/* Calculate (post)dominators in slightly super-linear time.
- Copyright (C) 2000 Free Software Foundation, Inc.
+ Copyright (C) 2000, 2003, 2004, 2005 Free Software Foundation, Inc.
Contributed by Michael Matz (matz@ifh.de).
-
+
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)
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. */
+ Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
+ 02110-1301, USA. */
/* This file implements the well known algorithm from Lengauer and Tarjan
to compute the dominators in a control flow graph. A basic block D is said
The algorithm computes this dominator tree implicitly by computing for
each block its immediate dominator. We use tree balancing and path
- compression, so its the O(e*a(e,v)) variant, where a(e,v) is the very
+ compression, so it's the O(e*a(e,v)) variant, where a(e,v) is the very
slowly growing functional inverse of the Ackerman function. */
#include "config.h"
#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
#include "rtl.h"
#include "hard-reg-set.h"
+#include "obstack.h"
#include "basic-block.h"
+#include "toplev.h"
+#include "et-forest.h"
+#include "timevar.h"
+/* Whether the dominators and the postdominators are available. */
+static enum dom_state dom_computed[2];
/* We name our nodes with integers, beginning with 1. Zero is reserved for
'undefined' or 'end of list'. The name of each node is given by the dfs
number of the corresponding basic block. Please note, that we include the
artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to
- support multiple entry points. As it has no real basic block index we use
- 'n_basic_blocks' for that. Its dfs number is of course 1. */
+ support multiple entry points. Its dfs number is of course 1. */
/* Type of Basic Block aka. TBB */
typedef unsigned int TBB;
number of that node in DFS order counted from 1. This is an index
into most of the other arrays in this structure. */
TBB *dfs_order;
- /* If x is the DFS-index of a node which corresponds with an basic block,
+ /* If x is the DFS-index of a node which corresponds with a basic block,
dfs_to_bb[x] is that basic block. Note, that in our structure there are
more nodes that basic blocks, so only dfs_to_bb[dfs_order[bb->index]]==bb
is true for every basic block bb, but not the opposite. */
basic_block *dfs_to_bb;
- /* This is the next free DFS number when creating the DFS tree or forest. */
+ /* This is the next free DFS number when creating the DFS tree. */
unsigned int dfsnum;
/* The number of nodes in the DFS tree (==dfsnum-1). */
unsigned int nodes;
+
+ /* Blocks with bits set here have a fake edge to EXIT. These are used
+ to turn a DFS forest into a proper tree. */
+ bitmap fake_exit_edge;
};
-static void init_dom_info PARAMS ((struct dom_info *));
-static void free_dom_info PARAMS ((struct dom_info *));
-static void calc_dfs_tree_nonrec PARAMS ((struct dom_info *,
- basic_block,
- enum cdi_direction));
-static void calc_dfs_tree PARAMS ((struct dom_info *,
- enum cdi_direction));
-static void compress PARAMS ((struct dom_info *, TBB));
-static TBB eval PARAMS ((struct dom_info *, TBB));
-static void link_roots PARAMS ((struct dom_info *, TBB, TBB));
-static void calc_idoms PARAMS ((struct dom_info *,
- enum cdi_direction));
-static void idoms_to_doms PARAMS ((struct dom_info *,
- sbitmap *));
+static void init_dom_info (struct dom_info *, enum cdi_direction);
+static void free_dom_info (struct dom_info *);
+static void calc_dfs_tree_nonrec (struct dom_info *, basic_block, bool);
+static void calc_dfs_tree (struct dom_info *, bool);
+static void compress (struct dom_info *, TBB);
+static TBB eval (struct dom_info *, TBB);
+static void link_roots (struct dom_info *, TBB, TBB);
+static void calc_idoms (struct dom_info *, bool);
+void debug_dominance_info (enum cdi_direction);
+
+/* Keeps track of the*/
+static unsigned n_bbs_in_dom_tree[2];
/* Helper macro for allocating and initializing an array,
for aesthetic reasons. */
#define init_ar(var, type, num, content) \
- do { \
- unsigned int i = 1; /* Catch content == i. */ \
- if (! (content)) \
- (var) = (type *) xcalloc ((num), sizeof (type)); \
- else \
- { \
- (var) = (type *) xmalloc ((num) * sizeof (type)); \
- for (i = 0; i < num; i++) \
- (var)[i] = (content); \
- } \
- } while (0)
+ do \
+ { \
+ unsigned int i = 1; /* Catch content == i. */ \
+ if (! (content)) \
+ (var) = XCNEWVEC (type, num); \
+ else \
+ { \
+ (var) = XNEWVEC (type, (num)); \
+ for (i = 0; i < num; i++) \
+ (var)[i] = (content); \
+ } \
+ } \
+ while (0)
/* Allocate all needed memory in a pessimistic fashion (so we round up).
