-/* Mode switching:
-
- The algorithm for setting the modes consists of scanning the insn list
- and finding all the insns which require a specific mode. Each insn gets
- a unique struct seginfo element. These structures are inserted into a list
- for each basic block. For each entity, there is an array of bb_info over
- the flow graph basic blocks (local var 'bb_info'), and contains a list
- of all insns within that basic block, in the order they are encountered.
-
- For each entity, any basic block WITHOUT any insns requiring a specific
- mode are given a single entry, without a mode. (Each basic block
- in the flow graph must have at least one entry in the segment table.)
-
- The LCM algorithm is then run over the flow graph to determine where to
- place the sets to the highest-priority value in respect of first the first
- insn in any one block. Any adjustments required to the transparancy
- vectors are made, then the next iteration starts for the next-lower
- priority mode, till for each entity all modes are exhasted.
-
- More details are located in the code for optimize_mode_switching(). */
-
-/* This structure contains the information for each insn which requires
- either single or double mode to be set.
- MODE is the mode this insn must be executed in.
- INSN_PTR is the insn to be executed (may be the note that marks the
- beginning of a basic block).
- BBNUM is the flow graph basic block this insn occurs in.
- NEXT is the next insn in the same basic block. */
-struct seginfo
-{
- int mode;
- rtx insn_ptr;
- int bbnum;
- struct seginfo *next;
- HARD_REG_SET regs_live;
-};
-
-struct bb_info
-{
- struct seginfo *seginfo;
- int computing;
-};
-
-/* These bitmaps are used for the LCM algorithm. */
-
-#ifdef OPTIMIZE_MODE_SWITCHING
-static sbitmap *antic;
-static sbitmap *transp;
-static sbitmap *comp;
-static sbitmap *delete;
-static sbitmap *insert;
-
-static struct seginfo * new_seginfo PARAMS ((int, rtx, int, HARD_REG_SET));
-static void add_seginfo PARAMS ((struct bb_info *, struct seginfo *));
-static void reg_dies PARAMS ((rtx, HARD_REG_SET));
-static void reg_becomes_live PARAMS ((rtx, rtx, void *));
-static void make_preds_opaque PARAMS ((basic_block, int));
-#endif
-\f
-#ifdef OPTIMIZE_MODE_SWITCHING
-
-/* This function will allocate a new BBINFO structure, initialized
- with the MODE, INSN, and basic block BB parameters. */
-
-static struct seginfo *
-new_seginfo (mode, insn, bb, regs_live)
- int mode;
- rtx insn;
- int bb;
- HARD_REG_SET regs_live;
-{
- struct seginfo *ptr;
- ptr = xmalloc (sizeof (struct seginfo));
- ptr->mode = mode;
- ptr->insn_ptr = insn;
- ptr->bbnum = bb;
- ptr->next = NULL;
- COPY_HARD_REG_SET (ptr->regs_live, regs_live);
- return ptr;
-}
-
-/* Add a seginfo element to the end of a list.
- HEAD is a pointer to the list beginning.
- INFO is the structure to be linked in. */
-
-static void
-add_seginfo (head, info)
- struct bb_info *head;
- struct seginfo *info;
-{
- struct seginfo *ptr;
-
- if (head->seginfo == NULL)
- head->seginfo = info;
- else
- {
- ptr = head->seginfo;
- while (ptr->next != NULL)
- ptr = ptr->next;
- ptr->next = info;
- }
-}
-
-/* Make all predecessors of basic block B opaque, recursively, till we hit
- some that are already non-transparent, or an edge where aux is set; that
- denotes that a mode set is to be done on that edge.
- J is the bit number in the bitmaps that corresponds to the entity that
- we are currently handling mode-switching for. */
-
-static void
-make_preds_opaque (b, j)
- basic_block b;
- int j;
-{
- edge e;
-
- for (e = b->pred; e; e = e->pred_next)
- {
- basic_block pb = e->src;
-
- if (e->aux || ! TEST_BIT (transp[pb->sindex], j))
- continue;
-
- RESET_BIT (transp[pb->sindex], j);
- make_preds_opaque (pb, j);
- }
-}
-
-/* Record in LIVE that register REG died. */
-
-static void
-reg_dies (reg, live)
- rtx reg;
- HARD_REG_SET live;
-{
- int regno, nregs;
-
- if (GET_CODE (reg) != REG)
- return;
-
- regno = REGNO (reg);
- if (regno < FIRST_PSEUDO_REGISTER)
- for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
- nregs--)
- CLEAR_HARD_REG_BIT (live, regno + nregs);
-}
-
-/* Record in LIVE that register REG became live.
