LCOV - code coverage report
Current view: directory - js/src/frontend - SemanticAnalysis.cpp (source / functions) Found Hit Coverage
Test: app.info Lines: 76 69 90.8 %
Date: 2012-04-07 Functions: 5 5 100.0 %

       1                 : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
       2                 :  * vim: set ts=8 sw=4 et tw=99:
       3                 :  *
       4                 :  * ***** BEGIN LICENSE BLOCK *****
       5                 :  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
       6                 :  *
       7                 :  * The contents of this file are subject to the Mozilla Public License Version
       8                 :  * 1.1 (the "License"); you may not use this file except in compliance with
       9                 :  * the License. You may obtain a copy of the License at
      10                 :  * http://www.mozilla.org/MPL/
      11                 :  *
      12                 :  * Software distributed under the License is distributed on an "AS IS" basis,
      13                 :  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
      14                 :  * for the specific language governing rights and limitations under the
      15                 :  * License.
      16                 :  *
      17                 :  * The Original Code is Mozilla Communicator client code, released
      18                 :  * March 31, 1998.
      19                 :  *
      20                 :  * The Initial Developer of the Original Code is
      21                 :  * Netscape Communications Corporation.
      22                 :  * Portions created by the Initial Developer are Copyright (C) 1998
      23                 :  * the Initial Developer. All Rights Reserved.
      24                 :  *
      25                 :  * Contributor(s):
      26                 :  *
      27                 :  * Alternatively, the contents of this file may be used under the terms of
      28                 :  * either of the GNU General Public License Version 2 or later (the "GPL"),
      29                 :  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
      30                 :  * in which case the provisions of the GPL or the LGPL are applicable instead
      31                 :  * of those above. If you wish to allow use of your version of this file only
      32                 :  * under the terms of either the GPL or the LGPL, and not to allow others to
      33                 :  * use your version of this file under the terms of the MPL, indicate your
      34                 :  * decision by deleting the provisions above and replace them with the notice
      35                 :  * and other provisions required by the GPL or the LGPL. If you do not delete
      36                 :  * the provisions above, a recipient may use your version of this file under
      37                 :  * the terms of any one of the MPL, the GPL or the LGPL.
      38                 :  *
      39                 :  * ***** END LICENSE BLOCK ***** */
      40                 : 
      41                 : #include "frontend/SemanticAnalysis.h"
      42                 : 
      43                 : #include "jsfun.h"
      44                 : 
      45                 : #include "frontend/BytecodeEmitter.h"
      46                 : #include "frontend/Parser.h"
      47                 : 
      48                 : #include "jsobjinlines.h"
      49                 : #include "jsfuninlines.h"
      50                 : 
      51                 : using namespace js;
      52                 : using namespace js::frontend;
      53                 : 
      54                 : /*
      55                 :  * Walk the function box list at |*funboxHead|, removing boxes for deleted
      56                 :  * functions and cleaning up method lists. We do this once, before
      57                 :  * performing function analysis, to avoid traversing possibly long function
      58                 :  * lists repeatedly when recycling nodes.
      59                 :  *
      60                 :  * There are actually three possible states for function boxes and their
      61                 :  * nodes:
      62                 :  *
      63                 :  * - Live: funbox->node points to the node, and funbox->node->pn_funbox
      64                 :  *   points back to the funbox.
      65                 :  *
      66                 :  * - Recycled: funbox->node points to the node, but funbox->node->pn_funbox
      67                 :  *   is NULL. When a function node is part of a tree that gets recycled, we
      68                 :  *   must avoid corrupting any method list the node is on, so we leave the
      69                 :  *   function node unrecycled until we call CleanFunctionList. At recycle
      70                 :  *   time, we clear such nodes' pn_funbox pointers to indicate that they
      71                 :  *   are deleted and should be recycled once we get here.
      72                 :  *
      73                 :  * - Mutated: funbox->node is NULL; the contents of the node itself could
      74                 :  *   be anything. When we mutate a function node into some other kind of
      75                 :  *   node, we lose all indication that the node was ever part of the
      76                 :  *   function box tree; it could later be recycled, reallocated, and turned
      77                 :  *   into anything at all. (Fortunately, method list members never get
      78                 :  *   mutated, so we don't have to worry about that case.)
      79                 :  *   ParseNodeAllocator::prepareNodeForMutation clears the node's function
      80                 :  *   box's node pointer, disconnecting it entirely from the function box tree,
      81                 :  *   and marking the function box to be trimmed out.
