/* Control flow graph analysis code for GNU compiler.
- Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
- 1999, 2000, 2001, 2003, 2004, 2005 Free Software Foundation, Inc.
+ Copyright (C) 1987-2019 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
+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
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. */
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
/* This file contains various simple utilities to analyze the CFG. */
+
#include "config.h"
#include "system.h"
#include "coretypes.h"
-#include "tm.h"
-#include "rtl.h"
-#include "obstack.h"
-#include "hard-reg-set.h"
-#include "basic-block.h"
-#include "insn-config.h"
-#include "recog.h"
-#include "toplev.h"
-#include "tm_p.h"
+#include "backend.h"
+#include "cfghooks.h"
#include "timevar.h"
+#include "cfganal.h"
+#include "cfgloop.h"
+namespace {
/* Store the data structures necessary for depth-first search. */
-struct depth_first_search_dsS {
- /* stack for backtracking during the algorithm */
- basic_block *stack;
+class depth_first_search
+ {
+public:
+ depth_first_search ();
- /* number of edges in the stack. That is, positions 0, ..., sp-1
- have edges. */
- unsigned int sp;
+ basic_block execute (basic_block);
+ void add_bb (basic_block);
+
+private:
+ /* stack for backtracking during the algorithm */
+ auto_vec<basic_block, 20> m_stack;
/* record of basic blocks already seen by depth-first search */
- sbitmap visited_blocks;
+ auto_sbitmap m_visited_blocks;
};
-typedef struct depth_first_search_dsS *depth_first_search_ds;
-
-static void flow_dfs_compute_reverse_init (depth_first_search_ds);
-static void flow_dfs_compute_reverse_add_bb (depth_first_search_ds,
- basic_block);
-static basic_block flow_dfs_compute_reverse_execute (depth_first_search_ds,
- basic_block);
-static void flow_dfs_compute_reverse_finish (depth_first_search_ds);
-static bool flow_active_insn_p (rtx);
-\f
-/* Like active_insn_p, except keep the return value clobber around
- even after reload. */
-
-static bool
-flow_active_insn_p (rtx insn)
-{
- if (active_insn_p (insn))
- return true;
-
- /* A clobber of the function return value exists for buggy
- programs that fail to return a value. Its effect is to
- keep the return value from being live across the entire
- function. If we allow it to be skipped, we introduce the
- possibility for register livetime aborts. */
- if (GET_CODE (PATTERN (insn)) == CLOBBER
- && REG_P (XEXP (PATTERN (insn), 0))
- && REG_FUNCTION_VALUE_P (XEXP (PATTERN (insn), 0)))
- return true;
-
- return false;
-}
-
-/* Return true if the block has no effect and only forwards control flow to
- its single destination. */
-
-bool
-forwarder_block_p (basic_block bb)
-{
- rtx insn;
-
- if (bb == EXIT_BLOCK_PTR || bb == ENTRY_BLOCK_PTR
- || !single_succ_p (bb))
- return false;
-
- for (insn = BB_HEAD (bb); insn != BB_END (bb); insn = NEXT_INSN (insn))
- if (INSN_P (insn) && flow_active_insn_p (insn))
- return false;
-
- return (!INSN_P (insn)
- || (JUMP_P (insn) && simplejump_p (insn))
- || !flow_active_insn_p (insn));
-}
-
-/* Return nonzero if we can reach target from src by falling through. */
-
-bool
-can_fallthru (basic_block src, basic_block target)
-{
- rtx insn = BB_END (src);
- rtx insn2;
- edge e;
- edge_iterator ei;
-
- if (target == EXIT_BLOCK_PTR)
- return true;
- if (src->next_bb != target)
- return 0;
- FOR_EACH_EDGE (e, ei, src->succs)
- if (e->dest == EXIT_BLOCK_PTR
- && e->flags & EDGE_FALLTHRU)
- return 0;
-
- insn2 = BB_HEAD (target);
- if (insn2 && !active_insn_p (insn2))
- insn2 = next_active_insn (insn2);
-
- /* ??? Later we may add code to move jump tables offline. */
- return next_active_insn (insn) == insn2;
-}
-
-/* Return nonzero if we could reach target from src by falling through,
- if the target was made adjacent. If we already have a fall-through
- edge to the exit block, we can't do that. */
-bool
-could_fall_through (basic_block src, basic_block target)
-{
- edge e;
- edge_iterator ei;
-
- if (target == EXIT_BLOCK_PTR)
- return true;
- FOR_EACH_EDGE (e, ei, src->succs)
- if (e->dest == EXIT_BLOCK_PTR
- && e->flags & EDGE_FALLTHRU)
- return 0;
- return true;
}
\f
/* Mark the back edges in DFS traversal.
Steven Muchnick
Morgan Kaufmann, 1997
- and heavily borrowed from flow_depth_first_order_compute. */
+ and heavily borrowed from pre_and_rev_post_order_compute. */
bool
mark_dfs_back_edges (void)
{
- edge_iterator *stack;
int *pre;
int *post;
- int sp;
int prenum = 1;
int postnum = 1;
- sbitmap visited;
bool found = false;
/* Allocate the preorder and postorder number arrays. */
- pre = xcalloc (last_basic_block, sizeof (int));
- post = xcalloc (last_basic_block, sizeof (int));
+ pre = XCNEWVEC (int, last_basic_block_for_fn (cfun));
+ post = XCNEWVEC (int, last_basic_block_for_fn (cfun));
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
- sp = 0;
+ auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1);
/* Allocate bitmap to track nodes that have been visited. */
- visited = sbitmap_alloc (last_basic_block);
+ auto_sbitmap visited (last_basic_block_for_fn (cfun));
/* None of the nodes in the CFG have been visited yet. */
- sbitmap_zero (visited);
+ bitmap_clear (visited);
/* Push the first edge on to the stack. */
- stack[sp++] = ei_start (ENTRY_BLOCK_PTR->succs);
+ stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs));
- while (sp)
+ while (!stack.is_empty ())
{
- edge_iterator ei;
basic_block src;
basic_block dest;
/* Look at the edge on the top of the stack. */
- ei = stack[sp - 1];
+ edge_iterator ei = stack.last ();
src = ei_edge (ei)->src;
dest = ei_edge (ei)->dest;
ei_edge (ei)->flags &= ~EDGE_DFS_BACK;
/* Check if the edge destination has been visited yet. */
- if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
+ if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun) && ! bitmap_bit_p (visited,
+ dest->index))
{
/* Mark that we have visited the destination. */
- SET_BIT (visited, dest->index);
+ bitmap_set_bit (visited, dest->index);
pre[dest->index] = prenum++;
if (EDGE_COUNT (dest->succs) > 0)
{
/* Since the DEST node has been visited for the first
