Date: Tue, 11 Apr 2000 16:50:03 -0700 (PDT) From: Randall Hopper <aa8vb@ipass.net> To: freebsd-bugs@FreeBSD.org Subject: Re: i386/17914: float-to-double core dump on 3.4R Message-ID: <200004112350.QAA53221@freefall.freebsd.org>
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The following reply was made to PR i386/17914; it has been noted by GNATS. From: Randall Hopper <aa8vb@ipass.net> To: Kevin Day <toasty@dragondata.com>, Bruce Evans <bde@zeta.org.au>, Thomas David Rivers <rivers@dignus.com> Cc: FreeBSD-gnats-submit@FreeBSD.ORG Subject: Re: i386/17914: float-to-double core dump on 3.4R Date: Tue, 11 Apr 2000 19:42:02 -0400 Randall Hopper: |Ok, thanks for your clarification. That seems like very odd behavior to |wait until the "next" floating point instruction before signaling the |exception for the prior. That could potentially be pages away in the |instruction stream. Thomas David Rivers: |> Intuitively it seems like a bug (like waiting for a while before |> tripping a divide by zero fault). But I'll trust that you know more |> about the issues involved here than I do. | | It's how the fpu works in the x86 chip; an artifact of when the | FPU was a different chip. | | Some x86 compilers can be told to emit an extra instruction (kinda | like a dummy floating pt. instruction) so that any except can be | caught synchronously; but when you do this, it *really* slows down | floating point operations. Ok, thank you. That makes sense. I understand the behavior now. Randall. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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