/* Compute register class preferences for pseudo-registers. Copyright (C) 1987, 1988, 1991, 1992 Free Software Foundation, Inc. This file is part of GNU CC. GNU CC 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 2, or (at your option) any later version. GNU CC 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 GNU CC; see the file COPYING. If not, write to the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ /* This file contains two passes of the compiler: reg_scan and reg_class. It also defines some tables of information about the hardware registers and a function init_reg_sets to initialize the tables. */ #include "config.h" #include "rtl.h" #include "hard-reg-set.h" #include "flags.h" #include "basic-block.h" #include "regs.h" #include "insn-config.h" #include "recog.h" #include "reload.h" #include "real.h" #ifndef REGISTER_MOVE_COST #define REGISTER_MOVE_COST(x, y) 2 #endif #ifndef MEMORY_MOVE_COST #define MEMORY_MOVE_COST(x) 4 #endif /* If we have auto-increment or auto-decrement and we can have secondary reloads, we are not allowed to use classes requiring secondary reloads for psuedos auto-incremented since reload can't handle it. */ #ifdef AUTO_INC_DEC #if defined(SECONDARY_INPUT_RELOAD_CLASS) || defined(SECONDARY_OUTPUT_RELOAD_CLASS) #define FORBIDDEN_INC_DEC_CLASSES #endif #endif /* Register tables used by many passes. */ /* Indexed by hard register number, contains 1 for registers that are fixed use (stack pointer, pc, frame pointer, etc.). These are the registers that cannot be used to allocate a pseudo reg whose life does not cross calls. */ char fixed_regs[FIRST_PSEUDO_REGISTER]; /* Same info as a HARD_REG_SET. */ HARD_REG_SET fixed_reg_set; /* Data for initializing the above. */ static char initial_fixed_regs[] = FIXED_REGISTERS; /* Indexed by hard register number, contains 1 for registers that are fixed use or are clobbered by function calls. These are the registers that cannot be used to allocate a pseudo reg whose life crosses calls. */ char call_used_regs[FIRST_PSEUDO_REGISTER]; /* Same info as a HARD_REG_SET. */ HARD_REG_SET call_used_reg_set; /* Data for initializing the above. */ static char initial_call_used_regs[] = CALL_USED_REGISTERS; /* Indexed by hard register number, contains 1 for registers that are fixed use -- i.e. in fixed_regs -- or a function value return register or STRUCT_VALUE_REGNUM or STATIC_CHAIN_REGNUM. These are the registers that cannot hold quantities across calls even if we are willing to save and restore them. */ char call_fixed_regs[FIRST_PSEUDO_REGISTER]; /* The same info as a HARD_REG_SET. */ HARD_REG_SET call_fixed_reg_set; /* Number of non-fixed registers. */ int n_non_fixed_regs; /* Indexed by hard register number, contains 1 for registers that are being used for global register decls. These must be exempt from ordinary flow analysis and are also considered fixed. */ char global_regs[FIRST_PSEUDO_REGISTER]; /* Table of register numbers in the order in which to try to use them. */ #ifdef REG_ALLOC_ORDER int reg_alloc_order[FIRST_PSEUDO_REGISTER] = REG_ALLOC_ORDER; #endif /* For each reg class, a HARD_REG_SET saying which registers are in it. */ HARD_REG_SET reg_class_contents[N_REG_CLASSES]; /* The same information, but as an array of ints. We copy from these ints to the table above. This is done so that the tm.h files do not have to be aware of the wordsize for machines with <= 64 regs. */ #define N_REG_INTS \ ((FIRST_PSEUDO_REGISTER + (HOST_BITS_PER_INT - 1)) / HOST_BITS_PER_INT) static int int_reg_class_contents[N_REG_CLASSES][N_REG_INTS] = REG_CLASS_CONTENTS; /* For each reg class, number of regs it contains. */ int reg_class_size[N_REG_CLASSES]; /* For each reg class, table listing all the containing classes. */ enum reg_class reg_class_superclasses[N_REG_CLASSES][N_REG_CLASSES]; /* For each reg class, table listing all the classes contained in it. */ enum reg_class reg_class_subclasses[N_REG_CLASSES][N_REG_CLASSES]; /* For each pair of reg classes, a largest reg class contained in their union. */ enum reg_class reg_class_subunion[N_REG_CLASSES][N_REG_CLASSES]; /* For each pair of reg classes, the smallest reg class containing their union. */ enum reg_class reg_class_superunion[N_REG_CLASSES][N_REG_CLASSES]; /* Array containing all of the register names */ char *reg_names[] = REGISTER_NAMES; /* Indexed by n, gives number of times (REG n) is set or clobbered. This information remains valid for the rest of the compilation of the current function; it is used to control register allocation. This information applies to both hard registers and pseudo registers, unlike much of the information above. */ short *reg_n_sets; /* Maximum cost of moving from a register in one class to a register in another class. Based on REGISTER_MOVE_COST. */ static int move_cost[N_REG_CLASSES][N_REG_CLASSES]; /* Similar, but here we don't have to move if the first index is a subset of the second so in that case the cost is zero. */ static int may_move_cost[N_REG_CLASSES][N_REG_CLASSES]; #ifdef FORBIDDEN_INC_DEC_CLASSES /* These are the classes that regs which are auto-incremented or decremented cannot be put in. */ static int forbidden_inc_dec_class[N_REG_CLASSES]; /* Indexed by n, is non-zero if (REG n) is used in an auto-inc or auto-dec context. */ static char *in_inc_dec; #endif /* FORBIDDEN_INC_DEC_CLASSES */ /* Function called only once to initialize the above data on reg usage. Once this is done, various