Re: [Qemu-devel] [PATCH] tests/tcg: add float_madds test to multiarch

[Alex Bennée]

Richard Henderson <address@hidden> writes:

> On 9/13/19 9:49 AM, Alex Bennée wrote:
>> +                    /* must be built with -O2 to generate fused op */
>> +                    r = a * b + c;
>
> I would prefer to use fmaf() or __builtin_fmaf() here.
>
> Although you'll need to link with -lm just in case the
> target doesn't support an instruction for fmaf and so
> the builtin expands to the standard library call.

I can do that - we have other tests that link to libm.

I was expecting to see more breakage but the ppc64 tests all passed (or
at least against the power8 David ran it on). What am I missing to hit
the cases you know are broken?

I've also experimented with reducing the number of iterations because if
we want to have golden references we probably don't want to dump several
hundred kilobytes of "golden" references into the source tree.

> I also like Paul's suggestion to use hex float constants.

Hmm I guess - look a bit weird but I guess that's lack of familiarity.
Is is still normalised? I guess the frac shows up (without the implicit
bit).

>
>
> r~


--
Alex Bennée