| /* Web construction code for GNU compiler. |
| Contributed by Jan Hubicka. |
| Copyright (C) 2001-2017 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/>. */ |
| |
| /* Simple optimization pass that splits independent uses of each pseudo, |
| increasing effectiveness of other optimizations. The optimization can |
| serve as an example of use for the dataflow module. |
| |
| We don't split registers with REG_USERVAR set unless -fmessy-debugging |
| is specified, because debugging information about such split variables |
| is almost unusable. |
| |
| TODO |
| - We may use profile information and ignore infrequent use for the |
| purpose of web unifying, inserting the compensation code later to |
| implement full induction variable expansion for loops (currently |
| we expand only if the induction variable is dead afterward, which |
| is often the case). */ |
| |
| #include "config.h" |
| #include "system.h" |
| #include "coretypes.h" |
| #include "backend.h" |
| #include "rtl.h" |
| #include "df.h" |
| #include "insn-config.h" |
| #include "recog.h" |
| |
| #include "tree-pass.h" |
| |
| |
| /* Find the root of unionfind tree (the representative of set). */ |
| |
| web_entry_base * |
| web_entry_base::unionfind_root () |
| { |
| web_entry_base *element = this, *element1 = this, *element2; |
| |
| while (element->pred ()) |
| element = element->pred (); |
| while (element1->pred ()) |
| { |
| element2 = element1->pred (); |
| element1->set_pred (element); |
| element1 = element2; |
| } |
| return element; |
| } |
| |
| /* Union sets. |
| Return true if FIRST and SECOND points to the same web entry structure and |
| nothing is done. Otherwise, return false. */ |
| |
| bool |
| unionfind_union (web_entry_base *first, web_entry_base *second) |
| { |
| first = first->unionfind_root (); |
| second = second->unionfind_root (); |
| if (first == second) |
| return true; |
| second->set_pred (first); |
| return false; |
| } |
| |
| class web_entry : public web_entry_base |
| { |
| private: |
| rtx reg_pvt; |
| |
| public: |
| rtx reg () { return reg_pvt; } |
| void set_reg (rtx r) { reg_pvt = r; } |
| }; |
| |
| /* For INSN, union all defs and uses that are linked by match_dup. |
| FUN is the function that does the union. */ |
| |
| static void |
| union_match_dups (rtx_insn *insn, web_entry *def_entry, web_entry *use_entry, |
| bool (*fun) (web_entry_base *, web_entry_base *)) |
| { |
| struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
| df_ref use_link = DF_INSN_INFO_USES (insn_info); |
| df_ref def_link = DF_INSN_INFO_DEFS (insn_info); |
| struct web_entry *dup_entry; |
| int i; |
| |
| extract_insn (insn); |
| |
| for (i = 0; i < recog_data.n_dups; i++) |
| { |
| int op = recog_data.dup_num[i]; |
| enum op_type type = recog_data.operand_type[op]; |
| df_ref ref, dupref; |
| struct web_entry *entry; |
| |
| dup_entry = use_entry; |
| for (dupref = use_link; dupref; dupref = DF_REF_NEXT_LOC (dupref)) |
| if (DF_REF_LOC (dupref) == recog_data.dup_loc[i]) |
| break; |
| |
| if (dupref == NULL && type == OP_INOUT) |
| { |
| dup_entry = def_entry; |
| for (dupref = def_link; dupref; dupref = DF_REF_NEXT_LOC (dupref)) |
| if (DF_REF_LOC (dupref) == recog_data.dup_loc[i]) |
| break; |
| } |
| /* ??? *DUPREF can still be zero, because when an operand matches |
| a memory, DF_REF_LOC (use_link[n]) points to the register part |
| of the address, whereas recog_data.dup_loc[m] points to the |
| entire memory ref, thus we fail to find the duplicate entry, |
| even though it is there. |
| Example: i686-pc-linux-gnu gcc.c-torture/compile/950607-1.c |
| -O3 -fomit-frame-pointer -funroll-loops */ |
| if (dupref == NULL |
| || DF_REF_REGNO (dupref) < FIRST_PSEUDO_REGISTER) |
| continue; |
| |
| ref = type == OP_IN ? use_link : def_link; |
| entry = type == OP_IN ? use_entry : def_entry; |
| for (; ref; ref = DF_REF_NEXT_LOC (ref)) |
| { |
| rtx *l = DF_REF_LOC (ref); |
| if (l == recog_data.operand_loc[op]) |
| break; |
| if (l && DF_REF_REAL_LOC (ref) == recog_data.operand_loc[op]) |
| break; |
| } |
| |
| if (!ref && type == OP_INOUT) |
| { |
| entry = use_entry; |
| for (ref = use_link; ref; ref = DF_REF_NEXT_LOC (ref)) |
| { |
| rtx *l = DF_REF_LOC (ref); |
