On Thu, Mar 16, 2023 at 9:11 AM Ajit Agarwal <aagar...@linux.ibm.com> wrote: > > Hello Richard: > > On 16/03/23 1:10 pm, Richard Biener wrote: > > On Thu, Mar 16, 2023 at 6:21 AM Ajit Agarwal via Gcc-patches > > <gcc-patches@gcc.gnu.org> wrote: > >> > >> Hello All: > >> > >> > >> This patch eliminates unnecessary zero extension instruction from power > >> generated assembly. > >> Bootstrapped and regtested on powerpc64-linux-gnu. > > > > What makes this so special that we cannot deal with it from generic code? > > In particular we do have the REE pass, why is target specific > > knowledge neccessary > > to eliminate the extension? > > > > For returning bool values and comparision with integers generates the > following by all the rtl passes. > > set compare (subreg) > set if_then_else > Convert SImode -> QImode > set zero_extend to SImode from QImode > set return value 0 in one path of cfg. > set return value 1 in other path of cfg. > > This pass replaces the above zero extension and conversion from QImode to > DImode with copy operation to keep QImode in 64 bit registers in powerpc > target.
Sorry, I can't parse that - as there's no testcase with the patch I cannot even try to see what the actual RTL looks like (without the pass). Richard. > Thanks & Regards > Ajit > >> + In cfgexpand pass QImode is generated with > >> + bool register value and this pass uses QI > >> + as 64 bit registers. > >> + > > >> rs6000: suboptimal code for returning bool value on target ppc. > >> > >> New pass to eliminate unnecessary zero extension. This pass > >> is registered after cse rtl pass. > >> > >> 2023-03-16 Ajit Kumar Agarwal <aagar...@linux.ibm.com> > >> > >> gcc/ChangeLog: > >> > >> * config/rs6000/rs6000-passes.def: Registered zero elimination > >> pass. > >> * config/rs6000/rs6000-zext-elim.cc: Add new pass. > >> * config.gcc: Add new executable. > >> * config/rs6000/rs6000-protos.h: Add new prototype for zero > >> elimination pass. > >> * config/rs6000/rs6000.cc: Add new prototype for zero > >> elimination pass. > >> * config/rs6000/t-rs6000: Add new rule. > >> * expr.cc: Modified gcc assert. > >> * explow.cc: Modified gcc assert. > >> * optabs.cc: Modified gcc assert. > >> --- > >> gcc/config.gcc | 4 +- > >> gcc/config/rs6000/rs6000-passes.def | 2 + > >> gcc/config/rs6000/rs6000-protos.h | 1 + > >> gcc/config/rs6000/rs6000-zext-elim.cc | 361 ++++++++++++++++++++++++++ > >> gcc/config/rs6000/rs6000.cc | 2 + > >> gcc/config/rs6000/t-rs6000 | 5 + > >> gcc/explow.cc | 3 +- > >> gcc/expr.cc | 4 +- > >> gcc/optabs.cc | 3 +- > >> 9 files changed, 379 insertions(+), 6 deletions(-) > >> create mode 100644 gcc/config/rs6000/rs6000-zext-elim.cc > >> > >> diff --git a/gcc/config.gcc b/gcc/config.gcc > >> index da3a6d3ba1f..e8ac9d882f0 100644 > >> --- a/gcc/config.gcc > >> +++ b/gcc/config.gcc > >> @@ -503,7 +503,7 @@ or1k*-*-*) > >> ;; > >> powerpc*-*-*) > >> cpu_type=rs6000 > >> - extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o" > >> + extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-zext-elim.o > >> rs6000-logue.o" > >> extra_objs="${extra_objs} rs6000-call.o rs6000-pcrel-opt.o" > >> extra_objs="${extra_objs} rs6000-builtins.o