- This initialises the contents of DI, which already must be allocated. */
+ This initializes the contents of DI, which already must be allocated. */
static void
-init_dom_info (di)
- struct dom_info *di;
+init_dom_info (struct dom_info *di, enum cdi_direction dir)
{
- /* We need memory for n_basic_blocks nodes and the ENTRY_BLOCK or
- EXIT_BLOCK. */
- unsigned int num = n_basic_blocks + 1 + 1;
+ unsigned int num = n_basic_blocks;
init_ar (di->dfs_parent, TBB, num, 0);
init_ar (di->path_min, TBB, num, i);
init_ar (di->key, TBB, num, i);
init_ar (di->set_size, unsigned int, num, 1);
init_ar (di->set_child, TBB, num, 0);
- init_ar (di->dfs_order, TBB, (unsigned int) n_basic_blocks + 1, 0);
+ init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0);
init_ar (di->dfs_to_bb, basic_block, num, 0);
di->dfsnum = 1;
di->nodes = 0;
+
+ switch (dir)
+ {
+ case CDI_DOMINATORS:
+ di->fake_exit_edge = NULL;
+ break;
+ case CDI_POST_DOMINATORS:
+ di->fake_exit_edge = BITMAP_ALLOC (NULL);
+ break;
+ default:
+ gcc_unreachable ();
+ break;
+ }
}
#undef init_ar
+/* Map dominance calculation type to array index used for various
+ dominance information arrays. This version is simple -- it will need
+ to be modified, obviously, if additional values are added to
+ cdi_direction. */
+
+static unsigned int
+dom_convert_dir_to_idx (enum cdi_direction dir)
+{
+ gcc_assert (dir == CDI_DOMINATORS || dir == CDI_POST_DOMINATORS);
+ return dir - 1;
+}
+
/* Free all allocated memory in DI, but not DI itself. */
static void
-free_dom_info (di)
- struct dom_info *di;
+free_dom_info (struct dom_info *di)
{
free (di->dfs_parent);
free (di->path_min);
free (di->set_child);
free (di->dfs_order);
free (di->dfs_to_bb);
+ BITMAP_FREE (di->fake_exit_edge);
}
/* The nonrecursive variant of creating a DFS tree. DI is our working
assigned their dfs number and are linked together to form a tree. */
static void
-calc_dfs_tree_nonrec (di, bb, reverse)
- struct dom_info *di;
- basic_block bb;
- enum cdi_direction reverse;
+calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb, bool reverse)
{
- /* We never call this with bb==EXIT_BLOCK_PTR (ENTRY_BLOCK_PTR if REVERSE). */
/* We call this _only_ if bb is not already visited. */
edge e;
TBB child_i, my_i = 0;
- edge *stack;
+ edge_iterator *stack;
+ edge_iterator ei, einext;
int sp;
/* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward
problem). */
/* Ending block. */
basic_block ex_block;
- stack = (edge *) xmalloc ((n_basic_blocks + 3) * sizeof (edge));
+ stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
sp = 0;
/* Initialize our border blocks, and the first edge. */
if (reverse)
{
- e = bb->pred;
+ ei = ei_start (bb->preds);
en_block = EXIT_BLOCK_PTR;
ex_block = ENTRY_BLOCK_PTR;
}
else
{
- e = bb->succ;
+ ei = ei_start (bb->succs);
en_block = ENTRY_BLOCK_PTR;
ex_block = EXIT_BLOCK_PTR;
}
/* This loop traverses edges e in depth first manner, and fills the
stack. */
- while (e)
+ while (!ei_end_p (ei))
{
- edge e_next;
+ e = ei_edge (ei);
/* Deduce from E the current and the next block (BB and BN), and the
next edge. */
with the next edge out of the current node. */
if (bn == ex_block || di->dfs_order[bn->index])
{
- e = e->pred_next;
+ ei_next (&ei);
continue;
}
bb = e->dest;
- e_next = bn->pred;
+ einext = ei_start (bn->preds);
}
else
{
bn = e->dest;
if (bn == ex_block || di->dfs_order[bn->index])
{
- e = e->succ_next;
+ ei_next (&ei);
continue;
}
bb = e->src;
- e_next = bn->succ;
+ einext = ei_start (bn->succs);
}
- if (bn == en_block)
- abort ();
