wine/gecko
0
0
Fork 0
mirror of https://gitlab.winehq.org/wine/wine-gecko.git synced 2024-09-13 09:24:08 -07:00
Code Issues Packages Projects Releases Wiki Activity

Bug 394673: avoid recursion with long chains of "||" or "&&" in JS code. r=brendan

Browse Source
This commit is contained in:
igor@mir2.org 2007-09-19 14:53:17 -07:00
parent 0badcb469f
commit fe1659e34d
3 changed files with 50 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
js/src/jsemit.c
View File

@ -5590,42 +5590,57 @@ js_EmitTree(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
* JSOP_AND converts the operand on the stack to boolean, and if false,
* leaves the original operand value on the stack and jumps; otherwise
* it pops and falls into the right operand's bytecode.
*
* Avoid tail recursion for long ||...|| expressions and long &&...&&
* expressions or long mixtures of ||'s and &&'s that can easily blow
* the stack, by forward-linking and then backpatching all the JSOP_OR
* and JSOP_AND bytecodes' immediate jump-offset operands.
*/
pn3 = pn;
if (!js_EmitTree(cx, cg, pn->pn_left))
return JS_FALSE;
top = EmitJump(cx, cg, JSOP_BACKPATCH_POP, 0);
if (top < 0)
return JS_FALSE;
jmp = top;
pn2 = pn->pn_right;
while (pn2->pn_type == TOK_OR || pn2->pn_type == TOK_AND) {
pn = pn2;
if (pn->pn_arity == PN_BINARY) {
if (!js_EmitTree(cx, cg, pn->pn_left))
return JS_FALSE;
off = EmitJump(cx, cg, JSOP_BACKPATCH_POP, 0);
if (off < 0)
top = EmitJump(cx, cg, JSOP_BACKPATCH_POP, 0);
if (top < 0)
return JS_FALSE;
if (!SetBackPatchDelta(cx, cg, CG_CODE(cg, jmp), off - jmp))
if (!js_EmitTree(cx, cg, pn->pn_right))
return JS_FALSE;
jmp = off;
pn2 = pn->pn_right;
}
if (!js_EmitTree(cx, cg, pn2))
return JS_FALSE;
off = CG_OFFSET(cg);
do {
off = CG_OFFSET(cg);
pc = CG_CODE(cg, top);
tmp = GetJumpOffset(cg, pc);
CHECK_AND_SET_JUMP_OFFSET(cx, cg, pc, off - top);
*pc = pn3->pn_op;
top += tmp;
} while ((pn3 = pn3->pn_right) != pn2);
*pc = pn->pn_op;
} else {
JS_ASSERT(pn->pn_arity == PN_LIST);
JS_ASSERT(pn->pn_head->pn_next->pn_next);
/* Left-associative operator chain: avoid too much recursion. */
pn2 = pn->pn_head;
if (!js_EmitTree(cx, cg, pn2))
return JS_FALSE;
top = EmitJump(cx, cg, JSOP_BACKPATCH_POP, 0);
if (top < 0)
return JS_FALSE;
/* Emit nodes between the head and the tail. */
jmp = top;
while ((pn2 = pn2->pn_next)->pn_next) {
if (!js_EmitTree(cx, cg, pn2))
return JS_FALSE;
off = EmitJump(cx, cg, JSOP_BACKPATCH_POP, 0);
if (off < 0)
return JS_FALSE;
if (!SetBackPatchDelta(cx, cg, CG_CODE(cg, jmp), off - jmp))
return JS_FALSE;
jmp = off;
}
if (!js_EmitTree(cx, cg, pn2))
return JS_FALSE;
pn2 = pn->pn_head;
off = CG_OFFSET(cg);
do {
pc = CG_CODE(cg, top);
tmp = GetJumpOffset(cg, pc);
CHECK_AND_SET_JUMP_OFFSET(cx, cg, pc, off - top);
*pc = pn->pn_op;
top += tmp;
} while ((pn2 = pn2->pn_next)->pn_next);
}
break;
case TOK_BITOR:

4
js/src/jsopcode.tbl
View File

@ -171,8 +171,8 @@ OPDEF(JSOP_NULL, 64, js_null_str, js_null_str, 1, 0, 1, 19, JOF_BYTE)
OPDEF(JSOP_THIS, 65, js_this_str, js_this_str, 1, 0, 1, 19, JOF_BYTE)
OPDEF(JSOP_FALSE, 66, js_false_str, js_false_str, 1, 0, 1, 19, JOF_BYTE)
OPDEF(JSOP_TRUE, 67, js_true_str, js_true_str, 1, 0, 1, 19, JOF_BYTE)
OPDEF(JSOP_OR, 68, "or", NULL, 3, 1, 0, 5, JOF_JUMP|JOF_DETECTING)
OPDEF(JSOP_AND, 69, "and", NULL, 3, 1, 0, 6, JOF_JUMP|JOF_DETECTING)
OPDEF(JSOP_OR, 68, "or", NULL, 3, 1, 0, 5, JOF_JUMP|JOF_DETECTING|JOF_LEFTASSOC)
OPDEF(JSOP_AND, 69, "and", NULL, 3, 1, 0, 6, JOF_JUMP|JOF_DETECTING|JOF_LEFTASSOC)
/* The switch bytecodes have variable length. */
OPDEF(JSOP_TABLESWITCH, 70, "tableswitch", NULL, -1, 1, 0, 0, JOF_TABLESWITCH|JOF_DETECTING|JOF_PARENHEAD)

8
js/src/jsparse.c
View File

@ -3993,8 +3993,8 @@ OrExpr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc)
JSParseNode *pn;
pn = AndExpr(cx, ts, tc);
if (pn && js_MatchToken(cx, ts, TOK_OR))
pn = NewBinary(cx, TOK_OR, JSOP_OR, pn, OrExpr(cx, ts, tc), tc);
while (pn && js_MatchToken(cx, ts, TOK_OR))
pn = NewBinary(cx, TOK_OR, JSOP_OR, pn, AndExpr(cx, ts, tc), tc);
return pn;
}
@ -4004,8 +4004,8 @@ AndExpr(JSContext *cx, JSTokenStream *ts, JSTreeContext *tc)
JSParseNode *pn;
pn = BitOrExpr(cx, ts, tc);
if (pn && js_MatchToken(cx, ts, TOK_AND))
pn = NewBinary(cx, TOK_AND, JSOP_AND, pn, AndExpr(cx, ts, tc), tc);
while (pn && js_MatchToken(cx, ts, TOK_AND))
pn = NewBinary(cx, TOK_AND, JSOP_AND, pn, BitOrExpr(cx, ts, tc), tc);
return pn;
}