rs6000-builtin.o" > >> extra_headers="ppc-asm.h altivec.h htmintrin.h htmxlintrin.h" > >> @@ -538,7 +538,7 @@ riscv*) > >> ;; > >> rs6000*-*-*) > >> extra_options="${extra_options} g.opt fused-madd.opt > >> rs6000/rs6000-tables.opt" > >> - extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-logue.o" > >> + extra_objs="rs6000-string.o rs6000-p8swap.o rs6000-zext-elim.o > >> rs6000-logue.o" > >> extra_objs="${extra_objs} rs6000-call.o rs6000-pcrel-opt.o" > >> target_gtfiles="$target_gtfiles > >> \$(srcdir)/config/rs6000/rs6000-logue.cc > >> \$(srcdir)/config/rs6000/rs6000-call.cc" > >> target_gtfiles="$target_gtfiles > >> \$(srcdir)/config/rs6000/rs6000-pcrel-opt.cc" > >> diff --git a/gcc/config/rs6000/rs6000-passes.def > >> b/gcc/config/rs6000/rs6000-passes.def > >> index ca899d5f7af..d7500feddf1 100644 > >> --- a/gcc/config/rs6000/rs6000-passes.def > >> +++ b/gcc/config/rs6000/rs6000-passes.def > >> @@ -28,6 +28,8 @@ along with GCC; see the file COPYING3. If not see > >> The power8 does not have instructions that automaticaly do the byte > >> swaps > >> for loads and stores. */ > >> INSERT_PASS_BEFORE (pass_cse, 1, pass_analyze_swaps); > >> + INSERT_PASS_AFTER (pass_cse, 1, pass_analyze_zext); > >> + > >> > >> /* Pass to do the PCREL_OPT optimization that combines the load of an > >> external symbol's address along with a single load or store using > >> that > >> diff --git a/gcc/config/rs6000/rs6000-protos.h > >> b/gcc/config/rs6000/rs6000-protos.h > >> index 1a4fc1df668..f6cf2d673d4 100644 > >> --- a/gcc/config/rs6000/rs6000-protos.h > >> +++ b/gcc/config/rs6000/rs6000-protos.h > >> @@ -340,6 +340,7 @@ namespace gcc { class context; } > >> class rtl_opt_pass; > >> > >> extern rtl_opt_pass *make_pass_analyze_swaps (gcc::context *); > >> +extern rtl_opt_pass *make_pass_analyze_zext (gcc::context *); > >> extern rtl_opt_pass *make_pass_pcrel_opt (gcc::context *); > >> extern bool rs6000_sum_of_two_registers_p (const_rtx expr); > >> extern bool rs6000_quadword_masked_address_p (const_rtx exp); > >> diff --git a/gcc/config/rs6000/rs6000-zext-elim.cc > >> b/gcc/config/rs6000/rs6000-zext-elim.cc > >> new file mode 100644 > >> index 00000000000..777c7a5a387 > >> --- /dev/null > >> +++ b/gcc/config/rs6000/rs6000-zext-elim.cc > >> @@ -0,0 +1,361 @@ > >> +/* Subroutine to eliminate redundant zero extend for power architecture. > >> + Copyright (C) 1991-2023 Free Software Foundation, Inc. > >> + > >> + This file is part of GCC. > >> + > >> + GCC is free software; you can redistribute it and/or modify it > >> + under the terms of the GNU General Public License as published > >> + by the Free Software Foundation; either version 3, or (at your > >> + option) any later version. > >> + > >> + GCC is distributed in the hope that it will be useful, but WITHOUT > >> + ANY WARRANTY; without even the implied warranty of MERCHANTABILITY > >> + or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public > >> + License for more details. > >> + > >> + You should have received a copy of the GNU General Public License > >> + along with GCC; see the file COPYING3. If not see > >> + <http://www.gnu.org/licenses/>. */ > >> + > >> +/* This pass