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<div style="direction:ltr">Huh I'll check head later.</div>
<div style="direction:ltr">No I probably removed LTO sorry, but C backend...</div>
<div style="direction:ltr">Or maybe llvm?</div>
<div style="direction:ltr">Or report latest gcc?</div>
<div style="direction:ltr">LTO doesn't scale in compile time but Llvm has ThinLTO now..</div>
<div style="direction:ltr">LTO requires linker support. A matching linker? I'm not sure.</div>
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<div class="acompli_signature">- Jay</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> Peter McKinna <peter.mckinna@gmail.com><br>
<b>Sent:</b> Monday, August 14, 2017 6:21:15 PM<br>
<b>To:</b> Jay K<br>
<b>Cc:</b> m3devel<br>
<b>Subject:</b> Re: [M3devel] modula3 fork and virtual timer</font>
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<div dir="ltr">Hi Jay,
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<div> I can't see that code anywhere in that file on git. What version are you using?</div>
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<div>By the way, you wouldnt happen to know if we can get LTO support in the backend would you? </div>
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<div>Regards Peter</div>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Aug 15, 2017 at 8:20 AM, Jay K <span dir="ltr"><<a href="mailto:jayk123@hotmail.com" target="_blank">jayk123@hotmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex; border-left:1px #ccc solid; padding-left:1ex">
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<p><br>
/mnt/d/dev2/cm3-5.8.6/m3-libs/<wbr>libm3/src/os/POSIX/<wbr>ProcessPosixCommon.m3</p>
<p><br>
</p>
<p>PROCEDURE Create_ForkExec:</p>
<p>.<br>
.<br>
.<br>
(* Turn off the interval timer (so it won't be running in child). *)</p>
<p> nit := Utime.struct_itimerval { <br>
it_interval := Utime.struct_timeval {0, 0}, <br>
it_value := Utime.struct_timeval {0, 0}}; <br>
IF Utime.setitimer(Utime.ITIMER_<wbr>VIRTUAL, nit, oit) < 0 THEN <br>
<* ASSERT FALSE *> <br>
END; <br>
. <br>
. </p>
<p> .</p>
<p> fork() </p>
<p> . <br>
. </p>
<p><br>
(* Enable scheduler. *) <br>
Scheduler.EnableSwitching (); </p>
<p> (* Restore previous virtual timer. *) <br>
IF Utime.setitimer(Utime.ITIMER_<wbr>VIRTUAL, oit, nit) < 0 THEN <br>
<* ASSERT FALSE *> <br>
END; </p>
<p> <br>
This code has a number of problems. </p>
<p> - It looks thread-unsafe -- another thread could be changing the timer. </p>
<p> </p>
<p> - The comments are wrong in multiple ways.<br>
The timer doesn't have to be turned off to not run in the child.<br>
Timers except alarm() are not inherited by child.<br>
It goes ahead and enables in the child anyway. Granted, after EnableSwitching,<br>
which also enables it! </p>
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</p>
<p> - Doesn't work on Microsoft's Windows Subsystem for Linux (WSL).</p>
<p> You get back -1/EINVAL.</p>
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</p>
<p> - Is probably specific to user threads?</p>
<p> </p>
<p>- Fails to put a useful message in the assert other than "FALSE"</p>
<p> </p>
<p>Proposals:</p>
<p> 1. Remove it.<br>
2. Make it check for and ignore EINVAL, and possibly WSL, and not then enable in child.<br>
3. Change it to get in parent and set in child if enabled. </p>
<p> 4. Move it to Thread.AtFork in user threads. Though again, not clearly needed there.</p>
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<p> 5. Consider that fork+exec should work from C/C++ code in a process that is using Modula3.</p>
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<p> 6. Research posix_spawn and use it more. </p>
<p> We can probably just use it and forget about any system that lacks it.</p>
<p><br>
Thoughts?</p>
<p> WSL can be detected by searching for "Microsoft" in /proc/sys/kernel/osrelease or /proc/version.</p>
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<p> Or we can just accept -1/EINVAL here for any OS.</p>
<span class="HOEnZb"><font color="#888888">
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<p> - Jay</p>
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