[webkit-dev] Windows 32-bit support?

[Adrian Perez de Castro]

I was mistaken about one thing (sorry!), please read below...

On Tue, 25 Jun 2019 19:01:54 +0300, Adrian Perez de Castro <aperez at igalia.com> wrote:
> On Tue, 25 Jun 2019 10:42:04 -0500, Michael Catanzaro <mcatanzaro at igalia.com> wrote:
> > It's great that you find our stable branches helpful, but keep in mind 
> > those branches do not include Windows-specific fixes.
> > 
> > On Tue, Jun 25, 2019 at 9:53 AM, Arunprasad Rajkumar 
> > <ararunprasad at gmail.com> wrote:
> > > Right. Actually the problem is in 32-bit Windows platform. I see that 
> > > the JIT support has been dropped some time ago, and CLOOP based 
> > > backend seems to be unstable on 32-bit Windows. Any thoughts on that?
> > 
> > So I'm not an expert here, but I understand there are three ways you 
> > can build JSC:
> > 
> > (1) -DENABLE_JIT=ON, -DENABLE_C_LOOP=OFF
> > (2) -DENABLE_JIT=OFF, -DENABLE_C_LOOP=OFF (?)
> > (3) -DENABLE_JIT=OFF, -DENABLE_C_LOOP=ON
> > 
> > (-DENABLE_JIT=ON and -DENABLE_C_LOOP=ON are incompatible.)
> > 
> > I believe that nowadays the only 32-bit platforms supported by JIT are 
> > Linux, and there only for ARM and MIPS, not x86. So you're almost 
> > certainly going to need to use -DENABLE_JIT=OFF. That eliminates option 
> > (1).
> 
> JIT works on x86 as long as your CPU has support for SSE2 instructions.

Oops, this is not quite true: JIT does NOT work on 32-bit x86 at the moment.

(The JIT compiler does emit SSE2 instructions, though. When/If the JIT is
made to work on 32-bit x86, support for SSE2 will be needed.)
 
> > You say the cloop seems unstable for you, which is option (3). So 
> > perhaps you should try option (2) if you haven't already. I'm not 
> > actually sure if that works, because I'm not an expert, which is why I 
> > added that (?) to it. But at least it couldn't hurt to try.
> 
> Option (2) would be using the LLint bytecode interpreter, without JIT.
> 
> In principle CLoop is expected to work “everywhere” because the interpreter
> is generated C/C++ code, which gets then built by the same compiler used to
> build all the rest of WebKit.
> 
> > Maybe the Windows port maintainers know more about the status of 32-bit 
> > Windows support?
> 
> Cheers,
> —Adrián
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