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/* Perform simple optimizations to clean up the result of reload. Copyright (C) 1987, 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007 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/>. */ #include "config.h" #include "system.h" #include "coretypes.h" #include "tm.h" #include "machmode.h" #include "hard-reg-set.h" #include "rtl.h" #include "tm_p.h" #include "obstack.h" #include "insn-config.h" #include "flags.h" #include "function.h" #include "expr.h" #include "optabs.h" #include "regs.h" #include "basic-block.h" #include "reload.h" #include "recog.h" #include "output.h" #include "cselib.h" #include "real.h" #include "toplev.h" #include "except.h" #include "tree.h" #include "timevar.h" #include "tree-pass.h" static int reload_cse_noop_set_p (rtx); static void reload_cse_simplify (rtx, rtx); static void reload_cse_regs_1 (rtx); static int reload_cse_simplify_set (rtx, rtx); static int reload_cse_simplify_operands (rtx, rtx); static void reload_combine (void); static void reload_combine_note_use (rtx *, rtx); static void reload_combine_note_store (rtx, rtx, void *); static void reload_cse_move2add (rtx); static void move2add_note_store (rtx, rtx, void *); /* Call cse / combine like post-reload optimization phases. FIRST is the first instruction. */ void reload_cse_regs (rtx first ATTRIBUTE_UNUSED) { reload_cse_regs_1 (first); reload_combine (); reload_cse_move2add (first); if (flag_expensive_optimizations) reload_cse_regs_1 (first); } /* See whether a single set SET is a noop. */ static int reload_cse_noop_set_p (rtx set) { if (cselib_reg_set_mode (SET_DEST (set)) != GET_MODE (SET_DEST (set))) return 0; return rtx_equal_for_cselib_p (SET_DEST (set), SET_SRC (set)); } /* Try to simplify INSN. */ static void reload_cse_simplify (rtx insn, rtx testreg) { rtx body = PATTERN (insn); if (GET_CODE (body) == SET) { int count = 0; /* Simplify even if we may think it is a no-op. We may think a memory load of a value smaller than WORD_SIZE is redundant because we haven't taken into account possible implicit extension. reload_cse_simplify_set() will bring this out, so it's safer to simplify before we delete. */ count += reload_cse_simplify_set (body, insn); if (!count && reload_cse_noop_set_p (body)) { rtx value = SET_DEST (body); if (REG_P (value) && ! REG_FUNCTION_VALUE_P (value)) value = 0; delete_insn_and_edges (insn); return; } if (count > 0) apply_change_group (); else reload_cse_simplify_operands (insn, testreg); } else if (GET_CODE (body) == PARALLEL) { int i; int count = 0; rtx value = NULL_RTX; /* Registers mentioned in the clobber list for an asm cannot be reused within the body of the asm. Invalidate those registers now so that we don't try to substitute values for them. */ if (asm_noperands (body) >= 0) { for (i = XVECLEN (body, 0) - 1; i >= 0; --i) { rtx part = XVECEXP (body, 0, i); if (GET_CODE (part) == CLOBBER && REG_P (XEXP (part, 0))) cselib_invalidate_rtx (XEXP (part, 0)); } } /* If every action in a PARALLEL is a noop, we can delete the entire PARALLEL. */ for (i = XVECLEN (body, 0) - 1; i >= 0; --i) { rtx part = XVECEXP (body, 0, i); if (GET_CODE (part) == SET) { if (! reload_cse_noop_set_p (part)) break; if (REG_P (SET_DEST (part)) && REG_FUNCTION_VALUE_P (SET_DEST (part))) { if (value) break; value = SET_DEST (part); } } else if (GET_CODE (part) != CLOBBER) break; } if (i < 0) { delete_insn_and_edges (insn); /* We're done with this insn. */ return; } /* It's not a no-op, but we can try to simplify it. */ for (i = XVECLEN (body, 0) - 1; i >= 0; --i) if (GET_CODE (XVECEXP (body, 0, i)) == SET) count += reload_cse_simplify_set (XVECEXP (body, 0, i), insn); if (count > 0) apply_change_group (); else reload_cse_simplify_operands (insn, testreg); } } /* Do a very simple CSE pass over the hard registers. This function detects no-op moves where we happened to assign two different pseudo-registers to the same hard register, and then copied one to the other. Reload will generate a useless instruction copying a register to itself. This function also detects cases where we load a value from memory into two different registers, and (if memory is more expensive than registers) changes it to simply copy the first register into the second register. Another optimization is performed that scans the operands of each instruction to see whether the value is already available in a hard register. It then replaces the operand with the hard register if possible, much like an optional reload would. */ static void reload_cse_regs_1 (rtx first) { rtx insn; rtx testreg = gen_rtx_REG (VOIDmode, -1); cselib_init (true); init_alias_analysis (); for (insn = first; insn; insn = NEXT_INSN (insn)) { if (INSN_P (insn)) reload_cse_simplify (insn, testreg); cselib_process_insn (insn); } /* Clean up. */ end_alias_analysis (); cselib_finish (); } /* Try to simplify a single SET instruction. SET is the set pattern. INSN is the instruction it came from. This function only handles one case: if we set a register to a value which is not a register, we try to find that value in some other register and change the set into a register copy. */ static int reload_cse_simplify_set (rtx set, rtx insn) { int