--- /dev/null
+/* Rtl-level loop invariant motion.
+ Copyright (C) 2004 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 2, 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 COPYING. If not, write to the Free
+Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA. */
+
+/* This implements the loop invariant motion pass. It is very simple
+ (no calls, libcalls, etc.). This should be sufficient to cleanup things like
+ address arithmetics -- other more complicated invariants should be
+ eliminated on tree level 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 "hard-reg-set.h"
+#include "basic-block.h"
+#include "cfgloop.h"
+#include "expr.h"
+#include "output.h"
+#include "function.h"
+#include "flags.h"
+#include "df.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;
+
+ /* Whether we already processed the invariant. */
+ bool processed;
+
+ /* 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 if 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;
+};
+
+/* The actual stamp for marking already visited invariants during determining
+ costs of movements. */
+
+static unsigned actual_stamp;
+
+/* The invariants. */
+
+static varray_type invariants;
+
+/* 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 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 (RTX_UNCHANGING_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;
+}
+
+/* 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 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 (GET_CODE (insn) == CALL_INSN
+ && !CONST_OR_PURE_CALL_P (insn))
+ {
+ has_call = true;
+ bitmap_set_bit (may_exit, i);
+ break;
+ }
+ }
+
+ for (e = body[i]->succ; e; e = e->succ_next)
+ {
+ 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 can_copy_p (GET_MODE (x));
+}
+
+/* Finds definitions that may correspond to invariants in LOOP with body BODY.
+ DF is the dataflow object. */
+
+static void
+find_defs (struct loop *loop, basic_block *body, struct df *df)
+{
+ unsigned i;
+ bitmap blocks = BITMAP_XMALLOC ();
+
+ for (i = 0; i < loop->num_nodes; i++)
+ bitmap_set_bit (blocks, body[i]->index);
+
+ df_analyze_subcfg (df, blocks, DF_UD_CHAIN | DF_HARD_REGS | DF_EQUIV_NOTES);
+ BITMAP_XFREE (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. */
+
+static void
+create_new_invariant (struct def *def, rtx insn, bitmap depends_on,
+ bool always_executed)
+{
+ struct invariant *inv = xmalloc (sizeof (struct invariant));
+ rtx set = single_set (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);
+ else
+ inv->cost = rtx_cost (SET_SRC (set), SET);
+
+ inv->move = false;
+ inv->processed = false;
+ inv->stamp = 0;
+ inv->insn = insn;
+
+ inv->invno = VARRAY_ACTIVE_SIZE (invariants);
+ if (def)
+ def->invno = inv->invno;
+ VARRAY_PUSH_GENERIC_PTR_NOGC (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);
+ }
+}
+
+/* Record USE at DEF. */
+
+static void
+record_use (struct def *def, rtx *use, rtx insn)
+{
+ struct use *u = xmalloc (sizeof (struct use));
+
+ if (GET_CODE (*use) == SUBREG)
+ use = &SUBREG_REG (*use);
+ if (!REG_P (*use))
+ abort ();
+
+ u->pos = use;
+ u->insn = insn;
+ u->next = def->uses;
+ def->uses = u;
+ def->n_uses++;
+}
+
+/* Finds the invariants INSN depends on and store them to the DEPENDS_ON
+ bitmap. DF is the dataflow object. */
+
+static bool
+check_dependencies (rtx insn, struct df *df, bitmap depends_on)
+{
+ struct df_link *uses, *defs;
+ struct ref *use, *def;
+ basic_block bb = BLOCK_FOR_INSN (insn), def_bb;
+ struct def *def_data;
+
+ for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
+ {
+ use = uses->ref;
+
+ defs = DF_REF_CHAIN (use);
+ if (!defs)
+ continue;
+
+ if (defs->next)
+ return false;
+
+ def = defs->ref;
+ def_data = DF_REF_DATA (def);
+ if (!def_data)
+ return false;
+
+ def_bb = DF_REF_BB (def);
+ if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
+ return false;
+
+ bitmap_set_bit (depends_on, def_data->invno);
+ }
+
+ 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. DF is the dataflow
+ object. */
+
+static void
+find_invariant_insn (rtx insn, bool always_reached, bool always_executed,
+ struct df *df)
+{
+ struct ref *ref;
+ struct def *def;
+ bitmap depends_on;
+ rtx set, dest;
+ bool simple = true;
+
+ /* Until we get rid of LIBCALLS. */
+ if (find_reg_note (insn, REG_RETVAL, NULL_RTX)
+ || find_reg_note (insn, REG_LIBCALL, NULL_RTX)
+ || find_reg_note (insn, REG_NO_CONFLICT, NULL_RTX))
+ return;
+
+ set = single_set (insn);
+ if (!set)
+ return;
+ dest = SET_DEST (set);
+
+ if (GET_CODE (dest) != REG
+ || HARD_REGISTER_P (dest))
+ simple = false;
+
+ if (!check_maybe_invariant (SET_SRC (set))
+ || !may_assign_reg_p (SET_DEST (set)))
+ return;
+
+ if (may_trap_p (PATTERN (insn)))
+ {
+ if (!always_reached)
+ return;
+
+ /* Unless the exceptions are handled, the behavior is undefined
+ if the trap occurs. */
+ if (flag_non_call_exceptions)
+ return;
+ }
+
+ depends_on = BITMAP_XMALLOC ();
+ if (!check_dependencies (insn, df, depends_on))
+ {
+ BITMAP_XFREE (depends_on);
+ return;
+ }
+
+ if (simple)
+ {
+ ref = df_find_def (df, insn, dest);
+ def = xcalloc (1, sizeof (struct def));
+ DF_REF_DATA (ref) = def;
+ }
+ else
+ def = NULL;
+
+ create_new_invariant (def, insn, depends_on, always_executed);
+}
+
+/* Record registers used in INSN that have an unique invariant definition.
