Date: Sun, 12 Jan 2003 13:14:11 -0800 (PST) From: John Polstra <jdp@polstra.com> To: Jake Burkholder <jake@locore.ca> Cc: sparc@FreeBSD.ORG Subject: Re: Question about odd stack pointer values on sparc64 Message-ID: <XFMail.20030112131411.jdp@polstra.com> In-Reply-To: <20030112155525.K212@locore.ca>
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Jake Burkholder wrote: > Apparently, On Sun, Jan 12, 2003 at 12:44:44PM -0800, > John Polstra said words to the effect of; > >> In GDB I notice that the stack pointer and frame pointer are often >> (always?) odd numbers, e.g.: [...] > Its because the stack is offset by -2047, to get the real stack pointer > add 2047. Ohhhhh! No _wonder_ M3 hasn't been working right ... > As for reasons why this was done, apparently it allows a larger region > of stack to be addressed with 13 bit immediate offsets, also 32 bit sparc > code doesn't use a stack bias so it can be distinguished by testing the > alignment of the unmodified stack pointer. Makes sense. Thanks for the info! John To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-sparc" in the body of the message
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