--- /dev/null
+/* RTL-level loop invariant motion.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
+ Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 3, or (at your option) any
+later version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+/* This implements the loop invariant motion pass. It is very simple
+ (no calls, no loads/stores, etc.). This should be sufficient to cleanup
+ things like address arithmetics -- other more complicated invariants should
+ be eliminated on GIMPLE either in tree-ssa-loop-im.c or in tree-ssa-pre.c.
+
+ We proceed loop by loop -- it is simpler than trying to handle things
+ globally and should not lose much. First we inspect all sets inside loop
+ and create a dependency graph on insns (saying "to move this insn, you must
+ also move the following insns").
+
+ We then need to determine what to move. We estimate the number of registers
+ used and move as many invariants as possible while we still have enough free
+ registers. We prefer the expensive invariants.
+
+ Then we move the selected invariants out of the loop, creating a new
+ temporaries for them if necessary. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "rtl.h"
+#include "tm_p.h"
+#include "hard-reg-set.h"
+#include "obstack.h"
+#include "basic-block.h"
+#include "cfgloop.h"
+#include "expr.h"
+#include "recog.h"
+#include "output.h"
+#include "function.h"
+#include "flags.h"
+#include "df.h"
+#include "hashtab.h"
+#include "except.h"
+#include "params.h"
+
+/* The data stored for the loop. */
+
+struct loop_data
+{
+ struct loop *outermost_exit; /* The outermost exit of the loop. */
+ bool has_call; /* True if the loop contains a call. */
+};
+
+#define LOOP_DATA(LOOP) ((struct loop_data *) (LOOP)->aux)
+
+/* The description of an use. */
+
+struct use
+{
+ rtx *pos; /* Position of the use. */
+ rtx insn; /* The insn in that the use occurs. */
+
+ struct use *next; /* Next use in the list. */
+};
+
+/* The description of a def. */
+
+struct def
+{
+ struct use *uses; /* The list of uses that are uniquely reached
+ by it. */
+ unsigned n_uses; /* Number of such uses. */
+ unsigned invno; /* The corresponding invariant. */
+};
+
+/* The data stored for each invariant. */
+
+struct invariant
+{
+ /* The number of the invariant. */
+ unsigned invno;
+
+ /* The number of the invariant with the same value. */
+ unsigned eqto;
+
+ /* If we moved the invariant out of the loop, the register that contains its
+ value. */
+ rtx reg;
+
+ /* The definition of the invariant. */
+ struct def *def;
+
+ /* The insn in that it is defined. */
+ rtx insn;
+
+ /* Whether it is always executed. */
+ bool always_executed;
+
+ /* Whether to move the invariant. */
+ bool move;
+
+ /* Cost of the invariant. */
+ unsigned cost;
+
+ /* The invariants it depends on. */
+ bitmap depends_on;
+
+ /* Used for detecting already visited invariants during determining
+ costs of movements. */
+ unsigned stamp;
+};
+
+/* Table of invariants indexed by the df_ref uid field. */
+
+static unsigned int invariant_table_size = 0;
+static struct invariant ** invariant_table;
+
+/* Entry for hash table of invariant expressions. */
+
+struct invariant_expr_entry
+{
+ /* The invariant. */
+ struct invariant *inv;
+
+ /* Its value. */
+ rtx expr;
+
+ /* Its mode. */
+ enum machine_mode mode;
+
+ /* Its hash. */
+ hashval_t hash;
+};
+
+/* The actual stamp for marking already visited invariants during determining
+ costs of movements. */
+
+static unsigned actual_stamp;
+
+typedef struct invariant *invariant_p;
+
+DEF_VEC_P(invariant_p);
+DEF_VEC_ALLOC_P(invariant_p, heap);
+
+/* The invariants. */
+
+static VEC(invariant_p,heap) *invariants;
+
+/* Check the size of the invariant table and realloc if necessary. */
+
+static void
+check_invariant_table_size (void)
+{
+ if (invariant_table_size < DF_DEFS_TABLE_SIZE())
+ {
+ unsigned int new_size = DF_DEFS_TABLE_SIZE () + (DF_DEFS_TABLE_SIZE () / 4);
+ invariant_table = XRESIZEVEC (struct invariant *, invariant_table, new_size);
+ memset (&invariant_table[invariant_table_size], 0,
+ (new_size - invariant_table_size) * sizeof (struct rtx_iv *));
+ invariant_table_size = new_size;
+ }
+}
+
+/* Test for possibility of invariantness of X. */
+
+static bool
+check_maybe_invariant (rtx x)
+{
+ enum rtx_code code = GET_CODE (x);
+ int i, j;
+ const char *fmt;
+
+ switch (code)
+ {
+ case CONST_INT:
+ case CONST_DOUBLE:
+ case CONST_FIXED:
+ case SYMBOL_REF:
+ case CONST:
+ case LABEL_REF:
+ return true;
+
+ case PC:
+ case CC0:
+ case UNSPEC_VOLATILE:
+ case CALL:
+ return false;
+
+ case REG:
+ return true;
+
+ case MEM:
+ /* Load/store motion is done elsewhere. ??? Perhaps also add it here?