- This is called via note_stores. */
-
-static void
-reg_becomes_live (reg, setter, live)
- rtx reg;
- rtx setter ATTRIBUTE_UNUSED;
- void *live;
-{
- int regno, nregs;
-
- if (GET_CODE (reg) == SUBREG)
- reg = SUBREG_REG (reg);
-
- if (GET_CODE (reg) != REG)
- return;
-
- regno = REGNO (reg);
- if (regno < FIRST_PSEUDO_REGISTER)
- for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
- nregs--)
- SET_HARD_REG_BIT (* (HARD_REG_SET *) live, regno + nregs);
-}
-
-/* Find all insns that need a particular mode setting, and insert the
- necessary mode switches. Return true if we did work. */
-
-int
-optimize_mode_switching (file)
- FILE *file;
-{
- rtx insn;
- int e;
- basic_block bb;
- int need_commit = 0;
- sbitmap *kill;
- struct edge_list *edge_list;
- static const int num_modes[] = NUM_MODES_FOR_MODE_SWITCHING;
-#define N_ENTITIES ARRAY_SIZE (num_modes)
- int entity_map[N_ENTITIES];
- struct bb_info *bb_info[N_ENTITIES];
- int i, j;
- int n_entities;
- int max_num_modes = 0;
- bool emited = false;
-
- clear_bb_flags ();
-#ifdef NORMAL_MODE
- /* Increment last_basic_block before allocating bb_info. */
- last_basic_block++;
-#endif
-
- for (e = N_ENTITIES - 1, n_entities = 0; e >= 0; e--)
- if (OPTIMIZE_MODE_SWITCHING (e))
- {
- /* Create the list of segments within each basic block. */
- bb_info[n_entities]
- = (struct bb_info *) xcalloc (last_basic_block, sizeof **bb_info);
- entity_map[n_entities++] = e;
- if (num_modes[e] > max_num_modes)
- max_num_modes = num_modes[e];
- }
-
-#ifdef NORMAL_MODE
- /* Decrement it back in case we return below. */
- last_basic_block--;
-#endif
-
- if (! n_entities)
- return 0;
-
-#ifdef NORMAL_MODE
- /* We're going to pretend the EXIT_BLOCK is a regular basic block,
- so that switching back to normal mode when entering the
- EXIT_BLOCK isn't optimized away. We do this by incrementing the
- basic block count, growing the VARRAY of basic_block_info and
- appending the EXIT_BLOCK_PTR to it. */
- last_basic_block++;
- if (VARRAY_SIZE (basic_block_info) < last_basic_block)
- VARRAY_GROW (basic_block_info, last_basic_block);
- BASIC_BLOCK (last_basic_block - 1) = EXIT_BLOCK_PTR;
- EXIT_BLOCK_PTR->sindex = last_basic_blocks;
-#endif
-
- /* Create the bitmap vectors. */
-
- antic = sbitmap_vector_alloc (last_basic_block, n_entities);
- transp = sbitmap_vector_alloc (last_basic_block, n_entities);
- comp = sbitmap_vector_alloc (last_basic_block, n_entities);
-
- sbitmap_vector_ones (transp, last_basic_block);
-
- for (j = n_entities - 1; j >= 0; j--)
- {
- int e = entity_map[j];
- int no_mode = num_modes[e];
- struct bb_info *info = bb_info[j];
-
- /* Determine what the first use (if any) need for a mode of entity E is.
- This will be the mode that is anticipatable for this block.
