<html><head><base href="x-msg://291/"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">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>
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<br><div><div>On 13 Mar 2010, at 05:19, Jay K wrote:</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; "><*UNUSED*>PROCEDURE CardinalGE0(a:CARDINAL):BOOLEAN=BEGIN RETURN a>=0; END CardinalGE0;<br><*UNUSED*>PROCEDURE CardinalEQN1(a:CARDINAL):BOOLEAN=BEGIN RETURN a=-1; END CardinalEQN1;<br><br> <br>Seems to me, the front end should notice these.<br>The first should always be TRUE.<br> And possibly, possibly warn.<br>The second should always be FALSE.<br> And possibly, possibly warn.<br> <br>"Generic" programming often hits this sort of thing though, a good reason not to warn.<br>Programmer might also be working with existing code and have changed INTEGER to CARDINAL.<br> Or be defending against future maintainers changing CARDINAL to INTEGER.<br> <br> <br>The backend isn't give enough information, because CARDINAL = INTEGER as far<br>as it is told. 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></body></html>