/* Loop manipulation code for GNU compiler.
- Copyright (C) 2002, 2003, 2004, 2005, 2007, 2008 Free Software
- Foundation, Inc.
+ Copyright (C) 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
+ Free Software Foundation, Inc.
This file is part of GCC.
#include "cfglayout.h"
#include "cfghooks.h"
#include "output.h"
+#include "tree-flow.h"
-static void duplicate_subloops (struct loop *, struct loop *);
static void copy_loops_to (struct loop **, int,
struct loop *);
static void loop_redirect_edge (edge, basic_block);
struct loop *father = current_loops->tree_root, *act;
bool ret = false;
- for (i = 0; VEC_iterate (edge, exits, i, e); i++)
+ FOR_EACH_VEC_ELT (edge, exits, i, e)
{
act = find_common_loop (loop, e->dest->loop_father);
if (flow_loop_nested_p (father, act))
/* The exit edges of LOOP no longer exits its original immediate
superloops; remove them from the appropriate exit lists. */
- for (i = 0; VEC_iterate (edge, exits, i, e); i++)
+ FOR_EACH_VEC_ELT (edge, exits, i, e)
rescan_loop_exit (e, false, false);
ret = true;
placement of subloops of FROM->loop_father, that might also be altered due
to this change; the condition for them is similar, except that instead of
successors we consider edges coming out of the loops.
-
+
If the changes may invalidate the information about irreducible regions,
IRRED_INVALIDATED is set to true. */
{
sbitmap in_queue;
basic_block *queue, *qtop, *qbeg, *qend;
- struct loop *base_loop;
+ struct loop *base_loop, *target_loop;
edge e;
/* We pass through blocks back-reachable from FROM, testing whether some
fix_loop_placement. */
base_loop = from->loop_father;
- if (base_loop == current_loops->tree_root)
+ /* If we are already in the outermost loop, the basic blocks cannot be moved
+ outside of it. If FROM is the header of the base loop, it cannot be moved
+ outside of it, either. In both cases, we can end now. */
+ if (base_loop == current_loops->tree_root
+ || from == base_loop->header)
return;
in_queue = sbitmap_alloc (last_basic_block);
/* Subloop header, maybe move the loop upward. */
if (!fix_loop_placement (from->loop_father))
continue;
+ target_loop = loop_outer (from->loop_father);
}
else
{
/* Ordinary basic block. */
if (!fix_bb_placement (from))
continue;
+ target_loop = from->loop_father;
}
FOR_EACH_EDGE (e, ei, from->succs)
&& (nca == base_loop
|| nca != pred->loop_father))
pred = pred->loop_father->header;
- else if (!flow_loop_nested_p (from->loop_father, pred->loop_father))
+ else if (!flow_loop_nested_p (target_loop, pred->loop_father))
{
- /* No point in processing it. */
+ /* If PRED is already higher in the loop hierarchy than the
+ TARGET_LOOP to that we moved FROM, the change of the position
+ of FROM does not affect the position of PRED, so there is no
+ point in processing it. */
continue;
}
edge ae;
basic_block *rem_bbs, *bord_bbs, from, bb;
VEC (basic_block, heap) *dom_bbs;
- int i, nrem, n_bord_bbs, nreml;