+ gcc_assert (bn != en_block);
/* Fill the DFS tree info calculatable _before_ recursing. */
if (bb != en_block)
my_i = di->dfs_order[bb->index];
else
- my_i = di->dfs_order[n_basic_blocks];
+ my_i = di->dfs_order[last_basic_block];
child_i = di->dfs_order[bn->index] = di->dfsnum++;
di->dfs_to_bb[child_i] = bn;
di->dfs_parent[child_i] = my_i;
/* Save the current point in the CFG on the stack, and recurse. */
- stack[sp++] = e;
- e = e_next;
+ stack[sp++] = ei;
+ ei = einext;
}
if (!sp)
break;
- e = stack[--sp];
+ ei = stack[--sp];
/* OK. The edge-list was exhausted, meaning normally we would
end the recursion. After returning from the recursive call,
the block not yet completed (the parent of the one above)
in e->src. This could be used e.g. for computing the number of
descendants or the tree depth. */
- if (reverse)
- e = e->pred_next;
- else
- e = e->succ_next;
+ ei_next (&ei);
}
free (stack);
}
because there may be nodes from which the EXIT_BLOCK is unreachable. */
static void
-calc_dfs_tree (di, reverse)
- struct dom_info *di;
- enum cdi_direction reverse;
+calc_dfs_tree (struct dom_info *di, bool reverse)
{
/* The first block is the ENTRY_BLOCK (or EXIT_BLOCK if REVERSE). */
basic_block begin = reverse ? EXIT_BLOCK_PTR : ENTRY_BLOCK_PTR;
- di->dfs_order[n_basic_blocks] = di->dfsnum;
+ di->dfs_order[last_basic_block] = di->dfsnum;
di->dfs_to_bb[di->dfsnum] = begin;
di->dfsnum++;
{
/* In the post-dom case we may have nodes without a path to EXIT_BLOCK.
They are reverse-unreachable. In the dom-case we disallow such
- nodes, but in post-dom we have to deal with them, so we simply
- include them in the DFS tree which actually becomes a forest. */
- int i;
- for (i = n_basic_blocks - 1; i >= 0; i--)
+ nodes, but in post-dom we have to deal with them.
+
+ There are two situations in which this occurs. First, noreturn
+ functions. Second, infinite loops. In the first case we need to
+ pretend that there is an edge to the exit block. In the second
+ case, we wind up with a forest. We need to process all noreturn
+ blocks before we know if we've got any infinite loops. */
+
+ basic_block b;
+ bool saw_unconnected = false;
+
+ FOR_EACH_BB_REVERSE (b)
{
- basic_block b = BASIC_BLOCK (i);
- if (di->dfs_order[b->index])
- continue;
+ if (EDGE_COUNT (b->succs) > 0)
+ {
+ if (di->dfs_order[b->index] == 0)
+ saw_unconnected = true;
+ continue;
+ }
+ bitmap_set_bit (di->fake_exit_edge, b->index);
di->dfs_order[b->index] = di->dfsnum;
di->dfs_to_bb[di->dfsnum] = b;
+ di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block];
di->dfsnum++;
calc_dfs_tree_nonrec (di, b, reverse);
}
+
+ if (saw_unconnected)
+ {
+ FOR_EACH_BB_REVERSE (b)
+ {
+ if (di->dfs_order[b->index])
+ continue;
+ bitmap_set_bit (di->fake_exit_edge, b->index);
+ di->dfs_order[b->index] = di->dfsnum;
+ di->dfs_to_bb[di->dfsnum] = b;
+ di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block];
+ di->dfsnum++;
+ calc_dfs_tree_nonrec (di, b, reverse);
+ }
+ }
}
di->nodes = di->dfsnum - 1;
/* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */
- if (di->nodes != (unsigned int) n_basic_blocks + 1)
- abort ();
+ gcc_assert (di->nodes == (unsigned int) n_basic_blocks - 1);
}
/* Compress the path from V to the root of its set and update path_min at the
from V to that root. */
static void
-compress (di, v)
- struct dom_info *di;
- TBB v;
+compress (struct dom_info *di, TBB v)
{
/* Btw. It's not worth to unrecurse compress() as the depth is usually not
greater than 5 even for huge graphs (I've not seen call depth > 4).
