Re: Alpha FP Fixes

Richard Henderson (richard@stommel.tamu.edu)
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
snapshots.

> 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.

r~