time, check its successors. */
- stack[sp++] = ei_start (dest->succs);
+ stack.quick_push (ei_start (dest->succs));
}
else
post[dest->index] = postnum++;
}
else
{
- if (dest != EXIT_BLOCK_PTR && src != ENTRY_BLOCK_PTR
+ if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
+ && src != ENTRY_BLOCK_PTR_FOR_FN (cfun)
&& pre[src->index] >= pre[dest->index]
&& post[dest->index] == 0)
ei_edge (ei)->flags |= EDGE_DFS_BACK, found = true;
- if (ei_one_before_end_p (ei) && src != ENTRY_BLOCK_PTR)
+ if (ei_one_before_end_p (ei)
+ && src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
post[src->index] = postnum++;
if (!ei_one_before_end_p (ei))
- ei_next (&stack[sp - 1]);
+ ei_next (&stack.last ());
else
- sp--;
+ stack.pop ();
}
}
free (pre);
free (post);
- free (stack);
- sbitmap_free (visited);
return found;
}
-/* Set the flag EDGE_CAN_FALLTHRU for edges that can be fallthru. */
-
-void
-set_edge_can_fallthru_flag (void)
-{
- basic_block bb;
-
- FOR_EACH_BB (bb)
- {
- edge e;
- edge_iterator ei;
-
- FOR_EACH_EDGE (e, ei, bb->succs)
- {
- e->flags &= ~EDGE_CAN_FALLTHRU;
-
- /* The FALLTHRU edge is also CAN_FALLTHRU edge. */
- if (e->flags & EDGE_FALLTHRU)
- e->flags |= EDGE_CAN_FALLTHRU;
- }
-
- /* If the BB ends with an invertible condjump all (2) edges are
- CAN_FALLTHRU edges. */
- if (EDGE_COUNT (bb->succs) != 2)
- continue;
- if (!any_condjump_p (BB_END (bb)))
- continue;
- if (!invert_jump (BB_END (bb), JUMP_LABEL (BB_END (bb)), 0))
- continue;
- invert_jump (BB_END (bb), JUMP_LABEL (BB_END (bb)), 0);
- EDGE_SUCC (bb, 0)->flags |= EDGE_CAN_FALLTHRU;
- EDGE_SUCC (bb, 1)->flags |= EDGE_CAN_FALLTHRU;
- }
-}
-
/* Find unreachable blocks. An unreachable block will have 0 in
the reachable bit in block->flags. A nonzero value indicates the
block is reachable. */
edge_iterator ei;
basic_block *tos, *worklist, bb;
- tos = worklist = xmalloc (sizeof (basic_block) * n_basic_blocks);
+ tos = worklist = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
/* Clear all the reachability flags. */
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
bb->flags &= ~BB_REACHABLE;
/* Add our starting points to the worklist. Almost always there will
be only one. It isn't inconceivable that we might one day directly
support Fortran alternate entry points. */
- FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
+ FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs)
{
*tos++ = e->dest;
free (worklist);
}
+
+/* Verify that there are no unreachable blocks in the current function. */
+
+void
+verify_no_unreachable_blocks (void)
+{
+ find_unreachable_blocks ();
+
+ basic_block bb;
+ FOR_EACH_BB_FN (bb, cfun)
+ gcc_assert ((bb->flags & BB_REACHABLE) != 0);
+}
+
\f
/* Functions to access an edge list with a vector representation.
Enough data is kept such that given an index number, the
struct edge_list *elist;
edge e;
int num_edges;
- int block_count;
basic_block bb;
edge_iterator ei;
- block_count = n_basic_blocks + 2; /* Include the entry and exit blocks. */
-
- num_edges = 0;
-
/* Determine the number of edges in the flow graph by counting successor
edges on each basic block. */
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
+ num_edges = 0;
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
{
num_edges += EDGE_COUNT (bb->succs);
}
- elist = xmalloc (sizeof (struct edge_list));
- elist->num_blocks = block_count;
+ elist = XNEW (struct edge_list);
elist->num_edges = num_edges;
- elist->index_to_edge = xmalloc (sizeof (edge) * num_edges);
+ elist->index_to_edge = XNEWVEC (edge, num_edges);
num_edges = 0;
/* Follow successors of blocks, and register these edges. */
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
FOR_EACH_EDGE (e, ei, bb->succs)
elist->index_to_edge[num_edges++] = e;
/* This function provides debug output showing an edge list. */
-void
+DEBUG_FUNCTION void
print_edge_list (FILE *f, struct edge_list *elist)
{
int x;
fprintf (f, "Compressed edge list, %d BBs + entry & exit, and %d edges\n",
- elist->num_blocks - 2, elist->num_edges);
+ n_basic_blocks_for_fn (cfun), elist->num_edges);
for (x = 0; x < elist->num_edges; x++)
{
fprintf (f, " %-4d - edge(", x);
- if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR)
+ if (INDEX_EDGE_PRED_BB (elist, x) == ENTRY_BLOCK_PTR_FOR_FN (cfun))
fprintf (f, "entry,");
else
fprintf (f, "%d,", INDEX_EDGE_PRED_BB (elist, x)->index);
- if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR)
+ if (INDEX_EDGE_SUCC_BB (elist, x) == EXIT_BLOCK_PTR_FOR_FN (cfun))
fprintf (f, "exit)\n");
else
fprintf (f, "%d)\n", INDEX_EDGE_SUCC_BB (elist, x)->index);
verifying that all edges are present, and that there are no
extra edges. */
-void
+DEBUG_FUNCTION void
verify_edge_list (FILE *f, struct edge_list *elist)
{
int pred, succ, index;
basic_block bb, p, s;
edge_iterator ei;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
{
FOR_EACH_EDGE (e, ei, bb->succs)
{
}
/* We've verified that all the edges are in the list, now lets make sure
- there are no spurious edges in the list. */
+ there are no spurious edges in the list. This is an expensive check! */
- FOR_BB_BETWEEN (p, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
- FOR_BB_BETWEEN (s, ENTRY_BLOCK_PTR->next_bb, NULL, next_bb)
+ FOR_BB_BETWEEN (p, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
+ FOR_BB_BETWEEN (s, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb, NULL, next_bb)
{
int found_edge = 0;
}
}
+
+/* Functions to compute control dependences. */
+
+/* Indicate block BB is control dependent on an edge with index EDGE_INDEX. */
+void
+control_dependences::set_control_dependence_map_bit (basic_block bb,
+ int edge_index)
+{
+ if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ return;
+ gcc_assert (bb != EXIT_BLOCK_PTR_FOR_FN (cfun));
+ bitmap_set_bit (control_dependence_map[bb->index], edge_index);
+}
+
+/* Clear all control dependences for block BB. */
+void
+control_dependences::clear_control_dependence_bitmap (basic_block bb)
+{
+ bitmap_clear (control_dependence_map[bb->index]);
+}
+
+/* Find the immediate postdominator PDOM of the specified basic block BLOCK.
