/* Return true if the CFG contains at least one path from START_BB to END_BB.
When a path is found, record in PATH the blocks from END_BB to START_BB.
VISITED_BBS is used to make sure we don't fall into an infinite loop. Bound
- the recursion to basic blocks belonging to LOOP.
- SPEED_P indicate that we could increase code size to improve the code path */
+ the recursion to basic blocks belonging to LOOP. */
static bool
fsm_find_thread_path (basic_block start_bb, basic_block end_bb,
vec<basic_block, va_gc> *&path,
- hash_set<basic_block> *visited_bbs, loop_p loop,
- bool speed_p)
+ hash_set<basic_block> *visited_bbs, loop_p loop)
{
if (loop != start_bb->loop_father)
return false;
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, start_bb->succs)
- if (fsm_find_thread_path (e->dest, end_bb, path, visited_bbs, loop,
- speed_p))
+ if (fsm_find_thread_path (e->dest, end_bb, path, visited_bbs, loop))
{
vec_safe_push (path, start_bb);
return true;
--max_threaded_paths;
}
+/* While following a chain of SSA_NAME definitions, we jumped from a definition
+ in LAST_BB to a definition in VAR_BB (walking backwards).
+
+ Verify there is a single path between the blocks and none of the blocks
+ in the path is already in VISITED_BBS. If so, then update VISISTED_BBS,
+ add the new blocks to PATH and return TRUE. Otherwise return FALSE.
+
+ Store the length of the subpath in NEXT_PATH_LENGTH. */
+
+static bool
+check_subpath_and_update_thread_path (basic_block last_bb, basic_block new_bb,
+ hash_set<basic_block> *visited_bbs,
+ vec<basic_block, va_gc> *&path,
+ int *next_path_length)
+{
+ edge e;
+ int e_count = 0;
+ edge_iterator ei;
+ vec<basic_block, va_gc> *next_path;
+ vec_alloc (next_path, 10);
+
+ FOR_EACH_EDGE (e, ei, last_bb->preds)
+ {
+ hash_set<basic_block> *visited_bbs = new hash_set<basic_block>;
+
+ if (fsm_find_thread_path (new_bb, e->src, next_path, visited_bbs,
+ e->src->loop_father))
+ ++e_count;
+
+ delete visited_bbs;
+
+ /* If there is more than one path, stop. */
+ if (e_count > 1)
+ {
+ vec_free (next_path);
+ return false;
+ }
+ }
+
+ /* Stop if we have not found a path: this could occur when the recursion
+ is stopped by one of the bounds. */
+ if (e_count == 0)
+ {
+ vec_free (next_path);
+ return false;
+ }
+
+ /* Make sure we haven't already visited any of the nodes in
+ NEXT_PATH. Don't add them here to avoid pollution. */
+ for (unsigned int i = 0; i < next_path->length () - 1; i++)
+ {
+ if (visited_bbs->contains ((*next_path)[i]))
+ {
+ vec_free (next_path);
+ return false;
+ }
+ }
+
+ /* Now add the nodes to VISISTED_BBS. */
+ for (unsigned int i = 0; i < next_path->length () - 1; i++)
+ visited_bbs->add ((*next_path)[i]);
+
+ /* Append all the nodes from NEXT_PATH to PATH. */
+ vec_safe_splice (path, next_path);
+ *next_path_length = next_path->length ();
+ vec_free (next_path);
+
+ return true;
+}
+
+static void fsm_find_control_statement_thread_paths (tree,
+ hash_set<basic_block> *,
+ vec<basic_block, va_gc> *&,
+ bool, bool);
+
+/* Given PHI which defines NAME in block VAR_BB, recurse through the
+ PHI's arguments searching for paths where NAME will ultimately have
+ a constant value.
+
+ VISITED_BBS tracks the blocks that have been encountered.
+
+ PATH contains the series of blocks to traverse that will result in
+ NAME having a constant value.
+
+ SEEN_LOOP_PHI tracks if we have recursed through a loop PHI node.