+ It should not be hard, and might be faster than "elsewhere". */
+
+ /* Just handle the most trivial case where we load from an unchanging
+ location (most importantly, pic tables). */
+ if (MEM_READONLY_P (x) && !MEM_VOLATILE_P (x))
+ break;
+
+ return false;
+
+ case ASM_OPERANDS:
+ /* Don't mess with insns declared volatile. */
+ if (MEM_VOLATILE_P (x))
+ return false;
+ break;
+
+ default:
+ break;
+ }
+
+ fmt = GET_RTX_FORMAT (code);
+ for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ {
+ if (!check_maybe_invariant (XEXP (x, i)))
+ return false;
+ }
+ else if (fmt[i] == 'E')
+ {
+ for (j = 0; j < XVECLEN (x, i); j++)
+ if (!check_maybe_invariant (XVECEXP (x, i, j)))
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/* Returns the invariant definition for USE, or NULL if USE is not
+ invariant. */
+
+static struct invariant *
+invariant_for_use (df_ref use)
+{
+ struct df_link *defs;
+ df_ref def;
+ basic_block bb = DF_REF_BB (use), def_bb;
+
+ if (DF_REF_FLAGS (use) & DF_REF_READ_WRITE)
+ return NULL;
+
+ defs = DF_REF_CHAIN (use);
+ if (!defs || defs->next)
+ return NULL;
+ def = defs->ref;
+ check_invariant_table_size ();
+ if (!invariant_table[DF_REF_ID(def)])
+ return NULL;
+
+ def_bb = DF_REF_BB (def);
+ if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
+ return NULL;
+ return invariant_table[DF_REF_ID(def)];
+}
+
+/* Computes hash value for invariant expression X in INSN. */
+
+static hashval_t
+hash_invariant_expr_1 (rtx insn, rtx x)
+{
+ enum rtx_code code = GET_CODE (x);
+ int i, j;
+ const char *fmt;
+ hashval_t val = code;
+ int do_not_record_p;
+ df_ref use;
+ struct invariant *inv;
+
+ switch (code)
+ {
+ case CONST_INT:
+ case CONST_DOUBLE:
+ case CONST_FIXED:
+ case SYMBOL_REF:
+ case CONST:
+ case LABEL_REF:
+ return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+
+ case REG:
+ use = df_find_use (insn, x);
+ if (!use)
+ return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+ inv = invariant_for_use (use);
+ if (!inv)
+ return hash_rtx (x, GET_MODE (x), &do_not_record_p, NULL, false);
+
+ gcc_assert (inv->eqto != ~0u);
+ return inv->eqto;
+
+ default:
+ break;
+ }
+
+ fmt = GET_RTX_FORMAT (code);
+ for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ val ^= hash_invariant_expr_1 (insn, XEXP (x, i));
+ else if (fmt[i] == 'E')
+ {
+ for (j = 0; j < XVECLEN (x, i); j++)
+ val ^= hash_invariant_expr_1 (insn, XVECEXP (x, i, j));
+ }
+ else if (fmt[i] == 'i' || fmt[i] == 'n')
+ val ^= XINT (x, i);
+ }
+
+ return val;
+}
+
+/* Returns true if the invariant expressions E1 and E2 used in insns INSN1
+ and INSN2 have always the same value. */
+
+static bool
+invariant_expr_equal_p (rtx insn1, rtx e1, rtx insn2, rtx e2)
+{
+ enum rtx_code code = GET_CODE (e1);
+ int i, j;
+ const char *fmt;
+ df_ref use1, use2;
+ struct invariant *inv1 = NULL, *inv2 = NULL;
+ rtx sub1, sub2;
+
+ /* If mode of only one of the operands is VOIDmode, it is not equivalent to
+ the other one. If both are VOIDmode, we rely on the caller of this
+ function to verify that their modes are the same. */
+ if (code != GET_CODE (e2) || GET_MODE (e1) != GET_MODE (e2))
+ return false;
+
+ switch (code)
+ {
+ case CONST_INT:
+ case CONST_DOUBLE:
+ case CONST_FIXED:
+ case SYMBOL_REF:
+ case CONST:
+ case LABEL_REF:
+ return rtx_equal_p (e1, e2);
+
+ case REG:
+ use1 = df_find_use (insn1, e1);
+ use2 = df_find_use (insn2, e2);
+ if (use1)
+ inv1 = invariant_for_use (use1);
+ if (use2)
+ inv2 = invariant_for_use (use2);
+
+ if (!inv1 && !inv2)
+ return rtx_equal_p (e1, e2);
+
+ if (!inv1 || !inv2)
+ return false;
+
+ gcc_assert (inv1->eqto != ~0u);
+ gcc_assert (inv2->eqto != ~0u);
+ return inv1->eqto == inv2->eqto;
+
+ default:
+ break;
+ }
+
+ fmt = GET_RTX_FORMAT (code);
+ for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
+ {
+ if (fmt[i] == 'e')
+ {
+ sub1 = XEXP (e1, i);
+ sub2 = XEXP (e2, i);
+
+ if (!invariant_expr_equal_p (insn1, sub1, insn2, sub2))
+ return false;
+ }
+
+ else if (fmt[i] == 'E')
+ {
+ if (XVECLEN (e1, i) != XVECLEN (e2, i))