+ This function is necessary because some blocks have negative numbers. */
+
+static inline basic_block
+find_pdom (basic_block block)
+{
+ gcc_assert (block != ENTRY_BLOCK_PTR_FOR_FN (cfun));
+
+ if (block == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ return EXIT_BLOCK_PTR_FOR_FN (cfun);
+ else
+ {
+ basic_block bb = get_immediate_dominator (CDI_POST_DOMINATORS, block);
+ if (! bb)
+ return EXIT_BLOCK_PTR_FOR_FN (cfun);
+ return bb;
+ }
+}
+
+/* Determine all blocks' control dependences on the given edge with edge_list
+ EL index EDGE_INDEX, ala Morgan, Section 3.6. */
+
+void
+control_dependences::find_control_dependence (int edge_index)
+{
+ basic_block current_block;
+ basic_block ending_block;
+
+ gcc_assert (get_edge_src (edge_index) != EXIT_BLOCK_PTR_FOR_FN (cfun));
+
+ /* For abnormal edges, we don't make current_block control
+ dependent because instructions that throw are always necessary
+ anyway. */
+ edge e = find_edge (get_edge_src (edge_index), get_edge_dest (edge_index));
+ if (e->flags & EDGE_ABNORMAL)
+ return;
+
+ if (get_edge_src (edge_index) == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ ending_block = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ else
+ ending_block = find_pdom (get_edge_src (edge_index));
+
+ for (current_block = get_edge_dest (edge_index);
+ current_block != ending_block
+ && current_block != EXIT_BLOCK_PTR_FOR_FN (cfun);
+ current_block = find_pdom (current_block))
+ set_control_dependence_map_bit (current_block, edge_index);
+}
+
+/* Record all blocks' control dependences on all edges in the edge
+ list EL, ala Morgan, Section 3.6. */
+
+control_dependences::control_dependences ()
+{
+ timevar_push (TV_CONTROL_DEPENDENCES);
+
+ /* Initialize the edge list. */
+ int num_edges = 0;
+ basic_block bb;
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
+ num_edges += EDGE_COUNT (bb->succs);
+ m_el.create (num_edges);
+ edge e;
+ edge_iterator ei;
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ m_el.quick_push (std::make_pair (e->src->index, e->dest->index));
+
+ control_dependence_map.create (last_basic_block_for_fn (cfun));
+ for (int i = 0; i < last_basic_block_for_fn (cfun); ++i)
+ control_dependence_map.quick_push (BITMAP_ALLOC (NULL));
+ for (int i = 0; i < num_edges; ++i)
+ find_control_dependence (i);
+
+ timevar_pop (TV_CONTROL_DEPENDENCES);
+}
+
+/* Free control dependences and the associated edge list. */
+
+control_dependences::~control_dependences ()
+{
+ for (unsigned i = 0; i < control_dependence_map.length (); ++i)
+ BITMAP_FREE (control_dependence_map[i]);
+ control_dependence_map.release ();
+ m_el.release ();
+}
+
+/* Returns the bitmap of edges the basic-block I is dependent on. */
+
+bitmap
+control_dependences::get_edges_dependent_on (int i)
+{
+ return control_dependence_map[i];
+}
+
+/* Returns the edge source with index I from the edge list. */
+
+basic_block
+control_dependences::get_edge_src (int i)
+{
+ return BASIC_BLOCK_FOR_FN (cfun, m_el[i].first);
+}
+
+/* Returns the edge destination with index I from the edge list. */
+
+basic_block
+control_dependences::get_edge_dest (int i)
+{
+ return BASIC_BLOCK_FOR_FN (cfun, m_el[i].second);
+}
+
+
/* Given PRED and SUCC blocks, return the edge which connects the blocks.
If no such edge exists, return NULL. */
return (EDGE_INDEX_NO_EDGE);
}
-
-/* Dump the list of basic blocks in the bitmap NODES. */
-
-void
-flow_nodes_print (const char *str, const sbitmap nodes, FILE *file)
-{
- int node;
-
- if (! nodes)
- return;
-
- fprintf (file, "%s { ", str);
- EXECUTE_IF_SET_IN_SBITMAP (nodes, 0, node, {fprintf (file, "%d ", node);});
- fputs ("}\n", file);
-}
-
-/* Dump the list of edges in the array EDGE_LIST. */
-
-void
-flow_edge_list_print (const char *str, const edge *edge_list, int num_edges, FILE *file)
-{
- int i;
-
- if (! edge_list)
- return;
-
- fprintf (file, "%s { ", str);
- for (i = 0; i < num_edges; i++)
- fprintf (file, "%d->%d ", edge_list[i]->src->index,
- edge_list[i]->dest->index);
-
- fputs ("}\n", file);
-}
-
\f
/* This routine will remove any fake predecessor edges for a basic block.
When the edge is removed, it is also removed from whatever successor
{
basic_block bb;
- FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb, NULL, next_bb)
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb, NULL, next_bb)
remove_fake_predecessors (bb);
}
void
remove_fake_exit_edges (void)
{
- remove_fake_predecessors (EXIT_BLOCK_PTR);
+ remove_fake_predecessors (EXIT_BLOCK_PTR_FOR_FN (cfun));
}
{
basic_block bb;
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
if (EDGE_COUNT (bb->succs) == 0)
- make_single_succ_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
+ make_single_succ_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun), EDGE_FAKE);
}
/* This function adds a fake edge between any infinite loops to the
void
connect_infinite_loops_to_exit (void)
{
- basic_block unvisited_block = EXIT_BLOCK_PTR;
- struct depth_first_search_dsS dfs_ds;
-
/* Perform depth-first search in the reverse graph to find nodes
reachable from the exit block. */
- flow_dfs_compute_reverse_init (&dfs_ds);
- flow_dfs_compute_reverse_add_bb (&dfs_ds, EXIT_BLOCK_PTR);
+ depth_first_search dfs;
+ dfs.add_bb (EXIT_BLOCK_PTR_FOR_FN (cfun));
/* Repeatedly add fake edges, updating the unreachable nodes. */
+ basic_block unvisited_block = EXIT_BLOCK_PTR_FOR_FN (cfun);
while (1)
{
- unvisited_block = flow_dfs_compute_reverse_execute (&dfs_ds,
- unvisited_block);
+ unvisited_block = dfs.execute (unvisited_block);
if (!unvisited_block)
break;
- make_edge (unvisited_block, EXIT_BLOCK_PTR, EDGE_FAKE);
- flow_dfs_compute_reverse_add_bb (&dfs_ds, unvisited_block);
+ basic_block deadend_block = dfs_find_deadend (unvisited_block);
+ edge e = make_edge (deadend_block, EXIT_BLOCK_PTR_FOR_FN (cfun),
+ EDGE_FAKE);
+ e->probability = profile_probability::never ();
+ dfs.add_bb (deadend_block);
}
-
- flow_dfs_compute_reverse_finish (&dfs_ds);
- return;
}
\f
-/* Compute reverse top sort order. */
+/* Compute reverse top sort order. This is computing a post order
+ numbering of the graph. If INCLUDE_ENTRY_EXIT is true, then
+ ENTRY_BLOCK and EXIT_BLOCK are included. If DELETE_UNREACHABLE is
+ true, unreachable blocks are deleted. */
-void
-flow_reverse_top_sort_order_compute (int *rts_order)
+int
+post_order_compute (int *post_order, bool include_entry_exit,
+ bool delete_unreachable)
{
- edge_iterator *stack;
- int sp;
- int postnum = 0;
- sbitmap visited;
+ int post_order_num = 0;
+ int count;
+
+ if (include_entry_exit)
+ post_order[post_order_num++] = EXIT_BLOCK;
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
- sp = 0;
+ auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1);
/* Allocate bitmap to track nodes that have been visited. */
- visited = sbitmap_alloc (last_basic_block);
+ auto_sbitmap visited (last_basic_block_for_fn (cfun));
/* None of the nodes in the CFG have been visited yet. */
- sbitmap_zero (visited);
+ bitmap_clear (visited);
/* Push the first edge on to the stack. */
- stack[sp++] = ei_start (ENTRY_BLOCK_PTR->succs);
+ stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (cfun)->succs));
- while (sp)
+ while (!stack.is_empty ())
{
- edge_iterator ei;
basic_block src;
basic_block dest;
/* Look at the edge on the top of the stack. */
- ei = stack[sp - 1];
+ edge_iterator ei = stack.last ();
src = ei_edge (ei)->src;
dest = ei_edge (ei)->dest;
/* Check if the edge destination has been visited yet. */
- if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
+ if (dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
+ && ! bitmap_bit_p (visited, dest->index))
{
/* Mark that we have visited the destination. */
- SET_BIT (visited, dest->index);
+ bitmap_set_bit (visited, dest->index);
if (EDGE_COUNT (dest->succs) > 0)
/* Since the DEST node has been visited for the first
time, check its successors. */
- stack[sp++] = ei_start (dest->succs);
+ stack.quick_push (ei_start (dest->succs));
else
- rts_order[postnum++] = dest->index;
+ post_order[post_order_num++] = dest->index;
}
else
{
- if (ei_one_before_end_p (ei) && src != ENTRY_BLOCK_PTR)
- rts_order[postnum++] = src->index;
+ if (ei_one_before_end_p (ei)
+ && src != ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ post_order[post_order_num++] = src->index;
if (!ei_one_before_end_p (ei))
- ei_next (&stack[sp - 1]);
+ ei_next (&stack.last ());
else
- sp--;
+ stack.pop ();
+ }
+ }
+
+ if (include_entry_exit)
+ {
+ post_order[post_order_num++] = ENTRY_BLOCK;
+ count = post_order_num;
+ }
+ else
+ count = post_order_num + 2;
+
+ /* Delete the unreachable blocks if some were found and we are
+ supposed to do it. */
+ if (delete_unreachable && (count != n_basic_blocks_for_fn (cfun)))
+ {
+ basic_block b;
+ basic_block next_bb;
+ for (b = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb; b
+ != EXIT_BLOCK_PTR_FOR_FN (cfun); b = next_bb)
+ {
+ next_bb = b->next_bb;
+
+ if (!(bitmap_bit_p (visited, b->index)))
+ delete_basic_block (b);
+ }
+
+ tidy_fallthru_edges ();
+ }
+
+ return post_order_num;
+}
+
+
+/* Helper routine for inverted_post_order_compute
+ flow_dfs_compute_reverse_execute, and the reverse-CFG
+ deapth first search in dominance.c.
