/* Allocate registers within a basic block, for GNU compiler. Copyright (C) 1987, 88, 91, 93-98, 1999 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ /* Allocation of hard register numbers to pseudo registers is done in two passes. In this pass we consider only regs that are born and die once within one basic block. We do this one basic block at a time. Then the next pass allocates the registers that remain. Two passes are used because this pass uses methods that work only on linear code, but that do a better job than the general methods used in global_alloc, and more quickly too. The assignments made are recorded in the vector reg_renumber whose space is allocated here. The rtl code itself is not altered. We assign each instruction in the basic block a number which is its order from the beginning of the block. Then we can represent the lifetime of a pseudo register with a pair of numbers, and check for conflicts easily. We can record the availability of hard registers with a HARD_REG_SET for each instruction. The HARD_REG_SET contains 0 or 1 for each hard reg. To avoid register shuffling, we tie registers together when one dies by being copied into another, or dies in an instruction that does arithmetic to produce another. The tied registers are allocated as one. Registers with different reg class preferences can never be tied unless the class preferred by one is a subclass of the one preferred by the other. Tying is represented with "quantity numbers". A non-tied register is given a new quantity number. Tied registers have the same quantity number. We have provision to exempt registers, even when they are contained within the block, that can be tied to others that are not contained in it. This is so that global_alloc could process them both and tie them then. But this is currently disabled since tying in global_alloc is not yet implemented. */ /* Pseudos allocated here can be reallocated by global.c if the hard register is used as a spill register. Currently we don't allocate such pseudos here if their preferred class is likely to be used by spills. */ #include "config.h" #include "system.h" #include "rtl.h" #include "flags.h" #include "basic-block.h" #include "regs.h" #include "hard-reg-set.h" #include "insn-config.h" #include "insn-attr.h" #include "recog.h" #include "output.h" #include "toplev.h" /* Next quantity number available for allocation. */ static int next_qty; /* In all the following vectors indexed by quantity number. */ /* Element Q is the hard reg number chosen for quantity Q, or -1 if none was found. */ static short *qty_phys_reg; /* We maintain two hard register sets that indicate suggested hard registers for each quantity. The first, qty_phys_copy_sugg, contains hard registers that are tied to the quantity by a simple copy. The second contains all hard registers that are tied to the quantity via an arithmetic operation. The former register set is given priority for allocation. This tends to eliminate copy insns. */ /* Element Q is a set of hard registers that are suggested for quantity Q by copy insns. */ static HARD_REG_SET *qty_phys_copy_sugg; /* Element Q is a set of hard registers that are suggested for quantity Q by arithmetic insns. */ static HARD_REG_SET *qty_phys_sugg; /* Element Q is the number of suggested registers in qty_phys_copy_sugg. */ static short *qty_phys_num_copy_sugg; /* Element Q is the number of suggested registers in qty_phys_sugg. */ static short *qty_phys_num_sugg; /* Element Q is the number of refs to quantity Q. */ static int *qty_n_refs; /* Element Q is a reg class contained in (smaller than) the preferred classes of all the pseudo regs that are tied in quantity Q. This is the preferred class for allocating that quantity. */ static enum reg_class *qty_min_class; /* Insn number (counting from head of basic block) where quantity Q was born. -1 if birth has not been recorded. */ static int *qty_birth; /* Insn number (counting from head of basic block) where quantity Q died. Due to the way tying is done, and the fact that we consider in this pass only regs that die but once, a quantity can die only once. Each quantity's life span is a set of consecutive insns. -1 if death has not been recorded. */ static int *qty_death; /* Number of words needed to hold the data in quantity Q. This depends on its machine mode. It is used for these purposes: 1. It is used in computing the relative importances of qtys, which determines the order in which we look for regs for them. 2. It is used in rules that prevent tying several registers of different sizes in a way that is geometrically impossible (see combine_regs). */ static int *qty_size; /* This holds the mode of the registers that are tied to qty Q, or VOIDmode if registers with differing modes are tied together. */ static enum machine_mode *qty_mode; /* Number of times a reg tied to qty Q lives across a CALL_INSN. */ static int *qty_n_calls_crossed; /* Register class within which we allocate qty Q if we can't get its preferred class. */ static enum reg_class *qty_alternate_class; /* Element Q is nonzero if this quantity has been used in a SUBREG that changes its size. */ static char *qty_changes_size; /* Element Q is the register number of one pseudo register whose reg_qty value is Q. This register should be the head of the chain maintained in reg_next_in_qty. */ static int *qty_first_reg; /* If (REG N) has been assigned a quantity number, is a register number of another register assigned the same quantity number, or -1 for the end of the chain. qty_first_reg point to the head of this chain. */ static int *reg_next_in_qty; /* reg_qty[N] (where N is a pseudo reg number) is the qty number of that reg if it is >= 0, of -1 if this register cannot be allocated by local-alloc, or -2 if not known yet. Note that if we see a use or death of pseudo register N with reg_qty[N] == -2, register N must be local to the current block. If it were used in more than one block, we would have reg_qty[N] == -1. This relies on the fact that if reg_basic_block[N] is >= 0, register N will not appear in any other block. We save a considerable number of tests by exploiting this. If N is < FIRST_PSEUDO_REGISTER, reg_qty[N] is undefined and should not be referenced. */ static int *reg_qty; /* The offset (in words) of register N within its quantity. This can be nonzero if register N is SImode, and has been tied to a subreg of a DImode register. */ static char *reg_offset; /* Vector of substitutions of register numbers, used to map pseudo regs into hardware regs. This is set up as a result of register allocation. Element N is the hard reg assigned to pseudo reg N, or is -1 if no hard reg was assigned. If N is a hard reg number, element N is N. */ short *reg_renumber; /* Set of hard registers live at the current point in the scan of the instructions in a basic block. */ static HARD_REG_SET regs_live; /* Each set of hard registers indicates registers live at a particular point in the basic block. For N even, regs_live_at[N] says which hard registers are needed *after* insn N/2 (i.e., they may not conflict with the outputs of insn N/2 or the inputs of insn N/2 + 1. If an object is to conflict with the inputs of insn J but not the outputs of insn J + 1, we say it is born at index J*2 - 1. Similarly, if it is to conflict with the outputs of insn J but not the inputs of insn J + 1, it is said to die at index J*2 + 1. */ static HARD_REG_SET *regs_live_at; /* Communicate local vars `insn_number' and `insn' from `block_alloc' to `reg_is_set', `wipe_dead_reg', and `alloc_qty'. */ static int this_insn_number; static rtx this_insn; /* Used to communicate changes made by update_equiv_regs to memref_referenced_p. reg_equiv_replacement is set for any REG_EQUIV note found or created, so that we can keep track of what memory accesses might be created later, e.g. by reload. */ static rtx *reg_equiv_replacement; /* Used for communication between update_equiv_regs and no_equiv. */ static rtx *reg_equiv_init_insns; /* Nonzero if we recorded an equivalence for a LABEL_REF. */ static int recorded_label_ref; static void alloc_qty PROTO((int, enum machine_mode, int, int)); static void validate_equiv_mem_from_store PROTO((rtx, rtx)); static