did_change = 0; int dreg; rtx src; enum reg_class dclass; int old_cost; cselib_val *val; struct elt_loc_list *l; #ifdef LOAD_EXTEND_OP enum rtx_code extend_op = UNKNOWN; #endif dreg = true_regnum (SET_DEST (set)); if (dreg < 0) return 0; src = SET_SRC (set); if (side_effects_p (src) || true_regnum (src) >= 0) return 0; dclass = REGNO_REG_CLASS (dreg); #ifdef LOAD_EXTEND_OP /* When replacing a memory with a register, we need to honor assumptions that combine made wrt the contents of sign bits. We'll do this by generating an extend instruction instead of a reg->reg copy. Thus the destination must be a register that we can widen. */ if (MEM_P (src) && GET_MODE_BITSIZE (GET_MODE (src)) < BITS_PER_WORD && (extend_op = LOAD_EXTEND_OP (GET_MODE (src))) != UNKNOWN && !REG_P (SET_DEST (set))) return 0; #endif val = cselib_lookup (src, GET_MODE (SET_DEST (set)), 0); if (! val) return 0; /* If memory loads are cheaper than register copies, don't change them. */ if (MEM_P (src)) old_cost = MEMORY_MOVE_COST (GET_MODE (src), dclass, 1); else if (REG_P (src)) old_cost = REGISTER_MOVE_COST (GET_MODE (src), REGNO_REG_CLASS (REGNO (src)), dclass); else old_cost = rtx_cost (src, SET); for (l = val->locs; l; l = l->next) { rtx this_rtx = l->loc; int this_cost; if (CONSTANT_P (this_rtx) && ! references_value_p (this_rtx, 0)) { #ifdef LOAD_EXTEND_OP if (extend_op != UNKNOWN) { HOST_WIDE_INT this_val; /* ??? I'm lazy and don't wish to handle CONST_DOUBLE. Other constants, such as SYMBOL_REF, cannot be extended. */ if (GET_CODE (this_rtx) != CONST_INT) continue; this_val = INTVAL (this_rtx); switch (extend_op) { case ZERO_EXTEND: this_val &= GET_MODE_MASK (GET_MODE (src)); break; case SIGN_EXTEND: /* ??? In theory we're already extended. */ if (this_val == trunc_int_for_mode (this_val, GET_MODE (src))) break; default: gcc_unreachable (); } this_rtx = GEN_INT (this_val); } #endif this_cost = rtx_cost (this_rtx, SET); } else if (REG_P (this_rtx)) { #ifdef LOAD_EXTEND_OP if (extend_op != UNKNOWN) { this_rtx = gen_rtx_fmt_e (extend_op, word_mode, this_rtx); this_cost = rtx_cost (this_rtx, SET); } else #endif this_cost = REGISTER_MOVE_COST (GET_MODE (this_rtx), REGNO_REG_CLASS (REGNO (this_rtx)), dclass); } else continue; /* If equal costs, prefer registers over anything else. That tends to lead to smaller instructions on some machines. */ if (this_cost < old_cost || (this_cost == old_cost && REG_P (this_rtx) && !REG_P (SET_SRC (set)))) { #ifdef LOAD_EXTEND_OP if (GET_MODE_BITSIZE (GET_MODE (SET_DEST (set))) < BITS_PER_WORD && extend_op != UNKNOWN #ifdef CANNOT_CHANGE_MODE_CLASS && !CANNOT_CHANGE_MODE_CLASS (GET_MODE (SET_DEST (set)), word_mode, REGNO_REG_CLASS (REGNO (SET_DEST (set)))) #endif ) { rtx wide_dest = gen_rtx_REG (word_mode, REGNO (SET_DEST (set))); ORIGINAL_REGNO (wide_dest) = ORIGINAL_REGNO (SET_DEST (set)); validate_change (insn, &SET_DEST (set), wide_dest, 1); } #endif validate_change (insn, &SET_SRC (set), copy_rtx (this_rtx), 1); old_cost = this_cost, did_change = 1; } } return did_change; } /* Try to replace operands in INSN with equivalent values that are already in registers. This can be viewed as optional reloading. For each non-register operand in the insn, see if any hard regs are known to be equivalent to that operand. Record the alternatives which can accept these hard registers. Among all alternatives, select the ones which are better or equal to the one currently matching, where "better" is in terms of '?' and '!' constraints. Among the remaining alternatives, select the one which replaces most operands with hard registers. */ static int reload_cse_simplify_operands (rtx insn, rtx testreg) { int i, j; /* For each operand, all registers that are equivalent to it. */ HARD_REG_SET equiv_regs[MAX_RECOG_OPERANDS]; const char *constraints[MAX_RECOG_OPERANDS]; /* Vector recording how bad an alternative is. */ int *alternative_reject; /* Vector recording how many registers can be introduced by choosing this alternative. */ int *alternative_nregs; /* Array of vectors recording, for each operand and each alternative, which hard register to substitute, or -1 if the operand should be left as it is. */ int *op_alt_regno[MAX_RECOG_OPERANDS]; /* Array of alternatives, sorted in order of decreasing desirability. */ int *alternative_order; extract_insn (insn); if (recog_data.n_alternatives == 0 || recog_data.n_operands == 0) return 0; /* Figure out which alternative currently matches. */ if (! constrain_operands (1)) fatal_insn_not_found (insn); alternative_reject = alloca (recog_data.n_alternatives * sizeof (int)); alternative_nregs = alloca (recog_data.n_alternatives * sizeof (int)); alternative_order = alloca (recog_data.n_alternatives * sizeof (int)); memset (alternative_reject, 0, recog_data.n_alternatives * sizeof (int)); memset (alternative_nregs, 0, recog_data.n_alternatives * sizeof (int)); /* For each operand, find out which regs are equivalent. */ for (i = 0; i < recog_data.n_operands; i++) { cselib_val *v; struct elt_loc_list *l; rtx op; enum machine_mode mode; CLEAR_HARD_REG_SET (equiv_regs[i]); /* cselib blows up on CODE_LABELs. Trying to fix that doesn't seem right, so avoid the problem here. Likewise if we have a constant and the insn