+ BB has to belong to a region of CFG
+ unreachable by inverted traversal from the exit.
+ i.e. there's no control flow path from ENTRY to EXIT
+ that contains this BB.
+ This can happen in two cases - if there's an infinite loop
+ or if there's a block that has no successor
+ (call to a function with no return).
+ Some RTL passes deal with this condition by
+ calling connect_infinite_loops_to_exit () and/or
+ add_noreturn_fake_exit_edges ().
+ However, those methods involve modifying the CFG itself
+ which may not be desirable.
+ Hence, we deal with the infinite loop/no return cases
+ by identifying a unique basic block that can reach all blocks
+ in such a region by inverted traversal.
+ This function returns a basic block that guarantees
+ that all blocks in the region are reachable
+ by starting an inverted traversal from the returned block. */
+
+basic_block
+dfs_find_deadend (basic_block bb)
+{
+ auto_bitmap visited;
+ basic_block next = bb;
+
+ for (;;)
+ {
+ if (EDGE_COUNT (next->succs) == 0)
+ return next;
+
+ if (! bitmap_set_bit (visited, next->index))
+ return bb;
+
+ bb = next;
+ /* If we are in an analyzed cycle make sure to try exiting it.
+ Note this is a heuristic only and expected to work when loop
+ fixup is needed as well. */
+ if (! bb->loop_father
+ || ! loop_outer (bb->loop_father))
+ next = EDGE_SUCC (bb, 0)->dest;
+ else
+ {
+ edge_iterator ei;
+ edge e;
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ if (loop_exit_edge_p (bb->loop_father, e))
+ break;
+ next = e ? e->dest : EDGE_SUCC (bb, 0)->dest;
}
}
- free (stack);
- sbitmap_free (visited);
+ gcc_unreachable ();
}
-/* Compute the depth first search order and store in the array
- DFS_ORDER if nonzero, marking the nodes visited in VISITED. If
- RC_ORDER is nonzero, return the reverse completion number for each
- node. Returns the number of nodes visited. A depth first search
- tries to get as far away from the starting point as quickly as
- possible. */
+
+/* Compute the reverse top sort order of the inverted CFG
+ i.e. starting from the exit block and following the edges backward
+ (from successors to predecessors).
+ This ordering can be used for forward dataflow problems among others.
+
+ Optionally if START_POINTS is specified, start from exit block and all
+ basic blocks in START_POINTS. This is used by CD-DCE.
+
+ This function assumes that all blocks in the CFG are reachable
+ from the ENTRY (but not necessarily from EXIT).
+
+ If there's an infinite loop,
+ a simple inverted traversal starting from the blocks
+ with no successors can't visit all blocks.
+ To solve this problem, we first do inverted traversal
+ starting from the blocks with no successor.
+ And if there's any block left that's not visited by the regular
+ inverted traversal from EXIT,
+ those blocks are in such problematic region.
+ Among those, we find one block that has
+ any visited predecessor (which is an entry into such a region),
+ and start looking for a "dead end" from that block
+ and do another inverted traversal from that block. */
+
+void
+inverted_post_order_compute (vec<int> *post_order,
+ sbitmap *start_points)
+{
+ basic_block bb;
+ post_order->reserve_exact (n_basic_blocks_for_fn (cfun));
+
+ if (flag_checking)
+ verify_no_unreachable_blocks ();
+
+ /* Allocate stack for back-tracking up CFG. */
+ auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (cfun) + 1);
+
+ /* Allocate bitmap to track nodes that have been visited. */
+ auto_sbitmap visited (last_basic_block_for_fn (cfun));
+
+ /* None of the nodes in the CFG have been visited yet. */
+ bitmap_clear (visited);
+
+ if (start_points)
+ {
+ FOR_ALL_BB_FN (bb, cfun)
+ if (bitmap_bit_p (*start_points, bb->index)
+ && EDGE_COUNT (bb->preds) > 0)
+ {
+ stack.quick_push (ei_start (bb->preds));
+ bitmap_set_bit (visited, bb->index);
+ }
+ if (EDGE_COUNT (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds))
+ {
+ stack.quick_push (ei_start (EXIT_BLOCK_PTR_FOR_FN (cfun)->preds));
+ bitmap_set_bit (visited, EXIT_BLOCK_PTR_FOR_FN (cfun)->index);
+ }
+ }
+ else
+ /* Put all blocks that have no successor into the initial work list. */
+ FOR_ALL_BB_FN (bb, cfun)
+ if (EDGE_COUNT (bb->succs) == 0)
+ {
+ /* Push the initial edge on to the stack. */
+ if (EDGE_COUNT (bb->preds) > 0)
+ {
+ stack.quick_push (ei_start (bb->preds));
+ bitmap_set_bit (visited, bb->index);
+ }
+ }
+
+ do
+ {
+ bool has_unvisited_bb = false;
+
+ /* The inverted traversal loop. */
+ while (!stack.is_empty ())
+ {
+ edge_iterator ei;
+ basic_block pred;
+
+ /* Look at the edge on the top of the stack. */
+ ei = stack.last ();
+ bb = ei_edge (ei)->dest;
+ pred = ei_edge (ei)->src;
+
+ /* Check if the predecessor has been visited yet. */
+ if (! bitmap_bit_p (visited, pred->index))
+ {
+ /* Mark that we have visited the destination. */
+ bitmap_set_bit (visited, pred->index);
+
+ if (EDGE_COUNT (pred->preds) > 0)
+ /* Since the predecessor node has been visited for the first
+ time, check its predecessors. */
+ stack.quick_push (ei_start (pred->preds));
+ else
+ post_order->quick_push (pred->index);
+ }
+ else
+ {
+ if (bb != EXIT_BLOCK_PTR_FOR_FN (cfun)
+ && ei_one_before_end_p (ei))
+ post_order->quick_push (bb->index);
+
+ if (!ei_one_before_end_p (ei))
+ ei_next (&stack.last ());
+ else
+ stack.pop ();
+ }
+ }
+
+ /* Detect any infinite loop and activate the kludge.