int validate_equiv_mem PROTO((rtx, rtx, rtx)); static int contains_replace_regs PROTO((rtx, char *)); static int memref_referenced_p PROTO((rtx, rtx)); static int memref_used_between_p PROTO((rtx, rtx, rtx)); static void update_equiv_regs PROTO((void)); static void no_equiv PROTO((rtx, rtx)); static void block_alloc PROTO((int)); static int qty_sugg_compare PROTO((int, int)); static int qty_sugg_compare_1 PROTO((const GENERIC_PTR, const GENERIC_PTR)); static int qty_compare PROTO((int, int)); static int qty_compare_1 PROTO((const GENERIC_PTR, const GENERIC_PTR)); static int combine_regs PROTO((rtx, rtx, int, int, rtx, int)); static int reg_meets_class_p PROTO((int, enum reg_class)); static void update_qty_class PROTO((int, int)); static void reg_is_set PROTO((rtx, rtx)); static void reg_is_born PROTO((rtx, int)); static void wipe_dead_reg PROTO((rtx, int)); static int find_free_reg PROTO((enum reg_class, enum machine_mode, int, int, int, int, int)); static void mark_life PROTO((int, enum machine_mode, int)); static void post_mark_life PROTO((int, enum machine_mode, int, int, int)); static int no_conflict_p PROTO((rtx, rtx, rtx)); static int requires_inout PROTO((const char *)); /* Allocate a new quantity (new within current basic block) for register number REGNO which is born at index BIRTH within the block. MODE and SIZE are info on reg REGNO. */ static void alloc_qty (regno, mode, size, birth) int regno; enum machine_mode mode; int size, birth; { register int qty = next_qty++; reg_qty[regno] = qty; reg_offset[regno] = 0; reg_next_in_qty[regno] = -1; qty_first_reg[qty] = regno; qty_size[qty] = size; qty_mode[qty] = mode; qty_birth[qty] = birth; qty_n_calls_crossed[qty] = REG_N_CALLS_CROSSED (regno); qty_min_class[qty] = reg_preferred_class (regno); qty_alternate_class[qty] = reg_alternate_class (regno); qty_n_refs[qty] = REG_N_REFS (regno); qty_changes_size[qty] = REG_CHANGES_SIZE (regno); } /* Main entry point of this file. */ int local_alloc () { register int b, i; int max_qty; /* We need to keep track of whether or not we recorded a LABEL_REF so that we know if the jump optimizer needs to be rerun. */ recorded_label_ref = 0; /* Leaf functions and non-leaf functions have different needs. If defined, let the machine say what kind of ordering we should use. */ #ifdef ORDER_REGS_FOR_LOCAL_ALLOC ORDER_REGS_FOR_LOCAL_ALLOC; #endif /* Promote REG_EQUAL notes to REG_EQUIV notes and adjust status of affected registers. */ update_equiv_regs (); /* This sets the maximum number of quantities we can have. Quantity numbers start at zero and we can have one for each pseudo. */ max_qty = (max_regno - FIRST_PSEUDO_REGISTER); /* Allocate vectors of temporary data. See the declarations of these variables, above, for what they mean. */ qty_phys_reg = (short *) alloca (max_qty * sizeof (short)); qty_phys_copy_sugg = (HARD_REG_SET *) alloca (max_qty * sizeof (HARD_REG_SET)); qty_phys_num_copy_sugg = (short *) alloca (max_qty * sizeof (short)); qty_phys_sugg = (HARD_REG_SET *) alloca (max_qty * sizeof (HARD_REG_SET)); qty_phys_num_sugg = (short *) alloca (max_qty * sizeof (short)); qty_birth = (int *) alloca (max_qty * sizeof (int)); qty_death = (int *) alloca (max_qty * sizeof (int)); qty_first_reg = (int *) alloca (max_qty * sizeof (int)); qty_size = (int *) alloca (max_qty * sizeof (int)); qty_mode = (enum machine_mode *) alloca (max_qty * sizeof (enum machine_mode)); qty_n_calls_crossed = (int *) alloca (max_qty * sizeof (int)); qty_min_class = (enum reg_class *) alloca (max_qty * sizeof (enum reg_class)); qty_alternate_class = (enum reg_class *) alloca (max_qty * sizeof (enum reg_class)); qty_n_refs = (int *) alloca (max_qty * sizeof (int)); qty_changes_size = (char *) alloca (max_qty * sizeof (char)); reg_qty = (int *) xmalloc (max_regno * sizeof (int)); reg_offset = (char *) xmalloc (max_regno * sizeof (char)); reg_next_in_qty = (int *) xmalloc(max_regno * sizeof (int)); /* Allocate the reg_renumber array */ allocate_reg_info (max_regno, FALSE, TRUE); /* Determine which pseudo-registers can be allocated by local-alloc. In general, these are the registers used only in a single block and which only die once. However, if a register's preferred class has only a few entries, don't allocate this register here unless it is preferred or nothing since retry_global_alloc won't be able to move it to GENERAL_REGS if a reload register of this class is needed. We need not be concerned with which block actually uses the register since we will never see it outside that block. */ for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) { if (REG_BASIC_BLOCK (i) >= 0 && REG_N_DEATHS (i) == 1 && (reg_alternate_class (i) == NO_REGS || ! CLASS_LIKELY_SPILLED_P (reg_preferred_class (i)))) reg_qty[i] = -2; else reg_qty[i] = -1; } /* Force loop below to initialize entire quantity array. */ next_qty = max_qty; /* Allocate each block's local registers, block by block. */ for (b = 0; b < n_basic_blocks; b++) { /* NEXT_QTY indicates which elements of the `qty_...' vectors might need to be initialized because they were used for the previous block; it is set to the entire array before block 0. Initialize those, with explicit loop if there are few, else with bzero and bcopy. Do not initialize vectors that are explicit set by `alloc_qty'. */ if (next_qty < 6) { for (i = 0; i < next_qty; i++) { CLEAR_HARD_REG_SET (qty_phys_copy_sugg[i]); qty_phys_num_copy_sugg[i] = 0; CLEAR_HARD_REG_SET (qty_phys_sugg[i]); qty_phys_num_sugg[i] = 0; } } else { #define CLEAR(vector) \ bzero ((char *) (vector), (sizeof (*(vector))) * next_qty); CLEAR (qty_phys_copy_sugg); CLEAR (qty_phys_num_copy_sugg); CLEAR (qty_phys_sugg); CLEAR (qty_phys_num_sugg); } next_qty = 0; block_alloc (b); #ifdef USE_C_ALLOCA alloca (0); #endif } free (reg_qty); free (reg_offset); free (reg_next_in_qty); return recorded_label_ref; } /* Depth of loops we are in while in update_equiv_regs. */ static int loop_depth; /* Used for communication between the following two functions: contains a MEM that we wish to ensure remains unchanged. */ static rtx equiv_mem; /* Set nonzero if EQUIV_MEM is modified. */ static int equiv_mem_modified; /* If EQUIV_MEM is modified by modifying DEST, indicate that it is modified. Called via note_stores. */ static void validate_equiv_mem_from_store (dest, set) rtx dest; rtx set ATTRIBUTE_UNUSED; { if ((GET_CODE (dest) == REG && reg_overlap_mentioned_p (dest, equiv_mem)) || (GET_CODE (dest) == MEM && true_dependence (dest, VOIDmode, equiv_mem, rtx_varies_p))) equiv_mem_modified = 1; } /* Verify that no store between START and the death of REG invalidates MEMREF. MEMREF is invalidated by modifying a register used in MEMREF, by storing into an overlapping memory location, or with a non-const CALL_INSN. Return 1 if MEMREF remains valid. */ static int validate_equiv_mem (start, reg, memref) rtx start; rtx reg; rtx memref; { rtx insn; rtx note; equiv_mem = memref; equiv_mem_modified = 0; /* If the memory reference has side effects or is volatile, it isn't a valid equivalence. */ if (side_effects_p (memref)) return 0; for (insn = start; insn && ! equiv_mem_modified; insn = NEXT_INSN (insn)) { if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') continue; if (find_reg_note (insn, REG_DEAD, reg)) return 1; if (GET_CODE (insn) == CALL_INSN && ! RTX_UNCHANGING_P (memref) && ! CONST_CALL_P (insn)) return 0; note_stores (PATTERN (insn), validate_equiv_mem_from_store); /* If a register mentioned in MEMREF is modified via an auto-increment, we lose the equivalence. Do the same if one dies; although we could extend the life, it doesn't seem worth the trouble. */ for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if ((REG_NOTE_KIND (note) == REG_INC || REG_NOTE_KIND (note) == REG_DEAD) && GET_CODE (XEXP (note, 0)) == REG && reg_overlap_mentioned_p (XEXP (note, 0), memref)) return 0; } return 0; } /* TRUE if X uses any registers for which reg_equiv_replace is true. */ static int contains_replace_regs (x, reg_equiv_replace) rtx x; char *reg_equiv_replace; { int i, j; char *fmt; enum rtx_code code = GET_CODE (x); switch (code) { case CONST_INT: case CONST: case LABEL_REF: case SYMBOL_REF: case CONST_DOUBLE: case PC: case CC0: case HIGH: case