| if (l == recog_data.operand_loc[op]) |
| break; |
| if (l && DF_REF_REAL_LOC (ref) == recog_data.operand_loc[op]) |
| break; |
| } |
| } |
| |
| gcc_assert (ref); |
| (*fun) (dup_entry + DF_REF_ID (dupref), entry + DF_REF_ID (ref)); |
| } |
| } |
| |
| /* For each use, all possible defs reaching it must come in the same |
| register, union them. |
| FUN is the function that does the union. |
| |
| In USED, we keep the DF_REF_ID of the first uninitialized uses of a |
| register, so that all uninitialized uses of the register can be |
| combined into a single web. We actually offset it by 2, because |
| the values 0 and 1 are reserved for use by entry_register. */ |
| |
| void |
| union_defs (df_ref use, web_entry *def_entry, |
| unsigned int *used, web_entry *use_entry, |
| bool (*fun) (web_entry_base *, web_entry_base *)) |
| { |
| struct df_insn_info *insn_info = DF_REF_INSN_INFO (use); |
| struct df_link *link = DF_REF_CHAIN (use); |
| rtx set; |
| |
| if (insn_info) |
| { |
| df_ref eq_use; |
| |
| set = single_set (insn_info->insn); |
| FOR_EACH_INSN_INFO_EQ_USE (eq_use, insn_info) |
| if (use != eq_use |
| && DF_REF_REAL_REG (use) == DF_REF_REAL_REG (eq_use)) |
| (*fun) (use_entry + DF_REF_ID (use), use_entry + DF_REF_ID (eq_use)); |
| } |
| else |
| set = NULL; |
| |
| /* Union all occurrences of the same register in reg notes. */ |
| |
| /* Recognize trivial noop moves and attempt to keep them as noop. */ |
| |
| if (set |
| && SET_SRC (set) == DF_REF_REG (use) |
| && SET_SRC (set) == SET_DEST (set)) |
| { |
| df_ref def; |
| |
| FOR_EACH_INSN_INFO_DEF (def, insn_info) |
| if (DF_REF_REAL_REG (use) == DF_REF_REAL_REG (def)) |
| (*fun) (use_entry + DF_REF_ID (use), def_entry + DF_REF_ID (def)); |
| } |
| |
| /* UD chains of uninitialized REGs are empty. Keeping all uses of |
| the same uninitialized REG in a single web is not necessary for |
| correctness, since the uses are undefined, but it's wasteful to |
| allocate one register or slot for each reference. Furthermore, |
| creating new pseudos for uninitialized references in debug insns |
| (see PR 42631) causes -fcompare-debug failures. We record the |
| number of the first uninitialized reference we found, and merge |
| with it any other uninitialized references to the same |
| register. */ |
| if (!link) |
| { |
| int regno = REGNO (DF_REF_REAL_REG (use)); |
| if (used[regno]) |
| (*fun) (use_entry + DF_REF_ID (use), use_entry + used[regno] - 2); |
| else |
| used[regno] = DF_REF_ID (use) + 2; |
| } |
| |
| while (link) |
| { |
| (*fun) (use_entry + DF_REF_ID (use), |
| def_entry + DF_REF_ID (link->ref)); |
| link = link->next; |
| } |
| |
| /* A READ_WRITE use requires the corresponding def to be in the same |
| register. Find it and union. */ |
| if (DF_REF_FLAGS (use) & DF_REF_READ_WRITE) |
| if (insn_info) |
| { |
| df_ref def; |
| |
| FOR_EACH_INSN_INFO_DEF (def, insn_info) |
| if (DF_REF_REAL_REG (use) == DF_REF_REAL_REG (def)) |
| (*fun) (use_entry + DF_REF_ID (use), def_entry + DF_REF_ID (def)); |
| } |
| } |
| |
| /* Find the corresponding register for the given entry. */ |
| |
| static rtx |
| entry_register (web_entry *entry, df_ref ref, unsigned int *used) |
| { |
| web_entry *root; |
| rtx reg, newreg; |
| |
| /* Find the corresponding web and see if it has been visited. */ |
| root = (web_entry *)entry->unionfind_root (); |
| if (root->reg ()) |
| return root->reg (); |
| |
| /* We are seeing this web for the first time, do the assignment. */ |
| reg = DF_REF_REAL_REG (ref); |
| |
| /* In case the original register is already assigned, generate new |
| one. Since we use USED to merge uninitialized refs into a single |
| web, we might found an element to be nonzero without our having |
| used it. Test for 1, because union_defs saves it for our use, |
| and there won't be any use for the other values when we get to |
| this point. */ |
| if (used[REGNO (reg)] != 1) |
| newreg = reg, used[REGNO (reg)] = 1; |
| else |
| { |
| newreg = gen_reg_rtx (GET_MODE (reg)); |
| REG_USERVAR_P (newreg) = REG_USERVAR_P (reg); |
| REG_POINTER (newreg) = REG_POINTER (reg); |
| REG_ATTRS (newreg) = REG_ATTRS (reg); |
| if (dump_file) |
| fprintf (dump_file, "Web oldreg=%i newreg=%i\n", REGNO (reg), |