+ int i, nrem, n_bord_bbs;
sbitmap seen;
bool irred_invalidated = false;
- struct loop **deleted_loop;
+ edge_iterator ei;
+ struct loop *l, *f;
if (!can_remove_branch_p (e))
return false;
we belong to. In this case first unloop the loops, then proceed
normally. We may assume that e->dest is not a header of any loop,
as it now has exactly one predecessor. */
- while (loop_outer (e->src->loop_father)
- && dominated_by_p (CDI_DOMINATORS,
- e->src->loop_father->latch, e->dest))
- unloop (e->src->loop_father, &irred_invalidated);
+ for (l = e->src->loop_father; loop_outer (l); l = f)
+ {
+ f = loop_outer (l);
+ if (dominated_by_p (CDI_DOMINATORS, l->latch, e->dest))
+ unloop (l, &irred_invalidated);
+ }
/* Identify the path. */
nrem = find_path (e, &rem_bbs);
/* Find "border" hexes -- i.e. those with predecessor in removed path. */
for (i = 0; i < nrem; i++)
SET_BIT (seen, rem_bbs[i]->index);
+ if (!irred_invalidated)
+ FOR_EACH_EDGE (ae, ei, e->src->succs)
+ if (ae != e && ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index)
+ && ae->flags & EDGE_IRREDUCIBLE_LOOP)
+ irred_invalidated = true;
for (i = 0; i < nrem; i++)
{
- edge_iterator ei;
bb = rem_bbs[i];
FOR_EACH_EDGE (ae, ei, rem_bbs[i]->succs)
if (ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index))
{
SET_BIT (seen, ae->dest->index);
bord_bbs[n_bord_bbs++] = ae->dest;
-
+
if (ae->flags & EDGE_IRREDUCIBLE_LOOP)
irred_invalidated = true;
}
dom_bbs = NULL;
/* Cancel loops contained in the path. */
- deleted_loop = XNEWVEC (struct loop *, nrem);
- nreml = 0;
for (i = 0; i < nrem; i++)
if (rem_bbs[i]->loop_father->header == rem_bbs[i])
- deleted_loop[nreml++] = rem_bbs[i]->loop_father;
+ cancel_loop_tree (rem_bbs[i]->loop_father);
remove_bbs (rem_bbs, nrem);
free (rem_bbs);
- for (i = 0; i < nreml; i++)
- cancel_loop_tree (deleted_loop[i]);
- free (deleted_loop);
-
/* Find blocks whose dominators may be affected. */
sbitmap_zero (seen);
for (i = 0; i < n_bord_bbs; i++)
free (bbs);
}
+/* Recompute dominance information for basic blocks outside LOOP. */
+
+static void
+update_dominators_in_loop (struct loop *loop)
+{
+ VEC (basic_block, heap) *dom_bbs = NULL;
+ sbitmap seen;
+ basic_block *body;
+ unsigned i;
+
+ seen = sbitmap_alloc (last_basic_block);
+ sbitmap_zero (seen);
+ body = get_loop_body (loop);
+
+ for (i = 0; i < loop->num_nodes; i++)
+ SET_BIT (seen, body[i]->index);
+
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ basic_block ldom;
+
+ for (ldom = first_dom_son (CDI_DOMINATORS, body[i]);
+ ldom;
+ ldom = next_dom_son (CDI_DOMINATORS, ldom))
+ if (!TEST_BIT (seen, ldom->index))
+ {
+ SET_BIT (seen, ldom->index);
+ VEC_safe_push (basic_block, heap, dom_bbs, ldom);
+ }
+ }
+
+ iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false);
+ free (body);
+ free (seen);
+ VEC_free (basic_block, heap, dom_bbs);
+}
+
+/* Creates an if region as shown above. CONDITION is used to create
+ the test for the if.