+ Note that this doesn't check EXIT_BLOCK itself
+ since EXIT_BLOCK is always added after the outer do-while loop. */
+ FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR_FOR_FN (cfun),
+ EXIT_BLOCK_PTR_FOR_FN (cfun), next_bb)
+ if (!bitmap_bit_p (visited, bb->index))
+ {
+ has_unvisited_bb = true;
+
+ if (EDGE_COUNT (bb->preds) > 0)
+ {
+ edge_iterator ei;
+ edge e;
+ basic_block visited_pred = NULL;
+
+ /* Find an already visited predecessor. */
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ if (bitmap_bit_p (visited, e->src->index))
+ visited_pred = e->src;
+ }
+
+ if (visited_pred)
+ {
+ basic_block be = dfs_find_deadend (bb);
+ gcc_assert (be != NULL);
+ bitmap_set_bit (visited, be->index);
+ stack.quick_push (ei_start (be->preds));
+ break;
+ }
+ }
+ }
+
+ if (has_unvisited_bb && stack.is_empty ())
+ {
+ /* No blocks are reachable from EXIT at all.
+ Find a dead-end from the ENTRY, and restart the iteration. */
+ basic_block be = dfs_find_deadend (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ gcc_assert (be != NULL);
+ bitmap_set_bit (visited, be->index);
+ stack.quick_push (ei_start (be->preds));
+ }
+
+ /* The only case the below while fires is
+ when there's an infinite loop. */
+ }
+ while (!stack.is_empty ());
+
+ /* EXIT_BLOCK is always included. */
+ post_order->quick_push (EXIT_BLOCK);
+}
+
+/* Compute the depth first search order of FN and store in the array
+ PRE_ORDER if nonzero. If REV_POST_ORDER is nonzero, return the
+ reverse completion number for each node. Returns the number of nodes
+ visited. A depth first search tries to get as far away from the starting
+ point as quickly as possible.
+
+ In case the function has unreachable blocks the number of nodes
+ visited does not include them.
+
+ pre_order is a really a preorder numbering of the graph.
+ rev_post_order is really a reverse postorder numbering of the graph. */
int
-flow_depth_first_order_compute (int *dfs_order, int *rc_order)
+pre_and_rev_post_order_compute_fn (struct function *fn,
+ int *pre_order, int *rev_post_order,
+ bool include_entry_exit)
{
- edge_iterator *stack;
- int sp;
- int dfsnum = 0;
- int rcnum = n_basic_blocks - 1;
- sbitmap visited;
+ int pre_order_num = 0;
+ int rev_post_order_num = n_basic_blocks_for_fn (fn) - 1;
/* Allocate stack for back-tracking up CFG. */
- stack = xmalloc ((n_basic_blocks + 1) * sizeof (edge_iterator));
- sp = 0;
+ auto_vec<edge_iterator, 20> stack (n_basic_blocks_for_fn (fn) + 1);
+
+ if (include_entry_exit)
+ {
+ if (pre_order)
+ pre_order[pre_order_num] = ENTRY_BLOCK;
+ pre_order_num++;
+ if (rev_post_order)
+ rev_post_order[rev_post_order_num--] = EXIT_BLOCK;
+ }
+ else
+ rev_post_order_num -= NUM_FIXED_BLOCKS;
/* Allocate bitmap to track nodes that have been visited. */
- visited = sbitmap_alloc (last_basic_block);
+ auto_sbitmap visited (last_basic_block_for_fn (fn));
/* None of the nodes in the CFG have been visited yet. */
- sbitmap_zero (visited);
+ bitmap_clear (visited);
/* Push the first edge on to the stack. */
- stack[sp++] = ei_start (ENTRY_BLOCK_PTR->succs);
+ stack.quick_push (ei_start (ENTRY_BLOCK_PTR_FOR_FN (fn)->succs));
- while (sp)
+ while (!stack.is_empty ())
{
- edge_iterator ei;
basic_block src;
basic_block dest;
/* Look at the edge on the top of the stack. */
- ei = stack[sp - 1];
+ edge_iterator ei = stack.last ();
src = ei_edge (ei)->src;
dest = ei_edge (ei)->dest;
/* Check if the edge destination has been visited yet. */
- if (dest != EXIT_BLOCK_PTR && ! TEST_BIT (visited, dest->index))
+ if (dest != EXIT_BLOCK_PTR_FOR_FN (fn)
+ && ! bitmap_bit_p (visited, dest->index))
{
/* Mark that we have visited the destination. */
- SET_BIT (visited, dest->index);
+ bitmap_set_bit (visited, dest->index);
- if (dfs_order)
- dfs_order[dfsnum] = dest->index;
+ if (pre_order)
+ pre_order[pre_order_num] = dest->index;
- dfsnum++;
+ pre_order_num++;
if (EDGE_COUNT (dest->succs) > 0)
/* Since the DEST node has been visited for the first
time, check its successors. */
- stack[sp++] = ei_start (dest->succs);
- else if (rc_order)
+ stack.quick_push (ei_start (dest->succs));
+ else if (rev_post_order)
/* There are no successors for the DEST node so assign
its reverse completion number. */
- rc_order[rcnum--] = dest->index;
+ rev_post_order[rev_post_order_num--] = dest->index;
}
else
{
- if (ei_one_before_end_p (ei) && src != ENTRY_BLOCK_PTR
- && rc_order)
+ if (ei_one_before_end_p (ei)
+ && src != ENTRY_BLOCK_PTR_FOR_FN (fn)
+ && rev_post_order)
/* There are no more successors for the SRC node
so assign its reverse completion number. */
- rc_order[rcnum--] = src->index;
+ rev_post_order[rev_post_order_num--] = src->index;
if (!ei_one_before_end_p (ei))
- ei_next (&stack[sp - 1]);
+ ei_next (&stack.last ());
+ else
+ stack.pop ();
+ }
+ }
+
+ if (include_entry_exit)
+ {
+ if (pre_order)
+ pre_order[pre_order_num] = EXIT_BLOCK;
+ pre_order_num++;
+ if (rev_post_order)
+ rev_post_order[rev_post_order_num--] = ENTRY_BLOCK;
+ }
+
+ return pre_order_num;
+}
+
+/* Like pre_and_rev_post_order_compute_fn but operating on the
+ current function and asserting that all nodes were visited. */
+
+int
+pre_and_rev_post_order_compute (int *pre_order, int *rev_post_order,
+ bool include_entry_exit)
+{
+ int pre_order_num
+ = pre_and_rev_post_order_compute_fn (cfun, pre_order, rev_post_order,
+ include_entry_exit);
+ if (include_entry_exit)
+ /* The number of nodes visited should be the number of blocks. */
+ gcc_assert (pre_order_num == n_basic_blocks_for_fn (cfun));
+ else
+ /* The number of nodes visited should be the number of blocks minus
+ the entry and exit blocks which are not visited here. */
+ gcc_assert (pre_order_num
+ == (n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS));
+
+ return pre_order_num;
+}
+
+/* Unlike pre_and_rev_post_order_compute we fill rev_post_order backwards
+ so iterating in RPO order needs to start with rev_post_order[n - 1]
+ going to rev_post_order[0]. If FOR_ITERATION is true then try to
+ make CFG cycles fit into small contiguous regions of the RPO order.