LO_SUM: return 0; case REG: return reg_equiv_replace[REGNO (x)]; default: break; } fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) switch (fmt[i]) { case 'e': if (contains_replace_regs (XEXP (x, i), reg_equiv_replace)) return 1; break; case 'E': for (j = XVECLEN (x, i) - 1; j >= 0; j--) if (contains_replace_regs (XVECEXP (x, i, j), reg_equiv_replace)) return 1; break; } return 0; } /* TRUE if X references a memory location that would be affected by a store to MEMREF. */ static int memref_referenced_p (memref, x) rtx x; rtx memref; { int i, j; char *fmt; enum rtx_code code = GET_CODE (x); switch (code) { case CONST_INT: case CONST: case LABEL_REF: case SYMBOL_REF: case CONST_DOUBLE: case PC: case CC0: case HIGH: case LO_SUM: return 0; case REG: return (reg_equiv_replacement[REGNO (x)] && memref_referenced_p (memref, reg_equiv_replacement[REGNO (x)])); case MEM: if (true_dependence (memref, VOIDmode, x, rtx_varies_p)) return 1; break; case SET: /* If we are setting a MEM, it doesn't count (its address does), but any other SET_DEST that has a MEM in it is referencing the MEM. */ if (GET_CODE (SET_DEST (x)) == MEM) { if (memref_referenced_p (memref, XEXP (SET_DEST (x), 0))) return 1; } else if (memref_referenced_p (memref, SET_DEST (x))) return 1; return memref_referenced_p (memref, SET_SRC (x)); default: break; } fmt = GET_RTX_FORMAT (code); for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--) switch (fmt[i]) { case 'e': if (memref_referenced_p (memref, XEXP (x, i))) return 1; break; case 'E': for (j = XVECLEN (x, i) - 1; j >= 0; j--) if (memref_referenced_p (memref, XVECEXP (x, i, j))) return 1; break; } return 0; } /* TRUE if some insn in the range (START, END] references a memory location that would be affected by a store to MEMREF. */ static int memref_used_between_p (memref, start, end) rtx memref; rtx start; rtx end; { rtx insn; for (insn = NEXT_INSN (start); insn != NEXT_INSN (end); insn = NEXT_INSN (insn)) if (GET_RTX_CLASS (GET_CODE (insn)) == 'i' && memref_referenced_p (memref, PATTERN (insn))) return 1; return 0; } /* Return nonzero if the rtx X is invariant over the current function. */ int function_invariant_p (x) rtx x; { if (CONSTANT_P (x)) return 1; if (x == frame_pointer_rtx || x == arg_pointer_rtx) return 1; if (GET_CODE (x) == PLUS && (XEXP (x, 0) == frame_pointer_rtx || XEXP (x, 0) == arg_pointer_rtx) && CONSTANT_P (XEXP (x, 1))) return 1; return 0; } /* Find registers that are equivalent to a single value throughout the compilation (either because they can be referenced in memory or are set once from a single constant). Lower their priority for a register. If such a register is only referenced once, try substituting its value into the using insn. If it succeeds, we can eliminate the register completely. */ static void update_equiv_regs () { /* Set when an attempt should be made to replace a register with the associated reg_equiv_replacement entry at the end of this function. */ char *reg_equiv_replace = (char *) alloca (max_regno * sizeof *reg_equiv_replace); rtx insn; int block, depth; reg_equiv_init_insns = (rtx *) alloca (max_regno * sizeof (rtx)); reg_equiv_replacement = (rtx *) alloca (max_regno * sizeof (rtx)); bzero ((char *) reg_equiv_init_insns, max_regno * sizeof (rtx)); bzero ((char *) reg_equiv_replacement, max_regno * sizeof (rtx)); bzero ((char *) reg_equiv_replace, max_regno * sizeof *reg_equiv_replace); init_alias_analysis (); loop_depth = 1; /* Scan the insns and find which registers have equivalences. Do this in a separate scan of the insns because (due to -fcse-follow-jumps) a register can be set below its use. */ for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) { rtx note; rtx set; rtx dest, src; int regno; if (GET_CODE (insn) == NOTE) { if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) loop_depth++; else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) loop_depth--; } if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') continue; for (note = REG_NOTES (insn); note; note = XEXP (note, 1)) if (REG_NOTE_KIND (note) == REG_INC) no_equiv (XEXP (note, 0), note); set = single_set (insn); /* If this insn contains more (or less) than a single SET, only mark all destinations as having no known equivalence. */ if (set == 0) { note_stores (PATTERN (insn), no_equiv); continue; } else if (GET_CODE (PATTERN (insn)) == PARALLEL) { int i; for (i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--) { rtx part = XVECEXP (PATTERN (insn), 0, i); if (part != set) note_stores (part, no_equiv); } } dest = SET_DEST (set); src = SET_SRC (set); /* If this sets a MEM to the contents of a REG that is only used in a single basic block, see if the register is always equivalent to that memory location and if moving the store from INSN to the insn that set REG is safe. If so, put a REG_EQUIV note on the initializing insn. Don't add a REG_EQUIV note if the insn already has one. The existing REG_EQUIV is likely more useful than the one we are adding. If one of the regs in the address is marked as reg_equiv_replace, then we can't add this REG_EQUIV note. The reg_equiv_replace optimization may move the set of this register immediately before insn, which puts it after reg_equiv_init_insns[regno], and hence the mention in the REG_EQUIV note would be to an uninitialized pseudo. */ /* ????? This test isn't good enough; we might see a MEM with a use of a pseudo register before we see its setting insn that will cause reg_equiv_replace for that pseudo to be set. Equivalences to MEMs should be made in another pass, after the reg_equiv_replace information has been gathered. */ if (GET_CODE (dest) == MEM && GET_CODE (src) == REG && (regno = REGNO (src)) >= FIRST_PSEUDO_REGISTER && REG_BASIC_BLOCK (regno) >= 0 && REG_N_SETS (regno) == 1 && reg_equiv_init_insns[regno] != 0 && reg_equiv_init_insns[regno] != const0_rtx && ! find_reg_note (XEXP (reg_equiv_init_insns[regno], 0), REG_EQUIV, NULL_RTX) && ! contains_replace_regs (XEXP (dest, 0), reg_equiv_replace)) { rtx init_insn = XEXP (reg_equiv_init_insns[regno], 0); if (validate_equiv_mem (init_insn, src, dest) && ! memref_used_between_p (dest, init_insn, insn)) REG_NOTES (init_insn) = gen_rtx_EXPR_LIST (REG_EQUIV, dest, REG_NOTES (init_insn)); } /* We only handle the case of a pseudo register being set once, or always to the same value. */ /* ??? The mn10200 port breaks if we add equivalences for values that need an ADDRESS_REGS register and set them equivalent to a MEM of a pseudo. The actual problem is in the over-conservative handling of INPADDR_ADDRESS / INPUT_ADDRESS / INPUT triples in calculate_needs, but we traditionally work around this problem here by rejecting equivalences when the destination is in a register that's likely spilled. This is fragile, of course, since the preferred class of a pseudo depends on all instructions that set or use it. */ if (GET_CODE (dest) != REG || (regno = REGNO (dest)) < FIRST_PSEUDO_REGISTER || reg_equiv_init_insns[regno] == const0_rtx || (CLASS_LIKELY_SPILLED_P (reg_preferred_class (regno)) && GET_CODE (src) == MEM)) { /* This might be seting a SUBREG of a pseudo, a pseudo that is also set somewhere else to a constant. */ note_stores (set, no_equiv); continue; } /* Don't handle the equivalence if the source is in a register class that's likely to be spilled. */ if (GET_CODE (src) == REG && REGNO (src) >= FIRST_PSEUDO_REGISTER && CLASS_LIKELY_SPILLED_P (reg_preferred_class (REGNO (src)))) { no_equiv (dest, set); continue; } note = find_reg_note (insn, REG_EQUAL, NULL_RTX); if (REG_N_SETS (regno) != 1 && (! note || ! function_invariant_p (XEXP (note, 0)) || (reg_equiv_replacement[regno] && ! rtx_equal_p (XEXP (note, 0), reg_equiv_replacement[regno])))) { no_equiv (dest, set); continue; } /* Record this insn as initializing this register. */ reg_equiv_init_insns[regno] = gen_rtx_INSN_LIST (VOIDmode, insn, reg_equiv_init_insns[regno]); /* If this register is known to be equal to a constant, record that it is always equivalent to the constant. */ if (note && function_invariant_p (XEXP (note, 0))) PUT_MODE (note, (enum machine_mode) REG_EQUIV); /* If this insn introduces a "constant" register, decrease the priority of that register. Record this insn