+ DF is the dataflow object. */
+
+static void
+record_uses (rtx insn, struct df *df)
+{
+ struct df_link *uses, *defs;
+ struct ref *use, *def;
+ basic_block bb = BLOCK_FOR_INSN (insn), def_bb;
+
+ for (uses = DF_INSN_USES (df, insn); uses; uses = uses->next)
+ {
+ use = uses->ref;
+
+ defs = DF_REF_CHAIN (use);
+ if (!defs || defs->next)
+ continue;
+ def = defs->ref;
+ if (!DF_REF_DATA (def))
+ continue;
+
+ def_bb = DF_REF_BB (def);
+ if (!dominated_by_p (CDI_DOMINATORS, bb, def_bb))
+ continue;
+
+ record_use (DF_REF_DATA (def), DF_REF_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. DF is the dataflow
+ object. */
+
+static void
+find_invariants_insn (rtx insn, bool always_reached, bool always_executed,
+ struct df *df)
+{
+ find_invariant_insn (insn, always_reached, always_executed, df);
+ record_uses (insn, df);
+}
+
+/* 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. DF is the dataflow object. */
+
+static void
+find_invariants_bb (basic_block bb, bool always_reached, bool always_executed,
+ struct df *df)
+{
+ rtx insn;
+
+ FOR_BB_INSNS (bb, insn)
+ {
+ if (!INSN_P (insn))
+ continue;
+
+ find_invariants_insn (insn, always_reached, always_executed, df);
+
+ if (always_reached
+ && GET_CODE (insn) == CALL_INSN
+ && !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. DF is the dataflow object. */
+
+static void
+find_invariants_body (struct loop *loop, basic_block *body,
+ bitmap always_reached, bitmap always_executed,
+ struct df *df)
+{
+ 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),
+ df);
+}
+
+/* Finds invariants in LOOP. DF is the dataflow object. */
+
+static void
+find_invariants (struct loop *loop, struct df *df)
+{
+ bitmap may_exit = BITMAP_XMALLOC ();
+ bitmap always_reached = BITMAP_XMALLOC ();
+ bitmap has_exit = BITMAP_XMALLOC ();
+ bitmap always_executed = BITMAP_XMALLOC ();
+ 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, df);
+ find_invariants_body (loop, body, always_reached, always_executed, df);
+
+ BITMAP_XFREE (always_reached);
+ BITMAP_XFREE (always_executed);
+ BITMAP_XFREE (may_exit);
+ BITMAP_XFREE (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;
+
+ *comp_cost = 0;
+ *regs_needed = 0;
+ if (inv->move
+ || inv->stamp == actual_stamp)
+ return;
+ inv->stamp = actual_stamp;
+
+ (*regs_needed)++;
+ (*comp_cost) += inv->cost;
+
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, depno,
+ {
+ dep = VARRAY_GENERIC_PTR_NOGC (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, N_INV_USES is the number of uses of
+ invariants, 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, unsigned n_inv_uses)
+{
+ int comp_cost, size_cost;
+
+ get_inv_cost (inv, &comp_cost, regs_needed);
+ actual_stamp++;
+
+ size_cost = (global_cost_for_size (new_regs + *regs_needed,
+ regs_used, n_inv_uses)
+ - global_cost_for_size (new_regs, regs_used, n_inv_uses));
+
+ 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, N_INV_USES is the number of uses of invariants. 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,
+ unsigned n_inv_uses)
+{
+ struct invariant *inv;
+ int gain = 0, again;
+ unsigned aregs_needed, invno;
+
+ for (invno = 0; invno < VARRAY_ACTIVE_SIZE (invariants); invno++)
+ {
+ inv = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
+ if (inv->move)
+ continue;
+
+ again = gain_for_invariant (inv, &aregs_needed,
+ new_regs, regs_used, n_inv_uses);
+ 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 = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
+
+ 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, set_move_mark (invno));
+}
+
+/* Determines which invariants to move. DF is the dataflow object. */
+
+static void
+find_invariants_to_move (struct df *df)
+{
+ unsigned i, regs_used, n_inv_uses, regs_needed = 0, new_regs;
+ struct invariant *inv = NULL;
+
+ if (flag_move_all_movables)
+ {
+ /* This is easy & stupid. */
+ for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
+ {
+ inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
+ inv->move = true;
+ }
+ return;
+ }
+