+ return false;
+
+ for (j = 0; j < XVECLEN (e1, i); j++)
+ {
+ sub1 = XVECEXP (e1, i, j);
+ sub2 = XVECEXP (e2, i, j);
+
+ if (!invariant_expr_equal_p (insn1, sub1, insn2, sub2))
+ return false;
+ }
+ }
+ else if (fmt[i] == 'i' || fmt[i] == 'n')
+ {
+ if (XINT (e1, i) != XINT (e2, i))
+ return false;
+ }
+ /* Unhandled type of subexpression, we fail conservatively. */
+ else
+ return false;
+ }
+
+ return true;
+}
+
+/* Returns hash value for invariant expression entry E. */
+
+static hashval_t
+hash_invariant_expr (const void *e)
+{
+ const struct invariant_expr_entry *const entry =
+ (const struct invariant_expr_entry *) e;
+
+ return entry->hash;
+}
+
+/* Compares invariant expression entries E1 and E2. */
+
+static int
+eq_invariant_expr (const void *e1, const void *e2)
+{
+ const struct invariant_expr_entry *const entry1 =
+ (const struct invariant_expr_entry *) e1;
+ const struct invariant_expr_entry *const entry2 =
+ (const struct invariant_expr_entry *) e2;
+
+ if (entry1->mode != entry2->mode)
+ return 0;
+
+ return invariant_expr_equal_p (entry1->inv->insn, entry1->expr,
+ entry2->inv->insn, entry2->expr);
+}
+
+/* Checks whether invariant with value EXPR in machine mode MODE is
+ recorded in EQ. If this is the case, return the invariant. Otherwise
+ insert INV to the table for this expression and return INV. */
+
+static struct invariant *
+find_or_insert_inv (htab_t eq, rtx expr, enum machine_mode mode,
+ struct invariant *inv)
+{
+ hashval_t hash = hash_invariant_expr_1 (inv->insn, expr);
+ struct invariant_expr_entry *entry;
+ struct invariant_expr_entry pentry;
+ PTR *slot;
+
+ pentry.expr = expr;
+ pentry.inv = inv;
+ pentry.mode = mode;
+ slot = htab_find_slot_with_hash (eq, &pentry, hash, INSERT);
+ entry = (struct invariant_expr_entry *) *slot;
+
+ if (entry)
+ return entry->inv;
+
+ entry = XNEW (struct invariant_expr_entry);
+ entry->inv = inv;
+ entry->expr = expr;
+ entry->mode = mode;
+ entry->hash = hash;
+ *slot = entry;
+
+ return inv;
+}
+
+/* Finds invariants identical to INV and records the equivalence. EQ is the
+ hash table of the invariants. */
+
+static void
+find_identical_invariants (htab_t eq, struct invariant *inv)
+{
+ unsigned depno;
+ bitmap_iterator bi;
+ struct invariant *dep;
+ rtx expr, set;
+ enum machine_mode mode;
+
+ if (inv->eqto != ~0u)
+ return;
+
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno, bi)
+ {
+ dep = VEC_index (invariant_p, invariants, depno);
+ find_identical_invariants (eq, dep);
+ }
+
+ set = single_set (inv->insn);
+ expr = SET_SRC (set);
+ mode = GET_MODE (expr);
+ if (mode == VOIDmode)
+ mode = GET_MODE (SET_DEST (set));
+ inv->eqto = find_or_insert_inv (eq, expr, mode, inv)->invno;
+
+ if (dump_file && inv->eqto != inv->invno)
+ fprintf (dump_file,
+ "Invariant %d is equivalent to invariant %d.\n",
+ inv->invno, inv->eqto);
+}
+
+/* Find invariants with the same value and record the equivalences. */
+
+static void
+merge_identical_invariants (void)
+{
+ unsigned i;
+ struct invariant *inv;
+ htab_t eq = htab_create (VEC_length (invariant_p, invariants),
+ hash_invariant_expr, eq_invariant_expr, free);
+
+ for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++)
+ find_identical_invariants (eq, inv);
+
+ htab_delete (eq);
+}
+
+/* Determines the basic blocks inside LOOP that are always executed and
+ stores their bitmap to ALWAYS_REACHED. MAY_EXIT is a bitmap of
+ basic blocks that may either exit the loop, or contain the call that
+ does not have to return. BODY is body of the loop obtained by
+ get_loop_body_in_dom_order. */
+
+static void
+compute_always_reached (struct loop *loop, basic_block *body,
+ bitmap may_exit, bitmap always_reached)
+{
+ unsigned i;
+
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ if (dominated_by_p (CDI_DOMINATORS, loop->latch, body[i]))
+ bitmap_set_bit (always_reached, i);
+
+ if (bitmap_bit_p (may_exit, i))
+ return;
+ }
+}
+
+/* Finds exits out of the LOOP with body BODY. Marks blocks in that we may
+ exit the loop by cfg edge to HAS_EXIT and MAY_EXIT. In MAY_EXIT