+ When FOR_ITERATION is true this requires up-to-date loop structures. */
+
+int
+rev_post_order_and_mark_dfs_back_seme (struct function *fn, edge entry,
+ bitmap exit_bbs, bool for_iteration,
+ int *rev_post_order)
+{
+ int pre_order_num = 0;
+ int rev_post_order_num = 0;
+
+ /* Allocate stack for back-tracking up CFG. Worst case we need
+ O(n^2) edges but the following should suffice in practice without
+ a need to re-allocate. */
+ auto_vec<edge, 20> stack (2 * n_basic_blocks_for_fn (fn));
+
+ int *pre = XNEWVEC (int, 2 * last_basic_block_for_fn (fn));
+ int *post = pre + last_basic_block_for_fn (fn);
+
+ /* BB flag to track nodes that have been visited. */
+ auto_bb_flag visited (fn);
+ /* BB flag to track which nodes have post[] assigned to avoid
+ zeroing post. */
+ auto_bb_flag post_assigned (fn);
+
+ /* Push the first edge on to the stack. */
+ stack.quick_push (entry);
+
+ while (!stack.is_empty ())
+ {
+ basic_block src;
+ basic_block dest;
+
+ /* Look at the edge on the top of the stack. */
+ int idx = stack.length () - 1;
+ edge e = stack[idx];
+ src = e->src;
+ dest = e->dest;
+ e->flags &= ~EDGE_DFS_BACK;
+
+ /* Check if the edge destination has been visited yet. */
+ if (! bitmap_bit_p (exit_bbs, dest->index)
+ && ! (dest->flags & visited))
+ {
+ /* Mark that we have visited the destination. */
+ dest->flags |= visited;
+
+ pre[dest->index] = pre_order_num++;
+
+ if (EDGE_COUNT (dest->succs) > 0)
+ {
+ /* Since the DEST node has been visited for the first
+ time, check its successors. */
+ /* Push the edge vector in reverse to match previous behavior. */
+ stack.reserve (EDGE_COUNT (dest->succs));
+ for (int i = EDGE_COUNT (dest->succs) - 1; i >= 0; --i)
+ stack.quick_push (EDGE_SUCC (dest, i));
+ /* Generalize to handle more successors? */
+ if (for_iteration
+ && EDGE_COUNT (dest->succs) == 2)
+ {
+ edge &e1 = stack[stack.length () - 2];
+ if (loop_exit_edge_p (e1->src->loop_father, e1))
+ std::swap (e1, stack.last ());
+ }
+ }
else
- sp--;
+ {
+ /* There are no successors for the DEST node so assign
+ its reverse completion number. */
+ post[dest->index] = rev_post_order_num;
+ dest->flags |= post_assigned;
+ rev_post_order[rev_post_order_num] = dest->index;
+ rev_post_order_num++;
+ }
+ }
+ else
+ {
+ if (dest->flags & visited
+ && src != entry->src
+ && pre[src->index] >= pre[dest->index]
+ && !(dest->flags & post_assigned))
+ e->flags |= EDGE_DFS_BACK;
+
+ if (idx != 0 && stack[idx - 1]->src != src)
+ {
+ /* There are no more successors for the SRC node
+ so assign its reverse completion number. */
+ post[src->index] = rev_post_order_num;
+ src->flags |= post_assigned;
+ rev_post_order[rev_post_order_num] = src->index;
+ rev_post_order_num++;
+ }
+
+ stack.pop ();
}
}
- free (stack);
- sbitmap_free (visited);
+ XDELETEVEC (pre);
- /* The number of nodes visited should be the number of blocks. */
- gcc_assert (dfsnum == n_basic_blocks);
+ /* Clear the temporarily allocated flags. */
+ for (int i = 0; i < rev_post_order_num; ++i)
+ BASIC_BLOCK_FOR_FN (fn, rev_post_order[i])->flags
+ &= ~(post_assigned|visited);
- return dfsnum;
+ return rev_post_order_num;
}
+
+
/* Compute the depth first search order on the _reverse_ graph and
- store in the array DFS_ORDER, marking the nodes visited in VISITED.
+ store it in the array DFS_ORDER, marking the nodes visited in VISITED.
Returns the number of nodes visited.
The computation is split into three pieces:
search context. If INITIALIZE_STACK is nonzero, there is an
element on the stack. */
-static void
-flow_dfs_compute_reverse_init (depth_first_search_ds data)
+depth_first_search::depth_first_search () :
+ m_stack (n_basic_blocks_for_fn (cfun)),
+ m_visited_blocks (last_basic_block_for_fn (cfun))
{
- /* Allocate stack for back-tracking up CFG. */
- data->stack = xmalloc ((n_basic_blocks - (INVALID_BLOCK + 1))
- * sizeof (basic_block));
- data->sp = 0;
-
- /* Allocate bitmap to track nodes that have been visited. */
- data->visited_blocks = sbitmap_alloc (last_basic_block - (INVALID_BLOCK + 1));
-
- /* None of the nodes in the CFG have been visited yet. */
- sbitmap_zero (data->visited_blocks);
-
- return;
+ bitmap_clear (m_visited_blocks);
}
/* Add the specified basic block to the top of the dfs data
structures. When the search continues, it will start at the
block. */
-static void
-flow_dfs_compute_reverse_add_bb (depth_first_search_ds data, basic_block bb)
+void
+depth_first_search::add_bb (basic_block bb)
{
- data->stack[data->sp++] = bb;
- SET_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1));
+ m_stack.quick_push (bb);
+ bitmap_set_bit (m_visited_blocks, bb->index);
}
/* Continue the depth-first search through the reverse graph starting with the
are marked. Returns an unvisited basic block, or NULL if there is none
available. */
-static basic_block
-flow_dfs_compute_reverse_execute (depth_first_search_ds data,
- basic_block last_unvisited)
+basic_block
+depth_first_search::execute (basic_block last_unvisited)
{
basic_block bb;
edge e;
edge_iterator ei;
- while (data->sp > 0)
+ while (!m_stack.is_empty ())
{
- bb = data->stack[--data->sp];
+ bb = m_stack.pop ();
/* Perform depth-first search on adjacent vertices. */
FOR_EACH_EDGE (e, ei, bb->preds)
- if (!TEST_BIT (data->visited_blocks,
- e->src->index - (INVALID_BLOCK + 1)))
- flow_dfs_compute_reverse_add_bb (data, e->src);
+ if (!bitmap_bit_p (m_visited_blocks, e->src->index))
+ add_bb (e->src);
}
/* Determine if there are unvisited basic blocks. */
FOR_BB_BETWEEN (bb, last_unvisited, NULL, prev_bb)
- if (!TEST_BIT (data->visited_blocks, bb->index - (INVALID_BLOCK + 1)))
+ if (!bitmap_bit_p (m_visited_blocks, bb->index))
return bb;
return NULL;
}
-/* Destroy the data structures needed for depth-first search on the
- reverse graph. */
-
-static void
-flow_dfs_compute_reverse_finish (depth_first_search_ds data)
-{
- free (data->stack);
- sbitmap_free (data->visited_blocks);
-}
-
/* Performs dfs search from BB over vertices satisfying PREDICATE;
if REVERSE, go against direction of edges. Returns number of blocks
found and their list in RSLT. RSLT can contain at most RSLT_MAX items. */
int
dfs_enumerate_from (basic_block bb, int reverse,
- bool (*predicate) (basic_block, void *),
- basic_block *rslt, int rslt_max, void *data)
+ bool (*predicate) (const_basic_block, const void *),
