> I see. But the implementation challenge is that this interacts badly with SSA > coalescing done before this and thus should really happen on GIMPLE before > that. > > And yes, I also like to see more of this, it's basically doing some > instruction > selection on (late) GIMPLE. Ideally we'd be able to generate an expand.pd > match.pd variant from the machine description (named) define_insns, > creating IFNs that we know how to expand.
Fair enough, Just to check I understood correctly. It should be a match.pd rule that uses a match predicate, so expand in gimple-match.c. but don't do this if the target doesn't have the xorsign optab and don't do it if honouring SNAN. I'll make the changes then. Thanks, Tamar > > Think of a combine pass combining GIMPLE stmts to (recognized) RTL insn > (sequences). Until RTL expansion the RTL insn (sequence) would be > represented by an internal function call (or alternatively for multi-output > cases an GIMPLE ASM with enumerated asm text). > > Richard. > > > > Thanks, > > > Richard. > > > > > > > > > > > gcc/ > > > > 2017-07-10 Tamar Christina <tamar.christ...@arm.com> > > > > Andrew Pinski <pins...@gmail.com> > > > > > > > > PR middle-end/19706 > > > > * expr.c (is_copysign_call_with_1): New. > > > > (maybe_expand_mult_copysign): Likewise. > > > > (expand_expr_real_2): Expand copysign. > > > > * optabs.def (xorsign_optab): New. > > > > > > > > ________________________________________ > > > > From: Andrew Pinski <pins...@gmail.com> > > > > Sent: Monday, July 10, 2017 12:21:29 AM > > > > To: Tamar Christina > > > > Cc: GCC Patches; nd; l...@redhat.com; i...@airs.com; > > > > rguent...@suse.de > > > > Subject: Re: [GCC][PATCH][mid-end] Optimize x * copysign (1.0, y) > > > > [Patch (1/2)] > > > > > > > > On Mon, Jun 12, 2017 at 12:56 AM, Tamar Christina > > > > <tamar.christ...@arm.com> wrote: > > > > > Hi All, > > > > > > > > > > this patch implements a optimization rewriting > > > > > > > > > > x * copysign (1.0, y) and > > > > > x * copysign (-1.0, y) > > > > > > > > > > to: > > > > > > > > > > x ^ (y & (1 << sign_bit_position)) > > > > > > > > > > This is done by creating a special builtin during matching and > > > > > generate the appropriate instructions during expand. This new > > > > > builtin is > > > called XORSIGN. > > > > > > > > > > The expansion of xorsign depends on if the backend has an > > > > > appropriate optab available. If this is not the case then we use > > > > > a modified version of the existing copysign which does not take > > > > > the abs > > > value of the first argument as a fall back. > > > > > > > > > > This patch is a revival of a previous patch > > > > > https://gcc.gnu.org/ml/gcc-patches/2015-10/msg00069.html > > > > > > > > > > Bootstrapped on both aarch64-none-linux-gnu and x86_64 with no > > > issues. > > > > > Regression done on aarch64-none-linux-gnu and no regressions. > > > > > > > > > > > > Note this is also PR 19706. > > > > > > > > Thanks, > > > > Andrew > > > > > > > > > > > > > > Ok for trunk? > > > > > > > > > > gcc/ > > > > > 2017-06-07 Tamar Christina <tamar.christ...@arm.com> > > > > > > > > > > * builtins.def (BUILT_IN_XORSIGN, BUILT_IN_XORSIGNF): New. > > > > > (BUILT_IN_XORSIGNL, BUILT_IN_XORSIGN_FLOAT_NX): > Likewise. > > > > > * match.pd (mult (COPYSIGN:s real_onep @0) @1): New > simplifier. > > > > > (mult (COPYSIGN:s real_mus_onep @0) @1): Likewise. > > > > > (copysigns @0 (negate @1)): Likewise. > > > > > * builtins.c (expand_builtin_copysign): Promoted local to > argument. > > > > > (expand_builtin): Added CASE_FLT_FN_FLOATN_NX > > > (BUILT_IN_XORSIGN) and > > > > > CASE_FLT_FN (BUILT_IN_XORSIGN). > > > > > (BUILT_IN_COPYSIGN): Updated function call. > > > > > * optabs.h (expand_copysign): New bool. > > > > > (expand_xorsign): New. > > > > > * optabs.def (xorsign_optab): New. > > > > > * optabs.c (expand_copysign): New parameter. > > > > > * fortran/f95-lang.c (xorsignl, xorsign, xorsignf): New. > > > > > * fortran/mathbuiltins.def (XORSIGN): New. > > > > > > > > > > gcc/testsuite/ > > > > > 2017-06-07 Tamar Christina <tamar.christ...@arm.com> > > > > > > > > > > * gcc.dg/tree-ssa/xorsign.c: New. > > > > > * gcc.dg/xorsign_exec.c: New. > > > > > * gcc.dg/vec-xorsign_exec.c: New. > > > > > * gcc.dg/tree-ssa/reassoc-39.c (f2, f3): Updated constant to > > > > > 2. > > > > > > > > > > -- > > > Richard Biener <rguent...@suse.de> > > > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham > > > Norton, HRB 21284 (AG Nuernberg) > > > > > > -- > Richard Biener <rguent...@suse.de> > SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, > HRB 21284 (AG Nuernberg)