+ additionally mark blocks that may exit due to a call. */
+
+static void
+find_exits (struct loop *loop, basic_block *body,
+ bitmap may_exit, bitmap has_exit)
+{
+ unsigned i;
+ edge_iterator ei;
+ edge e;
+ struct loop *outermost_exit = loop, *aexit;
+ bool has_call = false;
+ rtx insn;
+
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ if (body[i]->loop_father == loop)
+ {
+ FOR_BB_INSNS (body[i], insn)
+ {
+ if (CALL_P (insn)
+ && (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
+ || !RTL_CONST_OR_PURE_CALL_P (insn)))
+ {
+ has_call = true;
+ bitmap_set_bit (may_exit, i);
+ break;
+ }
+ }
+
+ FOR_EACH_EDGE (e, ei, body[i]->succs)
+ {
+ if (flow_bb_inside_loop_p (loop, e->dest))
+ continue;
+
+ bitmap_set_bit (may_exit, i);
+ bitmap_set_bit (has_exit, i);
+ outermost_exit = find_common_loop (outermost_exit,
+ e->dest->loop_father);
+ }
+ continue;
+ }
+
+ /* Use the data stored for the subloop to decide whether we may exit
+ through it. It is sufficient to do this for header of the loop,
+ as other basic blocks inside it must be dominated by it. */
+ if (body[i]->loop_father->header != body[i])
+ continue;
+
+ if (LOOP_DATA (body[i]->loop_father)->has_call)
+ {
+ has_call = true;
+ bitmap_set_bit (may_exit, i);
+ }
+ aexit = LOOP_DATA (body[i]->loop_father)->outermost_exit;
+ if (aexit != loop)
+ {
+ bitmap_set_bit (may_exit, i);
+ bitmap_set_bit (has_exit, i);
+
+ if (flow_loop_nested_p (aexit, outermost_exit))
+ outermost_exit = aexit;
+ }
+ }
+
+ loop->aux = xcalloc (1, sizeof (struct loop_data));
+ LOOP_DATA (loop)->outermost_exit = outermost_exit;
+ LOOP_DATA (loop)->has_call = has_call;
+}
+
+/* Check whether we may assign a value to X from a register. */
+
+static bool
+may_assign_reg_p (rtx x)
+{
+ return (GET_MODE (x) != VOIDmode
+ && GET_MODE (x) != BLKmode
+ && can_copy_p (GET_MODE (x))
+ && (!REG_P (x)
+ || !HARD_REGISTER_P (x)
+ || REGNO_REG_CLASS (REGNO (x)) != NO_REGS));
+}
+
+/* Finds definitions that may correspond to invariants in LOOP with body
+ BODY. */
+
+static void
+find_defs (struct loop *loop, basic_block *body)
+{
+ unsigned i;
+ bitmap blocks = BITMAP_ALLOC (NULL);
+
+ for (i = 0; i < loop->num_nodes; i++)
+ bitmap_set_bit (blocks, body[i]->index);
+
+ df_remove_problem (df_chain);
+ df_process_deferred_rescans ();
+ df_chain_add_problem (DF_UD_CHAIN);
+ df_set_blocks (blocks);
+ df_analyze ();
+
+ if (dump_file)
+ {
+ df_dump_region (dump_file);
+ fprintf (dump_file, "*****starting processing of loop ******\n");
+ print_rtl_with_bb (dump_file, get_insns ());
+ fprintf (dump_file, "*****ending processing of loop ******\n");
+ }
+ check_invariant_table_size ();
+
+ BITMAP_FREE (blocks);
+}
+
+/* Creates a new invariant for definition DEF in INSN, depending on invariants
+ in DEPENDS_ON. ALWAYS_EXECUTED is true if the insn is always executed,
+ unless the program ends due to a function call. The newly created invariant
+ is returned. */
+
+static struct invariant *
+create_new_invariant (struct def *def, rtx insn, bitmap depends_on,
+ bool always_executed)
+{
+ struct invariant *inv = XNEW (struct invariant);
+ rtx set = single_set (insn);
+ bool speed = optimize_bb_for_speed_p (BLOCK_FOR_INSN (insn));
+
+ inv->def = def;
+ inv->always_executed = always_executed;
+ inv->depends_on = depends_on;
+
+ /* If the set is simple, usually by moving it we move the whole store out of
+ the loop. Otherwise we save only cost of the computation. */
+ if (def)
+ inv->cost = rtx_cost (set, SET, speed);
+ else
+ inv->cost = rtx_cost (SET_SRC (set), SET, speed);
+
+ inv->move = false;
+ inv->reg = NULL_RTX;
+ inv->stamp = 0;
+ inv->insn = insn;
+
+ inv->invno = VEC_length (invariant_p, invariants);
+ inv->eqto = ~0u;
+ if (def)
+ def->invno = inv->invno;
+ VEC_safe_push (invariant_p, heap, invariants, inv);
+
+ if (dump_file)
+ {
+ fprintf (dump_file,
+ "Set in insn %d is invariant (%d), cost %d, depends on ",
+ INSN_UID (insn), inv->invno, inv->cost);
+ dump_bitmap (dump_file, inv->depends_on);
+ }
+
+ return inv;
