Correct. -----Original Message----- From: Richard Kenner [mailto:ken...@vlsi1.ultra.nyu.edu] Sent: Tuesday, August 8, 2017 1:20 PM To: Michael Collison <michael.colli...@arm.com> Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; pins...@gmail.com Subject: RE: [PATCH] [Aarch64] Optimize subtract in shift counts
> Correct. It is truncated for integer shift, but not simd shift > instructions. We generate a pattern in the split that only generates > the integer shift instructions. That's unfortunate, because it would be nice to do this in simplify_rtx, since it's machine-independent, but that has to be conditioned on SHIFT_COUNT_TRUNCATED, so you wouldn't get the benefit of it.