if the register is only used once more and the equivalence value is the same as our source. The latter condition is checked for two reasons: First, it is an indication that it may be more efficient to actually emit the insn as written (if no registers are available, reload will substitute the equivalence). Secondly, it avoids problems with any registers dying in this insn whose death notes would be missed. If we don't have a REG_EQUIV note, see if this insn is loading a register used only in one basic block from a MEM. If so, and the MEM remains unchanged for the life of the register, add a REG_EQUIV note. */ note = find_reg_note (insn, REG_EQUIV, NULL_RTX); if (note == 0 && REG_BASIC_BLOCK (regno) >= 0 && GET_CODE (SET_SRC (set)) == MEM && validate_equiv_mem (insn, dest, SET_SRC (set))) REG_NOTES (insn) = note = gen_rtx_EXPR_LIST (REG_EQUIV, SET_SRC (set), REG_NOTES (insn)); if (note) { int regno = REGNO (dest); /* Record whether or not we created a REG_EQUIV note for a LABEL_REF. We might end up substituting the LABEL_REF for uses of the pseudo here or later. That kind of transformation may turn an indirect jump into a direct jump, in which case we must rerun the jump optimizer to ensure that the JUMP_LABEL fields are valid. */ if (GET_CODE (XEXP (note, 0)) == LABEL_REF || (GET_CODE (XEXP (note, 0)) == CONST && GET_CODE (XEXP (XEXP (note, 0), 0)) == PLUS && (GET_CODE (XEXP (XEXP (XEXP (note, 0), 0), 0)) == LABEL_REF))) recorded_label_ref = 1; reg_equiv_replacement[regno] = XEXP (note, 0); /* Don't mess with things live during setjmp. */ if (REG_LIVE_LENGTH (regno) >= 0) { /* Note that the statement below does not affect the priority in local-alloc! */ REG_LIVE_LENGTH (regno) *= 2; /* If the register is referenced exactly twice, meaning it is set once and used once, indicate that the reference may be replaced by the equivalence we computed above. If the register is only used in one basic block, this can't succeed or combine would have done it. It would be nice to use "loop_depth * 2" in the compare below. Unfortunately, LOOP_DEPTH need not be constant within a basic block so this would be too complicated. This case normally occurs when a parameter is read from memory and then used exactly once, not in a loop. */ if (REG_N_REFS (regno) == 2 && REG_BASIC_BLOCK (regno) < 0 && rtx_equal_p (XEXP (note, 0), SET_SRC (set))) reg_equiv_replace[regno] = 1; } } } /* Now scan all regs killed in an insn to see if any of them are registers only used that once. If so, see if we can replace the reference with the equivalent from. If we can, delete the initializing reference and this register will go away. If we can't replace the reference, and the instruction is not in a loop, then move the register initialization just before the use, so that they are in the same basic block. */ block = -1; depth = 0; for (insn = get_insns (); insn; insn = NEXT_INSN (insn)) { rtx link; /* Keep track of which basic block we are in. */ if (block + 1 < n_basic_blocks && BLOCK_HEAD (block + 1) == insn) ++block; if (GET_RTX_CLASS (GET_CODE (insn)) != 'i') { if (GET_CODE (insn) == NOTE) { if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG) ++depth; else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END) { --depth; if (depth < 0) abort (); } } continue; } for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) { if (REG_NOTE_KIND (link) == REG_DEAD /* Make sure this insn still refers to the register. */ && reg_mentioned_p (XEXP (link, 0), PATTERN (insn))) { int regno = REGNO (XEXP (link, 0)); rtx equiv_insn; if (! reg_equiv_replace[regno]) continue; /* reg_equiv_replace[REGNO] gets set only when REG_N_REFS[REGNO] is 2, i.e. the register is set once and used once. (If it were only set, but not used, flow would have deleted the setting insns.) Hence there can only be one insn in reg_equiv_init_insns. */ equiv_insn = XEXP (reg_equiv_init_insns[regno], 0); if (validate_replace_rtx (regno_reg_rtx[regno], reg_equiv_replacement[regno], insn)) { remove_death (regno, insn); REG_N_REFS (regno) = 0; PUT_CODE (equiv_insn, NOTE); NOTE_LINE_NUMBER (equiv_insn) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (equiv_insn) = 0; } /* If we aren't in a loop, and there are no calls in INSN or in the initialization of the register, then move the initialization of the register to just before INSN. Update the flow information. */ else if (depth == 0 && GET_CODE (equiv_insn) == INSN && GET_CODE (insn) == INSN && REG_BASIC_BLOCK (regno) < 0) { int l; emit_insn_before (copy_rtx (PATTERN (equiv_insn)), insn); REG_NOTES (PREV_INSN (insn)) = REG_NOTES (equiv_insn); PUT_CODE (equiv_insn, NOTE); NOTE_LINE_NUMBER (equiv_insn) = NOTE_INSN_DELETED; NOTE_SOURCE_FILE (equiv_insn) = 0; REG_NOTES (equiv_insn) = 0; if (block < 0) REG_BASIC_BLOCK (regno) = 0; else REG_BASIC_BLOCK (regno) = block; REG_N_CALLS_CROSSED (regno) = 0; REG_LIVE_LENGTH (regno) = 2; if (block >= 0 && insn == BLOCK_HEAD (block)) BLOCK_HEAD (block) = PREV_INSN (insn); for (l = 0; l < n_basic_blocks; l++) CLEAR_REGNO_REG_SET (BASIC_BLOCK (l)->global_live_at_start, regno); } } } } } /* Mark REG as having no known equivalence. Some instructions might have been proceessed before and furnished with REG_EQUIV notes for this register; these notes will have to be removed. STORE is the piece of RTL that does the non-constant / conflicting assignment - a SET, CLOBBER or REG_INC note. It is currently not used, but needs to be there because this function is called from note_stores. */ static void no_equiv (reg, store) rtx reg, store ATTRIBUTE_UNUSED; { int regno; rtx list; if (GET_CODE (reg) != REG) return; regno = REGNO (reg); list = reg_equiv_init_insns[regno]; if (list == const0_rtx) return; for (; list; list = XEXP (list, 1)) { rtx insn = XEXP (list, 0); remove_note (insn, find_reg_note (insn, REG_EQUIV, NULL_RTX)); } reg_equiv_init_insns[regno] = const0_rtx; reg_equiv_replacement[regno] = NULL_RTX; } /* Allocate hard regs to the pseudo regs used only within block number B. Only the pseudos that die but once can be handled. */ static void block_alloc (b) int b; { register int i, q; register rtx insn; rtx note; int insn_number = 0; int insn_count = 0; int max_uid = get_max_uid (); int *qty_order; int no_conflict_combined_regno = -1; /* Count the instructions in the basic block. */ insn = BLOCK_END (b); while (1) { if (GET_CODE (insn) != NOTE) if (++insn_count > max_uid) abort (); if (insn == BLOCK_HEAD (b)) break; insn = PREV_INSN (insn); } /* +2 to leave room for a post_mark_life at the last insn and for the birth of a CLOBBER in the first insn. */ regs_live_at = (HARD_REG_SET *) alloca ((2 * insn_count + 2) * sizeof (HARD_REG_SET)); bzero ((char *) regs_live_at, (2 * insn_count + 2) * sizeof (HARD_REG_SET)); /* Initialize table of hardware registers currently live. */ REG_SET_TO_HARD_REG_SET (regs_live, BASIC_BLOCK (b)->global_live_at_start); /* This loop scans the instructions of the basic block and assigns quantities to registers. It computes which registers to tie. */ insn = BLOCK_HEAD (b); while (1) { register rtx body = PATTERN (insn); if (GET_CODE (insn) != NOTE) insn_number++; if (GET_RTX_CLASS (GET_CODE (insn)) == 'i') { register rtx link, set; register int win = 0; register rtx r0, r1; int combined_regno = -1; int i; this_insn_number = insn_number; this_insn = insn; extract_insn (insn); which_alternative = -1; /* Is this insn suitable for tying two registers? If so, try doing that. Suitable insns are those with at least two operands and where operand 0 is an output that is a register that is not earlyclobber. We can tie operand 0 with some operand that dies in this insn. First look for operands that are required to be in the same register as operand 0. If we find such, only try tying that operand or one that can be put into that operand if the operation is commutative. If we don't find an operand that is required to be in the same register as operand 0, we can tie with any operand. Subregs in place of regs are also ok. If tying is done, WIN is set nonzero. */ if (1 #ifdef REGISTER_CONSTRAINTS && recog_n_operands > 1 && recog_constraints[0][0] == '=' && recog_constraints[0][1] != '&' #else && GET_CODE (PATTERN (insn)) == SET && rtx_equal_p (SET_DEST (PATTERN (insn)), recog_operand[0]) #endif ) { #ifdef REGISTER_CONSTRAINTS /* If non-negative, is an operand that must match operand 0. */ int must_match_0 = -1; /* Counts number of alternatives that require a match with operand 0. */ int n_matching_alts = 0; for (i = 1; i < recog_n_operands; i++) { const char *p = recog_constraints[i]; int this_match = (requires_inout (p)); n_matching_alts += this_match; if (this_match == recog_n_alternatives) must_match_0 = i; } #endif r0 = recog_operand[0]; for (i = 1; i < recog_n_operands; i++) { #ifdef REGISTER_CONSTRAINTS /* Skip this operand if we found an operand that must match operand 0 and this operand isn't it and can't be made to be it by commutativity. */ if (must_match_0 >= 0 && i != must_match_0 && ! (i == must_match_0 + 1 && recog_constraints[i-1][0] == '%') && ! (i == must_match_0 - 1 && recog_constraints[i][0] == '%')) continue; /* Likewise if each alternative has some operand that must match operand zero. In that case, skip any operand that doesn't list operand 0 since we know that the operand always conflicts with operand 0. We ignore commutatity in this case to keep things simple. */ if (n_matching_alts == recog_n_alternatives && 0 == requires_inout (recog_constraints[i])) continue; #endif r1 = recog_operand[i]; /* If the operand is an address, find a register in it. There may be more than one register, but we only try one of them. */ if ( #ifdef REGISTER_CONSTRAINTS recog_constraints[i][0] == 'p' #else recog_operand_address_p[i] #endif ) while (GET_CODE (r1) == PLUS || GET_CODE (r1) == MULT) r1 = XEXP (r1, 0); if (GET_CODE (r0) == REG || GET_CODE (r0) == SUBREG) { /* We have two priorities for hard register preferences. If we have a move insn or an insn whose first input can only be in the same register as the output, give priority to an equivalence found from that insn. */ int may_save_copy = ((SET_DEST (body) == r0 && SET_SRC (body) == r1) #ifdef REGISTER_CONSTRAINTS || (r1 == recog_operand[i] && must_match_0 >= 0) #endif ); if (GET_CODE (r1) == REG || GET_CODE (r1) == SUBREG) win = combine_regs (r1, r0, may_save_copy, insn_number, insn, 0); } if (win) break; } } /* Recognize an insn sequence with an ultimate result which can safely overlap one of the inputs. The sequence begins with a CLOBBER of its result, and ends with an insn that copies the result to itself and has a REG_EQUAL note for an equivalent formula. That note indicates what the inputs are. The result and the input can overlap if each insn in the sequence either doesn't mention the input or has a REG_NO_CONFLICT note to inhibit the conflict. We do the combining test at the CLOBBER so that the destination register won't have had a quantity number assigned, since that would prevent combining. */ if (GET_CODE (PATTERN (insn)) == CLOBBER && (r0 = XEXP (PATTERN (insn), 0), GET_CODE (r0) == REG) && (link = find_reg_note (insn, REG_LIBCALL, NULL_RTX)) != 0 && XEXP (link, 0) != 0 && GET_CODE (XEXP (link, 0)) == INSN && (set = single_set (XEXP (link, 0))) != 0 && SET_DEST (set) == r0 && SET_SRC (set) == r0 && (note = find_reg_note (XEXP (link, 0), REG_EQUAL, NULL_RTX)) != 0) { if (r1 = XEXP (note, 0), GET_CODE (r1) == REG /* Check that we have such a sequence. */ && no_conflict_p (insn, r0, r1)) win = combine_regs (r1, r0, 1, insn_number, insn, 1); else if (GET_RTX_FORMAT (GET_CODE (XEXP (note, 0)))[0] == 'e' && (r1 = XEXP (XEXP (note, 0), 0), GET_CODE (r1) == REG || GET_CODE (r1) == SUBREG) && no_conflict_p (insn, r0, r1)) win = combine_regs (r1, r0, 0, insn_number, insn, 1); /* Here we care if the operation to be computed is commutative. */ else if ((GET_CODE (XEXP (note, 0)) == EQ || GET_CODE (XEXP (note, 0)) == NE || GET_RTX_CLASS (GET_CODE (XEXP (note, 0))) == 'c') && (r1 = XEXP (XEXP (note, 0), 1), (GET_CODE (r1) == REG || GET_CODE (r1) == SUBREG)) && no_conflict_p (insn, r0, r1)) win = combine_regs (r1, r0, 0, insn_number, insn, 1); /* If we did combine something, show the register number in question so that we know to ignore its death. */ if (win) no_conflict_combined_regno = REGNO (r1); } /* If registers were just tied, set COMBINED_REGNO to the number of the register used in this insn that was tied to the register set in this insn. This register's qty should not be "killed". */ if (win) { while (GET_CODE (r1) == SUBREG) r1 = SUBREG_REG (r1); combined_regno = REGNO (r1); } /* Mark the death of everything that dies in this instruction, except for anything that was just combined. */ for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_DEAD && GET_CODE (XEXP (link, 0)) == REG && combined_regno != REGNO (XEXP (link, 0)) && (no_conflict_combined_regno != REGNO (XEXP (link, 0)) || ! find_reg_note (insn, REG_NO_CONFLICT, XEXP (link, 0)))) wipe_dead_reg (XEXP (link, 0), 0); /* Allocate qty numbers for all registers local to this block that are born (set) in this instruction. A pseudo that already has a qty is not changed. */ note_stores (PATTERN (insn), reg_is_set); /* If anything is set in this insn and then unused, mark it as dying after this insn, so it will conflict with our outputs. This can't match with something that combined, and it doesn't matter if it did. Do this after the calls to reg_is_set since these die after, not during, the current insn. */ for (link = REG_NOTES (insn); link; link = XEXP (link, 1)) if (REG_NOTE_KIND (link) == REG_UNUSED && GET_CODE (XEXP (link, 0)) == REG) wipe_dead_reg (XEXP (link, 0), 1); /* If this is an insn that has a REG_RETVAL note pointing at a CLOBBER insn, we have reached the end of a REG_NO_CONFLICT block, so clear any register number that combined within it. */ if ((note = find_reg_note (insn, REG_RETVAL, NULL_RTX)) != 0 && GET_CODE (XEXP (note, 0)) == INSN && GET_CODE (PATTERN (XEXP (note, 0))) == CLOBBER) no_conflict_combined_regno = -1; } /* Set the registers live after INSN_NUMBER. Note that we never record the registers live before the block's first insn, since no pseudos we care about are live before that insn. */ IOR_HARD_REG_SET (regs_live_at[2 * insn_number], regs_live); IOR_HARD_REG_SET (regs_live_at[2 * insn_number + 1], regs_live); if (insn == BLOCK_END (b)) break; insn = NEXT_INSN (insn); } /* Now every register that is local to this basic block should have been given a quantity, or else -1 meaning ignore it. Every quantity should have a known birth and death. Order the qtys so we assign them registers in order of the number of suggested registers they need so we allocate those with the most restrictive needs first. */ qty_order = (int *) alloca (next_qty * sizeof (int)); for (i = 0; i < next_qty; i++) qty_order[i] = i; #define EXCHANGE(I1, I2) \ { i = qty_order[I1]; qty_order[I1] = qty_order[I2]; qty_order[I2] = i; } switch (next_qty) { case 3: /* Make qty_order[2] be the one to allocate last. */ if (qty_sugg_compare (0, 1) > 0) EXCHANGE (0, 1); if (qty_sugg_compare (1, 2) > 0) EXCHANGE (2, 1); /* ... Fall through ... */ case 2: /* Put the best one to allocate in qty_order[0]. */ if (qty_sugg_compare (0, 1) > 0) EXCHANGE (0, 1); /* ... Fall through ... */ case 1: case 0: /* Nothing to do here. */ break; default: qsort (qty_order, next_qty, sizeof (int), qty_sugg_compare_1); } /* Try to put each quantity in a suggested physical register, if it has one. This may cause registers to be allocated that otherwise wouldn't be, but this seems acceptable in local allocation (unlike global allocation). */ for (i = 0; i < next_qty; i++) { q = qty_order[i]; if (qty_phys_num_sugg[q] != 0 || qty_phys_num_copy_sugg[q] != 0) qty_phys_reg[q] = find_free_reg (qty_min_class[q], qty_mode[q], q, 0, 1, qty_birth[q], qty_death[q]); else qty_phys_reg[q] = -1; } /* Order the qtys so we assign them registers in order of decreasing length of life. Normally call qsort, but if we have only a very small number of quantities, sort them ourselves. */ for (i = 0; i < next_qty; i++) qty_order[i] = i; #define EXCHANGE(I1, I2) \ { i = qty_order[I1]; qty_order[I1] = qty_order[I2]; qty_order[I2] = i; } switch (next_qty) { case 3: /* Make qty_order[2] be the one to allocate last. */ if (qty_compare (0, 1) > 0) EXCHANGE (0, 1); if (qty_compare (1, 2) > 0) EXCHANGE (2, 1); /* ... Fall through ... */ case 2: /* Put the best one to allocate in