      82                 :  */
      83                 : static void
      84          474930 : CleanFunctionList(ParseNodeAllocator *allocator, FunctionBox **funboxHead)
      85                 : {
      86          474930 :     FunctionBox **link = funboxHead;
      87          783554 :     while (FunctionBox *box = *link) {
      88          154312 :         if (!box->node) {
      89                 :             /*
      90                 :              * This funbox's parse node was mutated into something else. Drop the box,
      91                 :              * and stay at the same link.
      92                 :              */
      93               0 :             *link = box->siblings;
      94          154312 :         } else if (!box->node->pn_funbox) {
      95                 :             /*
      96                 :              * This funbox's parse node is ready to be recycled. Drop the box, recycle
      97                 :              * the node, and stay at the same link.
      98                 :              */
      99               0 :             *link = box->siblings;
     100               0 :             allocator->freeNode(box->node);
     101                 :         } else {
     102                 :             /* The function is still live. */
     103                 : 
     104                 :             /* First, remove nodes for deleted functions from our methods list. */
     105                 :             {
     106          154312 :                 ParseNode **methodLink = &box->methods;
     107          154690 :                 while (ParseNode *method = *methodLink) {
     108                 :                     /* Method nodes are never rewritten in place to be other kinds of nodes. */
     109             189 :                     JS_ASSERT(method->isArity(PN_FUNC));
     110             189 :                     if (!method->pn_funbox) {
     111                 :                         /* Deleted: drop the node, and stay on this link. */
     112               0 :                         *methodLink = method->pn_link;
     113                 :                     } else {
     114                 :                         /* Live: keep the node, and move to the next link. */
     115             189 :                         methodLink = &method->pn_link;
     116                 :                     }
     117                 :                 }
     118                 :             }
     119                 : 
     120                 :             /* Second, remove boxes for deleted functions from our kids list. */
     121          154312 :             CleanFunctionList(allocator, &box->kids);
     122                 : 
     123                 :             /* Keep the box on the list, and move to the next link. */
     124          154312 :             link = &box->siblings;
     125                 :         }
     126                 :     }
     127          474930 : }
     128                 : 
     129                 : static void
     130           11315 : FlagHeavyweights(Definition *dn, FunctionBox *funbox, uint32_t *tcflags)
     131                 : {
     132           11315 :     unsigned dnLevel = dn->frameLevel();
     133                 : 
     134           24043 :     while ((funbox = funbox->parent) != NULL) {
     135                 :         /*
     136                 :          * Notice that funbox->level is the static level of the definition or
     137                 :          * expression of the function parsed into funbox, not the static level
     138                 :          * of its body. Therefore we must add 1 to match dn's level to find the
     139                 :          * funbox whose body contains the dn definition.
     140                 :          */
     141           12448 :         if (funbox->level + 1U == dnLevel || (dnLevel == 0 && dn->isLet())) {
     142           11035 :             funbox->tcflags |= TCF_FUN_HEAVYWEIGHT;
     143           11035 :             break;
     144                 :         }
     145                 :     }
     146                 : 
     147           11315 :     if (!funbox && (*tcflags & TCF_IN_FUNCTION))
     148              82 :         *tcflags |= TCF_FUN_HEAVYWEIGHT;
     149           11315 : }
     150                 : 
     151                 : static void
     152          149767 : SetFunctionKinds(FunctionBox *funbox, uint32_t *tcflags, bool isDirectEval)
     153                 : {
     154          304079 :     for (; funbox; funbox = funbox->siblings) {
     155          154312 :         ParseNode *fn = funbox->node;
     156          154312 :         ParseNode *pn = fn->pn_body;
     157                 : 
     158          154312 :         if (funbox->kids)
     159            8412 :             SetFunctionKinds(funbox->kids, tcflags, isDirectEval);
     160                 : 
     161          154312 :         JSFunction *fun = funbox->function();
     162                 : 
     163          154312 :         JS_ASSERT(fun->kind() == JSFUN_INTERPRETED);
     164                 : 
     165          154312 :         if (funbox->tcflags & TCF_FUN_HEAVYWEIGHT) {
     166                 :             /* nothing to do */
     167          146043 :         } else if (isDirectEval || funbox->inAnyDynamicScope()) {
     168                 :             /*
     169                 :              * Either we are in a with-block or a function scope that is
     170                 :              * subject to direct eval; or we are compiling strict direct eval
     171                 :              * code.
     172                 :              *
     173                 :              * In either case, fun may reference names that are not bound but
     174                 :              * are not necessarily global either. (In the strict direct eval
     175                 :              * case, we could bind them, but currently do not bother; see
     176                 :              * the comment about strict mode code in BindTopLevelVar.)
