[webkit-dev] SH4, MIPS, and legacy-ARM assemblers in JavaScriptCore

[Fu, Chao-Ying]

Hi All,

  Before a MIPS buildbot is ready, you can go ahead to change the assembler or any parts of code.  We (MIPS) will test new code and submit patches that are required to fix the MIPS JSC build.  Don't need to worry about breaking the MIPS build.  (I have a cron job that checks out code and builds JSC on a native MIPS Linux every night.)  This is the current process that we use, I think.  Thanks a lot!

Regards,
Chao-ying


> -----Original Message-----
> From: Osztrogonac Csaba [mailto:oszi at inf.u-szeged.hu] 
> Sent: Wednesday, August 29, 2012 3:35 AM
> To: WebKit Development
> Cc: Holger Hans Peter Freyther; Frederic Lepied; Fu, 
> Chao-Ying; Thouraya ANDOLSI
> Subject: Re: [webkit-dev] SH4, MIPS, and legacy-ARM 
> assemblers in JavaScriptCore
> 
> Hi All,
> 
> I'd like to inquire about the future of MIPS and SH4 assemblers.
> 
> A long time ago we had buildbots for MIPS and SH4 platforms 
> (hosted by Holger).
> But their last builds were at 29th June, machine were 
> stopped, bots were removed
> from build.webkit.org (2 months before!).  Is there anyone 
> interested in maintaining
> MIPS and SH4 buildbots (and probably EWS bots) to catch build 
> failures early?
> 
> Gábor is working on fixing 
> https://bugs.webkit.org/show_bug.cgi?id=79040 and it
> seems the fix will affect all assemblers. But I don't think 
> if it is a good idea
> to try to fix MIPS and SH4 assemblers blindly without EWS and 
> buildbots. And who
> knows if MIPS and SH4 builds work now or not?
> 
> br,
> Ossy
> 
> Filip Pizlo írta:
> > Hi all,
> > 
> > We are actively trying to improve the WebKit JavaScript 
> engine (JavaScriptCore), with new debugging, profiling, 
> memory efficiency, and performance features.  Because 
> JavaScriptCore is a JIT-based engine, this inevitably means 
> doing JIT work, which in turn includes adding new 
> instructions to the JIT assemblers and changing the API 
> between the assemblers and the JIT.
> > 
> > Currently, the maintenance situation in the assembler layer 
> is not great.  We have three well-supported assemblers, 
> X86-32, X86-64, and ARMv7. Then we have three assemblers that 
> appear to be on life support: legacy (non-THUMB2, pre-v7) 
> ARM, SH4, and MIPS.  It is increasingly painful to maintain 
> these three barely-supported assemblers.  None of these 
> assemblers has been updated to support the new JIT or 
> interpreter infrastructure, and there appears to be no 
> ongoing effort to do so.  That means that for progress to be 
> made on X86 and ARMv7, we need to increasingly scatter #if 
> ENABLE(...) noise throughout the system to keep those other 
> assemblers building.  Neither the active JavaScriptCore 
> contributors, nor those running the bots for those hardware 
> platforms, appear to have much interest in maintaining those 
> assemblers, other than the occasional build fix.
> > 
> > This is not a good situation to be in.
> > 
> > So, I am curious: is anyone shipping with the legacy ARM 
> assembler, the MIPS assembler, or the SH4 assembler?
> > 
> > As a secondary question, if you are shipping the legacy ARM 
> assembler, are you doing so because you have legacy ARM 
> hardware or because you have not had the chance to switch to 
> the new ARM assembler in your codebase?
> > 
> > -Filip
>