qty_order[0]. */ if (qty_compare (0, 1) > 0) EXCHANGE (0, 1); /* ... Fall through ... */ case 1: case 0: /* Nothing to do here. */ break; default: qsort (qty_order, next_qty, sizeof (int), qty_compare_1); } /* Now for each qty that is not a hardware register, look for a hardware register to put it in. First try the register class that is cheapest for this qty, if there is more than one class. */ for (i = 0; i < next_qty; i++) { q = qty_order[i]; if (qty_phys_reg[q] < 0) { #ifdef INSN_SCHEDULING /* These values represent the adjusted lifetime of a qty so that it conflicts with qtys which appear near the start/end of this qty's lifetime. The purpose behind extending the lifetime of this qty is to discourage the register allocator from creating false dependencies. The adjustment value is choosen to indicate that this qty conflicts with all the qtys in the instructions immediately before and after the lifetime of this qty. Experiments have shown that higher values tend to hurt overall code performance. If allocation using the extended lifetime fails we will try again with the qty's unadjusted lifetime. */ int fake_birth = MAX (0, qty_birth[q] - 2 + qty_birth[q] % 2); int fake_death = MIN (insn_number * 2 + 1, qty_death[q] + 2 - qty_death[q] % 2); #endif if (N_REG_CLASSES > 1) { #ifdef INSN_SCHEDULING /* We try to avoid using hard registers allocated to qtys which are born immediately after this qty or die immediately before this qty. This optimization is only appropriate when we will run a scheduling pass after reload and we are not optimizing for code size. */ if (flag_schedule_insns_after_reload && !optimize_size && !SMALL_REGISTER_CLASSES) { qty_phys_reg[q] = find_free_reg (qty_min_class[q], qty_mode[q], q, 0, 0, fake_birth, fake_death); if (qty_phys_reg[q] >= 0) continue; } #endif qty_phys_reg[q] = find_free_reg (qty_min_class[q], qty_mode[q], q, 0, 0, qty_birth[q], qty_death[q]); if (qty_phys_reg[q] >= 0) continue; } #ifdef INSN_SCHEDULING /* Similarly, avoid false dependencies. */ if (flag_schedule_insns_after_reload && !optimize_size && !SMALL_REGISTER_CLASSES && qty_alternate_class[q] != NO_REGS) qty_phys_reg[q] = find_free_reg (qty_alternate_class[q], qty_mode[q], q, 0, 0, fake_birth, fake_death); #endif if (qty_alternate_class[q] != NO_REGS) qty_phys_reg[q] = find_free_reg (qty_alternate_class[q], qty_mode[q], q, 0, 0, qty_birth[q], qty_death[q]); } } /* Now propagate the register assignments to the pseudo regs belonging to the qtys. */ for (q = 0; q < next_qty; q++) if (qty_phys_reg[q] >= 0) { for (i = qty_first_reg[q]; i >= 0; i = reg_next_in_qty[i]) reg_renumber[i] = qty_phys_reg[q] + reg_offset[i]; } } /* Compare two quantities' priority for getting real registers. We give shorter-lived quantities higher priority. Quantities with more references are also preferred, as are quantities that require multiple registers. This is the identical prioritization as done by global-alloc. We used to give preference to registers with *longer* lives, but using the same algorithm in both local- and global-alloc can speed up execution of some programs by as much as a factor of three! */ /* Note that the quotient will never be bigger than the value of floor_log2 times the maximum number of times a register can occur in one insn (surely less than 100). Multiplying this by 10000 can't overflow. QTY_CMP_PRI is also used by qty_sugg_compare. */ #define QTY_CMP_PRI(q) \ ((int) (((double) (floor_log2 (qty_n_refs[q]) * qty_n_refs[q] * qty_size[q]) \ / (qty_death[q] - qty_birth[q])) * 10000)) static int qty_compare (q1, q2) int q1, q2; { return QTY_CMP_PRI (q2) - QTY_CMP_PRI (q1); } static int qty_compare_1 (q1p, q2p) const GENERIC_PTR q1p; const GENERIC_PTR q2p; { register int q1 = *(int *)q1p, q2 = *(int *)q2p; register int tem = QTY_CMP_PRI (q2) - QTY_CMP_PRI (q1); if (tem != 0) return tem; /* If qtys are equally good, sort by qty number, so that the results of qsort leave nothing to chance. */ return q1 - q2; } /* Compare two quantities' priority for getting real registers. This version is called for quantities that have suggested hard registers. First priority goes to quantities that have copy preferences, then to those that have normal preferences. Within those groups, quantities with the lower number of preferences have the highest priority. Of those, we use the same algorithm as above. */ #define QTY_CMP_SUGG(q) \ (qty_phys_num_copy_sugg[q] \ ? qty_phys_num_copy_sugg[q] \ : qty_phys_num_sugg[q] * FIRST_PSEUDO_REGISTER) static int qty_sugg_compare (q1, q2) int q1, q2; { register int tem = QTY_CMP_SUGG (q1) - QTY_CMP_SUGG (q2); if (tem != 0) return tem; return QTY_CMP_PRI (q2) - QTY_CMP_PRI (q1); } static int qty_sugg_compare_1 (q1p, q2p) const GENERIC_PTR q1p; const GENERIC_PTR q2p; { register int q1 = *(int *)q1p, q2 = *(int *)q2p; register int tem = QTY_CMP_SUGG (q1) - QTY_CMP_SUGG (q2); if (tem != 0) return tem; tem = QTY_CMP_PRI (q2) - QTY_CMP_PRI (q1); if (tem != 0) return tem; /* If qtys are equally good, sort by qty number, so that the results of qsort leave nothing to chance. */ return q1 - q2; } #undef QTY_CMP_SUGG #undef QTY_CMP_PRI /* Attempt to combine the two registers (rtx's) USEDREG and SETREG. Returns 1 if have done so, or 0 if cannot. Combining registers means marking them as having the same quantity and adjusting the offsets within the quantity if either of them is a SUBREG). We don't actually combine a hard reg with a pseudo; instead we just record the hard reg as the suggestion for the pseudo's quantity. If we really combined them, we could lose if the pseudo lives across an insn that clobbers the hard reg (eg, movstr). ALREADY_DEAD is non-zero if USEDREG is known to be dead even though there is no REG_DEAD note on INSN. This occurs during the processing of REG_NO_CONFLICT blocks. MAY_SAVE_COPYCOPY is non-zero if this insn is simply copying USEDREG to SETREG or if the input and output must share a register. In that case, we record a hard reg suggestion in QTY_PHYS_COPY_SUGG. There are elaborate checks for the validity of combining. */ static int combine_regs (usedreg, setreg, may_save_copy, insn_number, insn, already_dead) rtx usedreg, setreg; int may_save_copy; int insn_number; rtx insn; int already_dead; { register int ureg, sreg; register int offset = 0; int usize, ssize; register int sqty; /* Determine the numbers and sizes of registers being used. If a subreg is present that does not change the entire register, don't consider this a copy insn. */ while (GET_CODE (usedreg) == SUBREG) { if (GET_MODE_SIZE (GET_MODE (SUBREG_REG (usedreg))) > UNITS_PER_WORD) may_save_copy = 0; offset += SUBREG_WORD (usedreg); usedreg = SUBREG_REG (usedreg); } if (GET_CODE (usedreg) != REG) return 0; ureg = REGNO (usedreg); usize = REG_SIZE (usedreg); while (GET_CODE (setreg) == SUBREG) { if (GET_MODE_SIZE (GET_MODE (SUBREG_REG (setreg))) > UNITS_PER_WORD) may_save_copy = 0; offset -= SUBREG_WORD (setreg); setreg = SUBREG_REG (setreg); } if (GET_CODE (setreg) != REG) return 0; sreg = REGNO (setreg); ssize = REG_SIZE (setreg); /* If UREG is a pseudo-register that hasn't already been assigned a quantity number, it means that it is not local to this block or dies more than once. In either event, we can't do anything with it. */ if ((ureg >= FIRST_PSEUDO_REGISTER && reg_qty[ureg] < 0) /* Do not combine registers unless one fits within the other. */ || (offset > 0 && usize + offset > ssize) || (offset < 0 && usize + offset < ssize) /* Do not combine with a smaller already-assigned object if that smaller object is already combined with something bigger. */ || (ssize > usize && ureg >= FIRST_PSEUDO_REGISTER && usize < qty_size[reg_qty[ureg]]) /* Can't combine if SREG is not a register we can allocate. */ || (sreg >= FIRST_PSEUDO_REGISTER && reg_qty[sreg] == -1) /* Don't combine with a pseudo mentioned in a REG_NO_CONFLICT note. These have already been taken care of. This probably wouldn't combine anyway, but don't take any chances. */ || (ureg >= FIRST_PSEUDO_REGISTER && find_reg_note (insn, REG_NO_CONFLICT, usedreg)) /* Don't tie something to itself. In most cases it would make no difference, but it would screw up if the reg being tied to itself also dies in this insn. */ || ureg == sreg /* Don't try to connect two different hardware registers. */ || (ureg < FIRST_PSEUDO_REGISTER && sreg < FIRST_PSEUDO_REGISTER) /* Don't use a hard reg that might be spilled. */ || (ureg < FIRST_PSEUDO_REGISTER && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (ureg))) || (sreg < FIRST_PSEUDO_REGISTER && CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (sreg))) /* Don't connect two different machine modes if they have different implications as to which registers may be used. */ || !MODES_TIEABLE_P (GET_MODE (usedreg), GET_MODE (setreg))) return 0; /* Now, if UREG is a hard reg and SREG is a pseudo, record the hard reg in qty_phys_sugg for the pseudo instead of tying them. Return "failure" so that the lifespan of UREG is terminated here; that way the two lifespans will be disjoint and nothing will prevent the pseudo reg from being given this hard reg. */ if (ureg < FIRST_PSEUDO_REGISTER) { /* Allocate a quantity number so we have a place to put our suggestions. */ if (reg_qty[sreg] == -2) reg_is_born (setreg, 2 * insn_number); if (reg_qty[sreg] >= 0) { if (may_save_copy && ! TEST_HARD_REG_BIT (qty_phys_copy_sugg[reg_qty[sreg]], ureg)) { SET_HARD_REG_BIT (qty_phys_copy_sugg[reg_qty[sreg]], ureg); qty_phys_num_copy_sugg[reg_qty[sreg]]++; } else if (! TEST_HARD_REG_BIT (qty_phys_sugg[reg_qty[sreg]], ureg)) { SET_HARD_REG_BIT (qty_phys_sugg[reg_qty[sreg]], ureg); qty_phys_num_sugg[reg_qty[sreg]]++; } } return 0; } /* Similarly for SREG a hard register and UREG a pseudo register. */ if (sreg < FIRST_PSEUDO_REGISTER) { if (may_save_copy && ! TEST_HARD_REG_BIT (qty_phys_copy_sugg[reg_qty[ureg]], sreg)) { SET_HARD_REG_BIT (qty_phys_copy_sugg[reg_qty[ureg]], sreg); qty_phys_num_copy_sugg[reg_qty[ureg]]++; } else if (! TEST_HARD_REG_BIT (qty_phys_sugg[reg_qty[ureg]], sreg)) { SET_HARD_REG_BIT (qty_phys_sugg[reg_qty[ureg]], sreg); qty_phys_num_sugg[reg_qty[ureg]]++; } return 0; } /* At this point we know that SREG and UREG are both pseudos. Do nothing if SREG already has a quantity or is a register that we don't allocate. */ if (reg_qty[sreg] >= -1 /* If we are not going to let any regs live across calls, don't tie a call-crossing reg to a non-call-crossing reg. */ || (current_function_has_nonlocal_label && ((REG_N_CALLS_CROSSED (ureg) > 0) != (REG_N_CALLS_CROSSED (sreg) > 0)))) return 0; /* We don't already know about SREG, so tie it to UREG if this is the last use of UREG, provided the classes they want are compatible. */ if ((already_dead || find_regno_note (insn, REG_DEAD, ureg)) && reg_meets_class_p (sreg, qty_min_class[reg_qty[ureg]])) { /* Add SREG to UREG's quantity. */ sqty = reg_qty[ureg]; reg_qty[sreg] = sqty; reg_offset[sreg] = reg_offset[ureg] + offset; reg_next_in_qty[sreg] = qty_first_reg[sqty]; qty_first_reg[sqty] = sreg; /* If SREG's reg class is smaller, set qty_min_class[SQTY]. */ update_qty_class (sqty, sreg); /* Update info about quantity SQTY. */ qty_n_calls_crossed[sqty] += REG_N_CALLS_CROSSED (sreg); qty_n_refs[sqty] += REG_N_REFS (sreg); if (usize < ssize) { register int i; for (i = qty_first_reg[sqty]; i >= 0; i = reg_next_in_qty[i]) reg_offset[i] -= offset; qty_size[sqty] = ssize; qty_mode[sqty] = GET_MODE (setreg); } } else return 0; return 1; } /* Return 1 if the preferred class of REG allows it to be tied to a quantity or register whose class is CLASS. True if REG's reg class either contains or is contained in CLASS. */ static int reg_meets_class_p (reg, class) int reg; enum reg_class class; { register enum reg_class rclass = reg_preferred_class (reg); return (reg_class_subset_p (rclass, class) || reg_class_subset_p (class, rclass)); } /* Update the class of QTY assuming that REG is being tied to it. */ static void update_qty_class (qty, reg) int qty; int reg; { enum reg_class rclass = reg_preferred_class (reg); if (reg_class_subset_p (rclass, qty_min_class[qty])) qty_min_class[qty] = rclass; rclass = reg_alternate_class (reg); if (reg_class_subset_p (rclass, qty_alternate_class[qty])) qty_alternate_class[qty] = rclass; if (REG_CHANGES_SIZE (reg)) qty_changes_size[qty] = 1; } /* Handle something which alters the value of an rtx REG. REG is whatever is set or clobbered. SETTER is the rtx that is modifying the register. If it is not really a register, we do nothing. The file-global variables `this_insn' and `this_insn_number' carry info from `block_alloc'. */ static void reg_is_set (reg, setter) rtx reg; rtx setter; { /* Note that note_stores will only pass us a SUBREG if it is a SUBREG of a hard register. These may actually not exist any more. */ if (GET_CODE (reg) != SUBREG && GET_CODE (reg) != REG) return; /* Mark this register as being born. If it is used in a CLOBBER, mark it as being born halfway between the previous insn and this insn so that it conflicts with our inputs but not the outputs of the previous insn. */ reg_is_born (reg, 2 * this_insn_number - (GET_CODE (setter) == CLOBBER)); } /* Handle beginning of the life of register REG. BIRTH is the index at which this is happening. */ static void reg_is_born (reg, birth) rtx reg; int birth; { register int regno; if (GET_CODE (reg) == SUBREG) regno = REGNO (SUBREG_REG (reg)) + SUBREG_WORD (reg); else regno = REGNO (reg); if (regno < FIRST_PSEUDO_REGISTER) { mark_life (regno, GET_MODE (reg), 1); /* If the register was to have been born earlier that the present insn, mark it as live where it is actually born. */ if (birth < 2 * this_insn_number) post_mark_life (regno, GET_MODE (reg), 1, birth, 2 * this_insn_number); } else { if (reg_qty[regno] == -2) alloc_qty (regno, GET_MODE (reg), PSEUDO_REGNO_SIZE (regno), birth); /* If this register has a quantity number, show that it isn't dead. */ if (reg_qty[regno] >= 0) qty_death[reg_qty[regno]] = -1; } } /* Record the death of REG in the current insn. If OUTPUT_P is non-zero, REG is an output that is dying (i.e., it is never used), otherwise it is an input (the normal case). If OUTPUT_P is 1, then we extend the life past the end of this insn. */ static void wipe_dead_reg (reg, output_p) register rtx reg; int output_p; { register int regno = REGNO (reg); /* If this insn has multiple results, and the dead reg is used in one of the results, extend its life to after this insn, so it won't get allocated together with any other result of this insn. It is unsafe to use !single_set here since it will ignore an unused output. Just because an output is unused does not mean the compiler can assume the side effect will not occur. Consider if REG appears in the address of an output and we reload the output. If we allocate REG to the same hard register as an unused output we could set the hard register before the output reload insn. */ if (GET_CODE (PATTERN (this_insn)) == PARALLEL && multiple_sets (this_insn)) { int i; for (i = XVECLEN (PATTERN (this_insn), 0) - 1; i >= 0; i--) { rtx set = XVECEXP (PATTERN (this_insn), 0, i); if (GET_CODE (set) == SET && GET_CODE (SET_DEST (set)) != REG && !rtx_equal_p (reg, SET_DEST (set)) && reg_overlap_mentioned_p (reg, SET_DEST (set))) output_p = 1; } } /* If this register is used in an auto-increment address, then extend its life to after this insn, so that it won't get allocated together with the result of this insn. */ if (! output_p && find_regno_note (this_insn, REG_INC, regno)) output_p = 1; if (regno < FIRST_PSEUDO_REGISTER) { mark_life (regno, GET_MODE (reg), 0); /* If a hard register is dying as an output, mark it as in use at the beginning of this insn (the above statement would cause this not to happen). */ if (output_p) post_mark_life (regno, GET_MODE (reg), 1, 2 * this_insn_number, 2 * this_insn_number+ 1); } else if (reg_qty[regno] >= 0) qty_death[reg_qty[regno]] = 2 * this_insn_number + output_p; } /* Find a block of SIZE words of hard regs in reg_class CLASS that can hold something of machine-mode MODE (but actually we test only the first of the block for holding MODE) and still free between insn BORN_INDEX and insn DEAD_INDEX, and return the number of the first of them. Return -1 if such a block cannot be found. If QTY crosses calls, insist on a register preserved by calls, unless ACCEPT_CALL_CLOBBERED is nonzero. If JUST_TRY_SUGGESTED is non-zero, only try to see if the suggested register is available. If