#include "except.h"
#include "cfgloop.h"
#include "cfglayout.h"
+#include "hashtab.h"
/* This file contains functions for building the Control Flow Graph (CFG)
for a function tree. */
building of the CFG in code with lots of gotos. */
static GTY(()) varray_type label_to_block_map;
+/* This hash table allows us to efficiently lookup the one and only one
+ CASE_LABEL_EXPR which contains the LABEL_DECL for the target block
+ of one or more case statements. Efficient access to this node
+ allows us to efficiently update the case vector in response to
+ edge redirections and similar operations.
+
+ Right now this is only used to set up case label leaders. In the
+ future we hope to make this table more persistent and use it to
+ more efficiently update case labels. */
+
+struct edge_to_case_leader_elt
+{
+ /* The edge itself. Necessary for hashing and equality tests. */
+ edge e;
+
+ /* The "leader" for all the CASE_LABEL_EXPRs which transfer control
+ to E->dest. When we change the destination of E, we will need to
+ update the CASE_LEADER_OR_LABEL of this CASE_LABEL_EXPR (and no
+ others). */
+ tree case_label;
+};
+
+static htab_t edge_to_case_leader;
+
/* CFG statistics. */
struct cfg_stats_d
{
static void tree_make_forwarder_block (edge);
static bool thread_jumps (void);
static bool tree_forwarder_block_p (basic_block);
-static void bsi_commit_edge_inserts_1 (edge e);
static void tree_cfg2vcg (FILE *);
/* Flowgraph optimization and cleanup. */
gcc_assert (!e);
- /* Create and initialize a new basic block. */
+ /* Create and initialize a new basic block. Since alloc_block uses
+ ggc_alloc_cleared to allocate a basic block, we do not have to
+ clear the newly allocated basic block here. */
bb = alloc_block ();
- memset (bb, 0, sizeof (*bb));
bb->index = last_basic_block;
bb->flags = BB_NEW;
make_edge (bb, else_bb, EDGE_FALSE_VALUE);
}
+/* Hashing routine for EDGE_TO_CASE_LEADER. */
+
+static hashval_t
+edge_to_case_leader_hash (const void *p)
+{
+ edge e = ((struct edge_to_case_leader_elt *)p)->e;
+
+ /* Hash on the edge itself (which is a pointer). */
+ return htab_hash_pointer (e);
+}
+
+/* Equality routine for EDGE_TO_CASE_LEADER, edges are unique, so testing
+ for equality is just a pointer comparison. */
+
+static int
+edge_to_case_leader_eq (const void *p1, const void *p2)
+{
+ edge e1 = ((struct edge_to_case_leader_elt *)p1)->e;
+ edge e2 = ((struct edge_to_case_leader_elt *)p2)->e;
+
+ return e1 == e2;
+}
+
+/* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
+
+static void
+record_switch_edge (edge e, tree case_label)
+{
+ struct edge_to_case_leader_elt *elt;
+ void **slot;
+
+ /* Build a hash table element so we can see if E is already
+ in the table. */
+ elt = xmalloc (sizeof (struct edge_to_case_leader_elt));
+ elt->e = e;
+ elt->case_label = case_label;
+
+ slot = htab_find_slot (edge_to_case_leader, elt, INSERT);
+
+ if (*slot == NULL)
+ {
+ /* E was not in the hash table. Install E into the hash table. */
+ *slot = (void *)elt;
+ }
+ else
+ {
+ /* E was already in the hash table. Free ELT as we do not need it
+ anymore. */
+ free (elt);
