Bug 124177 – REGRESSION (r158014): Many webpages throw stack overflow exceptions on iOS (because Parser::parseMemberExpression uses ~130K more stack)

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Michael Saboff]

The introduction of StringPrintStream as well as WTFString variables in http://trac.webkit.org/changeset/158014 in the error handling macros caused an increase in the stack space needed by Parser<LexerType>::parseMemberExpression.  On a X86 32 bit build, the size of the frame for parseMemberExpression (ebp - esp) is 82+K.

According to disassembly of parseMemberExpression, counting the number of StringPrintStream constructor calls we end up with 336.  Each of these appears to be allocated on the stack and has a static buffer of 128 bytes.  There are also 1348 calls to the String() destructor. Each of the strings is a RefPtr and a StringImpl, which also appear to be allocated on the stack.

Moving the StringPrintStream in the error macros to a member of the Parser class reduced the frame size to ~36K.  Even after the reduction we still get a "RangeError: Maximum call stack size exceeded.” JSC exception.

[Oliver Hunt]

hurk, i'll look into pushing that code out of the arser functions

[Geoffrey Garen]

<rdar://problem/15450444>

[Oliver Hunt]

Created attachment 216821 [details]
Patch

[Oliver Hunt]

Committed r159210: <http://trac.webkit.org/changeset/159210>