not, return -1. */ static int find_free_reg (class, mode, qty, accept_call_clobbered, just_try_suggested, born_index, dead_index) enum reg_class class; enum machine_mode mode; int qty; int accept_call_clobbered; int just_try_suggested; int born_index, dead_index; { register int i, ins; #ifdef HARD_REG_SET register /* Declare it register if it's a scalar. */ #endif HARD_REG_SET used, first_used; #ifdef ELIMINABLE_REGS static struct {int from, to; } eliminables[] = ELIMINABLE_REGS; #endif /* Validate our parameters. */ if (born_index < 0 || born_index > dead_index) abort (); /* Don't let a pseudo live in a reg across a function call if we might get a nonlocal goto. */ if (current_function_has_nonlocal_label && qty_n_calls_crossed[qty] > 0) return -1; if (accept_call_clobbered) COPY_HARD_REG_SET (used, call_fixed_reg_set); else if (qty_n_calls_crossed[qty] == 0) COPY_HARD_REG_SET (used, fixed_reg_set); else COPY_HARD_REG_SET (used, call_used_reg_set); if (accept_call_clobbered) IOR_HARD_REG_SET (used, losing_caller_save_reg_set); for (ins = born_index; ins < dead_index; ins++) IOR_HARD_REG_SET (used, regs_live_at[ins]); IOR_COMPL_HARD_REG_SET (used, reg_class_contents[(int) class]); /* Don't use the frame pointer reg in local-alloc even if we may omit the frame pointer, because if we do that and then we need a frame pointer, reload won't know how to move the pseudo to another hard reg. It can move only regs made by global-alloc. This is true of any register that can be eliminated. */ #ifdef ELIMINABLE_REGS for (i = 0; i < (int)(sizeof eliminables / sizeof eliminables[0]); i++) SET_HARD_REG_BIT (used, eliminables[i].from); #if FRAME_POINTER_REGNUM != HARD_FRAME_POINTER_REGNUM /* If FRAME_POINTER_REGNUM is not a real register, then protect the one that it might be eliminated into. */ SET_HARD_REG_BIT (used, HARD_FRAME_POINTER_REGNUM); #endif #else SET_HARD_REG_BIT (used, FRAME_POINTER_REGNUM); #endif #ifdef CLASS_CANNOT_CHANGE_SIZE if (qty_changes_size[qty]) IOR_HARD_REG_SET (used, reg_class_contents[(int) CLASS_CANNOT_CHANGE_SIZE]); #endif /* Normally, the registers that can be used for the first register in a multi-register quantity are the same as those that can be used for subsequent registers. However, if just trying suggested registers, restrict our consideration to them. If there are copy-suggested register, try them. Otherwise, try the arithmetic-suggested registers. */ COPY_HARD_REG_SET (first_used, used); if (just_try_suggested) { if (qty_phys_num_copy_sugg[qty] != 0) IOR_COMPL_HARD_REG_SET (first_used, qty_phys_copy_sugg[qty]); else IOR_COMPL_HARD_REG_SET (first_used, qty_phys_sugg[qty]); } /* If all registers are excluded, we can't do anything. */ GO_IF_HARD_REG_SUBSET (reg_class_contents[(int) ALL_REGS], first_used, fail); /* If at least one would be suitable, test each hard reg. */ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++) { #ifdef REG_ALLOC_ORDER int regno = reg_alloc_order[i]; #else int regno = i; #endif if (! TEST_HARD_REG_BIT (first_used, regno) && HARD_REGNO_MODE_OK (regno, mode) && (qty_n_calls_crossed[qty] == 0 || accept_call_clobbered || ! HARD_REGNO_CALL_PART_CLOBBERED (regno, mode))) { register int j; register int size1 = HARD_REGNO_NREGS (regno, mode); for (j = 1; j < size1 && ! TEST_HARD_REG_BIT (used, regno + j); j++); if (j == size1) { /* Mark that this register is in use between its birth and death insns. */ post_mark_life (regno, mode, 1, born_index, dead_index); return regno; } #ifndef REG_ALLOC_ORDER i += j; /* Skip starting points we know will lose */ #endif } } fail: /* If we are just trying suggested register, we have just tried copy- suggested registers, and there are arithmetic-suggested registers, try them. */ /* If it would be profitable to allocate a call-clobbered register and save and restore it around calls, do that. */ if (just_try_suggested && qty_phys_num_copy_sugg[qty] != 0 && qty_phys_num_sugg[qty] != 0) { /* Don't try the copy-suggested regs again. */ qty_phys_num_copy_sugg[qty] = 0; return find_free_reg (class, mode, qty, accept_call_clobbered, 1, born_index, dead_index); } /* We need not check to see if the current function has nonlocal labels because we don't put any pseudos that are live over calls in registers in that case. */ if (! accept_call_clobbered && flag_caller_saves && ! just_try_suggested && qty_n_calls_crossed[qty] != 0 && CALLER_SAVE_PROFITABLE (qty_n_refs[qty], qty_n_calls_crossed[qty])) { i = find_free_reg (class, mode, qty, 1, 0, born_index, dead_index); if (i >= 0) caller_save_needed = 1; return i; } return -1; } /* Mark that REGNO with machine-mode MODE is live starting from the current insn (if LIFE is non-zero) or dead starting at the current insn (if LIFE is zero). */ static void mark_life (regno, mode, life) register int regno; enum machine_mode mode; int life; { register int j = HARD_REGNO_NREGS (regno, mode); if (life) while (--j >= 0) SET_HARD_REG_BIT (regs_live, regno + j); else while (--j >= 0) CLEAR_HARD_REG_BIT (regs_live, regno + j); } /* Mark register number REGNO (with machine-mode MODE) as live (if LIFE is non-zero) or dead (if LIFE is zero) from insn number BIRTH (inclusive) to insn number DEATH (exclusive). */ static void post_mark_life (regno, mode, life, birth, death) int regno; enum machine_mode mode; int life, birth, death; { register int j = HARD_REGNO_NREGS (regno, mode); #ifdef HARD_REG_SET register /* Declare it register if it's a scalar. */ #endif HARD_REG_SET this_reg; CLEAR_HARD_REG_SET (this_reg); while (--j >= 0) SET_HARD_REG_BIT (this_reg, regno + j); if (life) while (birth < death) { IOR_HARD_REG_SET (regs_live_at[birth], this_reg); birth++; } else while (birth < death) { AND_COMPL_HARD_REG_SET (regs_live_at[birth], this_reg); birth++; } } /* INSN is the CLOBBER insn that starts a REG_NO_NOCONFLICT block, R0 is the register being clobbered, and R1 is a register being used in the equivalent expression. If R1 dies in the block and has a REG_NO_CONFLICT note on every insn in which it is used, return 1. Otherwise, return 0. */ static int no_conflict_p (insn, r0, r1) rtx insn, r0, r1; { int ok = 0; rtx note = find_reg_note (insn, REG_LIBCALL, NULL_RTX); rtx p, last; /* If R1 is a hard register, return 0 since we handle this case when we scan the insns that actually use it. */ if (note == 0 || (GET_CODE (r1) == REG && REGNO (r1) < FIRST_PSEUDO_REGISTER) || (GET_CODE (r1) == SUBREG && GET_CODE (SUBREG_REG (r1)) == REG && REGNO (SUBREG_REG (r1)) < FIRST_PSEUDO_REGISTER)) return 0; last = XEXP (note, 0); for (p = NEXT_INSN (insn); p && p != last; p = NEXT_INSN (p)) if (GET_RTX_CLASS (GET_CODE (p)) == 'i') { if (find_reg_note (p, REG_DEAD, r1)) ok = 1; /* There must be a REG_NO_CONFLICT note on every insn, otherwise some earlier optimization pass has inserted instructions into the sequence, and it is not safe to perform this optimization. Note that emit_no_conflict_block always ensures that this is true when these sequences are created. */ if (! find_reg_note (p, REG_NO_CONFLICT, r1)) return 0; } return ok; } #ifdef REGISTER_CONSTRAINTS /* Return the number of alternatives for which the constraint string P indicates that the operand must be equal to operand 0 and that no register is acceptable. */ static int requires_inout (p) const char *p; { char c; int found_zero = 0; int reg_allowed = 0; int num_matching_alts = 0; while ((c = *p++)) switch (c) { case '=': case '+': case '?': case '#': case '&': case '!': case '*': case '%': case '1': case '2': case '3': case '4': 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': #ifdef EXTRA_CONSTRAINT case 'Q': case 'R': case 'S': case 'T': case 'U': #endif case 'X': /* These don't say anything we care about. */ break; case ',': if (found_zero && ! reg_allowed) num_matching_alts++; found_zero = reg_allowed = 0; break; case '0': found_zero = 1; break; case 'p': case 'g': case 'r': default: reg_allowed = 1; break; } if (found_zero && ! reg_allowed) num_matching_alts++; return num_matching_alts; } #endif /* REGISTER_CONSTRAINTS */ void dump_local_alloc (file) FILE *file; { register int i; for (i = FIRST_PSEUDO_REGISTER; i < max_regno; i++) if (reg_renumber[i] != -1) fprintf (file, ";; Register %d in %d.\n", i, reg_renumber[i]); }