*To*: Paolo Bonzini <paolo.bonzini@polimi.it>, debian-alpha@lists.debian.org*Subject*: Re: math-emu on buildd machine?*From*: Paolo Bonzini <paolo.bonzini@polimi.it>*Date*: Mon, 14 Jan 2008 09:32:11 +0100*Message-id*: <[🔎] 478B1E0B.6010602@polimi.it>*In-reply-to*: <[🔎] 20080114071211.GA19588@dario.dodds.net>*References*: <[🔎] 478A0BB5.4060504@lu.unisi.ch> <[🔎] 20080113221942.GA19955@dario.dodds.net> <[🔎] 478B0407.1070700@polimi.it> <[🔎] 20080114071211.GA19588@dario.dodds.net>

So that might be a known errata? The following program should yield 1.4013e-45 twice (the bug might show up only at -mieee -O0, I don't know).float x = 1.0; double y;int g(float z) { printf ("%g\n", z); }Well, AFAICS this is an error; %g refers to a double, and you're passing a float, so that output would be undefined.

But regardless of whether I add a (double) cast here, and regardless of whether I use -mieee (which should still be the default now on Debian's gcc), if I build with -O2, I get 2.65249e-315 printed out twice. If I build with -O0 I instead get 2.65249e-315 0

Beyond that, I haven't looked closely at the math you're doing to verify that the alpha is getting it wrong, but I can confirm that this problem is consistently reproducible and isn't tied to math-emu.

Paolo

**References**:**math-emu on buildd machine?***From:*Paolo Bonzini <paolo.bonzini@lu.unisi.ch>

**Re: math-emu on buildd machine?***From:*Steve Langasek <vorlon@debian.org>

**Re: math-emu on buildd machine?***From:*Paolo Bonzini <paolo.bonzini@polimi.it>

**Re: math-emu on buildd machine?***From:*Steve Langasek <vorlon@debian.org>

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