switches may override. */ void init_reg_sets () { register int i, j; /* First copy the register information from the initial int form into the regsets. */ for (i = 0; i < N_REG_CLASSES; i++) { CLEAR_HARD_REG_SET (reg_class_contents[i]); for (j = 0; j < FIRST_PSEUDO_REGISTER; j++) if (int_reg_class_contents[i][j / HOST_BITS_PER_INT] & (1 << (j % HOST_BITS_PER_INT))) SET_HARD_REG_BIT (reg_class_contents[i], j); } bcopy (initial_fixed_regs, fixed_regs, sizeof fixed_regs); bcopy (initial_call_used_regs, call_used_regs, sizeof call_used_regs); bzero (global_regs, sizeof global_regs); /* Compute number of hard regs in each class. */ bzero (reg_class_size, sizeof reg_class_size); for (i = 0; i < N_REG_CLASSES; i++) for (j = 0; j < FIRST_PSEUDO_REGISTER; j++) if (TEST_HARD_REG_BIT (reg_class_contents[i], j)) reg_class_size[i]++; /* Initialize the table of subunions. reg_class_subunion[I][J] gets the largest-numbered reg-class that is contained in the union of classes I and J. */ for (i = 0; i < N_REG_CLASSES; i++) { for (j = 0; j < N_REG_CLASSES; j++) { #ifdef HARD_REG_SET register /* Declare it register if it's a scalar. */ #endif HARD_REG_SET c; register int k; COPY_HARD_REG_SET (c, reg_class_contents[i]); IOR_HARD_REG_SET (c, reg_class_contents[j]); for (k = 0; k < N_REG_CLASSES; k++) { GO_IF_HARD_REG_SUBSET (reg_class_contents[k], c, subclass1); continue; subclass1: /* keep the largest subclass */ /* SPEE 900308 */ GO_IF_HARD_REG_SUBSET (reg_class_contents[k], reg_class_contents[(int) reg_class_subunion[i][j]], subclass2); reg_class_subunion[i][j] = (enum reg_class) k; subclass2: ; } } } /* Initialize the table of superunions. reg_class_superunion[I][J] gets the smallest-numbered reg-class containing the union of classes I and J. */ for (i = 0; i < N_REG_CLASSES; i++) { for (j = 0; j < N_REG_CLASSES; j++) { #ifdef HARD_REG_SET register /* Declare it register if it's a scalar. */ #endif HARD_REG_SET c; register int k; COPY_HARD_REG_SET (c, reg_class_contents[i]); IOR_HARD_REG_SET (c, reg_class_contents[j]); for (k = 0; k < N_REG_CLASSES; k++) GO_IF_HARD_REG_SUBSET (c, reg_class_contents[k], superclass); superclass: reg_class_superunion[i][j] = (enum reg_class) k; } } /* Initialize the tables of subclasses and superclasses of each reg class. First clear the whole table, then add the elements as they are found. */ for (i = 0; i < N_REG_CLASSES; i++) { for (j = 0; j < N_REG_CLASSES; j++) { reg_class_superclasses[i][j] = LIM_REG_CLASSES; reg_class_subclasses[i][j] = LIM_REG_CLASSES; } } for (i = 0; i < N_REG_CLASSES; i++) { if (i == (int) NO_REGS) continue; for (j = i + 1; j < N_REG_CLASSES; j++) { enum reg_class *p; GO_IF_HARD_REG_SUBSET (reg_class_contents[i], reg_class_contents[j], subclass); continue; subclass: /* Reg class I is a subclass of J. Add J to the table of superclasses of I. */ p = ®_class_superclasses[i][0]; while (*p != LIM_REG_CLASSES) p++; *p = (enum reg_class) j; /* Add I to the table of superclasses of J. */ p = ®_class_subclasses[j][0]; while (*p != LIM_REG_CLASSES) p++; *p = (enum reg_class) i; } } /* Initialize the move cost table. Find every subset of each class and take the maximum cost of moving any subset to any other. */ for (i = 0; i < N_REG_CLASSES; i++) for (j = 0; j < N_REG_CLASSES; j++) { int cost = i == j ? 2 : REGISTER_MOVE_COST (i, j); enum reg_class *p1, *p2; for (p2 = ®_class_subclasses[j][0]; *p2 != LIM_REG_CLASSES; p2++) if (*p2 != i) cost = MAX (cost, REGISTER_MOVE_COST (i, *p2)); for (p1 = ®_class_subclasses[i][0]; *p1 != LIM_REG_CLASSES; p1++) { if (*p1 != j) cost = MAX (cost, REGISTER_MOVE_COST (*p1, j)); for (p2 = ®_class_subclasses[j][0]; *p2 != LIM_REG_CLASSES; p2++) if (*p1 != *p2) cost = MAX (cost, REGISTER_MOVE_COST (*p1, *p2)); } move_cost[i][j] = cost; if (reg_class_subset_p (i, j)) cost = 0; may_move_cost[i][j] = cost; } } /* After switches have been processed, which perhaps alter `fixed_regs' and `call_used_regs', convert them to HARD_REG_SETs. */ void init_reg_sets_1 () { register int i; /* This macro allows the fixed or call-used registers to depend on target flags. */ #ifdef CONDITIONAL_REGISTER_USAGE CONDITIONAL_REGISTER_USAGE; #endif for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) if (global_regs[i]) { if (call_used_regs[i] && ! fixed_regs[i]) warning ("call-clobbered register used for global register variable"); fixed_regs[i] = 1; /* Prevent saving/restoring of this reg. */ call_used_regs[i] = 1; } /* Initialize "constant" tables. */ CLEAR_HARD_REG_SET (fixed_reg_set); CLEAR_HARD_REG_SET (call_used_reg_set); CLEAR_HARD_REG_SET (call_fixed_reg_set); bcopy (fixed_regs, call_fixed_regs, sizeof call_fixed_regs); #ifdef STRUCT_VALUE_REGNUM call_fixed_regs[STRUCT_VALUE_REGNUM] = 1; #endif #ifdef STATIC_CHAIN_REGNUM call_fixed_regs[STATIC_CHAIN_REGNUM] = 1; #endif n_non_fixed_regs = 0; for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) { if (FUNCTION_VALUE_REGNO_P (i)) call_fixed_regs[i] = 1; if (fixed_regs[i]) SET_HARD_REG_BIT (fixed_reg_set, i); else n_non_fixed_regs++; if (call_used_regs[i]) SET_HARD_REG_BIT (call_used_reg_set, i); if (call_fixed_regs[i]) SET_HARD_REG_BIT (call_fixed_reg_set, i); } } /* Specify the usage characteristics of the register named NAME. It should be a fixed register if FIXED and a call-used register if CALL_USED. */ void fix_register (name, fixed, call_used) char *name; int fixed, call_used; { int i; /* Decode the name and update the primary form of the register info. */ if ((i = decode_reg_name (name)) >= 0) { fixed_regs[i] = fixed; call_used_regs[i] = call_used; } else { warning ("unknown register name: %s", name); } } /* Now the data and code for the `regclass' pass, which happens just before local-alloc. */ /* The `costs' struct records the cost of using a hard register of each class and of using memory for each pseudo. We use this data to set up register class preferences. */ struct costs { int cost[N_REG_CLASSES]; int mem_cost; }; /* Record the cost of each class for each pseudo. */ static struct costs *costs; /* Record the same data by operand number, accumulated for each alternative in an insn. The contribution to a pseudo is that of the minimum-cost alternative. */ static struct costs op_costs[MAX_RECOG_OPERANDS]; /* (enum reg_class) prefclass[R] is the preferred class for pseudo number R. This is available after `regclass' is run. */ static char *prefclass; /* altclass[R] is a register class that we should use for allocating pseudo number R if no register in the preferred class is available. If no register in this class is available, memory is preferred. It might appear to be more general to have a bitmask of classes here, but since it is recommended that there be a class corresponding to the union of most major pair of classes, that generality is not required. This is available after `regclass' is run. */ static char *altclass; /* Record the depth of loops that we are in. */ static int loop_depth; /* Account for the fact that insns within a loop are executed very commonly, but don't keep doing this as loops go too deep. */ static int loop_cost; static int copy_cost (); static void record_reg_classes (); static void record_address_regs (); /* Return the reg_class in which pseudo reg number REGNO is best allocated. This function is sometimes called before the info has been computed. When that happens, just return GENERAL_REGS, which is innocuous. */ enum reg_class reg_preferred_class (regno) int regno; { if (prefclass == 0) return GENERAL_REGS; return (enum reg_class) prefclass[regno]; } enum reg_class reg_alternate_class (regno) { if (prefclass == 0) return ALL_REGS; return (enum reg_class) altclass[regno]; } /* This prevents dump_flow_info from losing if called before regclass is run. */ void regclass_init () { prefclass = 0; } /* This is a pass of the compiler that scans all instructions and calculates the preferred class for each pseudo-register. This information can be accessed later by calling `reg_preferred_class'. This pass comes just before local register allocation. */ void regclass (f, nregs) rtx f; int nregs; { #ifdef REGISTER_CONSTRAINTS register rtx insn; register int i, j; struct costs init_cost; rtx set; int pass; init_recog (); costs = (struct costs *) alloca (nregs * sizeof (struct costs)); #ifdef FORBIDDEN_INC_DEC_CLASSES in_inc_dec = (char *) alloca (nregs); /* Initialize information about which register classes can be used for pseudos that are auto-incremented or auto-decremented. It would seem better to put this in init_reg_sets, but we need to be able to allocate rtx, which we can't do that early. */ for (i = 0; i < N_REG_CLASSES; i++) { rtx r = gen_rtx (REG, VOIDmode, 0); enum machine_mode m; for (j = 0; j < FIRST_PSEUDO_REGISTER; j++) if (TEST_HARD_REG_BIT (reg_class_contents[i], j)) { REGNO (r) = j; for (m = VOIDmode; (int) m < (int) MAX_MACHINE_MODE; m = (enum machine_mode) ((int) m) + 1) if (HARD_REGNO_MODE_OK (j, m)) { PUT_MODE (r, m); if (0 #ifdef SECONDARY_INPUT_RELOAD_CLASS || (SECONDARY_INPUT_RELOAD_CLASS (BASE_REG_CLASS, m, r) != NO_REGS) #endif #ifdef SECONDARY_OUTPUT_RELOAD_CLASS || (SECONDARY_OUTPUT_RELOAD_CLASS (BASE_REG_CLASS, m, r) != NO_REGS) #endif ) forbidden_inc_dec_class[i] = 1; } } } #endif /* FORBIDDEN_INC_DEC_CLASSES */ init_cost.mem_cost = 10000; for (i = 0; i < N_REG_CLASSES; i++) init_cost.cost[i] = 10000; /* Normally we scan the insns once and determine the best class to use for each register. However, if -fexpensive_optimizations are on, we do so twice, the second time using the tentative best classes to guide the selection. */ for (pass = 0; pass <= flag_expensive_optimizations; pass++) { /* Zero out our accumulation of the cost of each class for each reg. */ bzero (costs, nregs * sizeof (struct costs)); #ifdef FORBIDDEN_INC_DEC_CLASSES bzero (in_inc_dec, nregs); #endif loop_depth = 0, loop_cost = 1; /* Scan the instructions and record each time it would save code to put a certain register in a certain class. */ for (insn = f; insn; insn = NEXT_INSN (insn)) { char *constraints[MAX_RECOG_OPERANDS]; enum machine_mode modes[MAX_RECOG_OPERANDS]; int nalternatives; int noperands; /* Show that an insn inside a loop is likely to be executed three times more than insns outside a loop. This is much more agressive than the assumptions made elsewhere and is being tried as an experiment. */ if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) loop_depth++, loop_cost = 1 << (2 * MIN (loop_depth, 5)); else if (GET_CODE (insn) == NOTE && NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) loop_depth--, loop_cost = 1 << (2 * MIN (loop_depth, 5)); else if ((GET_CODE (insn) == INSN && GET_CODE (PATTERN (insn)) != USE && GET_CODE (PATTERN (insn)) != CLOBBER && GET_CODE (PATTERN (insn)) != ASM_INPUT) || (GET_CODE (insn) == JUMP_INSN && GET_CODE (PATTERN (insn)) != ADDR_VEC && GET_CODE (PATTERN (insn)) != ADDR_DIFF_VEC) || GET_CODE (insn) == CALL_INSN) { if (GET_CODE (insn) == INSN && (noperands = asm_noperands (PATTERN (insn))) >= 0) { decode_asm_operands (PATTERN (insn), recog_operand, NULL_PTR, constraints, modes); nalternatives = (noperands == 0 ? 