<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">I think we can argue that a programmer should program around this using TRY...FINALLY (i.e., even if they used FloatMode).<div><br></div><div>So, I think we are safe with jmpbuf instead of sigjmpbuf.<br><div><br><div>
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<br><div><div>On 8 May 2010, at 18:56, Jay K wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div><br>Is "proper" saving/restoring as much as we can think of, or is it fast, or is it matching Ada and C++, or .. ?<br>Ada and C++ (gnat and g++) have often/historically used setjmp/longjmp.<br> configure -enable-sjlj-exceptions<br>It might be interesting to see if they try to avoid the signal mask versions when they use setjmp/longjmp.<br>Lately they use table-based unwinding on platforms that they can -- which is to say, I *really* doubt<br>they save/restore the signal mask, but they might.<br><br><br> - Jay<br><br>----------------------------------------<br><blockquote type="cite">Subject: Re: [M3commit] CVS Update: cm3<br></blockquote><blockquote type="cite">From: <a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a><br></blockquote><blockquote type="cite">Date: Sat, 8 May 2010 18:51:18 -0400<br></blockquote><blockquote type="cite">CC: <a href="mailto:jkrell@elego.de">jkrell@elego.de</a>; <a href="mailto:m3commit@elegosoft.com">m3commit@elegosoft.com</a><br></blockquote><blockquote type="cite">To: <a href="mailto:jay.krell@cornell.edu">jay.krell@cornell.edu</a><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">On 8 May 2010, at 18:38, Jay K wrote:<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><blockquote type="cite">Or, understood, you really think we might throw around a signal mask change?<br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">It's possible.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><blockquote type="cite">Realize also that sigsetjmp or setjmp, whichever we use, is called incredibly often, and sigsetjmp is likely<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">much much slower. Also notice..this I'll have to check...have we ever called sigsetjmp?<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Well, no, I doubt it. But maybe setjmp vs. _setjmp.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Again though, this can be significantly slow.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Ultimately as well...see..I started this email without a firm opinion, but now I'm "firming" toward the change I made.<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Consider C++ exceptions. Consider libunwind. Consider the SPARC stack walker (which I have to look at).<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">Do they save/restore signal masks? I doubt it. Maybe. We can look into it. But I doubt it.<br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">We should confirm.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><blockquote type="cite">Raising an exception can indeed by slow. But entering a function with finally (or destructors) should not be overly so.<br></blockquote></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite">Ultimately, we should use proper stack unwinding wherever possible.<br></blockquote><blockquote type="cite"><br></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">- Jay<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite">----------------------------------------<br></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">From: <a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Date: Sat, 8 May 2010 18:28:36 -0400<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">To: <a href="mailto:jkrell@elego.de">jkrell@elego.de</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">CC: <a href="mailto:m3commit@elegosoft.com">m3commit@elegosoft.com</a><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Subject: Re: [M3commit] CVS Update: cm3<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Ah, now I remember. sigjmpbuf is important for unwinding on exception to make sure that if we unwind through a frame where the programmer changed the signal mask that we also restore the signal mask of the caller. I think you also probably break things like FloatMode by not restoring the signal mask properly.<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">On 9 May 2010, at 00:09, Jay Krell wrote:<br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">CVSROOT: /usr/cvs<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Changes by: jkrell@birch. 10/05/09 00:09:58<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Modified files:<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">cm3/m3-sys/m3middle/src/: Target.i3 Target.m3<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Log message:<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">add SPARC32_SOLARIS<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">correct jmpbuf sizes for I386_SOLARIS, AMD64_SOLARIS<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">notice again that jmpbuf is much much smaller than sigjmpbuf,<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">and this is jmpbuf; specifically:<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">I386_SOLARIS jmpbuf 40 bytes with 4 align<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">AMD64_SOLARIS jmpbuf 64 bytes with 8 align<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">I386_SOLARIS sigjmpbuf 512 bytes with 4 align<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">AMD64_SOLARIS sigjmpbuf 1024 bytes with 8 align<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">remove some level of heap allocation of calling conventions<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">accept all calling conventions for all targets<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">Only NT386 has calling conventions, and it *highly* likely<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">the only target ever to have them, therefore the mechanism<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">does not need to be further generalized. (MIPS32 has two<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">ABIs, but those will probably be two targets)<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">This might let us save some unnecessary forking of *.i3 files.<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">The initialization here can be further streamlined.<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">shrink SOLgnu/SOLsun from sigjmpbuf to jmpbuf<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">I'm not sure we use this though since we have a stack walker.<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">fix SPARC64_SOLARIS too to be smaller<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">SPARC32_SOLARIS<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">jmpbuf size: 48<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">sigjmpbuf size: 76<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">alignment: 4 4<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">SPARC64_SOLARIS<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">jmpbuf size: 96<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">sigjmpbuf size: 152<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><blockquote type="cite">alignment: 8 8<br></blockquote></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote></blockquote><blockquote type="cite"><blockquote type="cite"><br></blockquote></blockquote><blockquote type="cite"><br></blockquote> <span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span> <span class="Apple-tab-span" style="white-space:pre"> </span> <span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"> </span> <br></div></blockquote></div><br></div></div></body></html>