pattern doesn't tell us the mode we need. */ if (LABEL_P (recog_data.operand[i]) || (CONSTANT_P (recog_data.operand[i]) && recog_data.operand_mode[i] == VOIDmode)) continue; op = recog_data.operand[i]; mode = GET_MODE (op); #ifdef LOAD_EXTEND_OP if (MEM_P (op) && GET_MODE_BITSIZE (mode) < BITS_PER_WORD && LOAD_EXTEND_OP (mode) != UNKNOWN) { rtx set = single_set (insn); /* We might have multiple sets, some of which do implicit extension. Punt on this for now. */ if (! set) continue; /* If the destination is also a MEM or a STRICT_LOW_PART, no extension applies. Also, if there is an explicit extension, we don't have to worry about an implicit one. */ else if (MEM_P (SET_DEST (set)) || GET_CODE (SET_DEST (set)) == STRICT_LOW_PART || GET_CODE (SET_SRC (set)) == ZERO_EXTEND || GET_CODE (SET_SRC (set)) == SIGN_EXTEND) ; /* Continue ordinary processing. */ #ifdef CANNOT_CHANGE_MODE_CLASS /* If the register cannot change mode to word_mode, it follows that it cannot have been used in word_mode. */ else if (REG_P (SET_DEST (set)) && CANNOT_CHANGE_MODE_CLASS (GET_MODE (SET_DEST (set)), word_mode, REGNO_REG_CLASS (REGNO (SET_DEST (set))))) ; /* Continue ordinary processing. */ #endif /* If this is a straight load, make the extension explicit. */ else if (REG_P (SET_DEST (set)) && recog_data.n_operands == 2 && SET_SRC (set) == op && SET_DEST (set) == recog_data.operand[1-i]) { validate_change (insn, recog_data.operand_loc[i], gen_rtx_fmt_e (LOAD_EXTEND_OP (mode), word_mode, op), 1); validate_change (insn, recog_data.operand_loc[1-i], gen_rtx_REG (word_mode, REGNO (SET_DEST (set))), 1); if (! apply_change_group ()) return 0; return reload_cse_simplify_operands (insn, testreg); } else /* ??? There might be arithmetic operations with memory that are safe to optimize, but is it worth the trouble? */ continue; } #endif /* LOAD_EXTEND_OP */ v = cselib_lookup (op, recog_data.operand_mode[i], 0); if (! v) continue; for (l = v->locs; l; l = l->next) if (REG_P (l->loc)) SET_HARD_REG_BIT (equiv_regs[i], REGNO (l->loc)); } for (i = 0; i < recog_data.n_operands; i++) { enum machine_mode mode; int regno; const char *p; op_alt_regno[i] = alloca (recog_data.n_alternatives * sizeof (int)); for (j = 0; j < recog_data.n_alternatives; j++) op_alt_regno[i][j] = -1; p = constraints[i] = recog_data.constraints[i]; mode = recog_data.operand_mode[i]; /* Add the reject values for each alternative given by the constraints for this operand. */ j = 0; while (*p != '\0') { char c = *p++; if (c == ',') j++; else if (c == '?') alternative_reject[j] += 3; else if (c == '!') alternative_reject[j] += 300; } /* We won't change operands which are already registers. We also don't want to modify output operands. */ regno = true_regnum (recog_data.operand[i]); if (regno >= 0 || constraints[i][0] == '=' || constraints[i][0] == '+') continue; for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) { int class = (int) NO_REGS; if (! TEST_HARD_REG_BIT (equiv_regs[i], regno)) continue; REGNO (testreg) = regno; PUT_MODE (testreg, mode); /* We found a register equal to this operand. Now look for all alternatives that can accept this register and have not been assigned a register they can use yet. */ j = 0; p = constraints[i]; for (;;) { char c = *p; switch (c) { case '=': case '+': case '?': case '#': case '&': case '!': case '*': case '%': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': case 'm': case '<': case '>': case 'V': case 'o': case 'E': case 'F': case 'G': case 'H': case 's': case 'i': case 'n': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N': case 'O': case 'P': case 'p': case 'X': /* These don't say anything we care about. */ break; case 'g': case 'r': class = reg_class_subunion[(int) class][(int) GENERAL_REGS]; break; default: class = (reg_class_subunion [(int) class] [(int) REG_CLASS_FROM_CONSTRAINT ((unsigned char) c, p)]); break; case ',': case '\0': /* See if REGNO fits this alternative, and set it up as the replacement register if we don't have one for this alternative yet and the operand being replaced is not a cheap CONST_INT. */ if (op_alt_regno[i][j] == -1 && reg_fits_class_p (testreg, class, 0, mode) && (GET_CODE (recog_data.operand[i]) != CONST_INT || (rtx_cost (recog_data.operand[i], SET) > rtx_cost (testreg, SET)))) { alternative_nregs[j]++; op_alt_regno[i][j] = regno; } j++; class = (int) NO_REGS; break; } p += CONSTRAINT_LEN (c, p); if (c == '\0') break; } } } /* Record all alternatives which are better or equal to the currently matching one in the alternative_order array. */ for (i = j = 0; i < recog_data.n_alternatives; i++) if (alternative_reject[i] <= alternative_reject[which_alternative]) alternative_order[j++] = i; recog_data.n_alternatives = j; /* Sort it. Given a small number of alternatives, a dumb algorithm won't hurt too much. */ for (i = 0; i < recog_data.n_alternatives - 1; i++) { int best = i; int best_reject = alternative_reject[alternative_order[i]]; int best_nregs = alternative_nregs[alternative_order[i]]; int tmp; for (j = i + 1; j < recog_data.n_alternatives; j++) { int this_reject = alternative_reject[alternative_order[j]]; int this_nregs = alternative_nregs[alternative_order[j]]; if (this_reject < best_reject || (this_reject == best_reject && this_nregs > best_nregs)) { best = j; best_reject = this_reject; best_nregs = this_nregs; } } tmp = alternative_order[best]; alternative_order[best] = alternative_order[i]; alternative_order[i] = tmp; } /* Substitute the operands as determined by op_alt_regno for the best alternative. */ j = alternative_order[0]; for (i = 0; i < recog_data.n_operands; i++) { enum machine_mode mode = recog_data.operand_mode[i]; if (op_alt_regno[i][j] == -1) continue; validate_change (insn, recog_data.operand_loc[i], gen_rtx_REG (mode, op_alt_regno[i][j]), 1); } for (i = recog_data.n_dups - 1; i >= 0; i--) { int op = recog_data.dup_num[i]; enum machine_mode mode = recog_data.operand_mode[op]; if (op_alt_regno[op][j] == -1) continue; validate_change (insn, recog_data.dup_loc[i], gen_rtx_REG (mode, op_alt_regno[op][j]), 1); } return apply_change_group (); } /* If reload couldn't use reg+reg+offset addressing, try to use reg+reg addressing now. This code might also be useful when reload gave up on reg+reg addressing because of clashes between the return register and INDEX_REG_CLASS. */ /* The maximum number of uses of a register we can keep track of to replace them with reg+reg addressing. */ #define RELOAD_COMBINE_MAX_USES 6 /* INSN is the insn where a register has ben used, and USEP points to the location of the register within the rtl. */ struct reg_use { rtx insn, *usep; }; /* If the register is used in some unknown fashion, USE_INDEX is negative. If it is dead, USE_INDEX is RELOAD_COMBINE_MAX_USES, and STORE_RUID indicates where it becomes live again. Otherwise, USE_INDEX is the index of the last encountered use of the register (which is first among these we have seen since we scan backwards), OFFSET contains the constant offset that is added to the register in all encountered uses, and USE_RUID indicates the first encountered, i.e. last, of these uses. STORE_RUID is always meaningful if we only want to use a value in a register in a different place: it denotes the next insn in the insn stream (i.e. the last encountered) that sets or clobbers the register. */ static struct { struct reg_use reg_use[RELOAD_COMBINE_MAX_USES]; int use_index; rtx offset; int store_ruid; int use_ruid; } reg_state[FIRST_PSEUDO_REGISTER]; /* Reverse linear uid. This is increased in reload_combine while scanning the instructions from last to first. It is used to set last_label_ruid and the store_ruid / use_ruid fields in reg_state. */ static int reload_combine_ruid; #define LABEL_LIVE(LABEL) \ (label_live[CODE_LABEL_NUMBER (LABEL) - min_labelno]) static void reload_combine (void) { rtx insn, set; int first_index_reg = -1; int last_index_reg = 0; int i; basic_block bb; unsigned int r; int last_label_ruid; int min_labelno, n_labels; HARD_REG_SET ever_live_at_start, *label_live; /* If reg+reg can be used in offsetable memory addresses, the main chunk of reload has already used it where appropriate, so there is no use in trying to generate it now. */ if (double_reg_address_ok && INDEX_REG_CLASS != NO_REGS) return; /* To avoid wasting too much time later searching for an index register, determine the minimum and maximum index register numbers. */ for (r = 0; r < FIRST_PSEUDO_REGISTER; r++) if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], r)) { if (first_index_reg == -1) first_index_reg = r; last_index_reg = r; } /* If no index register is available, we can quit now. */ if (first_index_reg == -1) return; /* Set up LABEL_LIVE and EVER_LIVE_AT_START. The register lifetime information is a bit fuzzy immediately after reload, but it's still good enough to determine which registers are live at a jump destination. */ min_labelno = get_first_label_num (); n_labels = max_label_num () - min_labelno; label_live = XNEWVEC (HARD_REG_SET, n_labels); CLEAR_HARD_REG_SET (ever_live_at_start); FOR_EACH_BB_REVERSE (bb) { insn = BB_HEAD (bb); if (LABEL_P (insn)) { HARD_REG_SET live; REG_SET_TO_HARD_REG_SET (live, bb->il.rtl->global_live_at_start); compute_use_by_pseudos (&live, bb->il.rtl->global_live_at_start); COPY_HARD_REG_SET (LABEL_LIVE (insn), live); IOR_HARD_REG_SET (ever_live_at_start, live); } } /* Initialize last_label_ruid, reload_combine_ruid and reg_state. */ last_label_ruid = reload_combine_ruid = 0; for (r = 0; r < FIRST_PSEUDO_REGISTER; r++) { reg_state[r].store_ruid = reload_combine_ruid; if (fixed_regs[r]) reg_state[r].use_index = -1; else reg_state[r].use_index = RELOAD_COMBINE_MAX_USES; } for (insn = get_last_insn (); insn; insn = PREV_INSN (insn)) { rtx note; /* We cannot do our optimization across labels. Invalidating all the use information we have would be costly, so we just note where the label is and then later disable any optimization that would cross it. */ if (LABEL_P (insn)) last_label_ruid = reload_combine_ruid; else if (BARRIER_P (insn)) for (r = 0; r < FIRST_PSEUDO_REGISTER; r++) if (! fixed_regs[r]) reg_state[r].use_index = RELOAD_COMBINE_MAX_USES; if (! INSN_P (insn)) continue; reload_combine_ruid++; /* Look for (set (REGX) (CONST_INT)) (set (REGX) (PLUS (REGX) (REGY))) ... ... (MEM (REGX)) ... and convert it to (set (REGZ) (CONST_INT)) ... ... (MEM (PLUS (REGZ) (REGY)))... . First, check that we have (set (REGX) (PLUS (REGX) (REGY))) and