/* Calculate (post)dominators in slightly super-linear time.
- Copyright (C) 2000, 2003, 2004 Free Software Foundation, Inc.
+ Copyright (C) 2000-2020 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)
+ the Free 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
License for more details.
You should have received a copy of the GNU General Public License
- along with GCC; see the file COPYING. If not, write to the Free
- Software Foundation, 59 Temple Place - Suite 330, Boston, MA
- 02111-1307, USA. */
+ along with GCC; see the file COPYING3. If not see
+ <http://www.gnu.org/licenses/>. */
/* 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 "basic-block.h"
-#include "errors.h"
+#include "backend.h"
+#include "timevar.h"
+#include "diagnostic-core.h"
+#include "cfganal.h"
#include "et-forest.h"
-
-/* Whether the dominators and the postdominators are available. */
-enum dom_state dom_computed[2];
+#include "graphds.h"
/* 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
- 'last_basic_block' 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;
-/* We work in a poor-mans object oriented fashion, and carry an instance of
- this structure through all our 'methods'. It holds various arrays
- reflecting the (sub)structure of the flowgraph. Most of them are of type
- TBB and are also indexed by TBB. */
+namespace {
+
+/* This class holds various arrays reflecting the (sub)structure of the
+ flowgraph. Most of them are of type TBB and are also indexed by TBB. */
-struct dom_info
+class dom_info
{
+public:
+ dom_info (function *, cdi_direction);
+ dom_info (vec <basic_block>, cdi_direction);
+ ~dom_info ();
+ void calc_dfs_tree ();
+ void calc_idoms ();
+
+ inline basic_block get_idom (basic_block);
+private:
+ void calc_dfs_tree_nonrec (basic_block);
+ void compress (TBB);
+ void dom_init (void);
+ TBB eval (TBB);
+ void link_roots (TBB, TBB);
+
/* The parent of a node in the DFS tree. */
- TBB *dfs_parent;
- /* For a node x key[x] is roughly the node nearest to the root from which
+ TBB *m_dfs_parent;
+ /* For a node x m_key[x] is roughly the node nearest to the root from which
exists a way to x only over nodes behind x. Such a node is also called
semidominator. */
- TBB *key;
- /* The value in path_min[x] is the node y on the path from x to the root of
- the tree x is in with the smallest key[y]. */
- TBB *path_min;
- /* bucket[x] points to the first node of the set of nodes having x as key. */
- TBB *bucket;
- /* And next_bucket[x] points to the next node. */
- TBB *next_bucket;
- /* After the algorithm is done, dom[x] contains the immediate dominator
+ TBB *m_key;
+ /* The value in m_path_min[x] is the node y on the path from x to the root of
+ the tree x is in with the smallest m_key[y]. */
+ TBB *m_path_min;
+ /* m_bucket[x] points to the first node of the set of nodes having x as
+ key. */
+ TBB *m_bucket;
+ /* And m_next_bucket[x] points to the next node. */
+ TBB *m_next_bucket;
+ /* After the algorithm is done, m_dom[x] contains the immediate dominator
of x. */
- TBB *dom;
+ TBB *m_dom;
/* The following few fields implement the structures needed for disjoint
sets. */
- /* set_chain[x] is the next node on the path from x to the representant
- of the set containing x. If set_chain[x]==0 then x is a root. */
- TBB *set_chain;
- /* set_size[x] is the number of elements in the set named by x. */
- unsigned int *set_size;
- /* set_child[x] is used for balancing the tree representing a set. It can
+ /* m_set_chain[x] is the next node on the path from x to the representative
+ of the set containing x. If m_set_chain[x]==0 then x is a root. */
+ TBB *m_set_chain;
+ /* m_set_size[x] is the number of elements in the set named by x. */
+ unsigned int *m_set_size;
+ /* m_set_child[x] is used for balancing the tree representing a set. It can
be understood as the next sibling of x. */
- TBB *set_child;
+ TBB *m_set_child;
- /* If b is the number of a basic block (BB->index), dfs_order[b] is the
+ /* If b is the number of a basic block (BB->index), m_dfs_order[b] is the
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;
+ TBB *m_dfs_order;
+ /* Points to last element in m_dfs_order array. */
+ TBB *m_dfs_last;
/* 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;
+ m_dfs_to_bb[x] is that basic block. Note, that in our structure there are
+ more nodes that basic blocks, so only
+ m_dfs_to_bb[m_dfs_order[bb->index]]==bb is true for every basic block bb,
+ but not the opposite. */
+ basic_block *m_dfs_to_bb;
/* 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;
+ unsigned int m_dfsnum;
+ /* The number of nodes in the DFS tree (==m_dfsnum-1). */
+ unsigned int m_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;
+ bitmap m_fake_exit_edge;
+
+ /* Number of basic blocks in the function being compiled. */
+ unsigned m_n_basic_blocks;
+
+ /* True, if we are computing postdominators (rather than dominators). */
+ bool m_reverse;
+
+ /* Start block (the entry block for forward problem, exit block for backward
+ problem). */
+ basic_block m_start_block;
+ /* Ending block. */
+ basic_block m_end_block;
};
-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,
- enum cdi_direction);
-static void calc_dfs_tree (struct dom_info *, enum cdi_direction);
-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 *, enum cdi_direction);
-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) = xcalloc ((num), sizeof (type)); \
- else \
- { \
- (var) = xmalloc ((num) * sizeof (type)); \
- for (i = 0; i < num; i++) \
- (var)[i] = (content); \
- } \
- } \
- while (0)
-
-/* Allocate all needed memory in a pessimistic fashion (so we round up).