+ basic_block *rslt, int rslt_max, const void *data)
{
basic_block *st, lbb;
int sp = 0, tv = 0;
- unsigned size;
-
- /* A bitmap to keep track of visited blocks. Allocating it each time
- this function is called is not possible, since dfs_enumerate_from
- is often used on small (almost) disjoint parts of cfg (bodies of
- loops), and allocating a large sbitmap would lead to quadratic
- behavior. */
- static sbitmap visited;
- static unsigned v_size;
-
-#define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index + 2))
-#define UNMARK_VISITED(BB) (RESET_BIT (visited, (BB)->index + 2))
-#define VISITED_P(BB) (TEST_BIT (visited, (BB)->index + 2))
-
- /* Resize the VISITED sbitmap if necessary. */
- size = last_basic_block + 2;
- if (size < 10)
- size = 10;
-
- if (!visited)
- {
- visited = sbitmap_alloc (size);
- sbitmap_zero (visited);
- v_size = size;
- }
- else if (v_size < size)
- {
- /* Ensure that we increase the size of the sbitmap exponentially. */
- if (2 * v_size > size)
- size = 2 * v_size;
+ auto_bb_flag visited (cfun);
- visited = sbitmap_resize (visited, size, 0);
- v_size = size;
- }
+#define MARK_VISITED(BB) ((BB)->flags |= visited)
+#define UNMARK_VISITED(BB) ((BB)->flags &= ~visited)
+#define VISITED_P(BB) (((BB)->flags & visited) != 0)
- st = xcalloc (rslt_max, sizeof (basic_block));
+ st = XNEWVEC (basic_block, rslt_max);
rslt[tv++] = st[sp++] = bb;
MARK_VISITED (bb);
while (sp)
edge_iterator ei;
lbb = st[--sp];
if (reverse)
- {
+ {
FOR_EACH_EDGE (e, ei, lbb->preds)
if (!VISITED_P (e->src) && predicate (e->src, data))
{
- gcc_assert (tv != rslt_max);
- rslt[tv++] = st[sp++] = e->src;
- MARK_VISITED (e->src);
+ gcc_assert (tv != rslt_max);
+ rslt[tv++] = st[sp++] = e->src;
+ MARK_VISITED (e->src);
}
- }
+ }
else
- {
+ {
FOR_EACH_EDGE (e, ei, lbb->succs)
if (!VISITED_P (e->dest) && predicate (e->dest, data))
{
- gcc_assert (tv != rslt_max);
- rslt[tv++] = st[sp++] = e->dest;
- MARK_VISITED (e->dest);
+ gcc_assert (tv != rslt_max);
+ rslt[tv++] = st[sp++] = e->dest;
+ MARK_VISITED (e->dest);
}
}
}
/* Compute dominance frontiers, ala Harvey, Ferrante, et al.
-
+
This algorithm can be found in Timothy Harvey's PhD thesis, at
http://www.cs.rice.edu/~harv/dissertation.pdf in the section on iterative
dominance algorithms.
First, we identify each join point, j (any node with more than one
- incoming edge is a join point).
+ incoming edge is a join point).
We then examine each predecessor, p, of j and walk up the dominator tree
- starting at p.
-
+ starting at p.
+
We stop the walk when we reach j's immediate dominator - j is in the
dominance frontier of each of the nodes in the walk, except for j's
immediate dominator. Intuitively, all of the rest of j's dominators are
shared by j's predecessors as well.
Since they dominate j, they will not have j in their dominance frontiers.
- The number of nodes touched by this algorithm is equal to the size
+ The number of nodes touched by this algorithm is equal to the size
of the dominance frontiers, no more, no less.
*/
static void
-compute_dominance_frontiers_1 (bitmap *frontiers)
+compute_dominance_frontiers_1 (bitmap_head *frontiers)
{
edge p;
edge_iterator ei;
basic_block b;
- FOR_EACH_BB (b)
+ FOR_EACH_BB_FN (b, cfun)
{
if (EDGE_COUNT (b->preds) >= 2)
{
{
basic_block runner = p->src;
basic_block domsb;
- if (runner == ENTRY_BLOCK_PTR)
+ if (runner == ENTRY_BLOCK_PTR_FOR_FN (cfun))
continue;
-
+
domsb = get_immediate_dominator (CDI_DOMINATORS, b);
while (runner != domsb)
{
- bitmap_set_bit (frontiers[runner->index],
- b->index);
+ if (!bitmap_set_bit (&frontiers[runner->index],
+ b->index))
+ break;
runner = get_immediate_dominator (CDI_DOMINATORS,
runner);
}
}
}
}
-}
-
+}
+
void
-compute_dominance_frontiers (bitmap *frontiers)
+compute_dominance_frontiers (bitmap_head *frontiers)
{
timevar_push (TV_DOM_FRONTIERS);
timevar_pop (TV_DOM_FRONTIERS);
}
+/* Given a set of blocks with variable definitions (DEF_BLOCKS),
+ return a bitmap with all the blocks in the iterated dominance
+ frontier of the blocks in DEF_BLOCKS. DFS contains dominance
+ frontier information as returned by compute_dominance_frontiers.
+
+ The resulting set of blocks are the potential sites where PHI nodes
+ are needed. The caller is responsible for freeing the memory
+ allocated for the return value. */
+
+bitmap
+compute_idf (bitmap def_blocks, bitmap_head *dfs)
+{
+ bitmap_iterator bi;
+ unsigned bb_index, i;
+ bitmap phi_insertion_points;
+
+ /* Each block can appear at most twice on the work-stack. */
+ auto_vec<int> work_stack (2 * n_basic_blocks_for_fn (cfun));
+ phi_insertion_points = BITMAP_ALLOC (NULL);
+
+ /* Seed the work list with all the blocks in DEF_BLOCKS. We use
+ vec::quick_push here for speed. This is safe because we know that
+ the number of definition blocks is no greater than the number of
+ basic blocks, which is the initial capacity of WORK_STACK. */
+ EXECUTE_IF_SET_IN_BITMAP (def_blocks, 0, bb_index, bi)
+ work_stack.quick_push (bb_index);
+
+ /* Pop a block off the worklist, add every block that appears in
+ the original block's DF that we have not already processed to
+ the worklist. Iterate until the worklist is empty. Blocks
+ which are added to the worklist are potential sites for
+ PHI nodes. */
+ while (work_stack.length () > 0)
+ {
+ bb_index = work_stack.pop ();
+
+ /* Since the registration of NEW -> OLD name mappings is done
+ separately from the call to update_ssa, when updating the SSA
+ form, the basic blocks where new and/or old names are defined
+ may have disappeared by CFG cleanup calls. In this case,
+ we may pull a non-existing block from the work stack. */
+ gcc_checking_assert (bb_index
+ < (unsigned) last_basic_block_for_fn (cfun));
+
+ EXECUTE_IF_AND_COMPL_IN_BITMAP (&dfs[bb_index], phi_insertion_points,
+ 0, i, bi)
+ {
+ work_stack.quick_push (i);
+ bitmap_set_bit (phi_insertion_points, i);
+ }
+ }
+
+ return phi_insertion_points;
+}
+
+/* Intersection and union of preds/succs for sbitmap based data flow
+ solvers. All four functions defined below take the same arguments:
+ B is the basic block to perform the operation for. DST is the
+ target sbitmap, i.e. the result. SRC is an sbitmap vector of size
+ last_basic_block so that it can be indexed with basic block indices.
