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gcc/gcc/et-forest.c

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/* ET-trees data structure implementation.
Contributed by Pavel Nejedly
Copyright (C) 2002-2019 Free Software Foundation, Inc.
This file is part of the libiberty library.
Libiberty is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
Libiberty is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with libiberty; see the file COPYING3. If not see
<http://www.gnu.org/licenses/>.
The ET-forest structure is described in:
D. D. Sleator and R. E. Tarjan. A data structure for dynamic trees.
J. G'omput. System Sci., 26(3):362 381, 1983.
*/
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "alloc-pool.h"
#include "et-forest.h"
#include "selftest.h"
/* We do not enable this with CHECKING_P, since it is awfully slow. */
#undef DEBUG_ET
#ifdef DEBUG_ET
#include "backend.h"
#include "hard-reg-set.h"
#endif
/* The occurrence of a node in the et tree. */
struct et_occ
{
struct et_node *of; /* The node. */
struct et_occ *parent; /* Parent in the splay-tree. */
struct et_occ *prev; /* Left son in the splay-tree. */
struct et_occ *next; /* Right son in the splay-tree. */
int depth; /* The depth of the node is the sum of depth
fields on the path to the root. */
int min; /* The minimum value of the depth in the subtree
is obtained by adding sum of depth fields
on the path to the root. */
struct et_occ *min_occ; /* The occurrence in the subtree with the minimal
depth. */
};
static object_allocator<et_node> et_nodes ("et_nodes pool");
static object_allocator<et_occ> et_occurrences ("et_occ pool");
/* Changes depth of OCC to D. */
static inline void
set_depth (struct et_occ *occ, int d)
{
if (!occ)
return;
occ->min += d - occ->depth;
occ->depth = d;
}
/* Adds D to the depth of OCC. */
static inline void
set_depth_add (struct et_occ *occ, int d)
{
if (!occ)
return;
occ->min += d;
occ->depth += d;
}
/* Sets prev field of OCC to P. */
static inline void
set_prev (struct et_occ *occ, struct et_occ *t)
{
#ifdef DEBUG_ET
gcc_assert (occ != t);
#endif
occ->prev = t;
if (t)
t->parent = occ;
}
/* Sets next field of OCC to P. */
static inline void
set_next (struct et_occ *occ, struct et_occ *t)
{
#ifdef DEBUG_ET
gcc_assert (occ != t);
#endif
occ->next = t;
if (t)
t->parent = occ;
}
/* Recompute minimum for occurrence OCC. */
static inline void
et_recomp_min (struct et_occ *occ)
{
struct et_occ *mson = occ->prev;
if (!mson
|| (occ->next
&& mson->min > occ->next->min))
mson = occ->next;
if (mson && mson->min < 0)
{
occ->min = mson->min + occ->depth;
occ->min_occ = mson->min_occ;
}
else
{
occ->min = occ->depth;
occ->min_occ = occ;
}
}
#ifdef DEBUG_ET
/* Checks whether neighborhood of OCC seems sane. */
static void
et_check_occ_sanity (struct et_occ *occ)
{
if (!occ)
return;
gcc_assert (occ->parent != occ);
gcc_assert (occ->prev != occ);
gcc_assert (occ->next != occ);
gcc_assert (!occ->next || occ->next != occ->prev);
if (occ->next)
{
gcc_assert (occ->next != occ->parent);
gcc_assert (occ->next->parent == occ);
}
if (occ->prev)
{
gcc_assert (occ->prev != occ->parent);
gcc_assert (occ->prev->parent == occ);
}
gcc_assert (!occ->parent
|| occ->parent->prev == occ
|| occ->parent->next == occ);
}
/* Checks whether tree rooted at OCC is sane. */
static void
et_check_sanity (struct et_occ *occ)
{
et_check_occ_sanity (occ);
if (occ->prev)
et_check_sanity (occ->prev);
if (occ->next)
et_check_sanity (occ->next);
}
/* Checks whether tree containing OCC is sane. */
static void
et_check_tree_sanity (struct et_occ *occ)
{
while (occ->parent)
occ = occ->parent;
et_check_sanity (occ);
}
/* For recording the paths. */
/* An ad-hoc constant; if the function has more blocks, this won't work,
but since it is used for debugging only, it does not matter. */