+ if (!VARRAY_ACTIVE_SIZE (invariants))
+ return;
+
+ /* Now something slightly more involved. First estimate the number of used
+ registers. */
+ n_inv_uses = 0;
+
+ /* We do not really do a good job in this estimation; put some initial bound
+ here to stand for induction variables etc. that we do not detect. */
+ regs_used = 2;
+
+ for (i = 0; i < df->n_regs; i++)
+ {
+ if (!DF_REGNO_FIRST_DEF (df, i) && DF_REGNO_LAST_USE (df, i))
+ {
+ /* This is a value that is used but not changed inside loop. */
+ regs_used++;
+ }
+ }
+
+ for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
+ {
+ inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
+ if (inv->def)
+ n_inv_uses += inv->def->n_uses;
+ }
+
+ new_regs = 0;
+ while (best_gain_for_invariant (&inv, ®s_needed,
+ new_regs, regs_used, n_inv_uses) > 0)
+ {
+ set_move_mark (inv->invno);
+ new_regs += regs_needed;
+ }
+}
+
+/* Move invariant INVNO out of the LOOP. DF is the dataflow object. */
+
+static void
+move_invariant_reg (struct loop *loop, unsigned invno, struct df *df)
+{
+ struct invariant *inv = VARRAY_GENERIC_PTR_NOGC (invariants, invno);
+ unsigned i;
+ basic_block preheader = loop_preheader_edge (loop)->src;
+ rtx reg, set;
+ struct use *use;
+
+ if (inv->processed)
+ return;
+ inv->processed = true;
+
+ if (inv->depends_on)
+ {
+ EXECUTE_IF_SET_IN_BITMAP (inv->depends_on, 0, i,
+ {
+ move_invariant_reg (loop, i, df);
+ });
+ }
+
+ /* 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);
+ reg = gen_reg_rtx (GET_MODE (SET_DEST (set)));
+ df_pattern_emit_after (df, gen_move_insn (SET_DEST (set), reg),
+ BLOCK_FOR_INSN (inv->insn), inv->insn);
+ SET_DEST (set) = reg;
+ reorder_insns (inv->insn, inv->insn, BB_END (preheader));
+ df_insn_modify (df, preheader, inv->insn);
+
+ /* 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_modify (df, BLOCK_FOR_INSN (use->insn), use->insn);
+ }
+ }
+}
+
+/* Move selected invariant out of the LOOP. Newly created regs are marked
+ in TEMPORARY_REGS. DF is the dataflow object. */
+
+static void
+move_invariants (struct loop *loop, struct df *df)
+{
+ struct invariant *inv;
+ unsigned i;
+
+ for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
+ {
+ inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
+ if (inv->move)
+ move_invariant_reg (loop, i, df);
+ }
+}
+
+/* Initializes invariant motion data. */
+
+static void
+init_inv_motion_data (void)
+{
+ actual_stamp = 1;
+
+ if (!invariants)
+ VARRAY_GENERIC_PTR_NOGC_INIT (invariants, 100, "invariants");
+}
+
+/* Frees the data allocated by invariant motion. DF is the dataflow
+ object. */
+
+static void
+free_inv_motion_data (struct df *df)
+{
+ unsigned i;
+ struct def *def;
+ struct invariant *inv;
+
+ for (i = 0; i < df->n_defs; i++)
+ {
+ if (!df->defs[i])
+ continue;
+
+ def = DF_REF_DATA (df->defs[i]);
+ if (!def)
+ continue;
+
+ free_use_list (def->uses);
+ free (def);
+ DF_REF_DATA (df->defs[i]) = NULL;
+ }
+
+ for (i = 0; i < VARRAY_ACTIVE_SIZE (invariants); i++)
+ {
+ inv = VARRAY_GENERIC_PTR_NOGC (invariants, i);
+ BITMAP_XFREE (inv->depends_on);
+ free (inv);
+ }
+ VARRAY_POP_ALL (invariants);
+}
+
+/* Move the invariants out of the LOOP. DF is the dataflow object. */
+
+static void
+move_single_loop_invariants (struct loop *loop, struct df *df)
+{
+ init_inv_motion_data ();
+
+ find_invariants (loop, df);
+ find_invariants_to_move (df);
+ move_invariants (loop, df);
+
+ free_inv_motion_data (df);
+}
+
+/* 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 (struct loops *loops)
+{
+ struct loop *loop;
+ unsigned i;
+ struct df *df = df_init ();
+
+ /* Process the loops, innermost first. */
+ loop = loops->tree_root;
+ while (loop->inner)
+ loop = loop->inner;
+
+ while (loop != loops->tree_root)
+ {
+ move_single_loop_invariants (loop, df);
+
+ if (loop->next)
+ {
+ loop = loop->next;
+ while (loop->inner)
+ loop = loop->inner;
+ }
+ else
+ loop = loop->outer;
+ }
+
+ for (i = 1; i < loops->num; i++)
+ if (loops->parray[i])
+ free_loop_data (loops->parray[i]);
+
+ df_finish (df);
+}
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