+ DST may be (but does not have to be) SRC[B->index]. */
+
+/* Set the bitmap DST to the intersection of SRC of successors of
+ basic block B. */
+
+void
+bitmap_intersection_of_succs (sbitmap dst, sbitmap *src, basic_block b)
+{
+ unsigned int set_size = dst->size;
+ edge e;
+ unsigned ix;
+
+ for (e = NULL, ix = 0; ix < EDGE_COUNT (b->succs); ix++)
+ {
+ e = EDGE_SUCC (b, ix);
+ if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ bitmap_copy (dst, src[e->dest->index]);
+ break;
+ }
+
+ if (e == 0)
+ bitmap_ones (dst);
+ else
+ for (++ix; ix < EDGE_COUNT (b->succs); ix++)
+ {
+ unsigned int i;
+ SBITMAP_ELT_TYPE *p, *r;
+
+ e = EDGE_SUCC (b, ix);
+ if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ p = src[e->dest->index]->elms;
+ r = dst->elms;
+ for (i = 0; i < set_size; i++)
+ *r++ &= *p++;
+ }
+}
+
+/* Set the bitmap DST to the intersection of SRC of predecessors of
+ basic block B. */
+
+void
+bitmap_intersection_of_preds (sbitmap dst, sbitmap *src, basic_block b)
+{
+ unsigned int set_size = dst->size;
+ edge e;
+ unsigned ix;
+
+ for (e = NULL, ix = 0; ix < EDGE_COUNT (b->preds); ix++)
+ {
+ e = EDGE_PRED (b, ix);
+ if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ bitmap_copy (dst, src[e->src->index]);
+ break;
+ }
+
+ if (e == 0)
+ bitmap_ones (dst);
+ else
+ for (++ix; ix < EDGE_COUNT (b->preds); ix++)
+ {
+ unsigned int i;
+ SBITMAP_ELT_TYPE *p, *r;
+
+ e = EDGE_PRED (b, ix);
+ if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ p = src[e->src->index]->elms;
+ r = dst->elms;
+ for (i = 0; i < set_size; i++)
+ *r++ &= *p++;
+ }
+}
+
+/* Set the bitmap DST to the union of SRC of successors of
+ basic block B. */
+
+void
+bitmap_union_of_succs (sbitmap dst, sbitmap *src, basic_block b)
+{
+ unsigned int set_size = dst->size;
+ edge e;
+ unsigned ix;
+
+ for (ix = 0; ix < EDGE_COUNT (b->succs); ix++)
+ {
+ e = EDGE_SUCC (b, ix);
+ if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ bitmap_copy (dst, src[e->dest->index]);
+ break;
+ }
+
+ if (ix == EDGE_COUNT (b->succs))
+ bitmap_clear (dst);
+ else
+ for (ix++; ix < EDGE_COUNT (b->succs); ix++)
+ {
+ unsigned int i;
+ SBITMAP_ELT_TYPE *p, *r;
+
+ e = EDGE_SUCC (b, ix);
+ if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ p = src[e->dest->index]->elms;
+ r = dst->elms;
+ for (i = 0; i < set_size; i++)
+ *r++ |= *p++;
+ }
+}
+
+/* Set the bitmap DST to the union of SRC of predecessors of
+ basic block B. */
+
+void
+bitmap_union_of_preds (sbitmap dst, sbitmap *src, basic_block b)
+{
+ unsigned int set_size = dst->size;
+ edge e;
+ unsigned ix;
+
+ for (ix = 0; ix < EDGE_COUNT (b->preds); ix++)
+ {
+ e = EDGE_PRED (b, ix);
+ if (e->src== ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ bitmap_copy (dst, src[e->src->index]);
+ break;
+ }
+
+ if (ix == EDGE_COUNT (b->preds))
+ bitmap_clear (dst);
+ else
+ for (ix++; ix < EDGE_COUNT (b->preds); ix++)
+ {
+ unsigned int i;
+ SBITMAP_ELT_TYPE *p, *r;
+
+ e = EDGE_PRED (b, ix);
+ if (e->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ continue;
+
+ p = src[e->src->index]->elms;
+ r = dst->elms;
+ for (i = 0; i < set_size; i++)
+ *r++ |= *p++;
+ }
+}
+
+/* Returns the list of basic blocks in the function in an order that guarantees
+ that if a block X has just a single predecessor Y, then Y is after X in the
+ ordering. */
+
+basic_block *
+single_pred_before_succ_order (void)
+{
+ basic_block x, y;
+ basic_block *order = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
+ unsigned n = n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS;
+ unsigned np, i;
+ auto_sbitmap visited (last_basic_block_for_fn (cfun));
+
+#define MARK_VISITED(BB) (bitmap_set_bit (visited, (BB)->index))
+#define VISITED_P(BB) (bitmap_bit_p (visited, (BB)->index))
+
+ bitmap_clear (visited);
+
+ MARK_VISITED (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ FOR_EACH_BB_FN (x, cfun)
+ {
+ if (VISITED_P (x))
+ continue;
+
+ /* Walk the predecessors of x as long as they have precisely one
+ predecessor and add them to the list, so that they get stored
+ after x. */
+ for (y = x, np = 1;
+ single_pred_p (y) && !VISITED_P (single_pred (y));
+ y = single_pred (y))
+ np++;
+ for (y = x, i = n - np;
+ single_pred_p (y) && !VISITED_P (single_pred (y));
+ y = single_pred (y), i++)
+ {
+ order[i] = y;
+ MARK_VISITED (y);
+ }
+ order[i] = y;
+ MARK_VISITED (y);
+
+ gcc_assert (i == n - 1);
+ n -= np;
+ }
+
+ gcc_assert (n == 0);
+ return order;
+
+#undef MARK_VISITED
+#undef VISITED_P
+}
+
+/* Ignoring loop backedges, if BB has precisely one incoming edge then
+ return that edge. Otherwise return NULL.
+
+ When IGNORE_NOT_EXECUTABLE is true, also ignore edges that are not marked
+ as executable. */
+
+edge
+single_pred_edge_ignoring_loop_edges (basic_block bb,
+ bool ignore_not_executable)
+{
+ edge retval = NULL;
+ edge e;
+ edge_iterator ei;
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ /* A loop back edge can be identified by the destination of
+ the edge dominating the source of the edge. */
+ if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
+ continue;
+
+ /* We can safely ignore edges that are not executable. */
+ if (ignore_not_executable
+ && (e->flags & EDGE_EXECUTABLE) == 0)
+ continue;
+
+ /* If we have already seen a non-loop edge, then we must have
+ multiple incoming non-loop edges and thus we return NULL. */
+ if (retval)
+ return NULL;
+
+ /* This is the first non-loop incoming edge we have found. Record
+ it. */
+ retval = e;
+ }
+
+ return retval;
+}
projects / thirdparty / gcc.git / blobdiff