This case is covered by Wilco's previous reply: https://gcc.gnu.org/ml/gcc-patches/2017-08/msg00575.html
-----Original Message----- From: Richard Kenner [mailto:ken...@vlsi1.ultra.nyu.edu] Sent: Tuesday, August 8, 2017 5:13 AM 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 > The pattern will only be matched if the value is positive. More > specifically if the constant value is 32 (SImode) or 64 (DImode). I don't mean the constant, but the value subtracted from it. If that's negative, then we have a shift count larger than the wordsize.