+
+ /* Get the entry stored in the hash table. */
+ elt = (struct edge_to_case_leader_elt *) *slot;
+
+ /* Make ELT->case_label the leader for CASE_LABEL. */
+ CASE_LEADER_OR_LABEL (case_label) = elt->case_label;
+ }
+}
+
+/* Subroutine of get_case_leader_for_edge; returns the case leader for the
+ chain of CASE_LABEL_EXPRs associated with E using a hash table lookup. */
+
+static tree
+get_case_leader_for_edge_hash (edge e)
+{
+ struct edge_to_case_leader_elt elt, *elt_p;
+ void **slot;
+
+ elt.e = e;
+ elt.case_label = NULL;
+ slot = htab_find_slot (edge_to_case_leader, &elt, NO_INSERT);
+
+ if (slot)
+ {
+ tree t;
+
+ elt_p = (struct edge_to_case_leader_elt *)*slot;
+ t = elt_p->case_label;
+
+ while (TREE_CODE (CASE_LEADER_OR_LABEL (t)) == CASE_LABEL_EXPR)
+ t = CASE_LEADER_OR_LABEL (t);
+ return t;
+ }
+
+ return NULL;
+}
+
+/* Given an edge E, return the case leader for the chain of CASE_LABEL_EXPRs
+ which use E. */
+
+static tree
+get_case_leader_for_edge (edge e)
+{
+ tree vec, stmt;
+ size_t i, n;
+
+ /* If we have a hash table, then use it as it's significantly faster. */
+ if (edge_to_case_leader)
+ return get_case_leader_for_edge_hash (e);
+
+ /* No hash table. We have to walk the case vector. */
+ stmt = bsi_stmt (bsi_last (e->src));
+ vec = SWITCH_LABELS (stmt);
+ n = TREE_VEC_LENGTH (vec);
+
+ for (i = 0; i < n; i++)
+ {
+ tree elt = TREE_VEC_ELT (vec, i);
+ tree t = CASE_LEADER_OR_LABEL (elt);
+
+ if (TREE_CODE (t) == LABEL_DECL
+ && label_to_block (t) == e->dest)
+ return elt;
+ }
+
+ abort ();
+}
/* Create the edges for a SWITCH_EXPR starting at block BB.
At this point, the switch body has been lowered and the
vec = SWITCH_LABELS (entry);
n = TREE_VEC_LENGTH (vec);
+ edge_to_case_leader
+ = htab_create (n, edge_to_case_leader_hash, edge_to_case_leader_eq, free);
+
for (i = 0; i < n; ++i)
{
tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
basic_block label_bb = label_to_block (lab);
- make_edge (bb, label_bb, 0);
+ edge e = make_edge (bb, label_bb, 0);
+
+ if (!e)
+ e = find_edge (bb, label_bb);
+
+ record_switch_edge (e, TREE_VEC_ELT (vec, i));
}
+ htab_delete (edge_to_case_leader);
+ edge_to_case_leader = NULL;
}
/* Replace all destination labels. */
for (i = 0; i < n; ++i)
- CASE_LABEL (TREE_VEC_ELT (vec, i))
- = main_block_label (CASE_LABEL (TREE_VEC_ELT (vec, i)));
-
+ {
+ tree elt = TREE_VEC_ELT (vec, i);
+ tree label = main_block_label (CASE_LABEL (elt));
+ CASE_LEADER_OR_LABEL (elt) = label;
+ }
break;
}
else_has_label = data->has_label;
data->has_label = save_has_label | then_has_label | else_has_label;
- fold_stmt (stmt_p);
then_clause = COND_EXPR_THEN (*stmt_p);
else_clause = COND_EXPR_ELSE (*stmt_p);
cond = COND_EXPR_COND (*stmt_p);
}
}
break;
- case SWITCH_EXPR:
+ case ASM_EXPR:
fold_stmt (tp);
data->last_goto = NULL;
break;
}
-/* Given a control block BB and a predicate VAL, return the edge that
- will be taken out of the block. If VAL does not match a unique
- edge, NULL is returned. */
+/* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
+ predicate VAL, return the edge that will be taken out of the block.