- Also compute the initial transparency settings. */
- FOR_ALL_BB (bb)
- {
- struct seginfo *ptr;
- int last_mode = no_mode;
- HARD_REG_SET live_now;
-
- REG_SET_TO_HARD_REG_SET (live_now,
- bb->global_live_at_start);
- for (insn = bb->head;
- insn != NULL && insn != NEXT_INSN (bb->end);
- insn = NEXT_INSN (insn))
- {
- if (INSN_P (insn))
- {
- int mode = MODE_NEEDED (e, insn);
- rtx link;
-
- if (mode != no_mode && mode != last_mode)
- {
- last_mode = mode;
- ptr = new_seginfo (mode, insn, bb->sindex, live_now);
- add_seginfo (info + bb->sindex, ptr);
- RESET_BIT (transp[bb->sindex], j);
- }
-
- /* Update LIVE_NOW. */
- for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
- if (REG_NOTE_KIND (link) == REG_DEAD)
- reg_dies (XEXP (link, 0), live_now);
-
- note_stores (PATTERN (insn), reg_becomes_live, &live_now);
- for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
- if (REG_NOTE_KIND (link) == REG_UNUSED)
- reg_dies (XEXP (link, 0), live_now);
- }
- }
-
- info[bb->sindex].computing = last_mode;
- /* Check for blocks without ANY mode requirements. */
- if (last_mode == no_mode)
- {
- ptr = new_seginfo (no_mode, insn, bb->sindex, live_now);
- add_seginfo (info + bb->sindex, ptr);
- }
- }
-#ifdef NORMAL_MODE
- {
- int mode = NORMAL_MODE (e);
-
- if (mode != no_mode)
- {
- edge eg;
-
- for (eg = ENTRY_BLOCK_PTR->succ; eg; eg = eg->succ_next)
- {
- bb = eg->dest;
-
- /* By always making this nontransparent, we save
- an extra check in make_preds_opaque. We also
- need this to avoid confusing pre_edge_lcm when
- antic is cleared but transp and comp are set. */
- RESET_BIT (transp[bb->sindex], j);
-
- /* If the block already has MODE, pretend it
- has none (because we don't need to set it),
- but retain whatever mode it computes. */
- if (info[bb->sindex].seginfo->mode == mode)
- info[bb->sindex].seginfo->mode = no_mode;
-
- /* Insert a fake computing definition of MODE into entry
- blocks which compute no mode. This represents the mode on
- entry. */
- else if (info[bb->sindex].computing == no_mode)
- {
- info[bb->sindex].computing = mode;
- info[bb->sindex].seginfo->mode = no_mode;
- }
- }
-
- bb = EXIT_BLOCK_PTR;
- info[bb->sindex].seginfo->mode = mode;
- }
- }
-#endif /* NORMAL_MODE */
- }
-
- kill = sbitmap_vector_alloc (last_basic_block, n_entities);
- for (i = 0; i < max_num_modes; i++)
- {
- int current_mode[N_ENTITIES];
-
- /* Set the anticipatable and computing arrays. */
- sbitmap_vector_zero (antic, last_basic_block);
- sbitmap_vector_zero (comp, last_basic_block);
- for (j = n_entities - 1; j >= 0; j--)
- {
- int m = current_mode[j] = MODE_PRIORITY_TO_MODE (entity_map[j], i);
- struct bb_info *info = bb_info[j];
-
- FOR_ALL_BB (bb)
- {
- if (info[bb->sindex].seginfo->mode == m)
- SET_BIT (antic[bb->sindex], j);
-
- if (info[bb->sindex].computing == m)
- SET_BIT (comp[bb->sindex], j);
- }
- }
-
- /* Calculate the optimal locations for the
- placement mode switches to modes with priority I. */
-
- FOR_ALL_BB_REVERSE (bb)
- sbitmap_not (kill[bb->sindex], transp[bb->sindex]);
- edge_list = pre_edge_lcm (file, 1, transp, comp, antic,
- kill, &insert, &delete);
-
- for (j = n_entities - 1; j >= 0; j--)
- {
- /* Insert all mode sets that have been inserted by lcm. */
- int no_mode = num_modes[entity_map[j]];
-
- /* Wherever we have moved a mode setting upwards in the flow graph,
- the blocks between the new setting site and the now redundant
- computation ceases to be transparent for any lower-priority
- mode of the same entity. First set the aux field of each
- insertion site edge non-transparent, then propagate the new
- non-transparency from the redundant computation upwards till
- we hit an insertion site or an already non-transparent block. */
- for (e = NUM_EDGES (edge_list) - 1; e >= 0; e--)
- {
- edge eg = INDEX_EDGE (edge_list, e);
- int mode;
- basic_block src_bb;
- HARD_REG_SET live_at_edge;
- rtx mode_set;
-
- eg->aux = 0;
-
- if (! TEST_BIT (insert[e], j))
- continue;
-
- eg->aux = (void *)1;
-
- mode = current_mode[j];
- src_bb = eg->src;
-
- REG_SET_TO_HARD_REG_SET (live_at_edge,
- src_bb->global_live_at_end);
-
- start_sequence ();
- EMIT_MODE_SET (entity_map[j], mode, live_at_edge);
- mode_set = gen_sequence ();
- end_sequence ();
-
- /* Do not bother to insert empty sequence. */
- if (GET_CODE (mode_set) == SEQUENCE
- && !XVECLEN (mode_set, 0))
- continue;
-
- /* If this is an abnormal edge, we'll insert at the end
- of the previous block. */
- if (eg->flags & EDGE_ABNORMAL)
- {
- emited = true;
- if (GET_CODE (src_bb->end) == JUMP_INSN)
- emit_insn_before (mode_set, src_bb->end);
- /* It doesn't make sense to switch to normal mode
- after a CALL_INSN, so we're going to abort if we
- find one. The cases in which a CALL_INSN may
- have an abnormal edge are sibcalls and EH edges.
