<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Jay,<div><br></div><div>I have reverted your commits because they violate the language definition. Constant folding in the front-end is there only to support ha language definition of constant expressions. Your changes violated that spec. If you want such optimisations they should be performed in the back-end, or if we ever get one, in an optimising middle-end.</div><div><br></div><div><span class="Apple-style-span" style="font-size: 12px; "><font class="Apple-style-span" color="#0000FF"><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; "><span class="Apple-style-span" style="color: rgb(0, 0, 255); font-family: 'Gill Sans'; ">Antony Hosking</span></span></font></font><font class="Apple-style-span" face="Gill Sans"><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; "> | </span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; ">Associate Professor</span></span><span class="Apple-style-span" style="font-family: 'Gill Sans'; "><span class="Apple-style-span" style="font-family: 'Gill Sans'; 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<br><div><div>On 13 Mar 2010, at 14:23, Tony Hosking wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; 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text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><span class="Apple-style-span" style="border-collapse: separate; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; -webkit-text-decorations-in-effect: none; text-indent: 0px; -webkit-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><div><span class="Apple-style-span" style="font-size: medium; ">On 13 Mar 2010, at 13:26, Jay K wrote:</span></div></span></span></span></span></span></span></span></span></div></span></span></div><div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">Tony these are simple target-independent optimizations. I would dislike for each backend to do target-independent optimizations. Where can we put those? The front end currently does several. For example, operations on sets that fit in an integer. Division by powers of 2, Unrolling comparisons of records and sets (at least up to a certain size), removing runtime operations that are known to violate subranges (e.g. in insert/extract), occasional constant folding (in the same functions I modified), etc.<br> <br> <br>What is the point of these functions Fold?<br></div></span></blockquote><div><br></div><div>So that constants can be manipulated as first-class values in the language. See <a href="http://www.cs.purdue.edu/homes/hosking/m3/reference/constexpr.html">http://www.cs.purdue.edu/homes/hosking/m3/reference/constexpr.html</a>. There are many places where a compile-time constant expression is required. Fold is *not* intended for performing optimisations.</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">Why does it have these various "cost" computations?<br></div></span></blockquote><div><br></div><div>Which cost computations are you referring to?</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">Granted, they are rough.<br> <br> <br>Should we beef up m3middle?<br></div></span></blockquote><div><br></div><div>That might be the place... but ad hoc add-ons to m3front like you have been leaning towards are probably not the right place. Designing a reasonable place for all of these optimisations will take effort. I don't want to see us degrading the maintainability of m3front with gratuitous optimisations of dubious value.</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">m3back doesn't optimize comparisons to constants, and a *lot* of what it does is target-independent.<br>It would be nice to factor it better so that x86-independent code is not in files with "x86" in their name.<br>It'd be nice to extend it to AMD64 for example (which is why I was worrying about my notions of "TypeIs64" and multiplying register counts times 4 to get byte counts, etc..) and maybe even to Sparc, PPC, ARM, etc.<br></div></span></blockquote><div><br></div><div>Designing a decent optimising middle-end takes significant time and effort, and will require more thought.</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; "> m3back is correct or extremely close to correct as far as I know.<br>It is missing atomic operations for 8, 16, 64 bit operands.<br></div></span></blockquote><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; "> (PPC32 seems unable to support 64bit atomics btw.)<br></div></span></blockquote><div><br></div><div>Correct.</div><br><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div class="hmmessage" style="font-size: 10pt; font-family: Verdana; ">I have to test the subrange stuff for 64bit operands. It might work, but I think optimizations are missing there as well.<br> <br> <br>I'd also like to maybe inline more operations..and I was thinking about implementing inlining in general. It might not be so difficult.<br> <br> <br> - Jay<br><br> <br><hr id="stopSpelling">From:<span class="Apple-converted-space"> </span><a href="mailto:hosking@cs.purdue.edu">hosking@cs.purdue.edu</a><br>Date: Sat, 13 Mar 2010 13:03:18 -0500<br>To:<span class="Apple-converted-space"> </span><a href="mailto:jay.krell@cornell.edu">jay.krell@cornell.edu</a><br>CC:<span class="Apple-converted-space"> </span><a href="mailto:m3devel@elegosoft.com">m3devel@elegosoft.com</a><br>Subject: Re: [M3devel] comparisons vs. subranges<br><br>Jay,<div><br></div><div>I am disturbed that you are inserting optimisations into the front-end that don't really belong there. The front-end is responsible for semantics and not optimisation. It was never designed to be an optimising compiler. There are better ways to go about working in optimisation, but I would hate to muddy the waters of the front-end the way you seem to intend. Let's not go down this path until there is consensus! One approach would involve communicating more information to the "back"-ends (actually, the gcc back-end should be considered a middle-end from the global perspective of optimising compilers). For example, the back-ends gets very little in the way of type information (as you note w.r. to CARDINAL). In any case, I suggest that you not obsess about performance right now but simply concentrate on correctness in your backend.</div><div><br><div><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div style="word-wrap: break-word; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><span class="ecxApple-style-span" style="text-transform: none; text-indent: 0px; border-collapse: separate; font: normal normal normal 12px/normal Helvetica; white-space: normal; letter-spacing: normal; color: rgb(0, 0, 0); word-spacing: 0px; "><div><font class="ecxApple-style-span" color="#0000ff"><font class="ecxApple-style-span" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; color: rgb(0, 0, 255); ">Antony Hosking</span></span></font></font><font class="ecxApple-style-span" face="Gill Sans"><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-converted-space"> </span>|<span class="ecxApple-converted-space"> </span></span></span><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; ">Associate Professor</span></span><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "><span class="ecxApple-style-span" style="font-family: 'Gill Sans'; "> | Computer Science | Purdue University</span></span></font></div><div><font class="ecxApple-style-span" face="GillSans-Light"><span class="ecxApple-style-span" style="font-family: GillSans-Light; ">305 N. 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Due to the half range of CARDINAL and LONGCARD, that isn't wrong.<br>The only way to get unsigned types is to use ADDRESS from what I see.<br> <br> <br> - Jay<br><br></div></span></blockquote></div><br></div></div></span><br class="Apple-interchange-newline"></blockquote></div><br></div></blockquote></div><br></div></body></html>