0 : n_occurrences (',', constraints[0]) + 1); } else { int insn_code_number = recog_memoized (insn); rtx note; set = single_set (insn); insn_extract (insn); nalternatives = insn_n_alternatives[insn_code_number]; noperands = insn_n_operands[insn_code_number]; /* If this insn loads a parameter from its stack slot, then it represents a savings, rather than a cost, if the parameter is stored in memory. Record this fact. */ if (set != 0 && GET_CODE (SET_DEST (set)) == REG && GET_CODE (SET_SRC (set)) == MEM && (note = find_reg_note (insn, REG_EQUIV, NULL_RTX)) != 0 && GET_CODE (XEXP (note, 0)) == MEM) { costs[REGNO (SET_DEST (set))].mem_cost -= (MEMORY_MOVE_COST (GET_MODE (SET_DEST (set))) * loop_cost); record_address_regs (XEXP (SET_SRC (set), 0), BASE_REG_CLASS, loop_cost * 2); continue; } /* Improve handling of two-address insns such as (set X (ashift CONST Y)) where CONST must be made to match X. Change it into two insns: (set X CONST) (set X (ashift X Y)). If we left this for reloading, it would probably get three insns because X and Y might go in the same place. This prevents X and Y from receiving the same hard reg. We can only do this if the modes of operands 0 and 1 (which might not be the same) are tieable and we only need do this during our first pass. */ if (pass == 0 && optimize && noperands >= 3 && insn_operand_constraint[insn_code_number][1][0] == '0' && insn_operand_constraint[insn_code_number][1][1] == 0 && CONSTANT_P (recog_operand[1]) && ! rtx_equal_p (recog_operand[0], recog_operand[1]) && ! rtx_equal_p (recog_operand[0], recog_operand[2]) && GET_CODE (recog_operand[0]) == REG && MODES_TIEABLE_P (GET_MODE (recog_operand[0]), insn_operand_mode[insn_code_number][1])) { rtx previnsn = prev_real_insn (insn); rtx dest = gen_lowpart (insn_operand_mode[insn_code_number][1], recog_operand[0]); rtx newinsn = emit_insn_before (gen_move_insn (dest, recog_operand[1]), insn); /* If this insn was the start of a basic block, include the new insn in that block. We need not check for code_label here; while a basic block can start with a code_label, INSN could not be at the beginning of that block. */ if (previnsn == 0 || GET_CODE (previnsn) == JUMP_INSN) { int b; for (b = 0; b < n_basic_blocks; b++) if (insn == basic_block_head[b]) basic_block_head[b] = newinsn; } /* This makes one more setting of new insns's dest. */ reg_n_sets[REGNO (recog_operand[0])]++; *recog_operand_loc[1] = recog_operand[0]; for (i = insn_n_dups[insn_code_number] - 1; i >= 0; i--) if (recog_dup_num[i] == 1) *recog_dup_loc[i] = recog_operand[0]; insn = PREV_INSN (newinsn); continue; } /* If this is setting a pseudo from another pseudo or the sum of a pseudo and a constant integer and the other pseudo is known to be a pointer, set the destination to be a pointer as well. Likewise if it is setting the destination from an address or from a value equivalent to an address or to the sum of an address and something else. But don't do any of this if the pseudo corresponds to a user variable since it should have already been set as a pointer based on the type. There is no point in doing this during our second pass since not enough should have changed. */ if (pass == 0 && set != 0 && GET_CODE (SET_DEST (set)) == REG && REGNO (SET_DEST (set)) >= FIRST_PSEUDO_REGISTER && ! REG_USERVAR_P (SET_DEST (set)) && ! REGNO_POINTER_FLAG (REGNO (SET_DEST (set))) && ((GET_CODE (SET_SRC (set)) == REG && REGNO_POINTER_FLAG (REGNO (SET_SRC (set)))) || ((GET_CODE (SET_SRC (set)) == PLUS || GET_CODE (SET_SRC (set)) == LO_SUM) && (GET_CODE (XEXP (SET_SRC (set), 1)) == CONST_INT) && GET_CODE (XEXP (SET_SRC (set), 0)) == REG && REGNO_POINTER_FLAG (REGNO (XEXP (SET_SRC (set), 0)))) || GET_CODE (SET_SRC (set)) == CONST || GET_CODE (SET_SRC (set)) == SYMBOL_REF || GET_CODE (SET_SRC (set)) == LABEL_REF || (GET_CODE (SET_SRC (set)) == HIGH && (GET_CODE (XEXP (SET_SRC (set), 0)) == CONST || (GET_CODE (XEXP (SET_SRC (set), 0)) == SYMBOL_REF) || (GET_CODE (XEXP (SET_SRC (set), 0)) == LABEL_REF))) || ((GET_CODE (SET_SRC (set)) == PLUS || GET_CODE (SET_SRC (set)) == LO_SUM) && (GET_CODE (XEXP (SET_SRC (set), 1)) == CONST || (GET_CODE (XEXP (SET_SRC (set), 1)) == SYMBOL_REF) || (GET_CODE (XEXP (SET_SRC (set), 1)) == LABEL_REF))) || ((note = find_reg_note (insn, REG_EQUAL, 0)) != 0 && (GET_CODE (XEXP (note, 0)) == CONST || GET_CODE (XEXP (note, 0)) == SYMBOL_REF || GET_CODE (XEXP (note, 0)) == LABEL_REF)))) REGNO_POINTER_FLAG (REGNO (SET_DEST (set))) = 1; for (i = 0; i < noperands; i++) { constraints[i] = insn_operand_constraint[insn_code_number][i]; modes[i] = insn_operand_mode[insn_code_number][i]; } } /* If we get here, we are set up to record the costs of all the operands for this insn. Start by initializing the costs. Then handle any address registers. Finally record the desired classes for any pseudos, doing it twice if some pair of operands are commutative. */ for (i = 0; i < noperands; i++) { op_costs[i] = init_cost; if (GET_CODE (recog_operand[i]) == SUBREG) recog_operand[i] = SUBREG_REG (recog_operand[i]); if (GET_CODE (recog_operand[i]) == MEM) record_address_regs (XEXP (recog_operand[i], 0), BASE_REG_CLASS, loop_cost * 2); else if (constraints[i][0] == 'p') record_address_regs (recog_operand[i], BASE_REG_CLASS, loop_cost * 2); } /* Check