- This initializes the contents of DI, which already must be allocated. */
+} // anonymous namespace
-static void
-init_dom_info (struct dom_info *di, enum cdi_direction dir)
+void debug_dominance_info (cdi_direction);
+void debug_dominance_tree (cdi_direction, basic_block);
+
+/* Allocate and zero-initialize NUM elements of type T (T must be a
+ POD-type). Note: after transition to C++11 or later,
+ `x = new_zero_array <T> (num);' can be replaced with
+ `x = new T[num] {};'. */
+
+template<typename T>
+inline T *new_zero_array (unsigned num)
{
- /* We need memory for n_basic_blocks nodes and the ENTRY_BLOCK or
- EXIT_BLOCK. */
- unsigned int num = n_basic_blocks + 1 + 1;
- 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->dom, TBB, num, 0);
+ T *result = new T[num];
+ memset (result, 0, sizeof (T) * num);
+ return result;
+}
- init_ar (di->bucket, TBB, num, 0);
- init_ar (di->next_bucket, TBB, num, 0);
+/* Helper function for constructors to initialize a part of class members. */
- init_ar (di->set_chain, TBB, num, 0);
- init_ar (di->set_size, unsigned int, num, 1);
- init_ar (di->set_child, TBB, num, 0);
+void
+dom_info::dom_init (void)
+{
+ unsigned num = m_n_basic_blocks;
- init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0);
- init_ar (di->dfs_to_bb, basic_block, num, 0);
+ m_dfs_parent = new_zero_array <TBB> (num);
+ m_dom = new_zero_array <TBB> (num);
+
+ m_path_min = new TBB[num];
+ m_key = new TBB[num];
+ m_set_size = new unsigned int[num];
+ for (unsigned i = 0; i < num; i++)
+ {
+ m_path_min[i] = m_key[i] = i;
+ m_set_size[i] = 1;
+ }
- di->dfsnum = 1;
- di->nodes = 0;
+ m_bucket = new_zero_array <TBB> (num);
+ m_next_bucket = new_zero_array <TBB> (num);
- di->fake_exit_edge = dir ? BITMAP_XMALLOC () : NULL;
-}
+ m_set_chain = new_zero_array <TBB> (num);
+ m_set_child = new_zero_array <TBB> (num);
-#undef init_ar
+ m_dfs_to_bb = new_zero_array <basic_block> (num);
-/* Free all allocated memory in DI, but not DI itself. */
+ m_dfsnum = 1;
+ m_nodes = 0;
+}
-static void
-free_dom_info (struct dom_info *di)
-{
- free (di->dfs_parent);
- free (di->path_min);
- free (di->key);
- free (di->dom);
- free (di->bucket);
- free (di->next_bucket);
- free (di->set_chain);
- free (di->set_size);
- free (di->set_child);
- free (di->dfs_order);
- free (di->dfs_to_bb);
- BITMAP_XFREE (di->fake_exit_edge);
-}
-
-/* The nonrecursive variant of creating a DFS tree. DI is our working
- structure, BB the starting basic block for this tree and REVERSE
- is true, if predecessors should be visited instead of successors of a
- node. After this is done all nodes reachable from BB were visited, have
- assigned their dfs number and are linked together to form a tree. */
+/* Allocate all needed memory in a pessimistic fashion (so we round up). */
-static void
-calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb,
- enum cdi_direction reverse)
+dom_info::dom_info (function *fn, cdi_direction dir)
{
- /* We call this _only_ if bb is not already visited. */
- edge e;
- TBB child_i, my_i = 0;
- edge *stack;
- int sp;
- /* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward
- problem). */
- basic_block en_block;
- /* Ending block. */
- basic_block ex_block;
+ m_n_basic_blocks = n_basic_blocks_for_fn (fn);
- stack = xmalloc ((n_basic_blocks + 3) * sizeof (edge));
- sp = 0;
+ dom_init ();
- /* Initialize our border blocks, and the first edge. */
- if (reverse)
+ unsigned last_bb_index = last_basic_block_for_fn (fn);
+ m_dfs_order = new_zero_array <TBB> (last_bb_index + 1);
+ m_dfs_last = &m_dfs_order[last_bb_index];
+
+ switch (dir)
{
- e = bb->pred;
- en_block = EXIT_BLOCK_PTR;
- ex_block = ENTRY_BLOCK_PTR;
+ case CDI_DOMINATORS:
+ m_reverse = false;
+ m_fake_exit_edge = NULL;
+ m_start_block = ENTRY_BLOCK_PTR_FOR_FN (fn);
+ m_end_block = EXIT_BLOCK_PTR_FOR_FN (fn);
+ break;
+ case CDI_POST_DOMINATORS:
+ m_reverse = true;
+ m_fake_exit_edge = BITMAP_ALLOC (NULL);
+ m_start_block = EXIT_BLOCK_PTR_FOR_FN (fn);
+ m_end_block = ENTRY_BLOCK_PTR_FOR_FN (fn);
+ break;
+ default:
+ gcc_unreachable ();
}
- else
+}
+
+/* Constructor for reducible region REGION. */
+
+dom_info::dom_info (vec<basic_block> region, cdi_direction dir)
+{
+ m_n_basic_blocks = region.length ();
+ unsigned nm1 = m_n_basic_blocks - 1;
+
+ dom_init ();
+
+ /* Determine max basic block index in region. */
+ int max_index = region[0]->index;
+ for (unsigned i = 1; i <= nm1; i++)
+ if (region[i]->index > max_index)
+ max_index = region[i]->index;
+ max_index += 1; /* set index on the first bb out of region. */
+
+ m_dfs_order = new_zero_array <TBB> (max_index + 1);
+ m_dfs_last = &m_dfs_order[max_index];
+
+ m_fake_exit_edge = NULL; /* Assume that region is reducible. */
+
+ switch (dir)
{
- e = bb->succ;
- en_block = ENTRY_BLOCK_PTR;
- ex_block = EXIT_BLOCK_PTR;
+ case CDI_DOMINATORS:
+ m_reverse = false;
+ m_start_block = region[0];
+ m_end_block = region[nm1];
+ break;
+ case CDI_POST_DOMINATORS:
+ m_reverse = true;
+ m_start_block = region[nm1];
+ m_end_block = region[0];
+ break;
+ default:
+ gcc_unreachable ();
}
+}
+
+inline basic_block
+dom_info::get_idom (basic_block bb)
+{
+ TBB d = m_dom[m_dfs_order[bb->index]];
+ return m_dfs_to_bb[d];
+}
+
+/* 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 inline unsigned int
+dom_convert_dir_to_idx (cdi_direction dir)
+{
+ gcc_checking_assert (dir == CDI_DOMINATORS || dir == CDI_POST_DOMINATORS);
+ return dir - 1;
+}
+
+/* Free all allocated memory in dom_info. */
+
+dom_info::~dom_info ()
+{
+ delete[] m_dfs_parent;
+ delete[] m_path_min;
+ delete[] m_key;
+ delete[] m_dom;
+ delete[] m_bucket;
+ delete[] m_next_bucket;
+ delete[] m_set_chain;
+ delete[] m_set_size;
+ delete[] m_set_child;
+ delete[] m_dfs_order;
+ delete[] m_dfs_to_bb;
+ BITMAP_FREE (m_fake_exit_edge);
+}
+
+/* The nonrecursive variant of creating a DFS tree. BB is the starting basic
+ block for this tree and m_reverse is true, if predecessors should be visited
+ instead of successors of a node. After this is done all nodes reachable
+ from BB were visited, have assigned their dfs number and are linked together
+ to form a tree. */
+
+void
+dom_info::calc_dfs_tree_nonrec (basic_block bb)
+{
+ edge_iterator *stack = new edge_iterator[m_n_basic_blocks + 1];
+ int sp = 0;
+ unsigned d_i = dom_convert_dir_to_idx (m_reverse ? CDI_POST_DOMINATORS
+ : CDI_DOMINATORS);
+
+ /* Initialize the first edge. */
+ edge_iterator ei = m_reverse ? ei_start (bb->preds)
+ : ei_start (bb->succs);
/* When the stack is empty we break out of this loop. */
while (1)
{
basic_block bn;
+ edge_iterator einext;
/* This loop traverses edges e in depth first manner, and fills the
stack. */
- while (e)
+ while (!ei_end_p (ei))
{
- edge e_next;
+ edge e = ei_edge (ei);
/* Deduce from E the current and the next block (BB and BN), and the
next edge. */
- if (reverse)
+ if (m_reverse)
{
bn = e->src;