+
+ |
+ | ------------- -------------
+ | | pred_bb | | pred_bb |
+ | ------------- -------------
+ | | |
+ | | | ENTRY_EDGE
+ | | ENTRY_EDGE V
+ | | ====> -------------
+ | | | cond_bb |
+ | | | CONDITION |
+ | | -------------
+ | V / \
+ | ------------- e_false / \ e_true
+ | | succ_bb | V V
+ | ------------- ----------- -----------
+ | | false_bb | | true_bb |
+ | ----------- -----------
+ | \ /
+ | \ /
+ | V V
+ | -------------
+ | | join_bb |
+ | -------------
+ | | exit_edge (result)
+ | V
+ | -----------
+ | | succ_bb |
+ | -----------
+ |
+ */
+
+edge
+create_empty_if_region_on_edge (edge entry_edge, tree condition)
+{
+
+ basic_block cond_bb, true_bb, false_bb, join_bb;
+ edge e_true, e_false, exit_edge;
+ gimple cond_stmt;
+ tree simple_cond;
+ gimple_stmt_iterator gsi;
+
+ cond_bb = split_edge (entry_edge);
+
+ /* Insert condition in cond_bb. */
+ gsi = gsi_last_bb (cond_bb);
+ simple_cond =
+ force_gimple_operand_gsi (&gsi, condition, true, NULL,
+ false, GSI_NEW_STMT);
+ cond_stmt = gimple_build_cond_from_tree (simple_cond, NULL_TREE, NULL_TREE);
+ gsi = gsi_last_bb (cond_bb);
+ gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
+
+ join_bb = split_edge (single_succ_edge (cond_bb));
+
+ e_true = single_succ_edge (cond_bb);
+ true_bb = split_edge (e_true);
+
+ e_false = make_edge (cond_bb, join_bb, 0);
+ false_bb = split_edge (e_false);
+
+ e_true->flags &= ~EDGE_FALLTHRU;
+ e_true->flags |= EDGE_TRUE_VALUE;
+ e_false->flags &= ~EDGE_FALLTHRU;
+ e_false->flags |= EDGE_FALSE_VALUE;
+
+ set_immediate_dominator (CDI_DOMINATORS, cond_bb, entry_edge->src);
+ set_immediate_dominator (CDI_DOMINATORS, true_bb, cond_bb);
+ set_immediate_dominator (CDI_DOMINATORS, false_bb, cond_bb);
+ set_immediate_dominator (CDI_DOMINATORS, join_bb, cond_bb);
+
+ exit_edge = single_succ_edge (join_bb);
+
+ if (single_pred_p (exit_edge->dest))
+ set_immediate_dominator (CDI_DOMINATORS, exit_edge->dest, join_bb);
+
+ return exit_edge;
+}
+
+/* create_empty_loop_on_edge
+ |
+ | - pred_bb - ------ pred_bb ------
+ | | | | iv0 = initial_value |
+ | -----|----- ---------|-----------
+ | | ______ | entry_edge
+ | | entry_edge / | |
+ | | ====> | -V---V- loop_header -------------
+ | V | | iv_before = phi (iv0, iv_after) |
+ | - succ_bb - | ---|-----------------------------
+ | | | | |
+ | ----------- | ---V--- loop_body ---------------
+ | | | iv_after = iv_before + stride |
+ | | | if (iv_before < upper_bound) |
+ | | ---|--------------\--------------
+ | | | \ exit_e
+ | | V \
+ | | - loop_latch - V- succ_bb -
+ | | | | | |
+ | | /------------- -----------
+ | \ ___ /
+
+ Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME
+ that is used before the increment of IV. IV_BEFORE should be used for
+ adding code to the body that uses the IV. OUTER is the outer loop in
+ which the new loop should be inserted.