+}
+
+/* Record USE at DEF. */
+
+static void
+record_use (struct def *def, rtx *use, rtx insn)
+{
+ struct use *u = XNEW (struct use);
+
+ gcc_assert (REG_P (*use));
+
+ u->pos = use;
+ u->insn = insn;
+ u->next = def->uses;
+ def->uses = u;
+ def->n_uses++;
+}
+
+/* Finds the invariants USE depends on and store them to the DEPENDS_ON
+ bitmap. Returns true if all dependencies of USE are known to be
+ loop invariants, false otherwise. */
+
+static bool
+check_dependency (basic_block bb, df_ref use, bitmap depends_on)
+{
+ df_ref def;
+ basic_block def_bb;
+ struct df_link *defs;
+ struct def *def_data;
+ struct invariant *inv;
+
+ if (DF_REF_FLAGS (use) & DF_REF_READ_WRITE)
+ return false;
+
+ defs = DF_REF_CHAIN (use);
+ if (!defs)
+ return true;
+
+ if (defs->next)
+ return false;
+
+ def = defs->ref;
+ check_invariant_table_size ();
+ inv = invariant_table[DF_REF_ID(def)];
+ if (!inv)
+ return false;
+
+ def_data = inv->def;
+ gcc_assert (def_data != NULL);
+
+ def_bb = DF_REF_BB (def);
+ /* Note that in case bb == def_bb, we know that the definition
+ dominates insn, because def has invariant_table[DF_REF_ID(def)]
+ defined and we process the insns in the basic block bb
+ sequentially. */
+ if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
+ return false;
+
+ bitmap_set_bit (depends_on, def_data->invno);
+ return true;
+}
+
+
+/* Finds the invariants INSN depends on and store them to the DEPENDS_ON
+ bitmap. Returns true if all dependencies of INSN are known to be
+ loop invariants, false otherwise. */
+
+static bool
+check_dependencies (rtx insn, bitmap depends_on)
+{
+ struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+ df_ref *use_rec;
+ basic_block bb = BLOCK_FOR_INSN (insn);
+
+ for (use_rec = DF_INSN_INFO_USES (insn_info); *use_rec; use_rec++)
+ if (!check_dependency (bb, *use_rec, depends_on))
+ return false;
+ for (use_rec = DF_INSN_INFO_EQ_USES (insn_info); *use_rec; use_rec++)
+ if (!check_dependency (bb, *use_rec, depends_on))
+ return false;
+
+ return true;
+}
+
+/* Finds invariant in INSN. ALWAYS_REACHED is true if the insn is always
+ executed. ALWAYS_EXECUTED is true if the insn is always executed,
+ unless the program ends due to a function call. */
+
+static void
+find_invariant_insn (rtx insn, bool always_reached, bool always_executed)
+{
+ df_ref ref;
+ struct def *def;
+ bitmap depends_on;
+ rtx set, dest;
+ bool simple = true;
+ struct invariant *inv;
+
+#ifdef HAVE_cc0
+ /* We can't move a CC0 setter without the user. */
+ if (sets_cc0_p (insn))
+ return;
+#endif
+
+ set = single_set (insn);
+ if (!set)
+ return;
+ dest = SET_DEST (set);
+
+ if (!REG_P (dest)
+ || HARD_REGISTER_P (dest))
+ simple = false;
+
+ if (!may_assign_reg_p (SET_DEST (set))
+ || !check_maybe_invariant (SET_SRC (set)))
+ return;
+
+ /* If the insn can throw exception, we cannot move it at all without changing
+ cfg. */
+ if (can_throw_internal (insn))
+ return;
+
+ /* We cannot make trapping insn executed, unless it was executed before. */
+ if (may_trap_or_fault_p (PATTERN (insn)) && !always_reached)
+ return;
+
+ depends_on = BITMAP_ALLOC (NULL);
+ if (!check_dependencies (insn, depends_on))
+ {
+ BITMAP_FREE (depends_on);
+ return;
+ }
+
+ if (simple)
+ def = XCNEW (struct def);
+ else
+ def = NULL;
+
+ inv = create_new_invariant (def, insn, depends_on, always_executed);
+
+ if (simple)
+ {
+ ref = df_find_def (insn, dest);
+ check_invariant_table_size ();
+ invariant_table[DF_REF_ID(ref)] = inv;
+ }
+}
+
+/* Record registers used in INSN that have a unique invariant definition. */
+
+static void
+record_uses (rtx insn)
+{
+ struct df_insn_info *insn_info = DF_INSN_INFO_GET (insn);
+ df_ref *use_rec;
+ struct invariant *inv;
+
+ for (use_rec = DF_INSN_INFO_USES (insn_info); *use_rec; use_rec++)
+ {
+ df_ref use = *use_rec;
+ inv = invariant_for_use (use);
+ if (inv)
+ record_use (inv->def, DF_REF_REAL_LOC (use), DF_REF_INSN (use));
+ }
+ for (use_rec = DF_INSN_INFO_EQ_USES (insn_info); *use_rec; use_rec++)
+ {
+ df_ref use = *use_rec;