/* If the next node BN is either already visited or a border
- block the current edge is useless, and simply overwritten
- with the next edge out of the current node. */
- if (bn == ex_block || di->dfs_order[bn->index])
+ block or out of region the current edge is useless, and simply
+ overwritten with the next edge out of the current node. */
+ if (bn == m_end_block || bn->dom[d_i] == NULL
+ || m_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])
+ if (bn == m_end_block || bn->dom[d_i] == NULL
+ || m_dfs_order[bn->index])
{
- e = e->succ_next;
+ ei_next (&ei);
continue;
}
bb = e->src;
- e_next = bn->succ;
+ einext = ei_start (bn->succs);
}
- gcc_assert (bn != en_block);
+ gcc_assert (bn != m_start_block);
/* Fill the DFS tree info calculatable _before_ recursing. */
- if (bb != en_block)
- my_i = di->dfs_order[bb->index];
+ TBB my_i;
+ if (bb != m_start_block)
+ my_i = m_dfs_order[bb->index];
else
- 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;
+ my_i = *m_dfs_last;
+ TBB child_i = m_dfs_order[bn->index] = m_dfsnum++;
+ m_dfs_to_bb[child_i] = bn;
+ m_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);
+ delete[] stack;
}
-/* The main entry for calculating the DFS tree or forest. DI is our working
- structure and REVERSE is true, if we are interested in the reverse flow
- graph. In that case the result is not necessarily a tree but a forest,
- because there may be nodes from which the EXIT_BLOCK is unreachable. */
+/* The main entry for calculating the DFS tree or forest. m_reverse is true,
+ if we are interested in the reverse flow graph. In that case the result is
+ not necessarily a tree but a forest, because there may be nodes from which
+ the EXIT_BLOCK is unreachable. */
-static void
-calc_dfs_tree (struct dom_info *di, enum cdi_direction reverse)
+void
+dom_info::calc_dfs_tree ()
{
- /* 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[last_basic_block] = di->dfsnum;
- di->dfs_to_bb[di->dfsnum] = begin;
- di->dfsnum++;
+ *m_dfs_last = m_dfsnum;
+ m_dfs_to_bb[m_dfsnum] = m_start_block;
+ m_dfsnum++;
- calc_dfs_tree_nonrec (di, begin, reverse);
+ calc_dfs_tree_nonrec (m_start_block);
- if (reverse)
+ if (m_fake_exit_edge)
{
/* 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
basic_block b;
bool saw_unconnected = false;
- FOR_EACH_BB_REVERSE (b)
+ FOR_BB_BETWEEN (b, m_start_block->prev_bb, m_end_block, prev_bb)
{
- if (b->succ)
+ if (EDGE_COUNT (b->succs) > 0)
{
- if (di->dfs_order[b->index] == 0)
+ if (m_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);
+ bitmap_set_bit (m_fake_exit_edge, b->index);
+ m_dfs_order[b->index] = m_dfsnum;
+ m_dfs_to_bb[m_dfsnum] = b;
+ m_dfs_parent[m_dfsnum] = *m_dfs_last;
+ m_dfsnum++;
+ calc_dfs_tree_nonrec (b);
}
if (saw_unconnected)
{
- FOR_EACH_BB_REVERSE (b)
+ FOR_BB_BETWEEN (b, m_start_block->prev_bb, m_end_block, prev_bb)
{
- if (di->dfs_order[b->index])
+ if (m_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);
+ basic_block b2 = dfs_find_deadend (b);
+ gcc_checking_assert (m_dfs_order[b2->index] == 0);
+ bitmap_set_bit (m_fake_exit_edge, b2->index);
+ m_dfs_order[b2->index] = m_dfsnum;
+ m_dfs_to_bb[m_dfsnum] = b2;
+ m_dfs_parent[m_dfsnum] = *m_dfs_last;
+ m_dfsnum++;
+ calc_dfs_tree_nonrec (b2);
+ gcc_checking_assert (m_dfs_order[b->index]);
}
}
}
- di->nodes = di->dfsnum - 1;
+ m_nodes = m_dfsnum - 1;
/* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */
- gcc_assert (di->nodes == (unsigned int) n_basic_blocks + 1);
+ gcc_assert (m_nodes == (unsigned int) m_n_basic_blocks - 1);
}
/* Compress the path from V to the root of its set and update path_min at the
in and path_min[V] is the node with the smallest key[] value on the path
from V to that root. */
-static void
-compress (struct dom_info *di, TBB v)
+void
+dom_info::compress (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).
Also performance wise compress() ranges _far_ behind eval(). */
- TBB parent = di->set_chain[v];
- if (di->set_chain[parent])
+ TBB parent = m_set_chain[v];
+ if (m_set_chain[parent])
{
- compress (di, parent);
- if (di->key[di->path_min[parent]] < di->key[di->path_min[v]])
- di->path_min[v] = di->path_min[parent];
- di->set_chain[v] = di->set_chain[parent];
+ compress (parent);
+ if (m_key[m_path_min[parent]] < m_key[m_path_min[v]])
+ m_path_min[v] = m_path_min[parent];
+ m_set_chain[v] = m_set_chain[parent];
}
}
changed since the last call). Returns the node with the smallest key[]
value on the path from V to the root. */
-static inline TBB
-eval (struct dom_info *di, TBB v)
+inline TBB
+dom_info::eval (TBB v)
{
- /* The representant of the set V is in, also called root (as the set
+ /* The representative of the set V is in, also called root (as the set
representation is a tree). */
- TBB rep = di->set_chain[v];
+ TBB rep = m_set_chain[v];
/* V itself is the root. */
if (!rep)
- return di->path_min[v];
+ return m_path_min[v];
/* Compress only if necessary. */
- if (di->set_chain[rep])
+ if (m_set_chain[rep])
{
- compress (di, v);
- rep = di->set_chain[v];
+ compress (v);
+ rep = m_set_chain[v];
}
- if (di->key[di->path_min[rep]] >= di->key[di->path_min[v]])
- return di->path_min[v];
+ if (m_key[m_path_min[rep]] >= m_key[m_path_min[v]])
+ return m_path_min[v];
else
- return di->path_min[rep];
+ return m_path_min[rep];
}
/* This essentially merges the two sets of V and W, giving a single set with
balanced tree. Currently link(V,W) is only used with V being the parent
of W. */
-static void
-link_roots (struct dom_info *di, TBB v, TBB w)
+void
+dom_info::link_roots (TBB v, TBB w)
{
TBB s = w;
/* Rebalance the tree. */
- while (di->key[di->path_min[w]] < di->key[di->path_min[di->set_child[s]]])
+ while (m_key[m_path_min[w]] < m_key[m_path_min[m_set_child[s]]])
{
- if (di->set_size[s] + di->set_size[di->set_child[di->set_child[s]]]
- >= 2 * di->set_size[di->set_child[s]])
+ if (m_set_size[s] + m_set_size[m_set_child[m_set_child[s]]]
+ >= 2 * m_set_size[m_set_child[s]])
{
- di->set_chain[di->set_child[s]] = s;
- di->set_child[s] = di->set_child[di->set_child[s]];
+ m_set_chain[m_set_child[s]] = s;
+ m_set_child[s] = m_set_child[m_set_child[s]];
}
else
{
- di->set_size[di->set_child[s]] = di->set_size[s];
- s = di->set_chain[s] = di->set_child[s];
+ m_set_size[m_set_child[s]] = m_set_size[s];
+ s = m_set_chain[s] = m_set_child[s];
}
}
- di->path_min[s] = di->path_min[w];
- di->set_size[v] += di->set_size[w];
- if (di->set_size[v] < 2 * di->set_size[w])
- {
- TBB tmp = s;
- s = di->set_child[v];
- di->set_child[v] = tmp;
- }
+ m_path_min[s] = m_path_min[w];
+ m_set_size[v] += m_set_size[w];
+ if (m_set_size[v] < 2 * m_set_size[w])
+ std::swap (m_set_child[v], s);
/* Merge all subtrees. */
while (s)
{
- di->set_chain[s] = v;
- s = di->set_child[s];
+ m_set_chain[s] = v;
+ s = m_set_child[s];
}
}
-/* This calculates the immediate dominators (or post-dominators if REVERSE is
- true). DI is our working structure and should hold the DFS forest.