     177                 :              */
     178           10530 :             JS_ASSERT(!fun->isNullClosure());
     179                 :         } else {
     180          135513 :             bool hasUpvars = false;
     181                 : 
     182          135513 :             if (pn->isKind(PNK_UPVARS)) {
     183           45626 :                 AtomDefnMapPtr upvars = pn->pn_names;
     184           45626 :                 JS_ASSERT(!upvars->empty());
     185                 : 
     186                 :                 /* Determine whether the this function contains upvars. */
     187          104592 :                 for (AtomDefnRange r = upvars->all(); !r.empty(); r.popFront()) {
     188           63476 :                     if (!r.front().value()->resolve()->isFreeVar()) {
     189            4510 :                         hasUpvars = true;
     190            4510 :                         break;
     191                 :                     }
     192                 :                 }
     193                 :             }
     194                 : 
     195          135513 :             if (!hasUpvars) {
     196                 :                 /* No lexical dependencies => null closure, for best performance. */
     197          131003 :                 fun->setKind(JSFUN_NULL_CLOSURE);
     198                 :             }
     199                 :         }
     200                 : 
     201          154312 :         if (fun->kind() == JSFUN_INTERPRETED && pn->isKind(PNK_UPVARS)) {
     202                 :             /*
     203                 :              * We loop again over all upvars, and for each non-free upvar,
     204                 :              * ensure that its containing function has been flagged as
     205                 :              * heavyweight.
     206                 :              *
     207                 :              * The emitter must see TCF_FUN_HEAVYWEIGHT accurately before
     208                 :              * generating any code for a tree of nested functions.
     209                 :              */
     210           19521 :             AtomDefnMapPtr upvars = pn->pn_names;
     211           19521 :             JS_ASSERT(!upvars->empty());
     212                 : 
     213           55109 :             for (AtomDefnRange r = upvars->all(); !r.empty(); r.popFront()) {
     214           35588 :                 Definition *defn = r.front().value();
     215           35588 :                 Definition *lexdep = defn->resolve();
     216           35588 :                 if (!lexdep->isFreeVar())
     217           11315 :                     FlagHeavyweights(lexdep, funbox, tcflags);
     218                 :             }
     219                 :         }
     220                 :     }
     221          149767 : }
     222                 : 
     223                 : /*
     224                 :  * Walk the FunctionBox tree looking for functions whose call objects may
     225                 :  * acquire new bindings as they execute: non-strict functions that call eval,
     226                 :  * and functions that contain function statements (definitions not appearing
     227                 :  * within the top statement list, which don't take effect unless they are
     228                 :  * evaluated). Such call objects may acquire bindings that shadow variables
     229                 :  * defined in enclosing scopes, so any enclosed functions must have their
     230                 :  * bindings' extensibleParents flags set, and enclosed compiler-created blocks
     231                 :  * must have their OWN_SHAPE flags set; the comments for
     232                 :  * js::Bindings::extensibleParents explain why.
     233                 :  */
     234                 : static bool
     235          149767 : MarkExtensibleScopeDescendants(JSContext *context, FunctionBox *funbox, bool hasExtensibleParent) 
     236                 : {
     237          304079 :     for (; funbox; funbox = funbox->siblings) {
     238                 :         /*
     239                 :          * It would be nice to use fun->kind() here to recognize functions
     240                 :          * that will never consult their parent chains, and thus don't need
     241                 :          * their 'extensible parents' flag set. Filed as bug 619750.
     242                 :          */
     243                 : 
     244          154312 :         JS_ASSERT(!funbox->bindings.extensibleParents());
     245          154312 :         if (hasExtensibleParent) {
     246             559 :             if (!funbox->bindings.setExtensibleParents(context))
     247               0 :                 return false;
     248                 :         }
     249                 : 
     250          154312 :         if (funbox->kids) {
     251            8412 :             if (!MarkExtensibleScopeDescendants(context, funbox->kids,
     252            8412 :                                                 hasExtensibleParent || funbox->scopeIsExtensible())) {
     253               0 :                 return false;
     254                 :             }
     255                 :         }
     256                 :     }
     257                 : 
     258          149767 :     return true;
     259                 : }
     260                 : 
     261                 : bool
     262          320618 : frontend::AnalyzeFunctions(TreeContext *tc)
     263                 : {
     264          320618 :     CleanFunctionList(&tc->parser->allocator, &tc->functionList);
     265          320618 :     if (!tc->functionList)
     266          179263 :         return true;
     267          141355 :     if (!MarkExtensibleScopeDescendants(tc->parser->context, tc->functionList, false))
     268               0 :         return false;
     269          141355 :     bool isDirectEval = !!tc->parser->callerFrame;
     270          141355 :     SetFunctionKinds(tc->functionList, &tc->flags, isDirectEval);
     271          141355 :     return true;
     272                 : }

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