that we know all uses of REGX before it dies. Also, explicitly check that REGX != REGY; our life information does not yet show whether REGY changes in this insn. */ set = single_set (insn); if (set != NULL_RTX && REG_P (SET_DEST (set)) && (hard_regno_nregs[REGNO (SET_DEST (set))] [GET_MODE (SET_DEST (set))] == 1) && GET_CODE (SET_SRC (set)) == PLUS && REG_P (XEXP (SET_SRC (set), 1)) && rtx_equal_p (XEXP (SET_SRC (set), 0), SET_DEST (set)) && !rtx_equal_p (XEXP (SET_SRC (set), 1), SET_DEST (set)) && last_label_ruid < reg_state[REGNO (SET_DEST (set))].use_ruid) { rtx reg = SET_DEST (set); rtx plus = SET_SRC (set); rtx base = XEXP (plus, 1); rtx prev = prev_nonnote_insn (insn); rtx prev_set = prev ? single_set (prev) : NULL_RTX; unsigned int regno = REGNO (reg); rtx const_reg = NULL_RTX; rtx reg_sum = NULL_RTX; /* Now, we need an index register. We'll set index_reg to this index register, const_reg to the register that is to be loaded with the constant (denoted as REGZ in the substitution illustration above), and reg_sum to the register-register that we want to use to substitute uses of REG (typically in MEMs) with. First check REG and BASE for being index registers; we can use them even if they are not dead. */ if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], regno) || TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], REGNO (base))) { const_reg = reg; reg_sum = plus; } else { /* Otherwise, look for a free index register. Since we have checked above that neither REG nor BASE are index registers, if we find anything at all, it will be different from these two registers. */ for (i = first_index_reg; i <= last_index_reg; i++) { if (TEST_HARD_REG_BIT (reg_class_contents[INDEX_REG_CLASS], i) && reg_state[i].use_index == RELOAD_COMBINE_MAX_USES && reg_state[i].store_ruid <= reg_state[regno].use_ruid && hard_regno_nregs[i][GET_MODE (reg)] == 1) { rtx index_reg = gen_rtx_REG (GET_MODE (reg), i); const_reg = index_reg; reg_sum = gen_rtx_PLUS (GET_MODE (reg), index_reg, base); break; } } } /* Check that PREV_SET is indeed (set (REGX) (CONST_INT)) and that (REGY), i.e. BASE, is not clobbered before the last use we'll create. */ if (prev_set != 0 && GET_CODE (SET_SRC (prev_set)) == CONST_INT && rtx_equal_p (SET_DEST (prev_set), reg) && reg_state[regno].use_index >= 0 && (reg_state[REGNO (base)].store_ruid <= reg_state[regno].use_ruid) && reg_sum != 0) { int i; /* Change destination register and, if necessary, the constant value in PREV, the constant loading instruction. */ validate_change (prev, &SET_DEST (prev_set), const_reg, 1); if (reg_state[regno].offset != const0_rtx) validate_change (prev, &SET_SRC (prev_set), GEN_INT (INTVAL (SET_SRC (prev_set)) + INTVAL (reg_state[regno].offset)), 1); /* Now for every use of REG that we have recorded, replace REG with REG_SUM. */ for (i = reg_state[regno].use_index; i < RELOAD_COMBINE_MAX_USES; i++) validate_change (reg_state[regno].reg_use[i].insn, reg_state[regno].reg_use[i].usep, /* Each change must have its own replacement. */ copy_rtx (reg_sum), 1); if (apply_change_group ()) { rtx *np; /* Delete the reg-reg addition. */ delete_insn (insn); if (reg_state[regno].offset != const0_rtx) /* Previous REG_EQUIV / REG_EQUAL notes for PREV are now invalid. */ for (np = ®_NOTES (prev); *np;) { if (REG_NOTE_KIND (*np) == REG_EQUAL || REG_NOTE_KIND (*np) == REG_EQUIV) *np = XEXP (*np, 1); else np = &XEXP (*np, 1); } reg_state[regno].use_index = RELOAD_COMBINE_MAX_USES; reg_state[REGNO (const_reg)].store_ruid = reload_combine_ruid; continue; } } } note_stores (PATTERN (insn), reload_combine_note_store, NULL); if (CALL_P (insn)) { rtx link; for (r = 0; r < FIRST_PSEUDO_REGISTER; r++) if (call_used_regs[r]) { reg_state[r].use_index = RELOAD_COMBINE_MAX_USES; reg_state[r].store_ruid = reload_combine_ruid; } for (link = CALL_INSN_FUNCTION_USAGE (insn); link; link = XEXP (link, 1)) { rtx usage_rtx = XEXP (XEXP (link, 0), 0); if (REG_P (usage_rtx)) { unsigned int i; unsigned int start_reg = REGNO (usage_rtx); unsigned int num_regs = hard_regno_nregs[start_reg][GET_MODE (usage_rtx)]; unsigned int end_reg = start_reg + num_regs - 1; for (i = start_reg; i <= end_reg; i++) if (GET_CODE (XEXP (link, 0)) == CLOBBER) { reg_state[i].use_index = RELOAD_COMBINE_MAX_USES; reg_state[i].store_ruid = reload_combine_ruid; } else reg_state[i].use_index = -1; } } } else if (JUMP_P (insn) && GET_CODE (PATTERN (insn)) != RETURN) { /* Non-spill registers might be used at the call destination in some unknown fashion, so we have to mark the unknown use. */ HARD_REG_SET *live; if ((condjump_p (insn) || condjump_in_parallel_p (insn)) && JUMP_LABEL (insn)) live = &LABEL_LIVE (JUMP_LABEL (insn)); else live = &ever_live_at_start; for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; --i) if (TEST_HARD_REG_BIT (*live, i)) reg_state[i].use_index = -1; } reload_combine_note_use (&PATTERN (insn), insn); for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) { if (REG_NOTE_KIND (note) == REG_INC && REG_P (XEXP (note, 0))) { int regno = REGNO (XEXP (note, 0)); reg_state[regno].store_ruid = reload_combine_ruid; reg_state[regno].use_index = -1; } } } free (label_live); } /* Check if DST is a register or a subreg of a register; if