+
+ SPEED_P indicates if we are optimizing for speed over space. */
+
+static void
+handle_phi (gphi *phi, tree name, basic_block var_bb,
+ hash_set<basic_block> *visited_bbs,
+ vec<basic_block, va_gc> *&path,
+ bool seen_loop_phi, bool speed_p)
+{
+ /* Iterate over the arguments of PHI. */
+ for (unsigned int i = 0; i < gimple_phi_num_args (phi); i++)
+ {
+ tree arg = gimple_phi_arg_def (phi, i);
+ basic_block bbi = gimple_phi_arg_edge (phi, i)->src;
+
+ /* Skip edges pointing outside the current loop. */
+ if (!arg || var_bb->loop_father != bbi->loop_father)
+ continue;
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ {
+ vec_safe_push (path, bbi);
+ /* Recursively follow SSA_NAMEs looking for a constant
+ definition. */
+ fsm_find_control_statement_thread_paths (arg, visited_bbs, path,
+ seen_loop_phi, speed_p);
+
+ path->pop ();
+ continue;
+ }
+
+ if (TREE_CODE_CLASS (TREE_CODE (arg)) != tcc_constant)
+ continue;
+
+ /* If this is a profitable jump thread path, then convert it
+ into the canonical form and register it. */
+ bool irreducible = false;
+ edge taken_edge = profitable_jump_thread_path (path, bbi, name, arg,
+ speed_p, &irreducible);
+ if (taken_edge)
+ {
+ convert_and_register_jump_thread_path (path, taken_edge);
+ path->pop ();
+
+ if (irreducible)
+ vect_free_loop_info_assumptions ((*path)[0]->loop_father);
+ }
+ }
+}
+
+/* Return TRUE if STMT is a gimple assignment we want to either directly
+ handle or recurse through. Return FALSE otherwise.
+
+ Note that adding more cases here requires adding cases to handle_assignment
+ below. */
+
+static bool
+handle_assignment_p (gimple *stmt)
+{
+ if (is_gimple_assign (stmt))
+ {
+ enum tree_code def_code = gimple_assign_rhs_code (stmt);
+
+ /* If the RHS is an SSA_NAME, then we will recurse through it.
+ Go ahead and filter out cases where the SSA_NAME is a default
+ definition. There's little to be gained by trying to handle that. */
+ if (def_code == SSA_NAME
+ && !SSA_NAME_IS_DEFAULT_DEF (gimple_assign_rhs1 (stmt)))
+ return true;
+
+ /* If the RHS is a constant, then it's a terminal that we'll want
+ to handle as well. */
+ if (TREE_CODE_CLASS (def_code) == tcc_constant)
+ return true;
+ }
+
+ /* Anything not explicitly allowed is not handled. */
+ return false;
+}
+
+/* Given STMT which defines NAME in block VAR_BB, recurse through the
+ PHI's arguments searching for paths where NAME will ultimately have
+ a constant value.
+
+ VISITED_BBS tracks the blocks that have been encountered.
+
+ PATH contains the series of blocks to traverse that will result in
+ NAME having a constant value.
+
+ SEEN_LOOP_PHI tracks if we have recursed through a loop PHI node.
+
+ SPEED_P indicates if we are optimizing for speed over space. */
+
+static void
+handle_assignment (gimple *stmt, tree name, basic_block var_bb,
+ hash_set<basic_block> *visited_bbs,
+ vec<basic_block, va_gc> *&path,
+ bool seen_loop_phi, bool speed_p)
+{
+ tree arg = gimple_assign_rhs1 (stmt);
+
+ if (TREE_CODE (arg) == SSA_NAME)
+ fsm_find_control_statement_thread_paths (arg, visited_bbs,
+ path, seen_loop_phi, speed_p);
+
+ else
+ {
+ /* profitable_jump_thread_path is going to push the current
+ block onto the path. But the path will always have the current
+ block at this point. So we can just pop it. */
+ path->pop ();
+
+ bool irreducible = false;
+ edge taken_edge = profitable_jump_thread_path (path, var_bb,
+ name, arg, speed_p,
+ &irreducible);
+ if (taken_edge)
+ {
+ convert_and_register_jump_thread_path (path, taken_edge);
+ path->pop ();
+
+ if (irreducible)
+ vect_free_loop_info_assumptions ((*path)[0]->loop_father);
+ }
+
+ /* And put the current block back onto the path so that the
+ state of the stack is unchanged when we leave. */
+ vec_safe_push (path, var_bb);
+ }
+}
+
/* We trace the value of the SSA_NAME NAME back through any phi nodes looking
for places where it gets a constant value and save the path. Stop after
having recorded MAX_PATHS jump threading paths.