value on the path from V to the root. */
static inline TBB
-eval (di, v)
- struct dom_info *di;
- TBB v;
+eval (struct dom_info *di, TBB v)
{
/* The representant of the set V is in, also called root (as the set
representation is a tree). */
of W. */
static void
-link_roots (di, v, w)
- struct dom_info *di;
- TBB v, w;
+link_roots (struct dom_info *di, TBB v, TBB w)
{
TBB s = w;
On return the immediate dominator to node V is in di->dom[V]. */
static void
-calc_idoms (di, reverse)
- struct dom_info *di;
- enum cdi_direction reverse;
+calc_idoms (struct dom_info *di, bool reverse)
{
TBB v, w, k, par;
basic_block en_block;
+ edge_iterator ei, einext;
+
if (reverse)
en_block = EXIT_BLOCK_PTR;
else
while (v > 1)
{
basic_block bb = di->dfs_to_bb[v];
- edge e, e_next;
+ edge e;
par = di->dfs_parent[v];
k = v;
+
+ ei = (reverse) ? ei_start (bb->succs) : ei_start (bb->preds);
+
if (reverse)
- e = bb->succ;
- else
- e = bb->pred;
+ {
+ /* If this block has a fake edge to exit, process that first. */
+ if (bitmap_bit_p (di->fake_exit_edge, bb->index))
+ {
+ einext = ei;
+ einext.index = 0;
+ goto do_fake_exit_edge;
+ }
+ }
/* Search all direct predecessors for the smallest node with a path
to them. That way we have the smallest node with also a path to
us only over nodes behind us. In effect we search for our
semidominator. */
- for (; e; e = e_next)
+ while (!ei_end_p (ei))
{
TBB k1;
basic_block b;
- if (reverse)
- {
- b = e->dest;
- e_next = e->succ_next;
- }
- else
+ e = ei_edge (ei);
+ b = (reverse) ? e->dest : e->src;
+ einext = ei;
+ ei_next (&einext);
+
+ if (b == en_block)
{
- b = e->src;
- e_next = e->pred_next;
+ do_fake_exit_edge:
+ k1 = di->dfs_order[last_basic_block];
}
- if (b == en_block)
- k1 = di->dfs_order[n_basic_blocks];
else
k1 = di->dfs_order[b->index];
k1 = di->key[eval (di, k1)];
if (k1 < k)
k = k1;
+
+ ei = einext;
}
di->key[v] = k;
di->dom[v] = di->dom[di->dom[v]];
}
-/* Convert the information about immediate dominators (in DI) to sets of all
- dominators (in DOMINATORS). */
+/* Assign dfs numbers starting from NUM to NODE and its sons. */
static void
-idoms_to_doms (di, dominators)
- struct dom_info *di;
- sbitmap *dominators;
-{
- TBB i, e_index;
- int bb, bb_idom;
- sbitmap_vector_zero (dominators, n_basic_blocks);
- /* We have to be careful, to not include the ENTRY_BLOCK or EXIT_BLOCK
- in the list of (post)-doms, so remember that in e_index. */
- e_index = di->dfs_order[n_basic_blocks];
-
- for (i = 1; i <= di->nodes; i++)
+assign_dfs_numbers (struct et_node *node, int *num)
+{
+ struct et_node *son;
+
+ node->dfs_num_in = (*num)++;
+
+ if (node->son)
+ {
+ assign_dfs_numbers (node->son, num);
+ for (son = node->son->right; son != node->son; son = son->right)
+ assign_dfs_numbers (son, num);
+ }
+
+ node->dfs_num_out = (*num)++;
+}
+
+/* Compute the data necessary for fast resolving of dominator queries in a
+ static dominator tree. */
+
+static void
+compute_dom_fast_query (enum cdi_direction dir)
+{
+ int num = 0;
+ basic_block bb;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_assert (dom_info_available_p (dir));
+
+ if (dom_computed[dir_index] == DOM_OK)
+ return;
+
+ FOR_ALL_BB (bb)
+ {
+ if (!bb->dom[dir_index]->father)
+ assign_dfs_numbers (bb->dom[dir_index], &num);
+ }
+
+ dom_computed[dir_index] = DOM_OK;
+}
+
+/* The main entry point into this module. DIR is set depending on whether
+ we want to compute dominators or postdominators. */
+
+void
+calculate_dominance_info (enum cdi_direction dir)
+{
+ struct dom_info di;
+ basic_block b;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false;
+
