Bug 203942

Summary: Remove remnants of support code for an upwards growing stack.
Product: WebKit Reporter: Mark Lam <mark.lam>
Component: JavaScriptCoreAssignee: Mark Lam <mark.lam>
Status: RESOLVED FIXED    
Severity: Normal CC: benjamin, cdumez, cmarcelo, dbates, ews-watchlist, keith_miller, msaboff, saam, tzagallo, webkit-bug-importer, ysuzuki
Priority: P2 Keywords: InRadar
Version: WebKit Nightly Build   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
proposed patch. ysuzuki: review+

Description Mark Lam 2019-11-06 21:56:52 PST 
We haven't supported an upwards growing stack in years, and a lot of code has since been written specifically with only a downwards growing stack in mind (e.g. the LLInt, the JITs).  Also, all our currently supported platforms use a downward growing stack.

We should remove the remnants of support code for an upwards growing stack.  The presence of that code is deceptive in that it conveys support for an upwards growing stack where this hasn't been the case in years.
Comment 1 Mark Lam 2019-11-06 22:02:11 PST 
Created attachment 383022 [details]
proposed patch.
Comment 2 Yusuke Suzuki 2019-11-06 22:10:11 PST 
Comment on attachment 383022 [details]
proposed patch.

r=me
Comment 3 Mark Lam 2019-11-06 22:21:49 PST 
Comment on attachment 383022 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=383022&action=review

Thanks for the review.

> Source/WTF/wtf/StackBounds.h:113
> +        ASSERT(m_bound <= m_origin);

This one is redundant from a partial edit.  I opted to go with the private isGrowingDownwards() methods instead because it documents at a glance what we're asserting here.  I'll remove this redundant line before landing.
Comment 4 Mark Lam 2019-11-06 23:28:27 PST 
Landed in r252177: <http://trac.webkit.org/r252177>.
Comment 5 Radar WebKit Bug Importer 2019-11-06 23:29:16 PST 
<rdar://problem/56973526>