> -----Original Message----- > From: Richard Sandiford <richard.sandif...@arm.com> > Sent: Wednesday, May 15, 2024 11:56 AM > To: Tamar Christina <tamar.christ...@arm.com> > Cc: gcc-patches@gcc.gnu.org; nd <n...@arm.com>; Richard Earnshaw > <richard.earns...@arm.com>; Marcus Shawcroft > <marcus.shawcr...@arm.com>; ktkac...@gcc.gnu.org > Subject: Re: [PATCH 2/4]AArch64: add new tuning param and attribute for > enabling conditional early clobber > > Tamar Christina <tamar.christ...@arm.com> writes: > > Hi All, > > > > This adds a new tuning parameter EARLY_CLOBBER_SVE_PRED_DEST for AArch64 > to > > allow us to conditionally enable the early clobber alternatives based on the > > tuning models. > > > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > > > Ok for master? > > > > Thanks, > > Tamar > > > > gcc/ChangeLog: > > > > * config/aarch64/aarch64-tuning-flags.def > > (EARLY_CLOBBER_SVE_PRED_DEST): New. > > * config/aarch64/aarch64.h (TARGET_SVE_PRED_CLOBBER): New. > > * config/aarch64/aarch64.md (pred_clobber): New. > > (arch_enabled): Use it. > > > > --- > > diff --git a/gcc/config/aarch64/aarch64-tuning-flags.def > b/gcc/config/aarch64/aarch64-tuning-flags.def > > index > d5bcaebce770f0b217aac783063d39135f754c77..49fbad3ff28bc82b25c61ac50 > 1ccf533ec4b4c3f 100644 > > --- a/gcc/config/aarch64/aarch64-tuning-flags.def > > +++ b/gcc/config/aarch64/aarch64-tuning-flags.def > > @@ -48,4 +48,8 @@ AARCH64_EXTRA_TUNING_OPTION > ("avoid_cross_loop_fma", AVOID_CROSS_LOOP_FMA) > > > > AARCH64_EXTRA_TUNING_OPTION ("fully_pipelined_fma", > FULLY_PIPELINED_FMA) > > > > +/* Enable is the target prefers to use a fresh register for predicate > > outputs > > + rather than re-use an input predicate register. */ > > +AARCH64_EXTRA_TUNING_OPTION ("early_clobber_sve_pred_dest", > EARLY_CLOBBER_SVE_PRED_DEST) > > Sorry for the bike-shedding, but how about something like "avoid_pred_rmw"? > (I'm open to other suggestions.) Just looking for something that describes > either the architecture or the end result that we want to achieve. > And preferable something fairly short :) > > avoid_* would be consistent with the existing "avoid_cross_loop_fma".
Sure, happy to, it's something we initially struggled with naming internally as well. It sounds there's precedence so the avoid_ naming, so happy to use this naming. Will respin with it. Thanks, Tamar > > > + > > #undef AARCH64_EXTRA_TUNING_OPTION > > diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h > > index > bbf11faaf4b4340956094a983f8b0dc2649b2d27..76a18dd511f40ebb58ed12d5 > 6b46c74084ba7c3c 100644 > > --- a/gcc/config/aarch64/aarch64.h > > +++ b/gcc/config/aarch64/aarch64.h > > @@ -495,6 +495,11 @@ constexpr auto AARCH64_FL_DEFAULT_ISA_MODE = > AARCH64_FL_SM_OFF; > > enabled through +gcs. */ > > #define TARGET_GCS (AARCH64_ISA_GCS) > > > > +/* Prefer different predicate registers for the output of a predicated > > operation > over > > + re-using an existing input predicate. */ > > +#define TARGET_SVE_PRED_CLOBBER (TARGET_SVE \ > > + && (aarch64_tune_params.extra_tuning_flags \ > > + & > AARCH64_EXTRA_TUNE_EARLY_CLOBBER_SVE_PRED_DEST)) > > > > /* Standard register usage. */ > > > > diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md > > index > dbde066f7478bec51a8703b017ea553aa98be309..1ecd1a2812969504bd5114a > 53473b478c5ddba82 100644 > > --- a/gcc/config/aarch64/aarch64.md > > +++ b/gcc/config/aarch64/aarch64.md > > @@ -445,6 +445,10 @@ (define_enum_attr "arch" "arches" (const_string > "any")) > > ;; target-independent code. > > (define_attr "is_call" "no,yes" (const_string "no")) > > > > +;; Indicates whether we want to enable the pattern with an optional early > > +;; clobber for SVE predicates. > > +(define_attr "pred_clobber" "no,yes" (const_string "no")) > > + > > ;; [For compatibility with Arm in pipeline models] > > ;; Attribute that specifies whether or not the instruction touches fp > > ;; registers. > > @@ -461,7 +465,8 @@ (define_attr "fp" "no,yes" > > (define_attr "arch_enabled" "no,yes" > > (if_then_else > > (ior > > - (eq_attr "arch" "any") > > + (and (eq_attr "arch" "any") > > + (eq_attr "pred_clobber" "no")) > > > > (and (eq_attr "arch" "rcpc8_4") > > (match_test "AARCH64_ISA_RCPC8_4")) > > @@ -488,7 +493,10 @@ (define_attr "arch_enabled" "no,yes" > > (match_test "TARGET_SVE")) > > > > (and (eq_attr "arch" "sme") > > - (match_test "TARGET_SME"))) > > + (match_test "TARGET_SME")) > > + > > + (and (eq_attr "pred_clobber" "yes") > > + (match_test "TARGET_SVE_PRED_CLOBBER"))) > > IMO it'd be bettero handle pred_clobber separately from arch, as a new > top-level AND: > > (and > (ior > (eq_attr "pred_clobber" "no") > (match_test "!TARGET_...")) > (ior > ...existing arch tests...)) > > Thanks, > Richard