+ if (dom_computed[dir_index] == DOM_OK)
+ return;
+
+ timevar_push (TV_DOMINANCE);
+ if (!dom_info_available_p (dir))
{
- if (i == e_index)
- continue;
- bb = di->dfs_to_bb[i]->index;
+ gcc_assert (!n_bbs_in_dom_tree[dir_index]);
- if (di->dom[i] && (di->dom[i] != e_index))
+ FOR_ALL_BB (b)
{
- bb_idom = di->dfs_to_bb[di->dom[i]]->index;
- sbitmap_copy (dominators[bb], dominators[bb_idom]);
+ b->dom[dir_index] = et_new_tree (b);
}
- else
+ n_bbs_in_dom_tree[dir_index] = n_basic_blocks;
+
+ init_dom_info (&di, dir);
+ calc_dfs_tree (&di, reverse);
+ calc_idoms (&di, reverse);
+
+ FOR_EACH_BB (b)
{
- /* It has no immediate dom or only ENTRY_BLOCK or EXIT_BLOCK.
- If it is a child of ENTRY_BLOCK that's OK, and it's only
- dominated by itself; if it's _not_ a child of ENTRY_BLOCK, it
- means, it is unreachable. That case has been disallowed in the
- building of the DFS tree, so we are save here. For the reverse
- flow graph it means, it has no children, so, to be compatible
- with the old code, we set the post_dominators to all one. */
- if (!di->dom[i])
- {
- sbitmap_ones (dominators[bb]);
- }
+ TBB d = di.dom[di.dfs_order[b->index]];
+
+ if (di.dfs_to_bb[d])
+ et_set_father (b->dom[dir_index], di.dfs_to_bb[d]->dom[dir_index]);
}
- SET_BIT (dominators[bb], bb);
+
+ free_dom_info (&di);
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
+ }
+
+ compute_dom_fast_query (dir);
+
+ timevar_pop (TV_DOMINANCE);
+}
+
+/* Free dominance information for direction DIR. */
+void
+free_dominance_info (enum cdi_direction dir)
+{
+ basic_block bb;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ if (!dom_info_available_p (dir))
+ return;
+
+ FOR_ALL_BB (bb)
+ {
+ et_free_tree_force (bb->dom[dir_index]);
+ bb->dom[dir_index] = NULL;
+ }
+ et_free_pools ();
+
+ n_bbs_in_dom_tree[dir_index] = 0;
+
+ dom_computed[dir_index] = DOM_NONE;
+}
+
+/* Return the immediate dominator of basic block BB. */
+basic_block
+get_immediate_dominator (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *node = bb->dom[dir_index];
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (!node->father)
+ return NULL;
+
+ return node->father->data;
+}
+
+/* Set the immediate dominator of the block possibly removing
+ existing edge. NULL can be used to remove any edge. */
+inline void
+set_immediate_dominator (enum cdi_direction dir, basic_block bb,
+ basic_block dominated_by)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *node = bb->dom[dir_index];
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (node->father)
+ {
+ if (node->father->data == dominated_by)
+ return;
+ et_split (node);
}
+
+ if (dominated_by)
+ et_set_father (node, dominated_by->dom[dir_index]);
+
+ if (dom_computed[dir_index] == DOM_OK)
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
}
-/* The main entry point into this module. IDOM is an integer array with room
- for n_basic_blocks integers, DOMS is a preallocated sbitmap array having
- room for n_basic_blocks^2 bits, and POST is true if the caller wants to
- know post-dominators.
+/* Store all basic blocks immediately dominated by BB into BBS and return
+ their number. */
+int
+get_dominated_by (enum cdi_direction dir, basic_block bb, basic_block **bbs)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ int n;
+ struct et_node *node = bb->dom[dir_index], *son = node->son, *ason;
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (!son)
+ {
+ *bbs = NULL;
+ return 0;
+ }
- On return IDOM[i] will be the BB->index of the immediate (post) dominator
- of basic block i, and DOMS[i] will have set bit j if basic block j is a
- (post)dominator for block i.