- On return the immediate dominator to node V is in di->dom[V]. */
+/* This calculates the immediate dominators (or post-dominators). THIS is our
+ working structure and should hold the DFS forest.
+ On return the immediate dominator to node V is in m_dom[V]. */
-static void
-calc_idoms (struct dom_info *di, enum cdi_direction reverse)
+void
+dom_info::calc_idoms ()
{
- TBB v, w, k, par;
- basic_block en_block;
- if (reverse)
- en_block = EXIT_BLOCK_PTR;
- else
- en_block = ENTRY_BLOCK_PTR;
-
/* Go backwards in DFS order, to first look at the leafs. */
- v = di->nodes;
- while (v > 1)
+ for (TBB v = m_nodes; v > 1; v--)
{
- basic_block bb = di->dfs_to_bb[v];
- edge e, e_next;
+ basic_block bb = m_dfs_to_bb[v];
+ edge e;
- par = di->dfs_parent[v];
- k = v;
- if (reverse)
- {
- e = bb->succ;
+ TBB par = m_dfs_parent[v];
+ TBB k = v;
+
+ edge_iterator ei = m_reverse ? ei_start (bb->succs)
+ : ei_start (bb->preds);
+ edge_iterator einext;
+ if (m_fake_exit_edge)
+ {
/* If this block has a fake edge to exit, process that first. */
- if (bitmap_bit_p (di->fake_exit_edge, bb->index))
+ if (bitmap_bit_p (m_fake_exit_edge, bb->index))
{
- e_next = e;
+ einext = ei;
+ einext.index = 0;
goto do_fake_exit_edge;
}
}
- else
- e = bb->pred;
/* 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;
+ TBB k1;
- if (reverse)
- {
- b = e->dest;
- e_next = e->succ_next;
- }
- else
- {
- b = e->src;
- e_next = e->pred_next;
- }
- if (b == en_block)
+ e = ei_edge (ei);
+ b = m_reverse ? e->dest : e->src;
+ einext = ei;
+ ei_next (&einext);
+
+ if (b == m_start_block)
{
do_fake_exit_edge:
- k1 = di->dfs_order[last_basic_block];
+ k1 = *m_dfs_last;
}
else
- k1 = di->dfs_order[b->index];
+ k1 = m_dfs_order[b->index];
/* Call eval() only if really needed. If k1 is above V in DFS tree,
then we know, that eval(k1) == k1 and key[k1] == k1. */
if (k1 > v)
- k1 = di->key[eval (di, k1)];
+ k1 = m_key[eval (k1)];
if (k1 < k)
k = k1;
+
+ ei = einext;
}
- di->key[v] = k;
- link_roots (di, par, v);
- di->next_bucket[v] = di->bucket[k];
- di->bucket[k] = v;
+ m_key[v] = k;
+ link_roots (par, v);
+ m_next_bucket[v] = m_bucket[k];
+ m_bucket[k] = v;
/* Transform semidominators into dominators. */
- for (w = di->bucket[par]; w; w = di->next_bucket[w])
+ for (TBB w = m_bucket[par]; w; w = m_next_bucket[w])
{
- k = eval (di, w);
- if (di->key[k] < di->key[w])
- di->dom[w] = k;
+ k = eval (w);
+ if (m_key[k] < m_key[w])
+ m_dom[w] = k;
else
- di->dom[w] = par;
+ m_dom[w] = par;
}
/* We don't need to cleanup next_bucket[]. */
- di->bucket[par] = 0;
- v--;
+ m_bucket[par] = 0;
}
/* Explicitly define the dominators. */
- di->dom[1] = 0;
- for (v = 2; v <= di->nodes; v++)
- if (di->dom[v] != di->key[v])
- di->dom[v] = di->dom[di->dom[v]];
+ m_dom[1] = 0;
+ for (TBB v = 2; v <= m_nodes; v++)
+ if (m_dom[v] != m_key[v])
+ m_dom[v] = m_dom[m_dom[v]];
}
/* Assign dfs numbers starting from NUM to NODE and its sons. */
{
int num = 0;
basic_block bb;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_checking_assert (dom_info_available_p (dir));
+
+ if (dom_computed[dir_index] == DOM_OK)
+ return;
+
+ FOR_ALL_BB_FN (bb, cfun)
+ {
+ if (!bb->dom[dir_index]->father)
+ assign_dfs_numbers (bb->dom[dir_index], &num);
+ }
+
+ dom_computed[dir_index] = DOM_OK;
+}
+
+/* Analogous to the previous function but compute the data for reducible
+ region REGION. */
+
+static void
+compute_dom_fast_query_in_region (enum cdi_direction dir,
+ vec<basic_block> region)
+{
+ int num = 0;
+ basic_block bb;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
- gcc_assert (dom_computed[dir] >= DOM_NO_FAST_QUERY);
+ gcc_checking_assert (dom_info_available_p (dir));
- if (dom_computed[dir] == DOM_OK)
+ if (dom_computed[dir_index] == DOM_OK)
return;
- FOR_ALL_BB (bb)
+ /* Assign dfs numbers for region nodes except for entry and exit nodes. */
+ for (unsigned int i = 1; i < region.length () - 1; i++)
{
- if (!bb->dom[dir]->father)
- assign_dfs_numbers (bb->dom[dir], &num);
+ bb = region[i];
+ if (!bb->dom[dir_index]->father)
+ assign_dfs_numbers (bb->dom[dir_index], &num);
}
- dom_computed[dir] = DOM_OK;
+ 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)
+calculate_dominance_info (cdi_direction dir)
{
- struct dom_info di;
- basic_block b;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
- if (dom_computed[dir] == DOM_OK)
- return;
-
- if (dom_computed[dir] != DOM_NO_FAST_QUERY)
+ if (dom_computed[dir_index] == DOM_OK)
{
- if (dom_computed[dir] != DOM_NONE)
- free_dominance_info (dir);
+ checking_verify_dominators (dir);
+ return;
+ }
- gcc_assert (!n_bbs_in_dom_tree[dir]);
+ timevar_push (TV_DOMINANCE);
+ if (!dom_info_available_p (dir))
+ {
+ gcc_assert (!n_bbs_in_dom_tree[dir_index]);
- FOR_ALL_BB (b)
+ basic_block b;
+ FOR_ALL_BB_FN (b, cfun)
{
- b->dom[dir] = et_new_tree (b);
+ b->dom[dir_index] = et_new_tree (b);
}
- n_bbs_in_dom_tree[dir] = n_basic_blocks + 2;
+ n_bbs_in_dom_tree[dir_index] = n_basic_blocks_for_fn (cfun);
- init_dom_info (&di, dir);
- calc_dfs_tree (&di, dir);
- calc_idoms (&di, dir);
+ dom_info di (cfun, dir);
+ di.calc_dfs_tree ();
+ di.calc_idoms ();
- FOR_EACH_BB (b)
+ FOR_EACH_BB_FN (b, cfun)
{
- TBB d = di.dom[di.dfs_order[b->index]];
-
- if (di.dfs_to_bb[d])
- et_set_father (b->dom[dir], di.dfs_to_bb[d]->dom[dir]);
+ if (basic_block d = di.get_idom (b))
+ et_set_father (b->dom[dir_index], d->dom[dir_index]);
}
- free_dom_info (&di);
- dom_computed[dir] = DOM_NO_FAST_QUERY;
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
}
+ else
+ checking_verify_dominators (dir);
compute_dom_fast_query (dir);
+
+ timevar_pop (TV_DOMINANCE);
+}
+
+/* Analogous to the previous function but compute dominance info for regions
+ which are single entry, multiple exit regions for CDI_DOMINATORs and