#define MAX_NODES 100000
static int len;
static void *datas[MAX_NODES];
static int depths[MAX_NODES];
/* Records the path represented by OCC, with depth incremented by DEPTH. */
static int
record_path_before_1 (struct et_occ *occ, int depth)
{
int mn, m;
depth += occ->depth;
mn = depth;
if (occ->prev)
{
m = record_path_before_1 (occ->prev, depth);
if (m < mn)
mn = m;
}
fprintf (stderr, "%d (%d); ", ((basic_block) occ->of->data)->index, depth);
gcc_assert (len < MAX_NODES);
depths[len] = depth;
datas[len] = occ->of;
len++;
if (occ->next)
{
m = record_path_before_1 (occ->next, depth);
if (m < mn)
mn = m;
}
gcc_assert (mn == occ->min + depth - occ->depth);
return mn;
}
/* Records the path represented by a tree containing OCC. */
static void
record_path_before (struct et_occ *occ)
{
while (occ->parent)
occ = occ->parent;
len = 0;
record_path_before_1 (occ, 0);
fprintf (stderr, "\n");
}
/* Checks whether the path represented by OCC, with depth incremented by DEPTH,
was not changed since the last recording. */
static int
check_path_after_1 (struct et_occ *occ, int depth)
{
int mn, m;
depth += occ->depth;
mn = depth;
if (occ->next)
{
m = check_path_after_1 (occ->next, depth);
if (m < mn)
mn = m;
}
len--;
gcc_assert (depths[len] == depth && datas[len] == occ->of);
if (occ->prev)
{
m = check_path_after_1 (occ->prev, depth);
if (m < mn)
mn = m;
}
gcc_assert (mn == occ->min + depth - occ->depth);
return mn;
}
/* Checks whether the path represented by a tree containing OCC was
not changed since the last recording. */
static void
check_path_after (struct et_occ *occ)
{
while (occ->parent)
occ = occ->parent;
check_path_after_1 (occ, 0);
gcc_assert (!len);
}
#endif
/* Splay the occurrence OCC to the root of the tree. */
static void
et_splay (struct et_occ *occ)
{
struct et_occ *f, *gf, *ggf;
int occ_depth, f_depth, gf_depth;
#ifdef DEBUG_ET
record_path_before (occ);
et_check_tree_sanity (occ);
#endif
while (occ->parent)
{
occ_depth = occ->depth;
f = occ->parent;
f_depth = f->depth;
gf = f->parent;
if (!gf)
{
set_depth_add (occ, f_depth);
occ->min_occ = f->min_occ;
occ->min = f->min;
if (f->prev == occ)
{
/* zig */
set_prev (f, occ->next);
set_next (occ, f);
set_depth_add (f->prev, occ_depth);
}
else
{
/* zag */
set_next (f, occ->prev);
set_prev (occ, f);
set_depth_add (f->next, occ_depth);
}
set_depth (f, -occ_depth);
occ->parent = NULL;
et_recomp_min (f);
#ifdef DEBUG_ET
et_check_tree_sanity (occ);
check_path_after (occ);
#endif
return;
}
gf_depth = gf->depth;
set_depth_add (occ, f_depth + gf_depth);
occ->min_occ = gf->min_occ;
occ->min = gf->min;
ggf = gf->parent;
if (gf->prev == f)
{
if (f->prev == occ)
{
/* zig zig */
set_prev (gf, f->next);
set_prev (f, occ->next);
set_next (occ, f);
set_next (f, gf);
set_depth (f, -occ_depth);
set_depth_add (f->prev, occ_depth);
set_depth (gf, -f_depth);
set_depth_add (gf->prev, f_depth);
}
else
{
/* zag zig */
set_prev (gf, occ->next);
set_next (f, occ->prev);
set_prev (occ, f);
set_next (occ, gf);
set_depth (f, -occ_depth);
set_depth_add (f->next, occ_depth);
set_depth (gf, -occ_depth - f_depth);
set_depth_add (gf->prev, occ_depth + f_depth);
}
}
else
{
if (f->prev == occ)
{
/* zig zag */
set_next (gf, occ->prev);
set_prev (f, occ->next);
set_prev (occ, gf);
set_next (occ, f);
set_depth (f, -occ_depth);
set_depth_add (f->prev, occ_depth);
set_depth (gf, -occ_depth - f_depth);
set_depth_add (gf->next, occ_depth + f_depth);
}
else
{
/* zag zag */
set_next (gf, f->prev);
set_next (f, occ->prev);
set_prev (occ, f);
set_prev (f, gf);
set_depth (f, -occ_depth);
set_depth_add (f->next, occ_depth);
set_depth (gf, -f_depth);
set_depth_add (gf->next, f_depth);
}
}
occ->parent = ggf;
if (ggf)
{
if (ggf->prev == gf)
ggf->prev = occ;
else
ggf->next = occ;
}
et_recomp_min (gf);
et_recomp_min (f);
#ifdef DEBUG_ET