it is, update reg_state[regno].store_ruid and reg_state[regno].use_index accordingly. Called via note_stores from reload_combine. */ static void reload_combine_note_store (rtx dst, rtx set, void *data ATTRIBUTE_UNUSED) { int regno = 0; int i; enum machine_mode mode = GET_MODE (dst); if (GET_CODE (dst) == SUBREG) { regno = subreg_regno_offset (REGNO (SUBREG_REG (dst)), GET_MODE (SUBREG_REG (dst)), SUBREG_BYTE (dst), GET_MODE (dst)); dst = SUBREG_REG (dst); } if (!REG_P (dst)) return; regno += REGNO (dst); /* note_stores might have stripped a STRICT_LOW_PART, so we have to be careful with registers / register parts that are not full words. Similarly for ZERO_EXTRACT. */ if (GET_CODE (set) != SET || GET_CODE (SET_DEST (set)) == ZERO_EXTRACT || GET_CODE (SET_DEST (set)) == STRICT_LOW_PART) { for (i = hard_regno_nregs[regno][mode] - 1 + regno; i >= regno; i--) { reg_state[i].use_index = -1; reg_state[i].store_ruid = reload_combine_ruid; } } else { for (i = hard_regno_nregs[regno][mode] - 1 + regno; i >= regno; i--) { reg_state[i].store_ruid = reload_combine_ruid; reg_state[i].use_index = RELOAD_COMBINE_MAX_USES; } } } /* XP points to a piece of rtl that has to be checked for any uses of registers. *XP is the pattern of INSN, or a part of it. Called from reload_combine, and recursively by itself. */ static void reload_combine_note_use (rtx *xp, rtx insn) { rtx x = *xp; enum rtx_code code = x->code; const char *fmt; int i, j; rtx offset = const0_rtx; /* For the REG case below. */ switch (code) { case SET: if (REG_P (SET_DEST (x))) { reload_combine_note_use (&SET_SRC (x), insn); return; } break; case USE: /* If this is the USE of a return value, we can't change it. */ if (REG_P (XEXP (x, 0)) && REG_FUNCTION_VALUE_P (XEXP (x, 0))) { /* Mark the return register as used in an unknown fashion. */ rtx reg = XEXP (x, 0); int regno = REGNO (reg); int nregs = hard_regno_nregs[regno][GET_MODE (reg)]; while (--nregs >= 0) reg_state[regno + nregs].use_index = -1; return; } break; case CLOBBER: if (REG_P (SET_DEST (x))) { /* No spurious CLOBBERs of pseudo registers may remain. */ gcc_assert (REGNO (SET_DEST (x)) < FIRST_PSEUDO_REGISTER); return; } break; case PLUS: /* We are interested in (plus (reg) (const_int)) . */ if (!REG_P (XEXP (x, 0)) || GET_CODE (XEXP (x, 1)) != CONST_INT) break; offset = XEXP (x, 1); x = XEXP (x, 0); /* Fall through. */ case REG: { int regno = REGNO (x); int use_index; int nregs; /* No spurious USEs of pseudo registers may remain. */ gcc_assert (regno < FIRST_PSEUDO_REGISTER); nregs = hard_regno_nregs[regno][GET_MODE (x)]; /* We can't substitute into multi-hard-reg uses. */ if (nregs > 1) { while (--nregs >= 0) reg_state[regno + nregs].use_index = -1; return; } /* If this register is already used in some unknown fashion, we can't do anything. If we decrement the index from zero to -1, we can't store more uses, so this register becomes used in an unknown fashion. */ use_index = --reg_state[regno].use_index; if (use_index < 0) return; if (use_index != RELOAD_COMBINE_MAX_USES - 1) { /* We have found another use for a register that is already used later. Check if the offsets match; if not, mark the register as used in an unknown fashion. */ if (! rtx_equal_p (offset, reg_state[regno].offset)) { reg_state[regno].use_index = -1; return; } } else { /* This is the first use of this register we have seen since we marked it as dead. */ reg_state[regno].offset = offset; reg_state[regno].use_ruid = reload_combine_ruid; } reg_state[regno].reg_use[use_index].insn = insn; reg_state[regno].reg_use[use_index].usep = xp; return; } default: break; } /* Recursively process the components of X. */ fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') reload_combine_note_use (&XEXP (x, i), insn); else if (fmt[i] == 'E') { for (j = XVECLEN (x, i) - 1; j >= 0; j--) reload_combine_note_use (&XVECEXP (x, i, j), insn); } } } /* See if we can reduce the cost of a constant by replacing a move with an add. We track situations in which a register is set to a constant or to a register plus a constant. */ /* We cannot do our optimization across labels. Invalidating all the information about register contents we have would be costly, so we use move2add_last_label_luid to note where the label is and then later disable any optimization that would cross it. reg_offset[n] / reg_base_reg[n] / reg_mode[n] are only valid if reg_set_luid[n] is greater than move2add_last_label_luid. */ static int reg_set_luid[FIRST_PSEUDO_REGISTER]; /* If reg_base_reg[n] is negative, register n has been set to reg_offset[n] in mode reg_mode[n] . If reg_base_reg[n] is non-negative, register n has been set to the sum of reg_offset[n] and the value of register reg_base_reg[n] before reg_set_luid[n], calculated in mode reg_mode[n] . */ static HOST_WIDE_INT reg_offset[FIRST_PSEUDO_REGISTER]; static int reg_base_reg[FIRST_PSEUDO_REGISTER]; static enum machine_mode reg_mode[FIRST_PSEUDO_REGISTER]; /* move2add_luid is linearly increased while scanning the instructions from first to last. It is used to set reg_set_luid in reload_cse_move2add and move2add_note_store. */ static int move2add_luid; /* move2add_last_label_luid is set whenever a label is found. Labels invalidate all previously