The generic implementation is slight more optimized than the powerpc
one, where it has a more optimized inf/nan check (by not using FP
unit checks, along with branch prediction hints), and removed one
branch by issuing trunc instead of a combination of floor/ceil (which
also generated less code).
On power10 with gcc 14.2.1:
reciprocal-throughput master patch difference
workload-0_1 1.1351 0.9067 20.12%
workload-1_maxint 1.4230 0.9040 36.47%
workload-maxint_maxfloat 1.5038 0.9076 39.65%
workload-integral 1.1280 0.9111 19.23%
latency master patch difference
workload-0_1 1.1440 2.7117 -137.03%
workload-1_maxint 4.0556 2.7070 33.25%
workload-maxint_maxfloat 3.2122 2.7164 15.43%
workload-integral 3.2381 2.7281 15.75%
Checked on powerpc64le-linux-gnu.
Reviewed-by: Sachin Monga <smonga@linux.ibm.com>
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