+ multiple entry, single exit regions for CDI_POST_DOMINATORs. */
+
+void
+calculate_dominance_info_for_region (cdi_direction dir,
+ vec<basic_block> region)
+{
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ basic_block bb;
+ unsigned int i;
+
+ if (dom_computed[dir_index] == DOM_OK)
+ return;
+
+ timevar_push (TV_DOMINANCE);
+ /* Assume that dom info is not partially computed. */
+ gcc_assert (!dom_info_available_p (dir));
+
+ FOR_EACH_VEC_ELT (region, i, bb)
+ {
+ bb->dom[dir_index] = et_new_tree (bb);
+ }
+ dom_info di (region, dir);
+ di.calc_dfs_tree ();
+ di.calc_idoms ();
+
+ FOR_EACH_VEC_ELT (region, i, bb)
+ if (basic_block d = di.get_idom (bb))
+ et_set_father (bb->dom[dir_index], d->dom[dir_index]);
+
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
+ compute_dom_fast_query_in_region (dir, region);
+
+ timevar_pop (TV_DOMINANCE);
}
/* Free dominance information for direction DIR. */
+void
+free_dominance_info (function *fn, enum cdi_direction dir)
+{
+ basic_block bb;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ if (!dom_info_available_p (fn, dir))
+ return;
+
+ FOR_ALL_BB_FN (bb, fn)
+ {
+ et_free_tree_force (bb->dom[dir_index]);
+ bb->dom[dir_index] = NULL;
+ }
+ et_free_pools ();
+
+ fn->cfg->x_n_bbs_in_dom_tree[dir_index] = 0;
+
+ fn->cfg->x_dom_computed[dir_index] = DOM_NONE;
+}
+
void
free_dominance_info (enum cdi_direction dir)
+{
+ free_dominance_info (cfun, dir);
+}
+
+/* Free dominance information for direction DIR in region REGION. */
+
+void
+free_dominance_info_for_region (function *fn,
+ enum cdi_direction dir,
+ vec<basic_block> region)
{
basic_block bb;
+ unsigned int i;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
- if (!dom_computed[dir])
+ if (!dom_info_available_p (dir))
return;
- FOR_ALL_BB (bb)
+ FOR_EACH_VEC_ELT (region, i, bb)
{
- delete_from_dominance_info (dir, bb);
+ et_free_tree_force (bb->dom[dir_index]);
+ bb->dom[dir_index] = NULL;
}
+ et_free_pools ();
- /* If there are any nodes left, something is wrong. */
- gcc_assert (!n_bbs_in_dom_tree[dir]);
+ fn->cfg->x_dom_computed[dir_index] = DOM_NONE;
- dom_computed[dir] = DOM_NONE;
+ fn->cfg->x_n_bbs_in_dom_tree[dir_index] = 0;
}
/* Return the immediate dominator of basic block BB. */
basic_block
get_immediate_dominator (enum cdi_direction dir, basic_block bb)
{
- struct et_node *node = bb->dom[dir];
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *node = bb->dom[dir_index];
- gcc_assert (dom_computed[dir]);
+ gcc_checking_assert (dom_computed[dir_index]);
if (!node->father)
return NULL;
- return node->father->data;
+ return (basic_block) node->father->data;
}
/* Set the immediate dominator of the block possibly removing
existing edge. NULL can be used to remove any edge. */
-inline void
+void
set_immediate_dominator (enum cdi_direction dir, basic_block bb,
basic_block dominated_by)
{
- struct et_node *node = bb->dom[dir];
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *node = bb->dom[dir_index];
- gcc_assert (dom_computed[dir]);
+ gcc_checking_assert (dom_computed[dir_index]);
if (node->father)
{
}
if (dominated_by)
- et_set_father (node, dominated_by->dom[dir]);
+ et_set_father (node, dominated_by->dom[dir_index]);
- if (dom_computed[dir] == DOM_OK)
- dom_computed[dir] = DOM_NO_FAST_QUERY;
+ if (dom_computed[dir_index] == DOM_OK)
+ dom_computed[dir_index] = DOM_NO_FAST_QUERY;
}
-/* 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)
+/* Returns the list of basic blocks immediately dominated by BB, in the
+ direction DIR. */
+vec<basic_block>
+get_dominated_by (enum cdi_direction dir, basic_block bb)
{
- int n;
- struct et_node *node = bb->dom[dir], *son = node->son, *ason;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *node = bb->dom[dir_index], *son = node->son, *ason;
+ vec<basic_block> bbs = vNULL;
- gcc_assert (dom_computed[dir]);
+ gcc_checking_assert (dom_computed[dir_index]);
if (!son)
- {
- *bbs = NULL;
- return 0;
- }
+ return vNULL;
- for (ason = son->right, n = 1; ason != son; ason = ason->right)
- n++;
+ bbs.safe_push ((basic_block) son->data);
+ for (ason = son->right; ason != son; ason = ason->right)
+ bbs.safe_push ((basic_block) ason->data);
- *bbs = xmalloc (n * sizeof (basic_block));
- (*bbs)[0] = son->data;
- for (ason = son->right, n = 1; ason != son; ason = ason->right)
- (*bbs)[n++] = ason->data;
-
- return n;
+ return bbs;
}
-/* 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. */
+/* Returns the list of 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. */
-unsigned
+vec<basic_block>
get_dominated_by_region (enum cdi_direction dir, basic_block *region,
- unsigned n_region, basic_block *doms)
+ unsigned n_region)
{
- unsigned n_doms = 0, i;
+ unsigned i;
basic_block dom;
+ vec<basic_block> doms = vNULL;
for (i = 0; i < n_region; i++)
- region[i]->rbi->duplicated = 1;
+ 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->rbi->duplicated)
- doms[n_doms++] = dom;
+ if (!(dom->flags & BB_DUPLICATED))
+ doms.safe_push (dom);
for (i = 0; i < n_region; i++)
- region[i]->rbi->duplicated = 0;
+ region[i]->flags &= ~BB_DUPLICATED;
- return n_doms;
+ return doms;
+}
+
+/* Returns the list of basic blocks including BB dominated by BB, in the
+ direction DIR up to DEPTH in the dominator tree. The DEPTH of zero will
+ produce a vector containing all dominated blocks. The vector will be sorted
+ in preorder. */
+
+vec<basic_block>
+get_dominated_to_depth (enum cdi_direction dir, basic_block bb, int depth)
+{
+ vec<basic_block> bbs = vNULL;
+ unsigned i;
+ unsigned next_level_start;
+
+ i = 0;
+ bbs.safe_push (bb);
+ next_level_start = 1; /* = bbs.length (); */
+
+ do
+ {
+ basic_block son;
+
+ bb = bbs[i++];
+ for (son = first_dom_son (dir, bb);
+ son;
+ son = next_dom_son (dir, son))