collected reg_offset data. */ static int move2add_last_label_luid; /* ??? We don't know how zero / sign extension is handled, hence we can't go from a narrower to a wider mode. */ #define MODES_OK_FOR_MOVE2ADD(OUTMODE, INMODE) \ (GET_MODE_SIZE (OUTMODE) == GET_MODE_SIZE (INMODE) \ || (GET_MODE_SIZE (OUTMODE) <= GET_MODE_SIZE (INMODE) \ && TRULY_NOOP_TRUNCATION (GET_MODE_BITSIZE (OUTMODE), \ GET_MODE_BITSIZE (INMODE)))) static void reload_cse_move2add (rtx first) { int i; rtx insn; for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; i--) reg_set_luid[i] = 0; move2add_last_label_luid = 0; move2add_luid = 2; for (insn = first; insn; insn = NEXT_INSN (insn), move2add_luid++) { rtx pat, note; if (LABEL_P (insn)) { move2add_last_label_luid = move2add_luid; /* We're going to increment move2add_luid twice after a label, so that we can use move2add_last_label_luid + 1 as the luid for constants. */ move2add_luid++; continue; } if (! INSN_P (insn)) continue; pat = PATTERN (insn); /* For simplicity, we only perform this optimization on straightforward SETs. */ if (GET_CODE (pat) == SET && REG_P (SET_DEST (pat))) { rtx reg = SET_DEST (pat); int regno = REGNO (reg); rtx src = SET_SRC (pat); /* Check if we have valid information on the contents of this register in the mode of REG. */ if (reg_set_luid[regno] > move2add_last_label_luid && MODES_OK_FOR_MOVE2ADD (GET_MODE (reg), reg_mode[regno])) { /* Try to transform (set (REGX) (CONST_INT A)) ... (set (REGX) (CONST_INT B)) to (set (REGX) (CONST_INT A)) ... (set (REGX) (plus (REGX) (CONST_INT B-A))) or (set (REGX) (CONST_INT A)) ... (set (STRICT_LOW_PART (REGX)) (CONST_INT B)) */ if (GET_CODE (src) == CONST_INT && reg_base_reg[regno] < 0) { rtx new_src = gen_int_mode (INTVAL (src) - reg_offset[regno], GET_MODE (reg)); /* (set (reg) (plus (reg) (const_int 0))) is not canonical; use (set (reg) (reg)) instead. We don't delete this insn, nor do we convert it into a note, to avoid losing register notes or the return value flag. jump2 already knows how to get rid of no-op moves. */ if (new_src == const0_rtx) { /* If the constants are different, this is a truncation, that, if turned into (set (reg) (reg)), would be discarded. Maybe we should try a truncMN pattern? */ if (INTVAL (src) == reg_offset [regno]) validate_change (insn, &SET_SRC (pat), reg, 0); } else if (rtx_cost (new_src, PLUS) < rtx_cost (src, SET) && have_add2_insn (reg, new_src)) { rtx tem = gen_rtx_PLUS (GET_MODE (reg), reg, new_src); validate_change (insn, &SET_SRC (pat), tem, 0); } else if (GET_MODE (reg) != BImode) { enum machine_mode narrow_mode; for (narrow_mode = GET_CLASS_NARROWEST_MODE (MODE_INT); narrow_mode != VOIDmode && narrow_mode != GET_MODE (reg); narrow_mode = GET_MODE_WIDER_MODE (narrow_mode)) { if (have_insn_for (STRICT_LOW_PART, narrow_mode) && ((reg_offset[regno] & ~GET_MODE_MASK (narrow_mode)) == (INTVAL (src) & ~GET_MODE_MASK (narrow_mode)))) { rtx narrow_reg = gen_rtx_REG (narrow_mode, REGNO (reg)); rtx narrow_src = gen_int_mode (INTVAL (src), narrow_mode); rtx new_set = gen_rtx_SET (VOIDmode, gen_rtx_STRICT_LOW_PART (VOIDmode, narrow_reg), narrow_src); if (validate_change (insn, &PATTERN (insn), new_set, 0)) break; } } } reg_set_luid[regno] = move2add_luid; reg_mode[regno] = GET_MODE (reg); reg_offset[regno] = INTVAL (src); continue; } /* Try to transform (set (REGX) (REGY)) (set (REGX) (PLUS (REGX) (CONST_INT A))) ... (set (REGX) (REGY)) (set (REGX) (PLUS (REGX) (CONST_INT B))) to (set (REGX) (REGY)) (set (REGX) (PLUS (REGX) (CONST_INT A))) ... (set (REGX) (plus (REGX) (CONST_INT B-A))) */ else if (REG_P (src) && reg_set_luid[regno] == reg_set_luid[REGNO (src)] && reg_base_reg[regno] == reg_base_reg[REGNO (src)] && MODES_OK_FOR_MOVE2ADD (GET_MODE (reg), reg_mode[REGNO (src)])) { rtx next = next_nonnote_insn (insn); rtx set = NULL_RTX; if (next) set = single_set (next); if (set && SET_DEST (set) == reg && GET_CODE (SET_SRC (set)) == PLUS && XEXP (SET_SRC (set), 0) == reg && GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT) { rtx src3 = XEXP (SET_SRC (set), 1); HOST_WIDE_INT added_offset = INTVAL (src3); HOST_WIDE_INT base_offset = reg_offset[REGNO (src)]; HOST_WIDE_INT regno_offset = reg_offset[regno]; rtx new_src = gen_int_mode (added_offset + base_offset - regno_offset, GET_MODE (reg)); int success = 0; if (new_src == const0_rtx) /* See above why we create (set (reg) (reg)) here. */ success = validate_change (next, &SET_SRC (set), reg, 0); else if ((rtx_cost (new_src, PLUS) < COSTS_N_INSNS (1) + rtx_cost (src3, SET)) && have_add2_insn (reg, new_src)) { rtx newpat = gen_rtx_SET (VOIDmode, reg, gen_rtx_PLUS (GET_MODE (reg), reg, new_src)); success = validate_change (next, &PATTERN (next), newpat, 0); } if (success) delete_insn (insn); insn = next; reg_mode[regno] = GET_MODE (reg); reg_offset[regno] = trunc_int_for_mode (added_offset + base_offset, GET_MODE (reg)); continue; } } } } for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) { if (REG_NOTE_KIND (note) == REG_INC && REG_P (XEXP (note, 0))) { /* Reset the information about this register. */ int regno = REGNO (XEXP (note, 0)); if (regno < FIRST_PSEUDO_REGISTER) reg_set_luid[regno] = 0; } } note_stores (PATTERN (insn), move2add_note_store, NULL); /* If