On 6/28/24 17:53, Vineet Gupta wrote:
> Currently isfinite and isnormal use float compare instructions with fp
> flags save/restored around them. Our perf team complained this could be
> costly in uarch. RV Base ISA already has FCLASS.{d,s,h} instruction to
> do FP compares w/o disturbing FP exception flags.
>
> Coincidently, upstream ijust few days back got support for the
> corresponding optabs. All that is needed is to wire these up in the
> backend.
>
> I was also hoping to get __builtin_inf() done but unforutnately it
> requires little more rtl foo/bar to implement a tri-modal return.
>
> Currently going thru CI testing.
My local testing spotted one additional failure.
FAIL: g++.dg/opt/pr107569.C -std=gnu++20 scan-tree-dump-times vrp1
"return 1;" 2
The reason being
bool
bar (double x)
{
[[assume (std::isfinite (x))]];
return std::isfinite (x);
}
generating the new seq
.LFB4:
fclass.d a0,fa0
andi a0,a0,126
snez a0,a0
ret
vs.
li a0,1
ret
I have a hunch this requires the pending value range patch from Hao Chen
GUI.
Thx,
-Vineet
[1] https://gcc.gnu.org/pipermail/gcc-patches/2024-May/653094.html