+ bbs.safe_push (son);
+
+ if (i == next_level_start && --depth)
+ next_level_start = bbs.length ();
+ }
+ while (i < next_level_start);
+
+ return bbs;
+}
+
+/* Returns the list of basic blocks including BB dominated by BB, in the
+ direction DIR. The vector will be sorted in preorder. */
+
+vec<basic_block>
+get_all_dominated_blocks (enum cdi_direction dir, basic_block bb)
+{
+ return get_dominated_to_depth (dir, bb, 0);
}
/* Redirect all edges pointing to BB to TO. */
redirect_immediate_dominators (enum cdi_direction dir, basic_block bb,
basic_block to)
{
- struct et_node *bb_node = bb->dom[dir], *to_node = to->dom[dir], *son;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *bb_node, *to_node, *son;
- gcc_assert (dom_computed[dir]);
+ bb_node = bb->dom[dir_index];
+ to_node = to->dom[dir_index];
+
+ gcc_checking_assert (dom_computed[dir_index]);
if (!bb_node->son)
return;
et_set_father (son, to_node);
}
- if (dom_computed[dir] == DOM_OK)
- dom_computed[dir] = DOM_NO_FAST_QUERY;
+ 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)
{
- gcc_assert (dom_computed[dir]);
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_checking_assert (dom_computed[dir_index]);
if (!bb1)
return bb2;
if (!bb2)
return bb1;
- return et_nca (bb1->dom[dir], bb2->dom[dir])->data;
+ return (basic_block) 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_FOR_FN (cfun, first);
+ EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
+ if (dom != BASIC_BLOCK_FOR_FN (cfun, i))
+ dom = nearest_common_dominator (dir, dom, BASIC_BLOCK_FOR_FN (cfun, 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(B)
+ && 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)
-{
- struct et_node *n1 = bb1->dom[dir], *n2 = bb2->dom[dir];
+dominated_by_p (enum cdi_direction dir, const_basic_block bb1, const_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]);
+ gcc_checking_assert (dom_computed[dir_index]);
- if (dom_computed[dir] == DOM_OK)
+ 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_checking_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_checking_assert (dom_computed[dir_index] == DOM_OK);
+ return n->dfs_num_out;
+}
+
/* Verify invariants of dominator structure. */
-void
-verify_dominators (enum cdi_direction dir)
+DEBUG_FUNCTION void
+verify_dominators (cdi_direction dir)
{
- int err = 0;
- basic_block bb;
+ gcc_assert (dom_info_available_p (dir));
- gcc_assert (dom_computed[dir]);
+ dom_info di (cfun, dir);
+ di.calc_dfs_tree ();
+ di.calc_idoms ();
- FOR_EACH_BB (bb)
+ bool err = false;
+ basic_block bb;
+ FOR_EACH_BB_FN (bb, cfun)
{
- 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 imm_bb = get_immediate_dominator (dir, bb);
+ if (!imm_bb)
{
- 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;
+ error ("dominator of %d status unknown", bb->index);
+ err = true;
+ continue;
}
- }
- if (dir == CDI_DOMINATORS
- && dom_computed[dir] >= DOM_NO_FAST_QUERY)
- {
- FOR_EACH_BB (bb)
+ basic_block imm_bb_correct = di.get_idom (bb);
+ if (imm_bb != imm_bb_correct)
{
- if (!dominated_by_p (dir, bb, ENTRY_BLOCK_PTR))
- {
- error ("ENTRY does not dominate bb %d", bb->index);
- err = 1;
- }
+ error ("dominator of %d should be %d, not %d",
+ bb->index, imm_bb_correct->index, imm_bb->index);
+ err = true;
}
}
reaches a fixed point. */
basic_block
-recount_dominator (enum cdi_direction dir, basic_block bb)
+recompute_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]);
+ gcc_checking_assert (dom_computed[dir_index]);
if (dir == CDI_DOMINATORS)
{
- for (e = bb->pred; e; e = e->pred_next)
+ 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 (e = bb->succ; e; e = e->succ_next)
+ 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)
+/* Use simple heuristics (see iterate_fix_dominators) to determine dominators
+ of BBS. We assume that all the immediate dominators except for those of the
+ blocks in BBS are correct. If CONSERVATIVE is true, we also assume that the
+ currently recorded immediate dominators of blocks in BBS really dominate the
+ blocks. The basic blocks for that we determine the dominator are removed
+ from BBS. */
+
+static void
+prune_bbs_to_update_dominators (vec<basic_block> bbs,
+ bool conservative)
{
- int i, changed = 1;
- basic_block old_dom, new_dom;
+ unsigned i;
+ bool single;
+ basic_block bb, dom = NULL;
+ edge_iterator ei;
+ edge e;
+
+ for (i = 0; bbs.iterate (i, &bb);)
+ {
+ if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
+ goto succeed;
+
+ if (single_pred_p (bb))
+ {
+ set_immediate_dominator (CDI_DOMINATORS, bb, single_pred (bb));
+ goto succeed;
+ }
+
+ if (!conservative)
+ goto fail;
+
+ single = true;
+ dom = NULL;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ if (dominated_by_p (CDI_DOMINATORS, e->src, bb))
+ continue;
+
+ if (!dom)
+ dom = e->src;
+ else
+ {
+ single = false;
+ dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src);
+ }
+ }
+
+ gcc_assert (dom != NULL);
+ if (single
+ || find_edge (dom, bb))
+ {
+ set_immediate_dominator (CDI_DOMINATORS, bb, dom);
+ goto succeed;
+ }
+
+fail:
+ i++;
+ continue;
+
+succeed:
+ bbs.unordered_remove (i);
+ }
+}
+
+/* Returns root of the dominance tree in the direction DIR that contains
+ BB. */
+
+static basic_block
+root_of_dom_tree (enum cdi_direction dir, basic_block bb)
+{
+ return (basic_block) et_root (bb->dom[dom_convert_dir_to_idx (dir)])->data;
+}
+
+/* See the comment in iterate_fix_dominators. Finds the immediate dominators
+ for the sons of Y, found using the SON and BROTHER arrays representing
+ the dominance tree of graph G. BBS maps the vertices of G to the basic
+ blocks. */
+
+static void
+determine_dominators_for_sons (struct graph *g, vec<basic_block> bbs,
+ int y, int *son, int *brother)
+{
+ bitmap gprime;
