SET_DEFN(ale, dn);
dn->pn_type = TOK_NAME;
dn->pn_op = JSOP_NOP;
dn->pn_defn = true;
dn->pn_dflags |= PND_PLACEHOLDER;
return ale;
@ -2051,6 +2053,7 @@ Parser::markFunArgs(JSFunctionBox *funbox, uintN tcflags)
afunbox = afunbox->parent;
--staticLevel;
}
JS_ASSERT(afunbox->level + 1U == calleeLevel);
afunbox->node->setFunArg();
} else {
afunbox = lexdep->pn_funbox;
@ -2609,58 +2612,70 @@ LeaveFunction(JSParseNode *fn, JSTreeContext *funtc, JSAtom *funAtom = NULL,
DeoptimizeUsesWithin(dn, fn->pn_pos);
}
JSDefinition *outer_dn;
if (!outer_ale)
outer_ale = tc->lexdeps.lookup(atom);
if (outer_ale) {
/*
* Insert dn's uses list at the front of outer_dn's list.
if (!outer_ale) {
/*
* Create a new placeholder for our outer lexdep. We could simply re-use
* the inner placeholder, but that introduces subtleties in the case where
* we find a later definition that captures an existing lexdep. For
* example:
*
* Without loss of generality or correctness, we allow a dn to
* be in inner and outer lexdeps, since the purpose of lexdeps
* is one-pass coordination of name use and definition across
* functions, and if different dn's are used we'll merge lists
* when leaving the inner function.
* function f() { function g() { x; } let x; }
*
* The dn == outer_dn case arises with generator expressions
* (see CompExprTransplanter::transplant, the PN_FUNC/PN_NAME
* case), and nowhere else, currently.
* Here, g's TOK_UPVARS node lists the placeholder for x, which must be
* captured by the 'let' declaration later, since 'let's are hoisted.
* Taking g's placeholder as our own would work fine. But consider:
*
* function f() { x; { function g() { x; } let x; } }
*
* Here, the 'let' must not capture all the uses of f's lexdep entry for
* x, but it must capture the x node referred to from g's TOK_UPVARS node.
* Always turning inherited lexdeps into uses of a new outer definition
* allows us to handle both these cases in a natural way.
*/
outer_dn = ALE_DEFN(outer_ale);
if (dn != outer_dn) {
JSParseNode **pnup = &dn->dn_uses;
JSParseNode *pnu;
while ((pnu = *pnup) != NULL) {
pnu->pn_lexdef = outer_dn;
pnup = &pnu->pn_link;
}
/*
* Make dn be a use that redirects to outer_dn, because we
* can't replace dn with outer_dn in all the pn_namesets in
* the AST where it may be. Instead we make it forward to
* outer_dn. See JSDefinition::resolve.
*/
*pnup = outer_dn->dn_uses;
outer_dn->dn_uses = dn;
outer_dn->pn_dflags |= dn->pn_dflags & ~PND_PLACEHOLDER;
dn->pn_defn = false;
dn->pn_used = true;
dn->pn_lexdef = outer_dn;
/* Mark the outer dn as escaping. */
}
} else {
/* Add an outer lexical dependency for ale's definition. */
outer_ale = tc->lexdeps.add(tc->parser, atom);
if (!outer_ale)
return false;
outer_dn = ALE_DEFN(ale);
ALE_SET_DEFN(outer_ale, outer_dn);
outer_ale = MakePlaceholder(dn, tc);
}
JSDefinition *outer_dn = ALE_DEFN(outer_ale);
/*
* Insert dn's uses list at the front of outer_dn's list.
*
* Without loss of generality or correctness, we allow a dn to
* be in inner and outer lexdeps, since the purpose of lexdeps
* is one-pass coordination of name use and definition across
* functions, and if different dn's are used we'll merge lists
* when leaving the inner function.
*
* The dn == outer_dn case arises with generator expressions
* (see CompExprTransplanter::transplant, the PN_FUNC/PN_NAME
* case), and nowhere else, currently.
*/
if (dn != outer_dn) {
JSParseNode **pnup = &dn->dn_uses;
JSParseNode *pnu;
while ((pnu = *pnup) != NULL) {
pnu->pn_lexdef = outer_dn;
pnup = &pnu->pn_link;
}
/*
* Make dn be a use that redirects to outer_dn, because we
* can't replace dn with outer_dn in all the pn_namesets in
* the AST where it may be. Instead we make it forward to
* outer_dn. See JSDefinition::resolve.
*/
*pnup = outer_dn->dn_uses;
outer_dn->dn_uses = dn;
outer_dn->pn_dflags |= dn->pn_dflags & ~PND_PLACEHOLDER;
dn->pn_defn = false;
dn->pn_used = true;
dn->pn_lexdef = outer_dn;
}
/* Mark the outer dn as escaping. */
outer_dn->pn_dflags |= PND_CLOSED;
}
@ -4777,10 +4792,6 @@ RebindLets(JSParseNode *pn, JSTreeContext *tc)
ale = MakePlaceholder(pn, tc);
if (!ale)
return NULL;
JSDefinition *dn = ALE_DEFN(ale);
dn->pn_type = TOK_NAME;
dn->pn_op = JSOP_NOP;
}
LinkUseToDef(pn, ALE_DEFN(ale), tc);
}
@ -8632,8 +8643,6 @@ Parser::primaryExpr(TokenKind tt, JSBool afterDot)
* necessary for safe context->display-based optimiza-
* tion of the closure's static link.
*/
JS_ASSERT(PN_TYPE(dn) == TOK_NAME);
JS_ASSERT(dn->pn_op == JSOP_NOP);
if (tokenStream.peekToken() != TOK_LP)
dn->pn_dflags |= PND_FUNARG;
}

1
js/src/tests/js1_8_5/regress/jstests.list
View File

@ -11,6 +11,7 @@ script regress-546615.js
script regress-551763-0.js
script regress-551763-1.js
script regress-551763-2.js
script regress-553778.js
script regress-555246-0.js
script regress-555246-1.js
script regress-559438.js

16
js/src/tests/js1_8_5/regress/regress-553778.js Normal file
View File

@ -0,0 +1,16 @@
/*
* This should compile without triggering the following assertion:
*
* Assertion failure: cg->fun->u.i.skipmin <= skip, at ../jsemit.cpp:2346
*/
function f() {
function g() {
function h() {
g; x;
}
var [x] = [];
}
}
reportCompare(true, true);