| REGNO (newreg)); |
| } |
| |
| root->set_reg (newreg); |
| return newreg; |
| } |
| |
| /* Replace the reference by REG. */ |
| |
| static void |
| replace_ref (df_ref ref, rtx reg) |
| { |
| rtx oldreg = DF_REF_REAL_REG (ref); |
| rtx *loc = DF_REF_REAL_LOC (ref); |
| unsigned int uid = DF_REF_INSN_UID (ref); |
| |
| if (oldreg == reg) |
| return; |
| if (dump_file) |
| fprintf (dump_file, "Updating insn %i (%i->%i)\n", |
| uid, REGNO (oldreg), REGNO (reg)); |
| *loc = reg; |
| df_insn_rescan (DF_REF_INSN (ref)); |
| } |
| |
| |
| namespace { |
| |
| const pass_data pass_data_web = |
| { |
| RTL_PASS, /* type */ |
| "web", /* name */ |
| OPTGROUP_NONE, /* optinfo_flags */ |
| TV_WEB, /* tv_id */ |
| 0, /* properties_required */ |
| 0, /* properties_provided */ |
| 0, /* properties_destroyed */ |
| 0, /* todo_flags_start */ |
| TODO_df_finish, /* todo_flags_finish */ |
| }; |
| |
| class pass_web : public rtl_opt_pass |
| { |
| public: |
| pass_web (gcc::context *ctxt) |
| : rtl_opt_pass (pass_data_web, ctxt) |
| {} |
| |
| /* opt_pass methods: */ |
| virtual bool gate (function *) { return (optimize > 0 && flag_web); } |
| virtual unsigned int execute (function *); |
| |
| }; // class pass_web |
| |
| unsigned int |
| pass_web::execute (function *fun) |
| { |
| web_entry *def_entry; |
| web_entry *use_entry; |
| unsigned int max = max_reg_num (); |
| unsigned int *used; |
| basic_block bb; |
| unsigned int uses_num = 0; |
| rtx_insn *insn; |
| |
| df_set_flags (DF_NO_HARD_REGS + DF_EQ_NOTES); |
| df_set_flags (DF_RD_PRUNE_DEAD_DEFS); |
| df_chain_add_problem (DF_UD_CHAIN); |
| df_analyze (); |
| df_set_flags (DF_DEFER_INSN_RESCAN); |
| |
| /* Assign ids to the uses. */ |
| FOR_ALL_BB_FN (bb, fun) |
| FOR_BB_INSNS (bb, insn) |
| { |
| if (NONDEBUG_INSN_P (insn)) |
| { |
| struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
| df_ref use; |
| FOR_EACH_INSN_INFO_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| DF_REF_ID (use) = uses_num++; |
| FOR_EACH_INSN_INFO_EQ_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| DF_REF_ID (use) = uses_num++; |
| } |
| } |
| |
| /* Record the number of uses and defs at the beginning of the optimization. */ |
| def_entry = XCNEWVEC (web_entry, DF_DEFS_TABLE_SIZE ()); |
| used = XCNEWVEC (unsigned, max); |
| use_entry = XCNEWVEC (web_entry, uses_num); |
| |
| /* Produce the web. */ |
| FOR_ALL_BB_FN (bb, fun) |
| FOR_BB_INSNS (bb, insn) |
| if (NONDEBUG_INSN_P (insn)) |
| { |
| struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
| df_ref use; |
| union_match_dups (insn, def_entry, use_entry, unionfind_union); |
| FOR_EACH_INSN_INFO_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| union_defs (use, def_entry, used, use_entry, unionfind_union); |
| FOR_EACH_INSN_INFO_EQ_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| union_defs (use, def_entry, used, use_entry, unionfind_union); |
| } |
| |
| /* Update the instruction stream, allocating new registers for split pseudos |
| in progress. */ |
| FOR_ALL_BB_FN (bb, fun) |
| FOR_BB_INSNS (bb, insn) |
| if (NONDEBUG_INSN_P (insn) |
| /* Ignore naked clobber. For example, reg 134 in the second insn |
| of the following sequence will not be replaced. |
| |
| (insn (clobber (reg:SI 134))) |
| |
| (insn (set (reg:SI 0 r0) (reg:SI 134))) |
| |
| Thus the later passes can optimize them away. */ |
| && GET_CODE (PATTERN (insn)) != CLOBBER) |
| { |
| struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn); |
| df_ref def, use; |
| FOR_EACH_INSN_INFO_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| replace_ref (use, entry_register (use_entry + DF_REF_ID (use), |
| use, used)); |
| FOR_EACH_INSN_INFO_EQ_USE (use, insn_info) |
| if (DF_REF_REGNO (use) >= FIRST_PSEUDO_REGISTER) |
| replace_ref (use, entry_register (use_entry + DF_REF_ID (use), |
| use, used)); |
| FOR_EACH_INSN_INFO_DEF (def, insn_info) |
| if (DF_REF_REGNO (def) >= FIRST_PSEUDO_REGISTER) |
| replace_ref (def, entry_register (def_entry + DF_REF_ID (def), |
| def, used)); |
| } |
| |
| free (def_entry); |
| free (use_entry); |
| free (used); |
| return 0; |
| } |
| |
| } // anon namespace |
| |
| rtl_opt_pass * |
| make_pass_web (gcc::context *ctxt) |
| { |
| return new pass_web (ctxt); |
| } |