+ int i, a, nc;
+ vec<int> *sccs;
+ basic_block bb, dom, ybb;
+ unsigned si;
+ edge e;
+ edge_iterator ei;
+
+ if (son[y] == -1)
+ return;
+ if (y == (int) bbs.length ())
+ ybb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
+ else
+ ybb = bbs[y];
+
+ if (brother[son[y]] == -1)
+ {
+ /* Handle the common case Y has just one son specially. */
+ bb = bbs[son[y]];
+ set_immediate_dominator (CDI_DOMINATORS, bb,
+ recompute_dominator (CDI_DOMINATORS, bb));
+ identify_vertices (g, y, son[y]);
+ return;
+ }
+
+ gprime = BITMAP_ALLOC (NULL);
+ for (a = son[y]; a != -1; a = brother[a])
+ bitmap_set_bit (gprime, a);
- gcc_assert (dom_computed[dir]);
+ nc = graphds_scc (g, gprime);
+ BITMAP_FREE (gprime);
- for (i = 0; i < n; i++)
- set_immediate_dominator (dir, bbs[i], NULL);
+ /* ??? Needed to work around the pre-processor confusion with
+ using a multi-argument template type as macro argument. */
+ typedef vec<int> vec_int_heap;
+ sccs = XCNEWVEC (vec_int_heap, nc);
+ for (a = son[y]; a != -1; a = brother[a])
+ sccs[g->vertices[a].component].safe_push (a);
- while (changed)
+ for (i = nc - 1; i >= 0; i--)
{
- changed = 0;
- for (i = 0; i < n; i++)
+ dom = NULL;
+ FOR_EACH_VEC_ELT (sccs[i], si, a)
{
- old_dom = get_immediate_dominator (dir, bbs[i]);
- new_dom = recount_dominator (dir, bbs[i]);
- if (old_dom != new_dom)
+ bb = bbs[a];
+ FOR_EACH_EDGE (e, ei, bb->preds)
{
- changed = 1;
- set_immediate_dominator (dir, bbs[i], new_dom);
+ if (root_of_dom_tree (CDI_DOMINATORS, e->src) != ybb)
+ continue;
+
+ dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src);
}
}
+
+ gcc_assert (dom != NULL);
+ FOR_EACH_VEC_ELT (sccs[i], si, a)
+ {
+ bb = bbs[a];
+ set_immediate_dominator (CDI_DOMINATORS, bb, dom);
+ }
}
- for (i = 0; i < n; i++)
- gcc_assert (get_immediate_dominator (dir, bbs[i]));
+ for (i = 0; i < nc; i++)
+ sccs[i].release ();
+ free (sccs);
+
+ for (a = son[y]; a != -1; a = brother[a])
+ identify_vertices (g, y, a);
+}
+
+/* Recompute dominance information for basic blocks in the set BBS. The
+ function assumes that the immediate dominators of all the other blocks
+ in CFG are correct, and that there are no unreachable blocks.
+
+ If CONSERVATIVE is true, we additionally assume that all the ancestors of
+ a block of BBS in the current dominance tree dominate it. */
+
+void
+iterate_fix_dominators (enum cdi_direction dir, vec<basic_block> bbs,
+ bool conservative)
+{
+ unsigned i;
+ basic_block bb, dom;
+ struct graph *g;
+ int n, y;
+ size_t dom_i;
+ edge e;
+ edge_iterator ei;
+ int *parent, *son, *brother;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ /* We only support updating dominators. There are some problems with
+ updating postdominators (need to add fake edges from infinite loops
+ and noreturn functions), and since we do not currently use
+ iterate_fix_dominators for postdominators, any attempt to handle these
+ problems would be unused, untested, and almost surely buggy. We keep
+ the DIR argument for consistency with the rest of the dominator analysis
+ interface. */
+ gcc_checking_assert (dir == CDI_DOMINATORS && dom_computed[dir_index]);
+
+ /* The algorithm we use takes inspiration from the following papers, although
+ the details are quite different from any of them:
+
+ [1] G. Ramalingam, T. Reps, An Incremental Algorithm for Maintaining the
+ Dominator Tree of a Reducible Flowgraph
+ [2] V. C. Sreedhar, G. R. Gao, Y.-F. Lee: Incremental computation of
+ dominator trees
+ [3] K. D. Cooper, T. J. Harvey and K. Kennedy: A Simple, Fast Dominance
+ Algorithm
+
+ First, we use the following heuristics to decrease the size of the BBS
+ set:
+ a) if BB has a single predecessor, then its immediate dominator is this
+ predecessor
+ additionally, if CONSERVATIVE is true:
+ b) if all the predecessors of BB except for one (X) are dominated by BB,
+ then X is the immediate dominator of BB
+ c) if the nearest common ancestor of the predecessors of BB is X and
+ X -> BB is an edge in CFG, then X is the immediate dominator of BB
+
+ Then, we need to establish the dominance relation among the basic blocks
+ in BBS. We split the dominance tree by removing the immediate dominator
+ edges from BBS, creating a forest F. We form a graph G whose vertices
+ are BBS and ENTRY and X -> Y is an edge of G if there exists an edge
+ X' -> Y in CFG such that X' belongs to the tree of the dominance forest
+ whose root is X. We then determine dominance tree of G. Note that
+ for X, Y in BBS, X dominates Y in CFG if and only if X dominates Y in G.
+ In this step, we can use arbitrary algorithm to determine dominators.
+ We decided to prefer the algorithm [3] to the algorithm of
+ Lengauer and Tarjan, since the set BBS is usually small (rarely exceeding
+ 10 during gcc bootstrap), and [3] should perform better in this case.
+
+ Finally, we need to determine the immediate dominators for the basic
+ blocks of BBS. If the immediate dominator of X in G is Y, then
+ the immediate dominator of X in CFG belongs to the tree of F rooted in
+ Y. We process the dominator tree T of G recursively, starting from leaves.
+ Suppose that X_1, X_2, ..., X_k are the sons of Y in T, and that the
+ subtrees of the dominance tree of CFG rooted in X_i are already correct.
+ Let G' be the subgraph of G induced by {X_1, X_2, ..., X_k}. We make
+ the following observations:
+ (i) the immediate dominator of all blocks in a strongly connected
+ component of G' is the same
+ (ii) if X has no predecessors in G', then the immediate dominator of X
+ is the nearest common ancestor of the predecessors of X in the
+ subtree of F rooted in Y
+ Therefore, it suffices to find the topological ordering of G', and
+ process the nodes X_i in this order using the rules (i) and (ii).
