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Re: [Gcl-devel] [Maxima] Out of range floating point number determinatio
Re: [Gcl-devel] [Maxima] Out of range floating point number determination
Sat, 03 Nov 2012 09:22:01 -0700
Gnus/5.1008 (Gnus v5.10.8) XEmacs/21.5-b32 (darwin)
>>>>> "Camm" == Camm Maguire <address@hidden> writes:
Camm> Greetings, and thanks!
Camm> Raymond Toy <address@hidden> writes:
>> Don't know about the value fop or foff regs. But as I understand it,
>> the sse instructions signal exceptions at the offending instruction,
>> unlike x87 where the exception is signaled at the *next* x87
>> instruction. Hence, you need the fop and fooff regs to tell you what
>> the offending instruction actually is. I think; I haven't looked at
>> that stuff in decades, probably.
Camm> Exactly. The code needs to look at the instruction pointer contents
Camm> case of SSE. fop is not zeroed out in this case, so I suppose either
Camm> differentially examining the status words for the two fpus, or
Camm> the instruction pointer and defaulting to fop if an x87 instruction,
Camm> would suffice.
Oh, you don't know if you're using x87 or sse at runtime? You should
be able to tell at compile time, right? Isn't something like __SSE2
defined (with gcc) when compiling if sse2 instructions are being used?
Camm> All of this is identical on i386 and amd64, to my understanding.
I believe so, except I think amd64 might have more xmm registers.