INSN is a conditional branch, we try to extract an implicit set out of it. */ if (any_condjump_p (insn)) { rtx cnd = fis_get_condition (insn); if (cnd != NULL_RTX && GET_CODE (cnd) == NE && REG_P (XEXP (cnd, 0)) && !reg_set_p (XEXP (cnd, 0), insn) /* The following two checks, which are also in move2add_note_store, are intended to reduce the number of calls to gen_rtx_SET to avoid memory allocation if possible. */ && SCALAR_INT_MODE_P (GET_MODE (XEXP (cnd, 0))) && hard_regno_nregs[REGNO (XEXP (cnd, 0))][GET_MODE (XEXP (cnd, 0))] == 1 && GET_CODE (XEXP (cnd, 1)) == CONST_INT) { rtx implicit_set = gen_rtx_SET (VOIDmode, XEXP (cnd, 0), XEXP (cnd, 1)); move2add_note_store (SET_DEST (implicit_set), implicit_set, 0); } } /* If this is a CALL_INSN, all call used registers are stored with unknown values. */ if (CALL_P (insn)) { for (i = FIRST_PSEUDO_REGISTER - 1; i >= 0; i--) { if (call_used_regs[i]) /* Reset the information about this register. */ reg_set_luid[i] = 0; } } } } /* SET is a SET or CLOBBER that sets DST. Update reg_set_luid, reg_offset and reg_base_reg accordingly. Called from reload_cse_move2add via note_stores. */ static void move2add_note_store (rtx dst, rtx set, void *data ATTRIBUTE_UNUSED) { unsigned int regno = 0; unsigned int i; enum machine_mode mode = GET_MODE (dst); if (GET_CODE (dst) == SUBREG) { regno = subreg_regno_offset (REGNO (SUBREG_REG (dst)), GET_MODE (SUBREG_REG (dst)), SUBREG_BYTE (dst), GET_MODE (dst)); dst = SUBREG_REG (dst); } /* Some targets do argument pushes without adding REG_INC notes. */ if (MEM_P (dst)) { dst = XEXP (dst, 0); if (GET_CODE (dst) == PRE_INC || GET_CODE (dst) == POST_INC || GET_CODE (dst) == PRE_DEC || GET_CODE (dst) == POST_DEC) reg_set_luid[REGNO (XEXP (dst, 0))] = 0; return; } if (!REG_P (dst)) return; regno += REGNO (dst); if (SCALAR_INT_MODE_P (GET_MODE (dst)) && hard_regno_nregs[regno][mode] == 1 && GET_CODE (set) == SET && GET_CODE (SET_DEST (set)) != ZERO_EXTRACT && GET_CODE (SET_DEST (set)) != STRICT_LOW_PART) { rtx src = SET_SRC (set); rtx base_reg; HOST_WIDE_INT offset; int base_regno; /* This may be different from mode, if SET_DEST (set) is a SUBREG. */ enum machine_mode dst_mode = GET_MODE (dst); switch (GET_CODE (src)) { case PLUS: if (REG_P (XEXP (src, 0))) { base_reg = XEXP (src, 0); if (GET_CODE (XEXP (src, 1)) == CONST_INT) offset = INTVAL (XEXP (src, 1)); else if (REG_P (XEXP (src, 1)) && (reg_set_luid[REGNO (XEXP (src, 1))] > move2add_last_label_luid) && (MODES_OK_FOR_MOVE2ADD (dst_mode, reg_mode[REGNO (XEXP (src, 1))]))) { if (reg_base_reg[REGNO (XEXP (src, 1))] < 0) offset = reg_offset[REGNO (XEXP (src, 1))]; /* Maybe the first register is known to be a constant. */ else if (reg_set_luid[REGNO (base_reg)] > move2add_last_label_luid && (MODES_OK_FOR_MOVE2ADD (dst_mode, reg_mode[REGNO (XEXP (src, 1))])) && reg_base_reg[REGNO (base_reg)] < 0) { offset = reg_offset[REGNO (base_reg)]; base_reg = XEXP (src, 1); } else goto invalidate; } else goto invalidate; break; } goto invalidate; case REG: base_reg = src; offset = 0; break; case CONST_INT: /* Start tracking the register as a constant. */ reg_base_reg[regno] = -1; reg_offset[regno] = INTVAL (SET_SRC (set)); /* We assign the same luid to all registers set to constants. */ reg_set_luid[regno] = move2add_last_label_luid + 1; reg_mode[regno] = mode; return; default: invalidate: /* Invalidate the contents of the register. */ reg_set_luid[regno] = 0; return; } base_regno = REGNO (base_reg); /* If information about the base register is not valid, set it up as a new base register, pretending its value is known starting from the current insn. */ if (reg_set_luid[base_regno] <= move2add_last_label_luid) { reg_base_reg[base_regno] = base_regno; reg_offset[base_regno] = 0; reg_set_luid[base_regno] = move2add_luid; reg_mode[base_regno] = mode; } else if (! MODES_OK_FOR_MOVE2ADD (dst_mode, reg_mode[base_regno])) goto invalidate; reg_mode[regno] = mode; /* Copy base information from our base register. */ reg_set_luid[regno] = reg_set_luid[base_regno]; reg_base_reg[regno] = reg_base_reg[base_regno]; /* Compute the sum of the offsets or constants. */ reg_offset[regno] = trunc_int_for_mode (offset + reg_offset[base_regno], dst_mode); } else { unsigned int endregno = regno + hard_regno_nregs[regno][mode]; for (i = regno; i < endregno; i++) /* Reset the information about this register. */ reg_set_luid[i] = 0; } } static bool gate_handle_postreload (void) { return (optimize > 0); } static unsigned int rest_of_handle_postreload (void) { /* Do a very simple CSE pass over just the hard registers. */ reload_cse_regs (get_insns ()); /* reload_cse_regs can eliminate potentially-trapping MEMs. Remove any EH edges associated with them. */ if (flag_non_call_exceptions) purge_all_dead_edges (); return 0; } struct tree_opt_pass pass_postreload_cse = { "postreload", /* name */ gate_handle_postreload, /* gate */ rest_of_handle_postreload, /* execute */ NULL, /* sub */ NULL, /* next */ 0, /* static_pass_number */ TV_RELOAD_CSE_REGS, /* tv_id */ 0, /* properties_required */ 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ TODO_dump_func, /* todo_flags_finish */ 'o' /* letter */ };
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