Re: Alpha FP Fixes

Richard Henderson (
Tue, 10 Jun 1997 19:00:23 -0500 (CDT)

> The first problem is that the Dec Unix boxes default to trapping
> floating point exceptions and doing the IEEE math, where the default
> under Linux is not do that. I changes set_program_attributes to reset
> those flags for the current process. That's patch number one.

That is actually a libc problem. It seems that despite the comment
that the default fp settings were to disable exceptions, the bits
just below enabled them. Anyway, it is fixed in recent glibc

> The second problem is that there is an instruct CVTQL which actually
> causes a floating point exception even though it isn't a floating point
> operation. The code to emulate this instruction was writen, but was
> never being called in alpha_fp_emul_imprecise. That's patch number two.

That's wrong too.

> #define OPC_FLTV 0x14
> #define OPC_FLTI 0x15
> #define OPC_FLTL 0x16

These three are all off by one. They are fixed in a patch I sent to
Linus a week or two ago.