Rename the tuning option and related functions to enable the Newton series for the reciprocal square root to reflect its approximative characteristic.
gcc/
* config/aarch64/aarch64-protos.h (aarch64_emit_swrsqrt): Rename
function to "aarch64_emit_approx_rsqrt".
* config/aarch64/aarch64-tuning-flags.def: Rename tuning flag to
AARCH64_EXTRA_TUNE_APPROX_RSQRT.
* config/aarch64/aarch64.c (exynosm1_tunigs): Use new flag name.
(xgene1_tunings): Likewise.
(use_rsqrt_p): Likewise.
(aarch64_emit_swrsqrt): Use new function name.
* config/aarch64/aarch64-simd.md (aarch64_rsqrts_*): Likewise.
* config/aarch64/aarch64.opt (mlow-precision-recip-sqrt): Reword the
text explaining this option.
* doc/invoke.texi (-mlow-precision-recip-sqrt): Likewise.
From-SVN: r233772