+ for (ason = son->right, n = 1; ason != son; ason = ason->right)
+ n++;
- Either IDOM or DOMS may be NULL (meaning the caller is not interested in
- immediate resp. all dominators). */
+ *bbs = XNEWVEC (basic_block, n);
+ (*bbs)[0] = son->data;
+ for (ason = son->right, n = 1; ason != son; ason = ason->right)
+ (*bbs)[n++] = ason->data;
+ return n;
+}
+
+/* Find all basic blocks that are immediately dominated (in direction DIR)
+ by some block between N_REGION ones stored in REGION, except for blocks
+ in the REGION itself. The found blocks are stored to DOMS and their number
+ is returned. */
+
+unsigned
+get_dominated_by_region (enum cdi_direction dir, basic_block *region,
+ unsigned n_region, basic_block *doms)
+{
+ unsigned n_doms = 0, i;
+ basic_block dom;
+
+ for (i = 0; i < n_region; i++)
+ region[i]->flags |= BB_DUPLICATED;
+ for (i = 0; i < n_region; i++)
+ for (dom = first_dom_son (dir, region[i]);
+ dom;
+ dom = next_dom_son (dir, dom))
+ if (!(dom->flags & BB_DUPLICATED))
+ doms[n_doms++] = dom;
+ for (i = 0; i < n_region; i++)
+ region[i]->flags &= ~BB_DUPLICATED;
+
+ return n_doms;
+}
+
+/* Redirect all edges pointing to BB to TO. */
void
-calculate_dominance_info (idom, doms, reverse)
- int *idom;
- sbitmap *doms;
- enum cdi_direction reverse;
+redirect_immediate_dominators (enum cdi_direction dir, basic_block bb,
+ basic_block to)
{
- struct dom_info di;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *bb_node, *to_node, *son;
+
+ bb_node = bb->dom[dir_index];
+ to_node = to->dom[dir_index];
- if (!doms && !idom)
+ gcc_assert (dom_computed[dir_index]);
+
+ if (!bb_node->son)
return;
- init_dom_info (&di);
- calc_dfs_tree (&di, reverse);
- calc_idoms (&di, reverse);
- if (idom)
+ while (bb_node->son)
{
- int i;
- for (i = 0; i < n_basic_blocks; i++)
+ son = bb_node->son;
+
+ et_split (son);
+ et_set_father (son, to_node);
+ }
+
+ if (dom_computed[dir_index] == DOM_OK)
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
+}
+
+/* Find first basic block in the tree dominating both BB1 and BB2. */
+basic_block
+nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (!bb1)
+ return bb2;
+ if (!bb2)
+ return bb1;
+
+ return et_nca (bb1->dom[dir_index], bb2->dom[dir_index])->data;
+}
+
+
+/* Find the nearest common dominator for the basic blocks in BLOCKS,
+ using dominance direction DIR. */
+
+basic_block
+nearest_common_dominator_for_set (enum cdi_direction dir, bitmap blocks)
+{
+ unsigned i, first;
+ bitmap_iterator bi;
+ basic_block dom;
+
+ first = bitmap_first_set_bit (blocks);
+ dom = BASIC_BLOCK (first);
+ EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ if (dom != BASIC_BLOCK (i))
+ dom = nearest_common_dominator (dir, dom, BASIC_BLOCK (i));
+
+ return dom;
+}
+
+/* Given a dominator tree, we can determine whether one thing
+ dominates another in constant time by using two DFS numbers:
+
+ 1. The number for when we visit a node on the way down the tree
+ 2. The number for when we visit a node on the way back up the tree
+
+ You can view these as bounds for the range of dfs numbers the
+ nodes in the subtree of the dominator tree rooted at that node
+ will contain.
+
+ The dominator tree is always a simple acyclic tree, so there are
+ only three possible relations two nodes in the dominator tree have
+ to each other:
+
+ 1. Node A is above Node B (and thus, Node A dominates node B)
+
+ A
+ |
+ C
+ / \
+ B D
+
+
+ In the above case, DFS_Number_In of A will be <= DFS_Number_In of
+ B, and DFS_Number_Out of A will be >= DFS_Number_Out of B. This is
+ because we must hit A in the dominator tree *before* B on the walk
+ down, and we will hit A *after* B on the walk back up
+
+ 2. Node A is below node B (and thus, node B dominates node A)
+
+
+ B
+ |
+ A
+ / \
+ C D
+
+ In the above case, DFS_Number_In of A will be >= DFS_Number_In of
+ B, and DFS_Number_Out of A will be <= DFS_Number_Out of B.