et_check_tree_sanity (occ);
#endif
}
#ifdef DEBUG_ET
et_check_sanity (occ);
check_path_after (occ);
#endif
}
/* Create a new et tree occurrence of NODE. */
static struct et_occ *
et_new_occ (struct et_node *node)
{
et_occ *nw = et_occurrences.allocate ();
nw->of = node;
nw->parent = NULL;
nw->prev = NULL;
nw->next = NULL;
nw->depth = 0;
nw->min_occ = nw;
nw->min = 0;
return nw;
}
/* Create a new et tree containing DATA. */
struct et_node *
et_new_tree (void *data)
{
et_node *nw = et_nodes.allocate ();
nw->data = data;
nw->father = NULL;
nw->left = NULL;
nw->right = NULL;
nw->son = NULL;
nw->rightmost_occ = et_new_occ (nw);
nw->parent_occ = NULL;
return nw;
}
/* Releases et tree T. */
void
et_free_tree (struct et_node *t)
{
while (t->son)
et_split (t->son);
if (t->father)
et_split (t);
et_occurrences.remove (t->rightmost_occ);
et_nodes.remove (t);
}
/* Releases et tree T without maintaining other nodes. */
void
et_free_tree_force (struct et_node *t)
{
et_occurrences.remove (t->rightmost_occ);
if (t->parent_occ)
et_occurrences.remove (t->parent_occ);
et_nodes.remove (t);
}
/* Release the alloc pools, if they are empty. */
void
et_free_pools (void)
{
et_occurrences.release_if_empty ();
et_nodes.release_if_empty ();
}
/* Sets father of et tree T to FATHER. */
void
et_set_father (struct et_node *t, struct et_node *father)
{
struct et_node *left, *right;
struct et_occ *rmost, *left_part, *new_f_occ, *p;
/* Update the path represented in the splay tree. */
new_f_occ = et_new_occ (father);
rmost = father->rightmost_occ;
et_splay (rmost);
left_part = rmost->prev;
p = t->rightmost_occ;
et_splay (p);
set_prev (new_f_occ, left_part);
set_next (new_f_occ, p);
p->depth++;
p->min++;
et_recomp_min (new_f_occ);
set_prev (rmost, new_f_occ);
if (new_f_occ->min + rmost->depth < rmost->min)
{
rmost->min = new_f_occ->min + rmost->depth;
rmost->min_occ = new_f_occ->min_occ;
}
t->parent_occ = new_f_occ;
/* Update the tree. */
t->father = father;
right = father->son;
if (right)
left = right->left;
else
left = right = t;
left->right = t;
right->left = t;
t->left = left;
t->right = right;
father->son = t;
#ifdef DEBUG_ET
et_check_tree_sanity (rmost);
record_path_before (rmost);
#endif
}
/* Splits the edge from T to its father. */
void
et_split (struct et_node *t)
{
struct et_node *father = t->father;
struct et_occ *r, *l, *rmost, *p_occ;
/* Update the path represented by the splay tree. */
rmost = t->rightmost_occ;
et_splay (rmost);
for (r = rmost->next; r->prev; r = r->prev)
continue;
et_splay (r);
r->prev->parent = NULL;
p_occ = t->parent_occ;
et_splay (p_occ);
t->parent_occ = NULL;
l = p_occ->prev;
p_occ->next->parent = NULL;
set_prev (r, l);
et_recomp_min (r);
et_splay (rmost);
rmost->depth = 0;
rmost->min = 0;
et_occurrences.remove (p_occ);
/* Update the tree. */
if (father->son == t)
father->son = t->right;
if (father->son == t)
father->son = NULL;
else
{
t->left->right = t->right;
t->right->left = t->left;
}
t->left = t->right = NULL;
t->father = NULL;
#ifdef DEBUG_ET
et_check_tree_sanity (rmost);
record_path_before (rmost);
et_check_tree_sanity (r);
record_path_before (r);
#endif
}
/* Finds the nearest common ancestor of the nodes N1 and N2. */
struct et_node *
et_nca (struct et_node *n1, struct et_node *n2)
{
struct et_occ *o1 = n1->rightmost_occ, *o2 = n2->rightmost_occ, *om;
struct et_occ *l, *r, *ret;
int mn;
if (n1 == n2)
return n1;
et_splay (o1);
l = o1->prev;
r = o1->next;
if (l)
l->parent = NULL;
if (r)
r->parent = NULL;
et_splay (o2);
if (l == o2 || (l && l->parent != NULL))
{
ret = o2->next;
set_prev (o1, o2);
if (r)
r->parent = o1;
}
else if (r == o2 || (r && r->parent != NULL))
{
ret = o2->prev;
set_next (o1, o2);
if (l)
l->parent = o1;
}
else
{
/* O1 and O2 are in different components of the forest. */
if (l)
l->parent = o1;
if (r)
r->parent = o1;