+ If VAL does not match a unique edge, NULL is returned. */
edge
find_taken_edge (basic_block bb, tree val)
gcc_assert (stmt);
gcc_assert (is_ctrl_stmt (stmt));
+ gcc_assert (val);
/* If VAL is a predicate of the form N RELOP N, where N is an
SSA_NAME, we can usually determine its truth value. */
- if (val && COMPARISON_CLASS_P (val))
+ if (COMPARISON_CLASS_P (val))
val = fold (val);
/* If VAL is not a constant, we can't determine which edge might
be taken. */
- if (val == NULL || !really_constant_p (val))
+ if (!really_constant_p (val))
return NULL;
if (TREE_CODE (stmt) == COND_EXPR)
if (TREE_CODE (stmt) == SWITCH_EXPR)
return find_taken_edge_switch_expr (bb, val);
- return EDGE_SUCC (bb, 0);
+ gcc_unreachable ();
}
extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
- /* If both edges of the branch lead to the same basic block, it doesn't
- matter which edge is taken. */
- if (true_edge->dest == false_edge->dest)
- return true_edge;
-
/* Otherwise, try to determine which branch of the if() will be taken.
If VAL is a constant but it can't be reduced to a 0 or a 1, then
we don't really know which edge will be taken at runtime. This
The requirement for no PHI nodes could be relaxed. Basically we
would have to examine the PHIs to prove that none of them used
- the value set by the statement we want to insert on E. That
+ the value set by the statement we want to insert on E. That
hardly seems worth the effort. */
if (EDGE_COUNT (dest->preds) == 1
&& ! phi_nodes (dest)
/* This routine will commit all pending edge insertions, creating any new
- basic blocks which are necessary.
-
- If specified, NEW_BLOCKS returns a count of the number of new basic
- blocks which were created. */
+ basic blocks which are necessary. */
void
-bsi_commit_edge_inserts (int *new_blocks)
+bsi_commit_edge_inserts (void)
{
basic_block bb;
edge e;
- int blocks;
edge_iterator ei;
- blocks = n_basic_blocks;
-
- bsi_commit_edge_inserts_1 (EDGE_SUCC (ENTRY_BLOCK_PTR, 0));
+ bsi_commit_one_edge_insert (EDGE_SUCC (ENTRY_BLOCK_PTR, 0), NULL);
FOR_EACH_BB (bb)
FOR_EACH_EDGE (e, ei, bb->succs)
- bsi_commit_edge_inserts_1 (e);
-
- if (new_blocks)
- *new_blocks = n_basic_blocks - blocks;
+ bsi_commit_one_edge_insert (e, NULL);
}
-/* Commit insertions pending at edge E. */
+/* Commit insertions pending at edge E. If a new block is created, set NEW_BB
+ to this block, otherwise set it to NULL. */
-static void
-bsi_commit_edge_inserts_1 (edge e)
+void
+bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
{
+ if (new_bb)
+ *new_bb = NULL;
if (PENDING_STMT (e))
{
block_stmt_iterator bsi;
PENDING_STMT (e) = NULL_TREE;
- if (tree_find_edge_insert_loc (e, &bsi, NULL))
+ if (tree_find_edge_insert_loc (e, &bsi, new_bb))
bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
else
bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
break;
case COND_EXPR:
- x = TREE_OPERAND (t, 0);
+ x = COND_EXPR_COND (t);
if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
{
error ("non-boolean used in condition");
|| TREE_CODE (t) == SSA_NAME)
return true;
+ if (TREE_CODE (t) == CASE_LABEL_EXPR)
+ return true;
+
while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
/* We check for constants explicitly since they are not considered