+
+ This is because we must hit A in the dominator tree *after* B on
+ the walk down, and we will hit A *before* B on the walk back up
+
+ 3. Node A and B are siblings (and thus, neither dominates the other)
+
+ C
+ |
+ D
+ / \
+ A B
+
+ In the above case, DFS_Number_In of A will *always* be <=
+ DFS_Number_In of B, and DFS_Number_Out of A will *always* be <=
+ DFS_Number_Out of B. This is because we will always finish the dfs
+ walk of one of the subtrees before the other, and thus, the dfs
+ numbers for one subtree can't intersect with the range of dfs
+ numbers for the other subtree. If you swap A and B's position in
+ the dominator tree, the comparison changes direction, but the point
+ is that both comparisons will always go the same way if there is no
+ dominance relationship.
+
+ Thus, it is sufficient to write
+
+ A_Dominates_B (node A, node B)
+ {
+ return DFS_Number_In(A) <= DFS_Number_In(B)
+ && DFS_Number_Out (A) >= DFS_Number_Out(B);
+ }
+
+ A_Dominated_by_B (node A, node B)
+ {
+ return DFS_Number_In(A) >= DFS_Number_In(A)
+ && DFS_Number_Out (A) <= DFS_Number_Out(B);
+ } */
+
+/* Return TRUE in case BB1 is dominated by BB2. */
+bool
+dominated_by_p (enum cdi_direction dir, basic_block bb1, basic_block bb2)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *n1 = bb1->dom[dir_index], *n2 = bb2->dom[dir_index];
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (dom_computed[dir_index] == DOM_OK)
+ return (n1->dfs_num_in >= n2->dfs_num_in
+ && n1->dfs_num_out <= n2->dfs_num_out);
+
+ return et_below (n1, n2);
+}
+
+/* Returns the entry dfs number for basic block BB, in the direction DIR. */
+
+unsigned
+bb_dom_dfs_in (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *n = bb->dom[dir_index];
+
+ gcc_assert (dom_computed[dir_index] == DOM_OK);
+ return n->dfs_num_in;
+}
+
+/* Returns the exit dfs number for basic block BB, in the direction DIR. */
+
+unsigned
+bb_dom_dfs_out (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *n = bb->dom[dir_index];
+
+ gcc_assert (dom_computed[dir_index] == DOM_OK);
+ return n->dfs_num_out;
+}
+
+/* Verify invariants of dominator structure. */
+void
+verify_dominators (enum cdi_direction dir)
+{
+ int err = 0;
+ basic_block bb;
+
+ gcc_assert (dom_info_available_p (dir));
+
+ FOR_EACH_BB (bb)
+ {
+ basic_block dom_bb;
+ basic_block imm_bb;
+
+ dom_bb = recount_dominator (dir, bb);
+ imm_bb = get_immediate_dominator (dir, bb);
+ if (dom_bb != imm_bb)
{
- basic_block b = BASIC_BLOCK (i);
- TBB d = di.dom[di.dfs_order[b->index]];
+ if ((dom_bb == NULL) || (imm_bb == NULL))
+ error ("dominator of %d status unknown", bb->index);
+ else
+ error ("dominator of %d should be %d, not %d",
+ bb->index, dom_bb->index, imm_bb->index);
+ err = 1;
+ }
+ }
- /* The old code didn't modify array elements of nodes having only
- itself as dominator (d==0) or only ENTRY_BLOCK (resp. EXIT_BLOCK)
- (d==1). */
- if (d > 1)
- idom[i] = di.dfs_to_bb[d]->index;
+ if (dir == CDI_DOMINATORS)
+ {
+ FOR_EACH_BB (bb)
+ {
+ if (!dominated_by_p (dir, bb, ENTRY_BLOCK_PTR))
+ {
+ error ("ENTRY does not dominate bb %d", bb->index);
+ err = 1;
+ }
}
}
- if (doms)
- idoms_to_doms (&di, doms);
- free_dom_info (&di);
+ gcc_assert (!err);
+}
+
+/* Determine immediate dominator (or postdominator, according to DIR) of BB,
+ assuming that dominators of other blocks are correct. We also use it to
+ recompute the dominators in a restricted area, by iterating it until it
+ reaches a fixed point. */
+
+basic_block
+recount_dominator (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ basic_block dom_bb = NULL;
+ edge e;
+ edge_iterator ei;
+