return NULL;
}
if (o2->depth > 0)
{
om = o1;
mn = o1->depth;
}
else
{
om = o2;
mn = o2->depth + o1->depth;
}
#ifdef DEBUG_ET
et_check_tree_sanity (o2);
#endif
if (ret && ret->min + o1->depth + o2->depth < mn)
return ret->min_occ->of;
else
return om->of;
}
/* Checks whether the node UP is an ancestor of the node DOWN. */
bool
et_below (struct et_node *down, struct et_node *up)
{
struct et_occ *u = up->rightmost_occ, *d = down->rightmost_occ;
struct et_occ *l, *r;
if (up == down)
return true;
et_splay (u);
l = u->prev;
r = u->next;
if (!l)
return false;
l->parent = NULL;
if (r)
r->parent = NULL;
et_splay (d);
if (l == d || l->parent != NULL)
{
if (r)
r->parent = u;
set_prev (u, d);
#ifdef DEBUG_ET
et_check_tree_sanity (u);
#endif
}
else
{
l->parent = u;
/* In case O1 and O2 are in two different trees, we must just restore the
original state. */
if (r && r->parent != NULL)
set_next (u, d);
else
set_next (u, r);
#ifdef DEBUG_ET
et_check_tree_sanity (u);
#endif
return false;
}
if (d->depth <= 0)
return false;
return !d->next || d->next->min + d->depth >= 0;
}
/* Returns the root of the tree that contains NODE. */
struct et_node *
et_root (struct et_node *node)
{
struct et_occ *occ = node->rightmost_occ, *r;
/* The root of the tree corresponds to the rightmost occurrence in the
represented path. */
et_splay (occ);
for (r = occ; r->next; r = r->next)
continue;
et_splay (r);
return r->of;
}
#if CHECKING_P
namespace selftest {
/* Selftests for et-forest.c. */
/* Perform sanity checks for a tree consisting of a single node. */
static void
test_single_node ()
{
void *test_data = (void *)0xcafebabe;
et_node *n = et_new_tree (test_data);
ASSERT_EQ (n->data, test_data);
ASSERT_EQ (n, et_root (n));
et_free_tree (n);
}
/* Test of this tree:
a
/ \
/ \
b c
/ \ |
d e f. */
static void
test_simple_tree ()
{
et_node *a = et_new_tree (NULL);
et_node *b = et_new_tree (NULL);
et_node *c = et_new_tree (NULL);
et_node *d = et_new_tree (NULL);
et_node *e = et_new_tree (NULL);
et_node *f = et_new_tree (NULL);
et_set_father (b, a);
et_set_father (c, a);
et_set_father (d, b);
et_set_father (e, b);
et_set_father (f, c);
ASSERT_TRUE (et_below (a, a));
ASSERT_TRUE (et_below (b, a));
ASSERT_TRUE (et_below (c, a));
ASSERT_TRUE (et_below (d, a));
ASSERT_TRUE (et_below (e, a));
ASSERT_TRUE (et_below (f, a));
ASSERT_FALSE (et_below (a, b));
ASSERT_TRUE (et_below (b, b));
ASSERT_FALSE (et_below (c, b));
ASSERT_TRUE (et_below (d, b));
ASSERT_TRUE (et_below (e, b));
ASSERT_FALSE (et_below (f, b));
ASSERT_FALSE (et_below (a, c));
ASSERT_FALSE (et_below (b, c));
ASSERT_TRUE (et_below (c, c));
ASSERT_FALSE (et_below (d, c));
ASSERT_FALSE (et_below (e, c));
ASSERT_TRUE (et_below (f, c));
ASSERT_FALSE (et_below (a, d));
ASSERT_FALSE (et_below (b, d));
ASSERT_FALSE (et_below (c, d));
ASSERT_TRUE (et_below (d, d));
ASSERT_FALSE (et_below (e, d));
ASSERT_FALSE (et_below (f, d));
ASSERT_FALSE (et_below (a, e));
ASSERT_FALSE (et_below (b, e));
ASSERT_FALSE (et_below (c, e));
ASSERT_FALSE (et_below (d, e));
ASSERT_TRUE (et_below (e, e));
ASSERT_FALSE (et_below (f, e));
ASSERT_FALSE (et_below (a, f));
ASSERT_FALSE (et_below (b, f));
ASSERT_FALSE (et_below (c, f));
ASSERT_FALSE (et_below (d, f));
ASSERT_FALSE (et_below (e, f));
ASSERT_TRUE (et_below (f, f));
et_free_tree_force (a);
}
/* Verify that two disconnected nodes are unrelated. */
static void
test_disconnected_nodes ()
{
et_node *a = et_new_tree (NULL);
et_node *b = et_new_tree (NULL);
ASSERT_FALSE (et_below (a, b));
ASSERT_FALSE (et_below (b, a));
et_free_tree (a);
et_free_tree (b);
}
/* Run all of the selftests within this file. */
void
et_forest_c_tests ()
{
test_single_node ();
test_simple_tree ();
test_disconnected_nodes ();
}
} // namespace selftest
#endif /* CHECKING_P */
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