remove unnecessary zero extension instruction from > >> + power generated assembly. This pass is register after cse > >> + pass. > >> + Identifies the following sequence of instruction after cse > >> + rtl pass. > >> + > >> + set compare (subreg) > >> + set if_then_else > >> + set SImode -> QImode > >> + set zero_extend to DImode from QImode > >> + set return value 0 in one path of cfg. > >> + set return value 1 in other path of cfg. > >> + > >> + In cfgexpand pass QImode is generated with > >> + bool register value and this pass uses QI > >> + as 64 bit registers. > >> + > >> + This pass replace copy operation from QImode to DImode > >> + and return appropriate return values.*/ > >> + > >> +#define IN_TARGET_CODE 1 > >> + > >> +#include "config.h" > >> +#include "system.h" > >> +#include "coretypes.h" > >> +#include "backend.h" > >> +#include "rtl.h" > >> +#include "tree.h" > >> +#include "memmodel.h" > >> +#include "df.h" > >> +#include "tm_p.h" > >> +#include "ira.h" > >> +#include "print-tree.h" > >> +#include "varasm.h" > >> +#include "explow.h" > >> +#include "expr.h" > >> +#include "output.h" > >> +#include "tree-pass.h" > >> + > >> +/* This is based on the union-find logic in web.cc. web_entry_base is > >> + defined in df.h. */ > >> +class zext_web_entry : public web_entry_base > >> +{ > >> + public: > >> + /* Pointer to the insn. */ > >> + rtx_insn *insn; > >> + unsigned int is_relevant : 1; > >> + /* Set if insn is a load. */ > >> + unsigned int is_load : 1; > >> + /* Set if insn is a store. */ > >> + unsigned int is_store : 1; > >> + unsigned int is_zext :1 ; > >> + unsigned int is_move :1; > >> + unsigned int is_delete_move :1; > >> + /* Set if this insn should be deleted. */ > >> + unsigned int will_delete : 1; > >> + unsigned int will_delete_chances : 1; > >> +}; > >> + > >> +/* Checks if instruction is zero extension > >> + * with QIMode to DImode.*/ > >> +static unsigned int > >> +insn_is_zext_p(rtx insn) > >> +{ > >> + rtx body = PATTERN (insn); > >> + > >> + if (GET_CODE (body) == SET > >> + && GET_MODE(SET_DEST (body)) == DImode > >> + && GET_CODE(SET_SRC (body)) == ZERO_EXTEND) > >> + { > >> + rtx set = XEXP (SET_SRC (body), 0); > >> + > >> + if (REG_P (set)) > >> + { > >> + if (GET_MODE (set) == QImode) return 1; > >> + } > >> + else > >> + return 0; > >> + } > >> + return 0; > >> +} > >> + > >> +/* Checks if instruction is SET operation with QImode.*/ > >> +static unsigned int > >> +insn_is_store_p (rtx insn) > >> +{ > >> + rtx body = PATTERN (insn); > >> + if (GET_CODE (body) == SET > >> + && SUBREG_P(SET_SRC (body)) > >> + && !CONST_INT_P(SET_SRC (body)) > >> + && GET_MODE(XEXP (SET_SRC (body), 0)) == SImode > >> + && GET_MODE(SET_SRC (body)) == QImode) > >> + return 1; > >> + > >> + return 0; > >> +} > >> + > >> +/* Find out zero extension removal candidate with use-def web.