for commutative in a separate loop so everything will have been initialized. Don't bother doing anything if the second operand is a constant since that is the case for which the constraints should have been written. */ for (i = 0; i < noperands - 1; i++) if (constraints[i][0] == '%' && ! CONSTANT_P (recog_operand[i+1])) { char *xconstraints[MAX_RECOG_OPERANDS]; int j; /* Handle commutative operands by swapping the constraints. We assume the modes are the same. */ for (j = 0; j < noperands; j++) xconstraints[j] = constraints[j]; xconstraints[i] = constraints[i+1]; xconstraints[i+1] = constraints[i]; record_reg_classes (nalternatives, noperands, recog_operand, modes, xconstraints, insn); } record_reg_classes (nalternatives, noperands, recog_operand, modes, constraints, insn); /* Now add the cost for each operand to the total costs for its register. */ for (i = 0; i < noperands; i++) if (GET_CODE (recog_operand[i]) == REG && REGNO (recog_operand[i]) >= FIRST_PSEUDO_REGISTER) { int regno = REGNO (recog_operand[i]); struct costs *p = &costs[regno], *q = &op_costs[i]; p->mem_cost += q->mem_cost * loop_cost; for (j = 0; j < N_REG_CLASSES; j++) p->cost[j] += q->cost[j] * loop_cost; } } } /* Now for each register look at how desirable each class is and find which class is preferred. Store that in `prefclass[REGNO]'. Record in `altclass[REGNO]' the largest register class any of whose registers is better than memory. */ if (pass == 0) { prefclass = (char *) oballoc (nregs); altclass = (char *) oballoc (nregs); } for (i = FIRST_PSEUDO_REGISTER; i < nregs; i++) { register int best_cost = (1 << (HOST_BITS_PER_INT - 2)) - 1; enum reg_class best = ALL_REGS, alt = NO_REGS; /* This is an enum reg_class, but we call it an int to save lots of casts. */ register int class; register struct costs *p = &costs[i]; for (class = (int) ALL_REGS - 1; class > 0; class--) { /* Ignore classes that are too small for this operand or invalid for a operand that was auto-incremented. */ if (CLASS_MAX_NREGS (class, PSEUDO_REGNO_MODE (i)) > reg_class_size[class] #ifdef FORBIDDEN_INC_DEC_CLASSES || (in_inc_dec[i] && forbidden_inc_dec_class[class]) #endif ) ; else if (p->cost[class] < best_cost) { best_cost = p->cost[class]; best = (enum reg_class) class; } else if (p->cost[class] == best_cost) best = reg_class_subunion[(int)best][class]; } /* Record the alternate register class; i.e., a class for which every register in it is better than using memory. If adding a class would make a smaller class (i.e., no union of just those classes exists), skip that class. The major unions of classes should be provided as a register class. Don't do this if we will be doing it again later. */ if (pass == 1 || ! flag_expensive_optimizations) for (class = 0; class < N_REG_CLASSES; class++) if (p->cost[class] < p->mem_cost && (reg_class_size[(int) reg_class_subunion[(int) alt][class]] > reg_class_size[(int) alt]) #ifdef FORBIDDEN_INC_DEC_CLASSES && ! (in_inc_dec[i] && forbidden_inc_dec_class[class]) #endif ) alt = reg_class_subunion[(int) alt][class]; /* If we don't add any classes, nothing to try. */ if (alt == best) alt = (int) NO_REGS; /* We cast to (int) because (char) hits bugs in some compilers. */ prefclass[i] = (int) best; altclass[i] = (int) alt; } } #endif /* REGISTER_CONSTRAINTS */ } #ifdef REGISTER_CONSTRAINTS /* Record the cost of using memory or registers of various classes for the operands in INSN. N_ALTS is the number of alternatives. N_OPS is the number of operands. OPS is an array of the operands. MODES are the modes of the operands, in case any are VOIDmode. CONSTRAINTS are the constraints to use for the operands. This array is modified by this procedure. This procedure works alternative by alternative. For each alternative we assume that we will be able to allocate all pseudos to their ideal register class and calculate the cost of using that alternative. Then we compute for each operand that is a pseudo-register, the cost of having the pseudo allocated to each register class and using it in that alternative. To this cost is added the cost of the alternative. The cost of each class for this insn is its lowest cost among all the alternatives. */ static void record_reg_classes (n_alts, n_ops, ops, modes, constraints, insn) int n_alts; int n_ops; rtx *ops; enum machine_mode *modes; char **constraints; rtx insn; { int alt; enum op_type {OP_READ, OP_WRITE, OP_READ_WRITE} op_types[MAX_RECOG_OPERANDS]; int i, j; /* By default, each operand is an input operand. */ for (i = 0; i < n_ops; i++) op_types[i] = OP_READ; /* Process each alternative, each time minimizing an operand's cost with the cost for each operand in that alternative. */ for (alt = 0; alt < n_alts; alt++) { struct costs this_op_costs[MAX_RECOG_OPERANDS]; int alt_fail = 0; int alt_cost = 0; enum reg_class classes[MAX_RECOG_OPERANDS]; int class; for (i = 0; i < n_ops; i++) { char *p = constraints[i]; rtx op = ops[i]; enum machine_mode mode = modes[i]; int allows_mem = 0; int win = 0; char c; /* If this operand has no constraints at all, we can conclude nothing about it since anything is valid. */ if (*p == 0) { if (GET_CODE (op) == REG && REGNO (op) >= FIRST_PSEUDO_REGISTER) bzero ((char *) &this_op_costs[i], sizeof this_op_costs[i]); continue; } if (*p == '%') p++; /* If this alternative is only relevant when this operand matches a previous operand, we do different things depending on whether this operand is a pseudo-reg or not. */ if (p[0] >= '0' && p[0] <= '0' + i && (p[1] == ',' || p[1] == 0)) { j = p[0] - '0'; classes[i] = classes[j]; if (GET_CODE (op) != REG || REGNO (op) < FIRST_PSEUDO_REGISTER) { /* If this matches the other operand, we have no added cost. */ if (rtx_equal_p (ops[j], op)) ; /* If we can't put the other operand into a register, this alternative can't be used. */ else if (classes[j] == NO_REGS) alt_fail = 1; /* Otherwise, add to the cost of this alternative the cost to copy this operand to the register used for the other operand. */ else alt_cost += copy_cost (op, mode, classes[j], 1); } else if (GET_CODE (ops[j]) != REG || REGNO (ops[j]) < FIRST_PSEUDO_REGISTER) { /* This op is a pseudo but the one it matches is not. */ /* If we can't put the other operand into a register, this alternative can't be used. */ if (classes[j] == NO_REGS) alt_fail = 1; /* Otherwise, add to the cost of this alternative the cost to copy the other operand to the register used for this operand. */ else alt_cost += copy_cost (ops[j], mode, classes[j], 1); } else { /* The costs of this operand are the same as that of the other operand. However, if we cannot tie them, this alternative needs to do a copy, which is one instruction. */ this_op_costs[i] = this_op_costs[j]; if (! find_reg_note (insn, REG_DEAD, op)) alt_cost += 2; /* This is in place of ordinary cost computation for this operand. */ continue; } } /* Scan all the constraint letters. See if the operand matches any of the constraints. Collect the valid register classes and see if this operand accepts memory. */ classes[i] = NO_REGS; while (*p && (c = *p++) != ',') switch (c) { case '=': op_types[i] = OP_WRITE; break; case '+': op_types[i] = OP_READ_WRITE; break; case '*': /* Ignore the next letter for this pass. */ p++; break; case '%': case '?': case '!': case '#': case '&': case '0': case '1': case '2': case '3': case '4': case 'p': break; case 'm': case 'o': case 'V': /* It doesn't seem worth distingishing between offsettable and non-offsettable addresses here. */ allows_mem = 1; if (GET_CODE (op) == MEM) win = 1; break; case '<': if (GET_CODE (op) == MEM && (GET_CODE (XEXP (op, 0)) == PRE_DEC || GET_CODE (XEXP (op, 0)) == POST_DEC)) win = 1; break; case '>': if (GET_CODE (op) == MEM && (GET_CODE (XEXP (op, 0)) == PRE_INC || GET_CODE (XEXP (op, 0)) == POST_INC)) win = 1; break; case 'E': /* Match any floating double constant, but only if we can examine the bits of it reliably. */ if ((HOST_FLOAT_FORMAT != TARGET_FLOAT_FORMAT || HOST_BITS_PER_WIDE_INT != BITS_PER_WORD) && GET_MODE (op) != VOIDmode && ! flag_pretend_float) break; if (GET_CODE (op) == CONST_DOUBLE) win = 1; break; case 'F': if (GET_CODE (op) == CONST_DOUBLE) win = 1; break; case 'G': case 'H': if (GET_CODE (op) == CONST_DOUBLE && CONST_DOUBLE_OK_FOR_LETTER_P (op, c)) win = 1; break; case 's': if (GET_CODE (op) == CONST_INT || (GET_CODE (op) == CONST_DOUBLE && GET_MODE (op) == VOIDmode)) break; case 'i': if (CONSTANT_P (op) #ifdef LEGITIMATE_PIC_OPERAND_P && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op)) #endif ) win = 1; break; case 'n': if (GET_CODE (op) == CONST_INT || (GET_CODE (op) == CONST_DOUBLE && GET_MODE (op) == VOIDmode)) win = 1; break; case 'I': case 'J': case 'K': case 'L': case 'M': case 'N': case 'O': case 'P': if (GET_CODE (op) == CONST_INT && CONST_OK_FOR_LETTER_P (INTVAL (op), c)) win = 1; break; case 'X': win = 1; break; #ifdef EXTRA_CONSTRAINT case 'Q': case 'R': case 'S': case 'T': case 'U': if (EXTRA_CONSTRAINT (op, c)) win = 1; break; #endif case 'g': if (GET_CODE (op) == MEM || (CONSTANT_P (op) #ifdef LEGITIMATE_PIC_OPERAND_P && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (op)) #endif )) win = 1; allows_mem = 1; case 'r': classes[i] = reg_class_subunion[(int) classes[i]][(int) GENERAL_REGS]; break; default: classes[i] = reg_class_subunion[(int) classes[i]] [(int) REG_CLASS_FROM_LETTER (c)]; } constraints[i] = p; /* How we account for this operand now depends on whether it is a pseudo register or not. If it is, we first check if any register classes are valid. If not, we ignore this alternative, since we want to assume that all pseudos get allocated for register preferencing. If some register class is valid, compute the costs of moving the pseudo into that class. */ if (GET_CODE (op) == REG && REGNO (op) >= FIRST_PSEUDO_REGISTER) { if (classes[i] == NO_REGS) alt_fail = 1; else { struct costs *pp = &this_op_costs[i]; for (class = 0; class < N_REG_CLASSES; class++) pp->cost[class] = may_move_cost[class][(int) classes[i]]; /* If the alternative actually allows memory, make things a bit cheaper since we won't need an extra insn to load it. */ pp->mem_cost = MEMORY_MOVE_COST (mode) - allows_mem; /* If we have assigned a class to this register in our first pass, add a cost to this alternative corresponding to what we would add if this register were not in the appropriate class. */ if (prefclass) alt_cost += may_move_cost[prefclass[REGNO (op)]][(int) classes[i]]; } } /* Otherwise, if this alternative wins, either because we have already determined that or if we have a hard register of the proper class, there is no cost for this alternative. */ else if (win || (GET_CODE (op) == REG && reg_fits_class_p (op, classes[i], 0, GET_MODE (op)))) ; /* If registers are valid, the cost of this alternative includes copying the object to and/or from a register. */ else if (classes[i] != NO_REGS) { if (op_types[i] != OP_WRITE) alt_cost += copy_cost (op, mode, classes[i], 1); if (op_types[i] != OP_READ) alt_cost += copy_cost (op, mode, classes[i], 0); } /* The only other way this alternative can be used is if this is a constant that could be placed into memory. */ else if (CONSTANT_P (op) && allows_mem) alt_cost += MEMORY_MOVE_COST (mode); else alt_fail = 1; } if (alt_fail) continue; /* Finally, update the costs with the information we've calculated about this alternative. */ for (i = 0; i < n_ops; i++) if (GET_CODE (ops[i]) == REG && REGNO (ops[i]) >= FIRST_PSEUDO_REGISTER) { struct costs *pp = &op_costs[i], *qq = &this_op_costs[i]; int scale = 1 + (op_types[i] == OP_READ_WRITE); pp->mem_cost = MIN (pp->mem_cost, (qq->mem_cost + alt_cost) * scale); for (class = 0; class < N_REG_CLASSES; class++) pp->cost[class] = MIN (pp->cost[class], (qq->cost[class] + alt_cost) * scale); } } } /* Compute the cost of loading X into (if TO_P is non-zero) or from (if TO_P is zero) a register of class CLASS in mode MODE. X must not be a pseudo. */ static int copy_cost (x, mode, class, to_p) rtx x; enum machine_mode mode; enum reg_class class; int to_p; { enum reg_class secondary_class = NO_REGS; /* If X is a SCRATCH, there is actually nothing to move since we are assuming optimal allocation. */ if (GET_CODE (x) == SCRATCH) return 0; /* Get the class we will actually use for a reload. */ class = PREFERRED_RELOAD_CLASS (x, class); #ifdef HAVE_SECONDARY_RELOADS /* If we need a secondary reload (we assume here that we are using the secondary reload as an intermediate, not a scratch register), the cost is that to load the input into the intermediate register, then to copy them. We use a special value of TO_P to avoid recursion. */ #ifdef SECONDARY_INPUT_RELOAD_CLASS if (to_p == 1) secondary_class = SECONDARY_INPUT_RELOAD_CLASS (class, mode, x); #endif #ifdef SECONDARY_OUTPUT_RELOAD_CLASS if (! to_p) secondary_class = SECONDARY_OUTPUT_RELOAD_CLASS (class, mode, x); #endif if (secondary_class != NO_REGS) return (move_cost[(int) secondary_class][(int) class] + copy_cost (x, mode, secondary_class, 2)); #endif /* HAVE_SECONDARY_RELOADS */ /* For memory, use the memory move cost, for (hard) registers, use the cost to move between the register classes, and use 2 for everything else (constants). */ if (GET_CODE (x) == MEM || class == NO_REGS) return MEMORY_MOVE_COST (mode); else if (GET_CODE (x) == REG) return move_cost[(int) REGNO_REG_CLASS (REGNO (x))][(int) class]; else /* If this is a constant, we may eventually want to call rtx_cost here. */ return 2; } /* Record the pseudo registers we must reload into hard registers in a subexpression of a memory address, X. CLASS is the class that the register needs to be in and is either BASE_REG_CLASS or INDEX_REG_CLASS. SCALE is twice the amount to multiply the cost by (it is twice so we can represent half-cost adjustments). */ static void record_address_regs (x, class, scale) rtx x; enum reg_class class; int scale; { register enum rtx_code code = GET_CODE (x); switch (code) { case CONST_INT: case CONST: case CC0: case PC: case SYMBOL_REF: case LABEL_REF: return; case PLUS: /* When we have an address that is a sum, we must determine whether registers are "base" or "index" regs. If there is a sum of two registers, we must choose one to be the "base". Luckily, we can use the REGNO_POINTER_FLAG to make a good choice most of the time. We only need to do this on machines that can have two registers in an address and where the base and index register classes are different. ??? This code used to set REGNO_POINTER_FLAG in some cases, but that seems bogus since it should only be set when we are sure the register is being used as a pointer. */ { rtx arg0 = XEXP (x, 0); rtx arg1 = XEXP (x, 1); register enum rtx_code code0 = GET_CODE (arg0); register enum rtx_code code1 = GET_CODE (arg1); /* Look inside subregs. */ if (code0 == SUBREG) arg0 = SUBREG_REG (arg0), code0 = GET_CODE (arg0); if (code1 == SUBREG) arg1 = SUBREG_REG (arg1), code1 = GET_CODE (arg1); /* If this machine only allows one register per address, it must be in the first operand. */ if (MAX_REGS_PER_ADDRESS == 1) record_address_regs (arg0, class, scale); /* If index and base registers are the same on this machine, just record registers in any non-constant operands. We assume here, as well as in the tests below, that all addresses are in canonical form. */ else if (INDEX_REG_CLASS == BASE_REG_CLASS) { record_address_regs (arg0, class, scale); if (! CONSTANT_P (arg1)) record_address_regs (arg1, class, scale); } /* If the second operand is a constant integer, it doesn't change what class the first operand must be. */ else if (code1 == CONST_INT || code1 == CONST_DOUBLE) record_address_regs (arg0, class, scale); /* If the second operand is a symbolic constant, the first operand must be an index register. */ else if (code1 == SYMBOL_REF || code1 == CONST || code1 == LABEL_REF) record_address_regs (arg0, INDEX_REG_CLASS, scale); /* If this the sum of two registers where the first is known to be a pointer, it must be a base register with the second an index. */ else if (code0 == REG && code1 == REG && REGNO_POINTER_FLAG (REGNO (arg0))) { record_address_regs (arg0, BASE_REG_CLASS, scale); record_address_regs (arg1, INDEX_REG_CLASS, scale); } /* If this is the sum of two registers and neither is known to be a pointer, count equal chances that each might be a base or index register. This case should be rare. */ else if (code0 == REG && code1 == REG && ! REGNO_POINTER_FLAG (REGNO (arg0)) && ! REGNO_POINTER_FLAG (REGNO (arg1))) { record_address_regs (arg0, BASE_REG_CLASS, scale / 2); record_address_regs (arg0, INDEX_REG_CLASS, scale / 2); record_address_regs (arg1, BASE_REG_CLASS, scale / 2); record_address_regs (arg1, INDEX_REG_CLASS, scale / 2); } /* In all other cases, the first operand is an index and the second is the base. */ else { record_address_regs (arg0, INDEX_REG_CLASS, scale); record_address_regs (arg1, BASE_REG_CLASS, scale); } } break; case POST_INC: case PRE_INC: case POST_DEC: case PRE_DEC: /* Double the importance of a pseudo register that is incremented or decremented, since it would take two extra insns if it ends up in the wrong place. If the operand is a pseudo, show it is being used in an INC_DEC context. */ #ifdef FORBIDDEN_INC_DEC_CLASSES if (GET_CODE (XEXP (x, 0)) == REG && REGNO (XEXP (x, 0)) >= FIRST_PSEUDO_REGISTER) in_inc_dec[REGNO (XEXP (x, 0))] = 1; #endif record_address_regs (XEXP (x, 0), class, 2 * scale); break; case REG: { register struct costs *pp = &costs[REGNO (x)]; register int i; pp->mem_cost += (MEMORY_MOVE_COST (Pmode) * scale) / 2; for (i = 0; i < N_REG_CLASSES; i++) pp->cost[i] += (may_move_cost[i][(int) class] * scale) / 2; } break; default: { register char *fmt = GET_RTX_FORMAT (code); register int i; for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) if (fmt[i] == 'e') record_address_regs (XEXP (x, i), class, scale); } } } #endif /* REGISTER_CONSTRAINTS */ /* This is the `regscan' pass of the compiler, run just before cse and again just before loop. It finds the first and last use of each pseudo-register and records them in the vectors regno_first_uid, regno_last_uid and counts the number of sets in the vector reg_n_sets. REPEAT is nonzero the second time this is called. */ /* Indexed by pseudo register number, gives uid of first insn using the reg (as of the time reg_scan is called). */ int *regno_first_uid; /* Indexed by pseudo register number, gives uid of last insn using the reg (as of the time reg_scan is called). */ int *regno_last_uid; /* Record the number of registers we used when we allocated the above two tables. If we are called again with more than this, we must re-allocate the tables. */ static int highest_regno_in_uid_map; /* Maximum number of parallel sets and clobbers in any insn in this fn. Always at least 3, since the combiner could put that many togetherm and we want this to remain correct for all the remaining passes. */ int max_parallel; void reg_scan_mark_refs (); void reg_scan (f, nregs, repeat) rtx f; int nregs; int repeat; { register rtx insn; if (!repeat || nregs > highest_regno_in_uid_map) { /* Leave some spare space in case more regs are allocated. */ highest_regno_in_uid_map = nregs + nregs / 20; regno_first_uid = (int *) oballoc (highest_regno_in_uid_map * sizeof (int)); regno_last_uid = (int *) oballoc (highest_regno_in_uid_map * sizeof (int)); reg_n_sets = (short *) oballoc (highest_regno_in_uid_map * sizeof (short)); } bzero (regno_first_uid, highest_regno_in_uid_map * sizeof (int)); bzero (regno_last_uid, highest_regno_in_uid_map * sizeof (int)); bzero (reg_n_sets, highest_regno_in_uid_map * sizeof (short)); max_parallel = 3; for (insn = f; insn; insn = NEXT_INSN (insn)) if (GET_CODE (insn) == INSN || GET_CODE (insn) == CALL_INSN || GET_CODE (insn) == JUMP_INSN) { if (GET_CODE (PATTERN (insn)) == PARALLEL && XVECLEN (PATTERN (insn), 0) > max_parallel) max_parallel = XVECLEN (PATTERN (insn), 0); reg_scan_mark_refs (PATTERN (insn), INSN_UID (insn)); } } void reg_scan_mark_refs (x, uid) rtx x; int uid; { register enum rtx_code code = GET_CODE (x); register rtx dest; switch (code) { case CONST_INT: case CONST: case CONST_DOUBLE: case CC0: case PC: case SYMBOL_REF: case LABEL_REF: case ADDR_VEC: case ADDR_DIFF_VEC: return; case REG: { register int regno = REGNO (x); regno_last_uid[regno] = uid; if (regno_first_uid[regno] == 0) regno_first_uid[regno] = uid; } break; case SET: /* Count a set of the destination if it is a register. */ for (dest = SET_DEST (x); GET_CODE (dest) == SUBREG || GET_CODE (dest) == STRICT_LOW_PART || GET_CODE (dest) == ZERO_EXTEND; dest = XEXP (dest, 0)) ; if (GET_CODE (dest) == REG) reg_n_sets[REGNO (dest)]++; /* ... fall through ... */ default: { register char *fmt = GET_RTX_FORMAT (code); register int i; for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) { if (fmt[i] == 'e') reg_scan_mark_refs (XEXP (x, i), uid); else if (fmt[i] == 'E' && XVEC (x, i) != 0) { register int j; for (j = XVECLEN (x, i) - 1; j >= 0; j--) reg_scan_mark_refs (XVECEXP (x, i, j), uid); } } } } } /* Return nonzero if C1 is a subset of C2, i.e., if every register in C1 is also in C2. */ int reg_class_subset_p (c1, c2) register enum reg_class c1; register enum reg_class c2; { if (c1 == c2) return 1; if (c2 == ALL_REGS) win: return 1; GO_IF_HARD_REG_SUBSET (reg_class_contents[(int)c1], reg_class_contents[(int)c2], win); return 0; } /* Return nonzero if there is a register that is in both C1 and C2. */ int reg_classes_intersect_p (c1, c2) register enum reg_class c1; register enum reg_class c2; { #ifdef HARD_REG_SET register #endif HARD_REG_SET c; if (c1 == c2) return 1; if (c1 == ALL_REGS || c2 == ALL_REGS) return 1; COPY_HARD_REG_SET (c, reg_class_contents[(int) c1]); AND_HARD_REG_SET (c, reg_class_contents[(int) c2]); GO_IF_HARD_REG_SUBSET (c, reg_class_contents[(int) NO_REGS], lose); return 1; lose: return 0; }