>= (unsigned) PARAM_VALUE (PARAM_FSM_MAXIMUM_PHI_ARGUMENTS)))
return;
- if (gimple_code (def_stmt) == GIMPLE_ASSIGN
- && gimple_assign_rhs_code (def_stmt) != INTEGER_CST
- && gimple_assign_rhs_code (def_stmt) != SSA_NAME)
+ if (is_gimple_assign (def_stmt)
+ && ! handle_assignment_p (def_stmt))
return;
/* Avoid infinite recursion. */
different, append to PATH the blocks from LAST_BB_IN_PATH to VAR_BB. */
if (var_bb != last_bb_in_path)
{
- edge e;
- int e_count = 0;
- edge_iterator ei;
- vec<basic_block, va_gc> *next_path;
- vec_alloc (next_path, 10);
-
/* When VAR_BB == LAST_BB_IN_PATH, then the first block in the path
will already be in VISITED_BBS. When they are not equal, then we
must ensure that first block is accounted for to ensure we do not
create bogus jump threading paths. */
visited_bbs->add ((*path)[0]);
- FOR_EACH_EDGE (e, ei, last_bb_in_path->preds)
- {
- hash_set<basic_block> *visited_bbs = new hash_set<basic_block>;
-
- if (fsm_find_thread_path (var_bb, e->src, next_path, visited_bbs,
- e->src->loop_father, speed_p))
- ++e_count;
-
- delete visited_bbs;
-
- /* If there is more than one path, stop. */
- if (e_count > 1)
- {
- vec_free (next_path);
- return;
- }
- }
-
- /* Stop if we have not found a path: this could occur when the recursion
- is stopped by one of the bounds. */
- if (e_count == 0)
- {
- vec_free (next_path);
- return;
- }
-
- /* Make sure we haven't already visited any of the nodes in
- NEXT_PATH. Don't add them here to avoid pollution. */
- for (unsigned int i = 0; i < next_path->length () - 1; i++)
- {
- if (visited_bbs->contains ((*next_path)[i]))
- {
- vec_free (next_path);
- return;
- }
- }
-
- /* Now add the nodes to VISISTED_BBS. */
- for (unsigned int i = 0; i < next_path->length () - 1; i++)
- visited_bbs->add ((*next_path)[i]);
-
- /* Append all the nodes from NEXT_PATH to PATH. */
- vec_safe_splice (path, next_path);
- next_path_length = next_path->length ();
- vec_free (next_path);
+ if (!check_subpath_and_update_thread_path (last_bb_in_path, var_bb,
+ visited_bbs, path,
+ &next_path_length))
+ return;
}
gcc_assert (path->last () == var_bb);
- /* Iterate over the arguments of PHI. */
- unsigned int i;
if (gimple_code (def_stmt) == GIMPLE_PHI)
- {
- gphi *phi = as_a <gphi *> (def_stmt);
- for (i = 0; i < gimple_phi_num_args (phi); i++)
- {
- tree arg = gimple_phi_arg_def (phi, i);
- basic_block bbi = gimple_phi_arg_edge (phi, i)->src;
-
- /* Skip edges pointing outside the current loop. */
- if (!arg || var_bb->loop_father != bbi->loop_father)
- continue;
-
- if (TREE_CODE (arg) == SSA_NAME)
- {
- vec_safe_push (path, bbi);
- /* Recursively follow SSA_NAMEs looking for a constant
- definition. */
- fsm_find_control_statement_thread_paths (arg, visited_bbs, path,
- seen_loop_phi, speed_p);
-
- path->pop ();
- continue;
- }
-
- if (TREE_CODE (arg) != INTEGER_CST)
- continue;
-
- /* If this is a profitable jump thread path, then convert it
- into the canonical form and register it. */
- bool irreducible = false;
- edge taken_edge = profitable_jump_thread_path (path, bbi, name, arg,
- speed_p, &irreducible);
- if (taken_edge)
- {
- convert_and_register_jump_thread_path (path, taken_edge);
- path->pop ();
-
- if (irreducible)
- vect_free_loop_info_assumptions ((*path)[0]->loop_father);
- }
- }
- }
+ handle_phi (as_a <gphi *> (def_stmt), name, var_bb,
+ visited_bbs, path, seen_loop_phi, speed_p);
else if (gimple_code (def_stmt) == GIMPLE_ASSIGN)
- {
- tree arg = gimple_assign_rhs1 (def_stmt);
-
- if (TREE_CODE (arg) == SSA_NAME)
- fsm_find_control_statement_thread_paths (arg, visited_bbs,
- path, seen_loop_phi, speed_p);
-
- else
- {
- /* profitable_jump_thread_path is going to push the current
- block onto the path. But the path will always have the current
- block at this point. So we can just pop it. */
- path->pop ();
-
- bool irreducible = false;
- edge taken_edge = profitable_jump_thread_path (path, var_bb,
- name, arg, speed_p,
- &irreducible);
- if (taken_edge)
- {
- convert_and_register_jump_thread_path (path, taken_edge);
- path->pop ();
-
- if (irreducible)
- vect_free_loop_info_assumptions ((*path)[0]->loop_father);
- }
-
- /* And put the current block back onto the path so that the
- state of the stack is unchanged when we leave. */
- vec_safe_push (path, var_bb);
- }
- }
+ handle_assignment (def_stmt, name, var_bb,
+ visited_bbs, path, seen_loop_phi, speed_p);
/* Remove all the nodes that we added from NEXT_PATH. */
if (next_path_length)
else if (code == GIMPLE_COND)
{
if (TREE_CODE (gimple_cond_lhs (stmt)) == SSA_NAME
- && TREE_CODE (gimple_cond_rhs (stmt)) == INTEGER_CST
+ && TREE_CODE_CLASS (TREE_CODE (gimple_cond_rhs (stmt))) == tcc_constant
&& (INTEGRAL_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt)))
|| POINTER_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt)))))
name = gimple_cond_lhs (stmt);
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