+
+ Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and
+ inserted on the loop entry edge. This implies that this function
+ should be used only when the UPPER_BOUND expression is a loop
+ invariant. */
+
+struct loop *
+create_empty_loop_on_edge (edge entry_edge,
+ tree initial_value,
+ tree stride, tree upper_bound,
+ tree iv,
+ tree *iv_before,
+ tree *iv_after,
+ struct loop *outer)
+{
+ basic_block loop_header, loop_latch, succ_bb, pred_bb;
+ struct loop *loop;
+ gimple_stmt_iterator gsi;
+ gimple_seq stmts;
+ gimple cond_expr;
+ tree exit_test;
+ edge exit_e;
+ int prob;
+
+ gcc_assert (entry_edge && initial_value && stride && upper_bound && iv);
+
+ /* Create header, latch and wire up the loop. */
+ pred_bb = entry_edge->src;
+ loop_header = split_edge (entry_edge);
+ loop_latch = split_edge (single_succ_edge (loop_header));
+ succ_bb = single_succ (loop_latch);
+ make_edge (loop_header, succ_bb, 0);
+ redirect_edge_succ_nodup (single_succ_edge (loop_latch), loop_header);
+
+ /* Set immediate dominator information. */
+ set_immediate_dominator (CDI_DOMINATORS, loop_header, pred_bb);
+ set_immediate_dominator (CDI_DOMINATORS, loop_latch, loop_header);
+ set_immediate_dominator (CDI_DOMINATORS, succ_bb, loop_header);
+
+ /* Initialize a loop structure and put it in a loop hierarchy. */
+ loop = alloc_loop ();
+ loop->header = loop_header;
+ loop->latch = loop_latch;
+ add_loop (loop, outer);
+
+ /* TODO: Fix frequencies and counts. */
+ prob = REG_BR_PROB_BASE / 2;
+
+ scale_loop_frequencies (loop, REG_BR_PROB_BASE - prob, REG_BR_PROB_BASE);
+
+ /* Update dominators. */
+ update_dominators_in_loop (loop);
+
+ /* Modify edge flags. */
+ exit_e = single_exit (loop);
+ exit_e->flags = EDGE_LOOP_EXIT | EDGE_FALSE_VALUE;
+ single_pred_edge (loop_latch)->flags = EDGE_TRUE_VALUE;
+
+ /* Construct IV code in loop. */
+ initial_value = force_gimple_operand (initial_value, &stmts, true, iv);
+ if (stmts)
+ {
+ gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
+ gsi_commit_edge_inserts ();
+ }
+
+ upper_bound = force_gimple_operand (upper_bound, &stmts, true, NULL);
+ if (stmts)
+ {
+ gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
+ gsi_commit_edge_inserts ();
+ }
+
+ gsi = gsi_last_bb (loop_header);
+ create_iv (initial_value, stride, iv, loop, &gsi, false,
+ iv_before, iv_after);
+
+ /* Insert loop exit condition. */
+ cond_expr = gimple_build_cond
+ (LT_EXPR, *iv_before, upper_bound, NULL_TREE, NULL_TREE);
+
+ exit_test = gimple_cond_lhs (cond_expr);
+ exit_test = force_gimple_operand_gsi (&gsi, exit_test, true, NULL,
+ false, GSI_NEW_STMT);
+ gimple_cond_set_lhs (cond_expr, exit_test);
+ gsi = gsi_last_bb (exit_e->src);
+ gsi_insert_after (&gsi, cond_expr, GSI_NEW_STMT);
+
+ split_block_after_labels (loop_header);
+
+ return loop;
+}
+
/* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
latch to header and update loop tree and dominators
accordingly. Everything between them plus LATCH_EDGE destination must
{
basic_block succ_bb = latch_edge->dest;
basic_block pred_bb = header_edge->src;
- basic_block *body;
- VEC (basic_block, heap) *dom_bbs;
- unsigned i;
- sbitmap seen;
struct loop *loop = alloc_loop ();
struct loop *outer = loop_outer (succ_bb->loop_father);
int freq;
}
scale_loop_frequencies (loop, false_scale, REG_BR_PROB_BASE);
scale_loop_frequencies (succ_bb->loop_father, true_scale, REG_BR_PROB_BASE);
-
- /* Update dominators of blocks outside of LOOP. */
- dom_bbs = NULL;
- seen = sbitmap_alloc (last_basic_block);
- sbitmap_zero (seen);
- body = get_loop_body (loop);
-
- for (i = 0; i < loop->num_nodes; i++)
- SET_BIT (seen, body[i]->index);
-
- for (i = 0; i < loop->num_nodes; i++)
- {
- basic_block ldom;
-
- for (ldom = first_dom_son (CDI_DOMINATORS, body[i]);
- ldom;
- ldom = next_dom_son (CDI_DOMINATORS, ldom))
- if (!TEST_BIT (seen, ldom->index))
- {
- SET_BIT (seen, ldom->index);
- VEC_safe_push (basic_block, heap, dom_bbs, ldom);
- }
- }
-
- iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false);
-
- free (body);
- free (seen);
- VEC_free (basic_block, heap, dom_bbs);
+ update_dominators_in_loop (loop);
return loop;
}
condition stated in description of fix_loop_placement holds for them.