+ inv = invariant_for_use (use);
+ if (inv)
+ record_use (inv->def, DF_REF_REAL_LOC (use), DF_REF_INSN (use));
+ }
+}
+
+/* Finds invariants in INSN. ALWAYS_REACHED is true if the insn is always
+ executed. ALWAYS_EXECUTED is true if the insn is always executed,
+ unless the program ends due to a function call. */
+
+static void
+find_invariants_insn (rtx insn, bool always_reached, bool always_executed)
+{
+ find_invariant_insn (insn, always_reached, always_executed);
+ record_uses (insn);
+}
+
+/* Finds invariants in basic block BB. ALWAYS_REACHED is true if the
+ basic block is always executed. ALWAYS_EXECUTED is true if the basic
+ block is always executed, unless the program ends due to a function
+ call. */
+
+static void
+find_invariants_bb (basic_block bb, bool always_reached, bool always_executed)
+{
+ rtx insn;
+
+ FOR_BB_INSNS (bb, insn)
+ {
+ if (!INSN_P (insn))
+ continue;
+
+ find_invariants_insn (insn, always_reached, always_executed);
+
+ if (always_reached
+ && CALL_P (insn)
+ && (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
+ || ! RTL_CONST_OR_PURE_CALL_P (insn)))
+ always_reached = false;
+ }
+}
+
+/* Finds invariants in LOOP with body BODY. ALWAYS_REACHED is the bitmap of
+ basic blocks in BODY that are always executed. ALWAYS_EXECUTED is the
+ bitmap of basic blocks in BODY that are always executed unless the program
+ ends due to a function call. */
+
+static void
+find_invariants_body (struct loop *loop, basic_block *body,
+ bitmap always_reached, bitmap always_executed)
+{
+ unsigned i;
+
+ for (i = 0; i < loop->num_nodes; i++)
+ find_invariants_bb (body[i],
+ bitmap_bit_p (always_reached, i),
+ bitmap_bit_p (always_executed, i));
+}
+
+/* Finds invariants in LOOP. */
+
+static void
+find_invariants (struct loop *loop)
+{
+ bitmap may_exit = BITMAP_ALLOC (NULL);
+ bitmap always_reached = BITMAP_ALLOC (NULL);
+ bitmap has_exit = BITMAP_ALLOC (NULL);
+ bitmap always_executed = BITMAP_ALLOC (NULL);
+ basic_block *body = get_loop_body_in_dom_order (loop);
+
+ find_exits (loop, body, may_exit, has_exit);
+ compute_always_reached (loop, body, may_exit, always_reached);
+ compute_always_reached (loop, body, has_exit, always_executed);
+
+ find_defs (loop, body);
+ find_invariants_body (loop, body, always_reached, always_executed);
+ merge_identical_invariants ();
+
+ BITMAP_FREE (always_reached);
+ BITMAP_FREE (always_executed);
+ BITMAP_FREE (may_exit);
+ BITMAP_FREE (has_exit);
+ free (body);
+}
+
+/* Frees a list of uses USE. */
+
+static void
+free_use_list (struct use *use)
+{
+ struct use *next;
+
+ for (; use; use = next)
+ {
+ next = use->next;
+ free (use);
+ }
+}
+
+/* Calculates cost and number of registers needed for moving invariant INV
+ out of the loop and stores them to *COST and *REGS_NEEDED. */
+
+static void
+get_inv_cost (struct invariant *inv, int *comp_cost, unsigned *regs_needed)
+{
+ int acomp_cost;
+ unsigned aregs_needed;
+ unsigned depno;
+ struct invariant *dep;
+ bitmap_iterator bi;
+
+ /* Find the representative of the class of the equivalent invariants. */
+ inv = VEC_index (invariant_p, invariants, inv->eqto);
+
+ *comp_cost = 0;
+ *regs_needed = 0;
+ if (inv->move
+ || inv->stamp == actual_stamp)
+ return;
+ inv->stamp = actual_stamp;
+
+ (*regs_needed)++;
+ (*comp_cost) += inv->cost;
+
+#ifdef STACK_REGS
+ {
+ /* Hoisting constant pool constants into stack regs may cost more than
+ just single register. On x87, the balance is affected both by the
+ small number of FP registers, and by its register stack organization,
+ that forces us to add compensation code in and around the loop to
+ shuffle the operands to the top of stack before use, and pop them
+ from the stack after the loop finishes.
+
+ To model this effect, we increase the number of registers needed for
+ stack registers by two: one register push, and one register pop.
+ This usually has the effect that FP constant loads from the constant
+ pool are not moved out of the loop.
+
+ Note that this also means that dependent invariants can not be moved.