- In the case of sibcalls, the dest basic-block is
- the EXIT_BLOCK, that runs in normal mode; it is
- assumed that a sibcall insn requires normal mode
- itself, so no mode switch would be required after
- the call (it wouldn't make sense, anyway). In
- the case of EH edges, EH entry points also start
- in normal mode, so a similar reasoning applies. */
- else if (GET_CODE (src_bb->end) == INSN)
- emit_insn_after (mode_set, src_bb->end);
- else
- abort ();
- bb_info[j][src_bb->sindex].computing = mode;
- RESET_BIT (transp[src_bb->sindex], j);
- }
- else
- {
- need_commit = 1;
- insert_insn_on_edge (mode_set, eg);
- }
- }
-
- FOR_ALL_BB_REVERSE (bb)
- if (TEST_BIT (delete[bb->sindex], j))
- {
- make_preds_opaque (bb, j);
- /* Cancel the 'deleted' mode set. */
- bb_info[j][bb->sindex].seginfo->mode = no_mode;
- }
- }
-
- clear_aux_for_edges ();
- free_edge_list (edge_list);
- }
-
-#ifdef NORMAL_MODE
- /* Restore the special status of EXIT_BLOCK. */
- last_basic_block--;
- VARRAY_POP (basic_block_info);
- EXIT_BLOCK_PTR->sindex = EXIT_BLOCK;
-#endif
-
- /* Now output the remaining mode sets in all the segments. */
- for (j = n_entities - 1; j >= 0; j--)
- {
- int no_mode = num_modes[entity_map[j]];
-
-#ifdef NORMAL_MODE
- if (bb_info[j][last_basic_block].seginfo->mode != no_mode)
- {
- edge eg;
- struct seginfo *ptr = bb_info[j][last_basic_block].seginfo;
-
- for (eg = EXIT_BLOCK_PTR->pred; eg; eg = eg->pred_next)
- {
- rtx mode_set;
-
- if (bb_info[j][eg->src->sindex].computing == ptr->mode)
- continue;
-
- start_sequence ();
- EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
- mode_set = gen_sequence ();
- end_sequence ();
-
- /* Do not bother to insert empty sequence. */
- if (GET_CODE (mode_set) == SEQUENCE
- && !XVECLEN (mode_set, 0))
- continue;
-
- /* If this is an abnormal edge, we'll insert at the end of the
- previous block. */
- if (eg->flags & EDGE_ABNORMAL)
- {
- emited = true;
- if (GET_CODE (eg->src->end) == JUMP_INSN)
- emit_insn_before (mode_set, eg->src->end);
- else if (GET_CODE (eg->src->end) == INSN)
- emit_insn_after (mode_set, eg->src->end);
- else
- abort ();
- }
- else
- {
- need_commit = 1;
- insert_insn_on_edge (mode_set, eg);
- }
- }
-
- }
-#endif
-
- FOR_ALL_BB_REVERSE (bb)
- {
- struct seginfo *ptr, *next;
- for (ptr = bb_info[j][bb->sindex].seginfo; ptr; ptr = next)
- {
- next = ptr->next;
- if (ptr->mode != no_mode)
- {
- rtx mode_set;
-
- start_sequence ();
- EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
- mode_set = gen_sequence ();
- end_sequence ();
-
- /* Do not bother to insert empty sequence. */
- if (GET_CODE (mode_set) == SEQUENCE
- && !XVECLEN (mode_set, 0))
- continue;
-
- emited = true;
- if (GET_CODE (ptr->insn_ptr) == NOTE
- && (NOTE_LINE_NUMBER (ptr->insn_ptr)
- == NOTE_INSN_BASIC_BLOCK))
- emit_insn_after (mode_set, ptr->insn_ptr);
- else
- emit_insn_before (mode_set, ptr->insn_ptr);
- }
-
- free (ptr);
- }
- }
-
- free (bb_info[j]);
- }
-
- /* Finished. Free up all the things we've allocated. */
-
- sbitmap_vector_free (kill);
- sbitmap_vector_free (antic);
- sbitmap_vector_free (transp);
- sbitmap_vector_free (comp);
- sbitmap_vector_free (delete);
- sbitmap_vector_free (insert);
-
- if (need_commit)
- commit_edge_insertions ();
-
- if (!need_commit && !emited)
- return 0;
-
- max_regno = max_reg_num ();
- allocate_reg_info (max_regno, FALSE, FALSE);
- update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
- (PROP_DEATH_NOTES | PROP_KILL_DEAD_CODE
- | PROP_SCAN_DEAD_CODE));
-
- return 1;
-}
-#endif /* OPTIMIZE_MODE_SWITCHING */