*/ > >> +static void > >> +find_zero_ext_elimination_candidate (zext_web_entry *insn_entry, > >> + rtx insn, df_ref def) > >> +{ > >> + struct df_link *link = DF_REF_CHAIN (def); > >> + > >> + rtx move_insn = NULL_RTX; > >> + rtx compare_insn = NULL_RTX; > >> + > >> + while (link) > >> + { > >> + if (!DF_REF_INSN_INFO (link->ref)) > >> + insn_entry[INSN_UID(insn)].will_delete_chances = 0; > >> + > >> + if (DF_REF_INSN_INFO (link->ref)) > >> + { > >> + rtx use_insn = DF_REF_INSN (link->ref); > >> + > >> + if (GET_CODE (PATTERN (use_insn)) == SET > >> + && (GET_CODE (SET_SRC (PATTERN (use_insn))) == IF_THEN_ELSE)) > >> + { > >> + if (GET_CODE (PATTERN (insn)) == SET > >> + && GET_CODE (SET_SRC (PATTERN (insn))) == COMPARE) > >> + { > >> + rtx body = XEXP (SET_SRC (PATTERN (insn)), 0); > >> + > >> + if (SUBREG_P (body)) > >> + { > >> + compare_insn = use_insn; > >> + rtx compare_body = XEXP (SET_SRC (PATTERN > >> (compare_insn)), 0); > >> + > >> + if (compare_insn > >> + && ((REGNO (XEXP (compare_body, 0))) > >> + == REGNO (SET_DEST (PATTERN (insn))))) > >> + insn_entry[INSN_UID(use_insn)].will_delete_chances = > >> 1; > >> + } > >> + } > >> + } > >> + > >> + if (insn_is_store_p(use_insn) > >> + && GET_CODE (PATTERN (insn)) == SET > >> + && (GET_CODE (SET_SRC (PATTERN(insn))) == IF_THEN_ELSE)) > >> + { > >> + if (GET_MODE (SET_DEST (PATTERN (insn))) == SImode) > >> + { > >> + if (insn_entry[INSN_UID(insn)].will_delete_chances) > >> + insn_entry[INSN_UID(use_insn)].will_delete_chances = 1; > >> + } > >> + } > >> + > >> + if (insn_is_zext_p (insn)) > >> + { > >> + if (GET_CODE (PATTERN (use_insn)) == SET > >> + && REG_P (SET_SRC (PATTERN (use_insn)))) > >> + { > >> + if (move_insn > >> + && REGNO (SET_SRC (PATTERN (use_insn))) > >> + == REGNO (SET_SRC (PATTERN (move_insn))) > >> + && insn_entry[INSN_UID(insn)].is_delete_move) > >> + { > >> + insn_entry[INSN_UID (insn)].is_move = 1; > >> + break; > >> + } > >> + else if (insn_entry[INSN_UID (insn)].will_delete) > >> + { > >> + move_insn = use_insn; > >> + insn_entry[INSN_UID(insn)].is_delete_move= 1; > >> + } > >> + } > >> + } > >> + > >> + if (insn_is_zext_p (use_insn)) > >> + { > >> + insn_entry[INSN_UID (use_insn)].is_zext = 1; > >> + insn_entry[INSN_UID(use_insn)].is_relevant = 1; > >> + > >> + if (insn_is_store_p (insn) > >> + && insn_entry[INSN_UID (insn)].will_delete_chances) > >> + { > >> + insn_entry[INSN_UID (use_insn)].will_delete = 1; > >> + insn_entry[INSN_UID (insn)].will_delete = 1; > >> + insn_entry[INSN_UID( insn)].is_store = 1; > >> + } > >> + > >> + if (NONDEBUG_INSN_P (use_insn)) > >> + unionfind_union (insn_entry + INSN_UID (insn), > >> + insn_entry + INSN_UID (use_insn)); > >> + } > >> + } > >> + > >> + link = link->next; > >> + } > >> +} > >> + > >> +/* Replace QImode extensions with copy operations.*/ > >> +static void > >> +replace_marked_insns (zext_web_entry *insn_entry, unsigned i) > >> +{ > >> + rtx_insn *insn = insn_entry[i].insn; > >> + rtx body = PATTERN (insn); > >> + rtx src_reg; > >> + src_reg = XEXP (SET_SRC (body), 0); > >> + set_mode_and_regno (src_reg, DImode, REGNO(src_reg)); > >> + > >> + if (GET_MODE(SET_DEST(body)) != DImode) > >> + set_mode_and_regno (SET_DEST(body), DImode, REGNO (SET_DEST (body))); > >> + > >> + rtx copy = gen_rtx_SET (SET_DEST (body), src_reg); > >> + rtx_insn *new_insn = emit_insn_before (copy, insn); > >> + set_block_for_insn (new_insn, BLOCK_FOR_INSN (insn)); > >> + df_insn_rescan (new_insn); > >> + > >> + df_insn_delete (insn); > >> + remove_insn (insn); > >> + insn->set_deleted (); > >> +} > >> + > >> +/* Main entry point for this pass. */ > >> +unsigned int > >> +rs6000_analyze_zext (function *fun) > >> +{ > >> + zext_web_entry *insn_entry; > >> + basic_block bb; > >> + rtx_insn *insn, *curr_insn = 0; > >> + > >> + /* Dataflow analysis for use-def chains. */ > >> + df_set_flags (DF_RD_PRUNE_DEAD_DEFS); > >> + df_chain_add_problem (DF_DU_CHAIN | DF_UD_CHAIN); > >> + df_analyze (); > >> + df_set_flags (DF_DEFER_INSN_RESCAN); > >> + > >> + /* Rebuild ud- and du-chains. */ > >> + df_remove_problem (df_chain); > >> + df_process_deferred_rescans (); > >> + df_set_flags (DF_RD_PRUNE_DEAD_DEFS); > >> + df_chain_add_problem (DF_DU_CHAIN | DF_UD_CHAIN); > >> + df_analyze (); > >> + df_set_flags (DF_DEFER_INSN_RESCAN); > >> + > >> + /* Allocate structure to represent webs of insns. */ > >> + insn_entry = XCNEWVEC (zext_web_entry, get_max_uid ()); > >> + > >> + /* Walk the insns to gather basic data. */ > >> + FOR_ALL_BB_FN (bb, fun) > >> + FOR_BB_INSNS_SAFE (bb, insn, curr_insn) > >> + { > >> + unsigned int uid = INSN_UID (insn); > >> + if (NONDEBUG_INSN_P (insn)) > >> + { > >> + insn_entry[uid].insn = insn; > >> + > >> + if (GET_CODE (insn) == insn_is_store_p (insn)) > >> + { > >> + insn_entry[uid].is_store = 1; > >> + insn_entry[uid].is_relevant = 1; > >> + } > >> + > >> + /* Walk the uses and defs to identify the optimization > >> + candidates.*/ > >> + struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); > >> + df_ref mention; > >> + > >> + FOR_EACH_INSN_INFO_DEF (mention, insn_info) > >> + { > >> + insn_entry[uid].is_relevant = 1; > >> + insn_entry[uid].is_store = insn_is_store_p (insn); > >> + find_zero_ext_elimination_candidate (insn_entry, insn, > >> mention); > >> + } > >> + > >> + if (insn_entry[uid].is_relevant) > >> + { > >> + /* Determine if this is a store. */ > >> + insn_entry[uid].is_store = insn_is_store_p (insn); > >> + } > >> + } > >> + } > >> + > >> + unsigned e = get_max_uid (), i; > >> + > >> + int store_index = -1; > >> + > >> + /* Replace with copy operation.*/ > >> + for (i = 0; i < e; ++i) > >> + { > >> + if (insn_entry[i].is_store && insn_entry[i].will_delete) > >> + store_index = i; > >> + > >> + if ((store_index != -1) > >> + && insn_entry[i].is_move && insn_entry[i].will_delete) > >> + { > >> + replace_marked_insns (insn_entry, store_index); > >> + replace_marked_insns (insn_entry, i); > >> + } > >> + } > >> + /* Clean up. */ > >> + free (insn_entry); > >> + > >> + return 0; > >> +} > >> + > >> +const pass_data pass_data_analyze_zext = > >> +{ > >> + RTL_PASS, /* type */ > >> + "zext", /* name */ > >> + OPTGROUP_NONE, /* optinfo_flags */ > >> + TV_NONE, /* tv_id */ > >> + 0, /* properties_required */ > >> + 0, /* properties_provided */ > >> + 0, /* properties_destroyed */ > >> + 0, /* todo_flags_start */ > >> + TODO_df_finish, /* todo_flags_finish */ > >> +}; > >> + > >> +class pass_analyze_zext : public rtl_opt_pass > >> +{ > >> +public: > >> + pass_analyze_zext(gcc::context *ctxt) > >> + : rtl_opt_pass(pass_data_analyze_zext, ctxt) > >> + {} > >> + > >> + /* opt_pass methods: */ > >> + virtual bool gate (function *) > >> + { > >> + return (optimize > 0 ); > >> + } > >> + > >> + virtual unsigned int execute (function *fun) > >> + { > >> + return rs6000_analyze_zext (fun); > >> + } > >> + > >> + opt_pass *clone () > >> + { > >> + return new pass_analyze_zext (m_ctxt); > >> + } > >> + > >> +}; // class pass_analyze_zext > >> + > >> +rtl_opt_pass * > >> +make_pass_analyze_zext (gcc::context *ctxt) > >> +{ > >> + return new pass_analyze_zext (ctxt); > >> +} > >> + > >> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc > >> index 8e0b0d022db..6541334bf2d 100644 > >> --- a/gcc/config/rs6000/rs6000.cc > >> +++ b/gcc/config/rs6000/rs6000.cc > >> @@ -1178,6 +1178,8 @@ static bool rs6000_secondary_reload_move (enum > >> rs6000_reg_type, > >> bool); > >> rtl_opt_pass *make_pass_analyze_swaps (gcc::context*); > >> > >> +rtl_opt_pass *make_pass_analyze_zext (gcc::context*); > >> + > >> /* Hash table stuff for keeping track of TOC entries. */ > >> > >> struct GTY((for_user)) toc_hash_struct > >> diff --git a/gcc/config/rs6000/t-rs6000 b/gcc/config/rs6000/t-rs6000 > >> index f183b42ce1d..c1f61591d2f 100644 > >> --- a/gcc/config/rs6000/t-rs6000 > >> +++ b/gcc/config/rs6000/t-rs6000 > >> @@ -35,6 +35,11 @@ rs6000-p8swap.o: > >> $(srcdir)/config/rs6000/rs6000-p8swap.cc > >> $(COMPILE) $< > >> $(POSTCOMPILE) > >> > >> +rs6000-zext-elim.o: $(srcdir)/config/rs6000/rs6000-zext-elim.cc > >> + $(COMPILE) $< > >> + $(POSTCOMPILE) > >> + > >> + > >> rs6000-d.o: $(srcdir)/config/rs6000/rs6000-d.cc > >> $(COMPILE) $< > >> $(POSTCOMPILE) > >> diff --git a/gcc/explow.cc b/gcc/explow.cc > >> index 32e9498ee07..316aa975e40 100644 > >> --- a/gcc/explow.cc > >> +++ b/gcc/explow.cc > >> @@ -654,7 +654,8 @@ copy_to_mode_reg (machine_mode mode, rtx x) > >> if (! general_operand (x, VOIDmode)) > >> x = force_operand (x, temp); > >> > >> - gcc_assert (GET_MODE (x) == mode || GET_MODE (x) == VOIDmode); > >> + gcc_assert (mode == DImode || GET_MODE (x) == mode > >> + || GET_MODE (x) == VOIDmode); > >> if (x != temp) > >> emit_move_insn (temp, x); > >> return temp; > >> diff --git a/gcc/expr.cc b/gcc/expr.cc > >> index 15be1c8db99..6162ef92b88 100644 > >> --- a/gcc/expr.cc > >> +++ b/gcc/expr.cc > >> @@ -4223,9 +4223,9 @@ emit_move_insn (rtx x, rtx y) > >> rtx y_cst = NULL_RTX; > >> rtx_insn *last_insn; > >> rtx set; > >> - > >> gcc_assert (mode != BLKmode > >> - && (GET_MODE (y) == mode || GET_MODE (y) == VOIDmode)); > >> + && (mode == DImode || GET_MODE (y) == mode > >> + || GET_MODE (y) == VOIDmode)); > >> > >> /* If we have a copy that looks like one of the following patterns: > >> (set (subreg:M1 (reg:M2 ...)) (subreg:M1 (reg:M2 ...))) > >> diff --git a/gcc/optabs.cc b/gcc/optabs.cc > >> index 4c641cab192..9d22fadc7ef 100644 > >> --- a/gcc/optabs.cc > >> +++ b/gcc/optabs.cc > >> @@ -7902,7 +7902,8 @@ maybe_legitimize_operand (enum insn_code icode, > >> unsigned int opno, > >> input: > >> gcc_assert (mode != VOIDmode); > >> gcc_assert (GET_MODE (op->value) == VOIDmode > >> - || GET_MODE (op->value) == mode); > >> + || GET_MODE (op->value) == mode > >> + || mode == DImode); > >> if (maybe_legitimize_operand_same_code (icode, opno, op)) > >> return true; > >> > >> -- > >> 2.31.1 > >>