+ However, the primary purpose of this pass is to move loop invariant
+ address arithmetic out of loops, and address arithmetic that depends
+ on floating point constants is unlikely to ever occur. */
+ rtx set = single_set (inv->insn);
+ if (set
+ && IS_STACK_MODE (GET_MODE (SET_SRC (set)))
+ && constant_pool_constant_p (SET_SRC (set)))
+ (*regs_needed) += 2;
+ }
+#endif
+
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno, bi)
+ {
+ dep = VEC_index (invariant_p, invariants, depno);
+
+ get_inv_cost (dep, &acomp_cost, &aregs_needed);
+
+ if (aregs_needed
+ /* We need to check always_executed, since if the original value of
+ the invariant may be preserved, we may need to keep it in a
+ separate register. TODO check whether the register has an
+ use outside of the loop. */
+ && dep->always_executed
+ && !dep->def->uses->next)
+ {
+ /* If this is a single use, after moving the dependency we will not
+ need a new register. */
+ aregs_needed--;
+ }
+
+ (*regs_needed) += aregs_needed;
+ (*comp_cost) += acomp_cost;
+ }
+}
+
+/* Calculates gain for eliminating invariant INV. REGS_USED is the number
+ of registers used in the loop, NEW_REGS is the number of new variables
+ already added due to the invariant motion. The number of registers needed
+ for it is stored in *REGS_NEEDED. */
+
+static int
+gain_for_invariant (struct invariant *inv, unsigned *regs_needed,
+ unsigned new_regs, unsigned regs_used, bool speed)
+{
+ int comp_cost, size_cost;
+
+ get_inv_cost (inv, &comp_cost, regs_needed);
+ actual_stamp++;
+
+ size_cost = (estimate_reg_pressure_cost (new_regs + *regs_needed, regs_used, speed)
+ - estimate_reg_pressure_cost (new_regs, regs_used, speed));
+
+ return comp_cost - size_cost;
+}
+
+/* Finds invariant with best gain for moving. Returns the gain, stores
+ the invariant in *BEST and number of registers needed for it to
+ *REGS_NEEDED. REGS_USED is the number of registers used in the loop.
+ NEW_REGS is the number of new variables already added due to invariant
+ motion. */
+
+static int
+best_gain_for_invariant (struct invariant **best, unsigned *regs_needed,
+ unsigned new_regs, unsigned regs_used, bool speed)
+{
+ struct invariant *inv;
+ int gain = 0, again;
+ unsigned aregs_needed, invno;
+
+ for (invno = 0; VEC_iterate (invariant_p, invariants, invno, inv); invno++)
+ {
+ if (inv->move)
+ continue;
+
+ /* Only consider the "representatives" of equivalent invariants. */
+ if (inv->eqto != inv->invno)
+ continue;
+
+ again = gain_for_invariant (inv, &aregs_needed, new_regs, regs_used,
+ speed);
+ if (again > gain)
+ {
+ gain = again;
+ *best = inv;
+ *regs_needed = aregs_needed;
+ }
+ }
+
+ return gain;
+}
+
+/* Marks invariant INVNO and all its dependencies for moving. */
+
+static void
+set_move_mark (unsigned invno)
+{
+ struct invariant *inv = VEC_index (invariant_p, invariants, invno);
+ bitmap_iterator bi;
+
+ /* Find the representative of the class of the equivalent invariants. */
+ inv = VEC_index (invariant_p, invariants, inv->eqto);
+
+ if (inv->move)
+ return;
+ inv->move = true;
+
+ if (dump_file)
+ fprintf (dump_file, "Decided to move invariant %d\n", invno);
+
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, invno, bi)
+ {
+ set_move_mark (invno);
+ }
+}
+
+/* Determines which invariants to move. */
+
+static void
+find_invariants_to_move (bool speed)
+{
+ unsigned i, regs_used, regs_needed = 0, new_regs;
+ struct invariant *inv = NULL;
+ unsigned int n_regs = DF_REG_SIZE (df);
+
+ if (!VEC_length (invariant_p, invariants))
+ return;
+
+ /* We do not really do a good job in estimating number of registers used;
+ we put some initial bound here to stand for induction variables etc.
+ that we do not detect. */
+ regs_used = 2;
+
+ for (i = 0; i < n_regs; i++)
+ {
+ if (!DF_REGNO_FIRST_DEF (i) && DF_REGNO_LAST_USE (i))
+ {
+ /* This is a value that is used but not changed inside loop. */
+ regs_used++;
+ }
+ }
+
+ new_regs = 0;
+ while (best_gain_for_invariant (&inv, ®s_needed, new_regs, regs_used, speed) > 0)
+ {
+ set_move_mark (inv->invno);
+ new_regs += regs_needed;
+ }
+}
+
+/* Move invariant INVNO out of the LOOP. Returns true if this succeeds, false
+ otherwise. */
+
+static bool
+move_invariant_reg (struct loop *loop, unsigned invno)
+{
+ struct invariant *inv = VEC_index (invariant_p, invariants, invno);
+ struct invariant *repr = VEC_index (invariant_p, invariants, inv->eqto);
+ unsigned i;
+ basic_block preheader = loop_preheader_edge (loop)->src;
+ rtx reg, set, dest, note;
+ struct use *use;
+ bitmap_iterator bi;
+
+ if (inv->reg)
+ return true;
+ if (!repr->move)
+ return false;
+ /* If this is a representative of the class of equivalent invariants,
+ really move the invariant. Otherwise just replace its use with
+ the register used for the representative. */
+ if (inv == repr)
+ {
+ if (inv->depends_on)
+ {
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, i, bi)
+ {
+ if (!move_invariant_reg (loop, i))
+ goto fail;
+ }
+ }
+
+ /* Move the set out of the loop. If the set is always executed (we could
+ omit this condition if we know that the register is unused outside of the
+ loop, but it does not seem worth finding out) and it has no uses that
+ would not be dominated by it, we may just move it (TODO). Otherwise we
+ need to create a temporary register. */
+ set = single_set (inv->insn);
+ dest = SET_DEST (set);
+ reg = gen_reg_rtx_and_attrs (dest);
+
+ /* Try replacing the destination by a new pseudoregister. */
+ if (!validate_change (inv->insn, &SET_DEST (set), reg, false))
+ goto fail;
+ df_insn_rescan (inv->insn);
+
+ emit_insn_after (gen_move_insn (dest, reg), inv->insn);
+ reorder_insns (inv->insn, inv->insn, BB_END (preheader));
+
+ /* If there is a REG_EQUAL note on the insn we just moved, and
+ insn is in a basic block that is not always executed, the note
+ may no longer be valid after we move the insn.
