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Saying that, it might not be a bug but a design choice. If the compiler is able to extend the variable to 64 bits on the stack, it will do, including the use of "incq" over "incl" - whenever I try to exploit the upper 32 bits, the compiler is too smart for that!<br>
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The only problem is that it can hinder the peephole optimiser, and if I put in an exception that optimises, say, "movl addl movq" to "addl" or "incl" or whatnot, then that could be exploited. I'll have a think in regards to what to do with that one.<br>
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</div><div>Gareth aka. Kit<br>
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<span style="font-weight: bold;">On Sat 22/12/18 20:04 , "J. Gareth Moreton" gareth@moreton-family.com sent:<br>
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Have to apologise again for my web client making life difficult for the mail archive system.<br>
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Currently I'm a little reluctant to put in the "incq" fix because the code isn't equivalent. More than anything, it's a very minor bug with the node system in that it writes the full 64-bit register instead of the 32-bit register for LongInts and LongWords, it seems. I might be able to exploit the bug in a very narrow range of circumstances, and if I'm able to make a reproducible test case, I'll report it.<br>
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Nevertheless, if I'm not able to exploit it, it's something that might be worth fixing if only because it will make optimisation easier and correct.<br>
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<div>Also note that "INC" is generally only generated if you're optimising for size, because modern CPUs work better with "ADD" due to how it modifies the RFLAGS register.<br>
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For the overhaul in general, I have it ported over to i386 on my working branch, since I've got x86_64 working without any breaking bugs.<br>
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Even if just for a temporary debugging measure, I'm considering options to allow the writing of node trees to an XML file or some such, since I think this will allow easier debugging of that part of the compiler.<br>
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</div><div>Gareth aka. Kit<br>
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