gimple invariants if they overflowed. */
edge e;
edge_iterator ei;
basic_block dummy, bb;
- tree phi, new_phi, var, prev, next;
+ tree phi, new_phi, var;
dummy = fallthru->src;
bb = fallthru->dest;
}
/* Ensure that the PHI node chain is in the same order. */
- prev = NULL;
- for (phi = phi_nodes (bb); phi; phi = next)
- {
- next = PHI_CHAIN (phi);
- PHI_CHAIN (phi) = prev;
- prev = phi;
- }
- set_phi_nodes (bb, prev);
+ set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
/* Add the arguments we have stored on edges. */
FOR_EACH_EDGE (e, ei, bb->preds)
if (e == fallthru)
continue;
- for (phi = phi_nodes (bb), var = PENDING_STMT (e);
- phi;
- phi = PHI_CHAIN (phi), var = TREE_CHAIN (var))
- add_phi_arg (&phi, TREE_VALUE (var), e);
-
- PENDING_STMT (e) = NULL;
+ flush_pending_stmts (e);
}
}
basic_block bb;
bool retval = false;
basic_block *worklist = xmalloc (sizeof (basic_block) * last_basic_block);
- unsigned int size = 0;
+ basic_block *current = worklist;
FOR_EACH_BB (bb)
{
bb->flags &= ~BB_VISITED;
}
+ /* We pretend to have ENTRY_BLOCK_PTR in WORKLIST. This way,
+ ENTRY_BLOCK_PTR will never be entered into WORKLIST. */
+ ENTRY_BLOCK_PTR->flags |= BB_VISITED;
+
/* Initialize WORKLIST by putting non-forwarder blocks that
immediately precede forwarder blocks because those are the ones
that we know we can thread jumps from. We use BB_VISITED to
among BB's predecessors. */
FOR_EACH_EDGE (e, ei, bb->preds)
{
- /* We are not interested in threading jumps from a forwarder
- block. */
- if (!bb_ann (e->src)->forwardable
- /* We don't want to visit ENTRY_BLOCK_PTR. */
- && e->src->index >= 0
- /* We don't want to put a duplicate into WORKLIST. */
- && (e->src->flags & BB_VISITED) == 0)
+ /* We don't want to put a duplicate into WORKLIST. */
+ if ((e->src->flags & BB_VISITED) == 0
+ /* We are not interested in threading jumps from a forwarder
+ block. */
+ && !bb_ann (e->src)->forwardable)
{
e->src->flags |= BB_VISITED;
- worklist[size] = e->src;
- size++;
+ *current++ = e->src;
}
}
}
/* Now let's drain WORKLIST. */
- while (size > 0)
+ while (worklist != current)
{
- size--;
- bb = worklist[size];
+ bb = *--current;
- /* BB->INDEX is not longer in WORKLIST, so clear BB_VISITED. */
+ /* BB is no longer in WORKLIST, so clear BB_VISITED. */
bb->flags &= ~BB_VISITED;
if (thread_jumps_from_bb (bb))
predecessors. */
FOR_EACH_EDGE (f, ej, bb->preds)
{
- /* We are not interested in threading jumps from a
- forwarder block. */
- if (!bb_ann (f->src)->forwardable
- /* We don't want to visit ENTRY_BLOCK_PTR. */
- && f->src->index >= 0
- /* We don't want to put a duplicate into WORKLIST. */
- && (f->src->flags & BB_VISITED) == 0)
+ /* We don't want to put a duplicate into WORKLIST. */
+ if ((f->src->flags & BB_VISITED) == 0
+ /* We are not interested in threading jumps from a
+ forwarder block. */
+ && !bb_ann (f->src)->forwardable)
{
f->src->flags |= BB_VISITED;
- worklist[size] = f->src;
- size++;
+ *current++ = f->src;
}
}
}
}
}
+ ENTRY_BLOCK_PTR->flags &= ~BB_VISITED;
+
free (worklist);
return retval;
case SWITCH_EXPR:
{
- tree vec = SWITCH_LABELS (stmt);
- size_t i, n = TREE_VEC_LENGTH (vec);
+ edge e2;
+
+ /* We need to update the LABEL_DECL in the switch vector to
+ reflect the edge redirection.