+ Note that uses in REG_EQUAL notes are taken into account in
+ the computation of invariants. Hence it is safe to retain the
+ note even if the note contains register references. */
+ if (! inv->always_executed
+ && (note = find_reg_note (inv->insn, REG_EQUAL, NULL_RTX)))
+ remove_note (inv->insn, note);
+ }
+ else
+ {
+ if (!move_invariant_reg (loop, repr->invno))
+ goto fail;
+ reg = repr->reg;
+ set = single_set (inv->insn);
+ emit_insn_after (gen_move_insn (SET_DEST (set), reg), inv->insn);
+ delete_insn (inv->insn);
+ }
+
+
+ inv->reg = reg;
+
+ /* Replace the uses we know to be dominated. It saves work for copy
+ propagation, and also it is necessary so that dependent invariants
+ are computed right. */
+ if (inv->def)
+ {
+ for (use = inv->def->uses; use; use = use->next)
+ {
+ *use->pos = reg;
+ df_insn_rescan (use->insn);
+ }
+ }
+
+ return true;
+
+fail:
+ /* If we failed, clear move flag, so that we do not try to move inv
+ again. */
+ if (dump_file)
+ fprintf (dump_file, "Failed to move invariant %d\n", invno);
+ inv->move = false;
+ inv->reg = NULL_RTX;
+
+ return false;
+}
+
+/* Move selected invariant out of the LOOP. Newly created regs are marked
+ in TEMPORARY_REGS. */
+
+static void
+move_invariants (struct loop *loop)
+{
+ struct invariant *inv;
+ unsigned i;
+
+ for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++)
+ move_invariant_reg (loop, i);
+}
+
+/* Initializes invariant motion data. */
+
+static void
+init_inv_motion_data (void)
+{
+ actual_stamp = 1;
+
+ invariants = VEC_alloc (invariant_p, heap, 100);
+}
+
+/* Frees the data allocated by invariant motion. */
+
+static void
+free_inv_motion_data (void)
+{
+ unsigned i;
+ struct def *def;
+ struct invariant *inv;
+
+ check_invariant_table_size ();
+ for (i = 0; i < DF_DEFS_TABLE_SIZE (); i++)
+ {
+ inv = invariant_table[i];
+ if (inv)
+ {
+ def = inv->def;
+ gcc_assert (def != NULL);
+
+ free_use_list (def->uses);
+ free (def);
+ invariant_table[i] = NULL;
+ }
+ }
+
+ for (i = 0; VEC_iterate (invariant_p, invariants, i, inv); i++)
+ {
+ BITMAP_FREE (inv->depends_on);
+ free (inv);
+ }
+ VEC_free (invariant_p, heap, invariants);
+}
+
+/* Move the invariants out of the LOOP. */
+
+static void
+move_single_loop_invariants (struct loop *loop)
+{
+ init_inv_motion_data ();
+
+ find_invariants (loop);
+ find_invariants_to_move (optimize_loop_for_speed_p (loop));
+ move_invariants (loop);
+
+ free_inv_motion_data ();
+}
+
+/* Releases the auxiliary data for LOOP. */
+
+static void
+free_loop_data (struct loop *loop)
+{
+ struct loop_data *data = LOOP_DATA (loop);
+
+ free (data);
+ loop->aux = NULL;
+}
+
+/* Move the invariants out of the loops. */
+
+void
+move_loop_invariants (void)
+{
+ struct loop *loop;
+ loop_iterator li;
+
+ df_set_flags (DF_EQ_NOTES + DF_DEFER_INSN_RESCAN);
+ /* Process the loops, innermost first. */
+ FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST)
+ {
+ /* move_single_loop_invariants for very large loops
+ is time consuming and might need a lot of memory. */
+ if (loop->num_nodes <= (unsigned) LOOP_INVARIANT_MAX_BBS_IN_LOOP)
+ move_single_loop_invariants (loop);
+ }
+
+ FOR_EACH_LOOP (li, loop, 0)
+ {
+ free_loop_data (loop);
+ }
+
+ free (invariant_table);
+ invariant_table = NULL;
+ invariant_table_size = 0;
+
+#ifdef ENABLE_CHECKING
+ verify_flow_info ();
+#endif
+}
projects / msp430-gcc.git / blobdiff