+ gcc_assert (dom_computed[dir_index]);
+
+ if (dir == CDI_DOMINATORS)
+ {
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ /* Ignore the predecessors that either are not reachable from
+ the entry block, or whose dominator was not determined yet. */
+ if (!dominated_by_p (dir, e->src, ENTRY_BLOCK_PTR))
+ continue;
+
+ if (!dominated_by_p (dir, e->src, bb))
+ dom_bb = nearest_common_dominator (dir, dom_bb, e->src);
+ }
+ }
+ else
+ {
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ if (!dominated_by_p (dir, e->dest, bb))
+ dom_bb = nearest_common_dominator (dir, dom_bb, e->dest);
+ }
+ }
+
+ return dom_bb;
+}
+
+/* Iteratively recount dominators of BBS. The change is supposed to be local
+ and not to grow further. */
+void
+iterate_fix_dominators (enum cdi_direction dir, basic_block *bbs, int n)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ int i, changed = 1;
+ basic_block old_dom, new_dom;
+
+ gcc_assert (dom_computed[dir_index]);
+
+ for (i = 0; i < n; i++)
+ set_immediate_dominator (dir, bbs[i], NULL);
+
+ while (changed)
+ {
+ changed = 0;
+ for (i = 0; i < n; i++)
+ {
+ old_dom = get_immediate_dominator (dir, bbs[i]);
+ new_dom = recount_dominator (dir, bbs[i]);
+ if (old_dom != new_dom)
+ {
+ changed = 1;
+ set_immediate_dominator (dir, bbs[i], new_dom);
+ }
+ }
+ }
+
+ for (i = 0; i < n; i++)
+ gcc_assert (get_immediate_dominator (dir, bbs[i]));
+}
+
+void
+add_to_dominance_info (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_assert (dom_computed[dir_index]);
+ gcc_assert (!bb->dom[dir_index]);
+
+ n_bbs_in_dom_tree[dir_index]++;
+
+ bb->dom[dir_index] = et_new_tree (bb);
+
+ if (dom_computed[dir_index] == DOM_OK)
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
+}
+
+void
+delete_from_dominance_info (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_assert (dom_computed[dir_index]);
+
+ et_free_tree (bb->dom[dir_index]);
+ bb->dom[dir_index] = NULL;
+ n_bbs_in_dom_tree[dir_index]--;
+
+ if (dom_computed[dir_index] == DOM_OK)
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
+}
+
+/* Returns the first son of BB in the dominator or postdominator tree
+ as determined by DIR. */
+
+basic_block
+first_dom_son (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *son = bb->dom[dir_index]->son;
+
+ return son ? son->data : NULL;
+}
+
+/* Returns the next dominance son after BB in the dominator or postdominator
+ tree as determined by DIR, or NULL if it was the last one. */
+
+basic_block
+next_dom_son (enum cdi_direction dir, basic_block bb)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *next = bb->dom[dir_index]->right;
+
+ return next->father->son == next ? NULL : next->data;
+}
+
+/* Return dominance availability for dominance info DIR. */
+
+enum dom_state
+dom_info_state (enum cdi_direction dir)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ return dom_computed[dir_index];
+}
+
+/* Set the dominance availability for dominance info DIR to NEW_STATE. */
+
+void
+set_dom_info_availability (enum cdi_direction dir, enum dom_state new_state)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ dom_computed[dir_index] = new_state;
+}
+
+/* Returns true if dominance information for direction DIR is available. */
+
+bool
+dom_info_available_p (enum cdi_direction dir)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ return dom_computed[dir_index] != DOM_NONE;
+}
+
+void
+debug_dominance_info (enum cdi_direction dir)
+{
+ basic_block bb, bb2;
+ FOR_EACH_BB (bb)
+ if ((bb2 = get_immediate_dominator (dir, bb)))
+ fprintf (stderr, "%i %i\n", bb->index, bb2->index);
}
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