It is used in case when we removed some edges coming out of LOOP, which
may cause the right placement of LOOP inside loop tree to change.
-
+
IRRED_INVALIDATED is set to true if a change in the loop structures might
invalidate the information about irreducible regions. */
/* Copies structure of subloops of LOOP into TARGET loop, placing
newly created loops into loop tree. */
-static void
+void
duplicate_subloops (struct loop *loop, struct loop *target)
{
struct loop *aloop, *cloop;
bb->aux = 0;
dom_bbs = get_dominated_by (CDI_DOMINATORS, bb);
- for (j = 0; VEC_iterate (basic_block, dom_bbs, j, dominated); j++)
+ FOR_EACH_VEC_ELT (basic_block, dom_bbs, j, dominated)
{
if (flow_bb_inside_loop_p (loop, dominated))
continue;
return e != mfb_kj_edge;
}
+/* True when a candidate preheader BLOCK has predecessors from LOOP. */
+
+static bool
+has_preds_from_loop (basic_block block, struct loop *loop)
+{
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, block->preds)
+ if (e->src->loop_father == loop)
+ return true;
+ return false;
+}
+
/* Creates a pre-header for a LOOP. Returns newly created block. Unless
CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
entry; otherwise we also force preheader block to have only one successor.
+ When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block
+ to be a fallthru predecessor to the loop header and to have only
+ predecessors from outside of the loop.
The function also updates dominators. */
basic_block
gcc_assert (nentry);
if (nentry == 1)
{
- if (/* We do not allow entry block to be the loop preheader, since we
+ bool need_forwarder_block = false;
+
+ /* We do not allow entry block to be the loop preheader, since we
cannot emit code there. */
- single_entry->src != ENTRY_BLOCK_PTR
- /* If we want simple preheaders, also force the preheader to have
- just a single successor. */
- && !((flags & CP_SIMPLE_PREHEADERS)
- && !single_succ_p (single_entry->src)))
+ if (single_entry->src == ENTRY_BLOCK_PTR)
+ need_forwarder_block = true;
+ else
+ {
+ /* If we want simple preheaders, also force the preheader to have
+ just a single successor. */
+ if ((flags & CP_SIMPLE_PREHEADERS)
+ && !single_succ_p (single_entry->src))
+ need_forwarder_block = true;
+ /* If we want fallthru preheaders, also create forwarder block when
+ preheader ends with a jump or has predecessors from loop. */
+ else if ((flags & CP_FALLTHRU_PREHEADERS)
+ && (JUMP_P (BB_END (single_entry->src))
+ || has_preds_from_loop (single_entry->src, loop)))
+ need_forwarder_block = true;
+ }
+ if (! need_forwarder_block)
return NULL;
}
fprintf (dump_file, "Created preheader block for loop %i\n",
loop->num);
+ if (flags & CP_FALLTHRU_PREHEADERS)
+ gcc_assert ((single_succ_edge (dummy)->flags & EDGE_FALLTHRU)
+ && !JUMP_P (BB_END (dummy)));
+
return dummy;
}
is the ratio by that the frequencies in the original loop should
be scaled. ELSE_SCALE is the ratio by that the frequencies in the
new loop should be scaled.
-
+
If PLACE_AFTER is true, we place the new loop after LOOP in the
instruction stream, otherwise it is placed before LOOP. */
/* Duplicate loop. */
if (!cfg_hook_duplicate_loop_to_header_edge (loop, entry, 1,
NULL, NULL, NULL, 0))
- return NULL;
+ {
+ entry->flags |= irred_flag;
+ return NULL;
+ }
/* After duplication entry edge now points to new loop head block.
Note down new head as second_head. */
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