[AArch64] Emit division using the Newton series

[Evandro Menezes]

On 03/17/16 15:09, Evandro Menezes wrote:
> This patch implements FP division by an approximation using the Newton 
> series.
>
> With this patch, DF division is sped up by over 100% and SF division, 
> zilch, both on A57 and on M1.

         gcc/
             * config/aarch64/aarch64-tuning-flags.def
             (AARCH64_EXTRA_TUNE_APPROX_DIV_{SF,DF}: New tuning macros.
             * config/aarch64/aarch64-protos.h
             (AARCH64_EXTRA_TUNE_APPROX_DIV): New macro.
             (aarch64_emit_approx_div): Declare new function.
             * config/aarch64/aarch64.c
             (aarch64_emit_approx_div): Define new function.
             * config/aarch64/aarch64.md ("div<mode>3"): New expansion.
             * config/aarch64/aarch64-simd.md ("div<mode>3"): Likewise.


This version of the patch cleans up the changes to the MD files and 
optimizes the division when the numerator is 1.0.

Again, I look forward to your feedback.

Thank you,

-- 
Evandro Menezes