+ Then, we contract all the nodes X_i with Y in G, so that the further
+ steps work correctly. */
+
+ if (!conservative)
+ {
+ /* Split the tree now. If the idoms of blocks in BBS are not
+ conservatively correct, setting the dominators using the
+ heuristics in prune_bbs_to_update_dominators could
+ create cycles in the dominance "tree", and cause ICE. */
+ FOR_EACH_VEC_ELT (bbs, i, bb)
+ set_immediate_dominator (CDI_DOMINATORS, bb, NULL);
+ }
+
+ prune_bbs_to_update_dominators (bbs, conservative);
+ n = bbs.length ();
+
+ if (n == 0)
+ return;
+
+ if (n == 1)
+ {
+ bb = bbs[0];
+ set_immediate_dominator (CDI_DOMINATORS, bb,
+ recompute_dominator (CDI_DOMINATORS, bb));
+ return;
+ }
+
+ timevar_push (TV_DOMINANCE);
+
+ /* Construct the graph G. */
+ hash_map<basic_block, int> map (251);
+ FOR_EACH_VEC_ELT (bbs, i, bb)
+ {
+ /* If the dominance tree is conservatively correct, split it now. */
+ if (conservative)
+ set_immediate_dominator (CDI_DOMINATORS, bb, NULL);
+ map.put (bb, i);
+ }
+ map.put (ENTRY_BLOCK_PTR_FOR_FN (cfun), n);
+
+ g = new_graph (n + 1);
+ for (y = 0; y < g->n_vertices; y++)
+ g->vertices[y].data = BITMAP_ALLOC (NULL);
+ FOR_EACH_VEC_ELT (bbs, i, bb)
+ {
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ dom = root_of_dom_tree (CDI_DOMINATORS, e->src);
+ if (dom == bb)
+ continue;
+
+ dom_i = *map.get (dom);
+
+ /* Do not include parallel edges to G. */
+ if (!bitmap_set_bit ((bitmap) g->vertices[dom_i].data, i))
+ continue;
+
+ add_edge (g, dom_i, i);
+ }
+ }
+ for (y = 0; y < g->n_vertices; y++)
+ BITMAP_FREE (g->vertices[y].data);
+
+ /* Find the dominator tree of G. */
+ son = XNEWVEC (int, n + 1);
+ brother = XNEWVEC (int, n + 1);
+ parent = XNEWVEC (int, n + 1);
+ graphds_domtree (g, n, parent, son, brother);
+
+ /* Finally, traverse the tree and find the immediate dominators. */
+ for (y = n; son[y] != -1; y = son[y])
+ continue;
+ while (y != -1)
+ {
+ determine_dominators_for_sons (g, bbs, y, son, brother);
+
+ if (brother[y] != -1)
+ {
+ y = brother[y];
+ while (son[y] != -1)
+ y = son[y];
+ }
+ else
+ y = parent[y];
+ }
+
+ free (son);
+ free (brother);
+ free (parent);
+
+ free_graph (g);
+
+ timevar_pop (TV_DOMINANCE);
}
void
add_to_dominance_info (enum cdi_direction dir, basic_block bb)
{
- gcc_assert (dom_computed[dir]);
- gcc_assert (!bb->dom[dir]);
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+
+ gcc_checking_assert (dom_computed[dir_index] && !bb->dom[dir_index]);
+
+ n_bbs_in_dom_tree[dir_index]++;
- n_bbs_in_dom_tree[dir]++;
-
- bb->dom[dir] = et_new_tree (bb);
+ bb->dom[dir_index] = et_new_tree (bb);
- if (dom_computed[dir] == DOM_OK)
- dom_computed[dir] = DOM_NO_FAST_QUERY;
+ 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)
{
- gcc_assert (dom_computed[dir]);
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
- et_free_tree (bb->dom[dir]);
- bb->dom[dir] = NULL;
- n_bbs_in_dom_tree[dir]--;
+ gcc_checking_assert (dom_computed[dir_index]);
- if (dom_computed[dir] == DOM_OK)
- dom_computed[dir] = DOM_NO_FAST_QUERY;
+ 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
basic_block
first_dom_son (enum cdi_direction dir, basic_block bb)
{
- struct et_node *son = bb->dom[dir]->son;
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ struct et_node *son = bb->dom[dir_index]->son;
- return son ? son->data : NULL;
+ return (basic_block) (son ? son->data : NULL);
}
/* Returns the next dominance son after BB in the dominator or postdominator
basic_block
next_dom_son (enum cdi_direction dir, basic_block bb)
{
- struct et_node *next = bb->dom[dir]->right;
+ 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 (basic_block) (next->father->son == next ? NULL : next->data);
}
+/* Return dominance availability for dominance info DIR. */
+
+enum dom_state
+dom_info_state (function *fn, enum cdi_direction dir)
+{
+ if (!fn->cfg)
+ return DOM_NONE;
+
+ unsigned int dir_index = dom_convert_dir_to_idx (dir);
+ return fn->cfg->x_dom_computed[dir_index];
+}
+
+enum dom_state
+dom_info_state (enum cdi_direction dir)
+{
+ return dom_info_state (cfun, dir);
+}
+
+/* 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 (function *fn, enum cdi_direction dir)
+{
+ return dom_info_state (fn, dir) != DOM_NONE;
+}
+
+bool
+dom_info_available_p (enum cdi_direction dir)
+{
+ return dom_info_available_p (cfun, dir);
+}
+
+DEBUG_FUNCTION void
debug_dominance_info (enum cdi_direction dir)
{
basic_block bb, bb2;
- FOR_EACH_BB (bb)
+ FOR_EACH_BB_FN (bb, cfun)
if ((bb2 = get_immediate_dominator (dir, bb)))
fprintf (stderr, "%i %i\n", bb->index, bb2->index);
}
+
+/* Prints to stderr representation of the dominance tree (for direction DIR)
+ rooted in ROOT, indented by INDENT tabulators. If INDENT_FIRST is false,
+ the first line of the output is not indented. */
+
+static void
+debug_dominance_tree_1 (enum cdi_direction dir, basic_block root,
+ unsigned indent, bool indent_first)
+{
+ basic_block son;
+ unsigned i;
+ bool first = true;
+
+ if (indent_first)
+ for (i = 0; i < indent; i++)
+ fprintf (stderr, "\t");
+ fprintf (stderr, "%d\t", root->index);
+
+ for (son = first_dom_son (dir, root);
+ son;
+ son = next_dom_son (dir, son))
+ {
+ debug_dominance_tree_1 (dir, son, indent + 1, !first);
+ first = false;
+ }
+
+ if (first)
+ fprintf (stderr, "\n");
+}
+
+/* Prints to stderr representation of the dominance tree (for direction DIR)
+ rooted in ROOT. */
+
+DEBUG_FUNCTION void
+debug_dominance_tree (enum cdi_direction dir, basic_block root)
+{
+ debug_dominance_tree_1 (dir, root, 0, false);
+}
projects / thirdparty / gcc.git / blobdiff