- for (i = 0; i < n; ++i)
+ There is precisely one CASE_LABEL_EXPR in the switch vector
+ which needs updating. Either its label needs to be updated
+ or it needs to be directed to a new case leader. */
+ e2 = find_edge (e->src, dest);
+ if (e2)
+ {
+ /* In this case we need to change the case leader for the
+ current leader of E to be the case leader for E2. */
+ tree e_leader = get_case_leader_for_edge (e);
+ tree e2_leader = get_case_leader_for_edge (e2);
+ CASE_LEADER_OR_LABEL (e_leader) = e2_leader;
+ }
+ else
{
- tree elt = TREE_VEC_ELT (vec, i);
- if (label_to_block (CASE_LABEL (elt)) == e->dest)
- CASE_LABEL (elt) = label;
+ /* No edge exists from E->src to DEST, so we will simply
+ change E->dest. The case leader does not change, but
+ the LABEL_DECL for the leader does change. */
+ CASE_LEADER_OR_LABEL (get_case_leader_for_edge (e)) = label;
}
+ break;
}
- break;
case RETURN_EXPR:
bsi_remove (&bsi);
/* First copy the phi nodes. We do not copy phi node arguments here,
since the edges are not ready yet. Keep the chain of phi nodes in
the same order, so that we can add them later. */
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
{
mark_for_rewrite (PHI_RESULT (phi));
create_phi_node (PHI_RESULT (phi), new_bb);
}
- set_phi_nodes (new_bb, nreverse (phi_nodes (new_bb)));
+ set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
bsi_tgt = bsi_start (new_bb);
for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
phi;
- phi = phi_next, phi_copy = TREE_CHAIN (phi_copy))
+ phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
{
- phi_next = TREE_CHAIN (phi);
+ phi_next = PHI_CHAIN (phi);
gcc_assert (PHI_RESULT (phi) == PHI_RESULT (phi_copy));
def = PHI_ARG_DEF_FROM_EDGE (phi, e);
if (e->flags & EDGE_ABNORMAL)
break;
- for (phi = phi_nodes (bb); phi; phi = TREE_CHAIN (phi))
+ for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
{
rewrite_to_new_ssa_names_def (PHI_RESULT_PTR (phi), phi, map);
if (e)
v_must_defs = V_MUST_DEF_OPS (ann);
for (i = 0; i < NUM_V_MUST_DEFS (v_must_defs); i++)
- rewrite_to_new_ssa_names_def
- (V_MUST_DEF_OP_PTR (v_must_defs, i), stmt, map);
+ {
+ rewrite_to_new_ssa_names_def
+ (V_MUST_DEF_RESULT_PTR (v_must_defs, i), stmt, map);
+ rewrite_to_new_ssa_names_use
+ (V_MUST_DEF_KILL_PTR (v_must_defs, i), map);
+ }
}
FOR_EACH_EDGE (e, ei, bb->succs)
- for (phi = phi_nodes (e->dest); phi; phi = TREE_CHAIN (phi))
+ for (phi = phi_nodes (e->dest); phi; phi = PHI_CHAIN (phi))
{
rewrite_to_new_ssa_names_use
(PHI_ARG_DEF_PTR_FROM_EDGE (phi, e), map);
struct loop *loop = entry->dest->loop_father;
edge exit_copy;
bitmap definitions;
- tree phi, var;
+ tree phi;
basic_block *doms;
htab_t ssa_name_map = NULL;
edge redirected;
/* Redirect the entry and add the phi node arguments. */
redirected = redirect_edge_and_branch (entry, entry->dest->rbi->copy);
gcc_assert (redirected != NULL);
- for (phi = phi_nodes (entry->dest), var = PENDING_STMT (entry);
- phi;
- phi = TREE_CHAIN (phi), var = TREE_CHAIN (var))
- add_phi_arg (&phi, TREE_VALUE (var), entry);
- PENDING_STMT (entry) = NULL;
+ flush_pending_stmts (entry);
/* Concerning updating of dominators: We must recount dominators
for entry block and its copy. Anything that is outside of the region, but
if (e->dest == EXIT_BLOCK_PTR)
{
bsi_insert_on_edge (e, build_empty_stmt ());
- bsi_commit_edge_inserts ((int *)NULL);
+ bsi_commit_edge_inserts ();
break;
}
}
tree_purge_all_dead_eh_edges (bitmap blocks)
{
bool changed = false;
- size_t i;
+ unsigned i;
bitmap_iterator bi;
EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
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