/* Convert a program in SSA form into Normal form.
- Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
Contributed by Andrew Macleod <amacleod@redhat.com>
This file is part of GCC.
}
DECL_ARTIFICIAL (tmp) = DECL_ARTIFICIAL (t);
DECL_IGNORED_P (tmp) = DECL_IGNORED_P (t);
+ DECL_GIMPLE_REG_P (tmp) = DECL_GIMPLE_REG_P (t);
add_referenced_var (tmp);
/* add_referenced_var will create the annotation and set up some
if (remove)
bsi_remove (&si, true);
else
- bsi_next (&si);
+ {
+ if (changed)
+ if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
+ tree_purge_dead_eh_edges (bb);
+ bsi_next (&si);
+ }
}
phi = phi_nodes (bb);
BITMAP_FREE (leader_has_match);
}
+/* A helper function to be called via walk_tree. Return DATA if it is
+ contained in subtree TP. */
+
+static tree
+contains_tree_r (tree * tp, int *walk_subtrees, void *data)
+{
+ if (*tp == data)
+ {
+ *walk_subtrees = 0;
+ return data;
+ }
+ else
+ return NULL_TREE;
+}
+
+/* A threshold for the number of insns contained in the latch block.
+ It is used to prevent blowing the loop with too many copies from
+ the latch. */
+#define MAX_STMTS_IN_LATCH 2
+
+/* Return TRUE if the stmts on SINGLE-EDGE can be moved to the
+ body of the loop. This should be permitted only if SINGLE-EDGE is a
+ single-basic-block latch edge and thus cleaning the latch will help
+ to create a single-basic-block loop. Otherwise return FALSE. */
+
+static bool
+process_single_block_loop_latch (edge single_edge)
+{
+ tree stmts;
+ basic_block b_exit, b_pheader, b_loop = single_edge->src;
+ edge_iterator ei;
+ edge e;
+ block_stmt_iterator bsi, bsi_exit;
+ tree_stmt_iterator tsi;
+ tree expr, stmt;
+ unsigned int count = 0;
+
+ if (single_edge == NULL || (single_edge->dest != single_edge->src)
+ || (EDGE_COUNT (b_loop->succs) != 2)
+ || (EDGE_COUNT (b_loop->preds) != 2))
+ return false;
+
+ /* Get the stmts on the latch edge. */
+ stmts = PENDING_STMT (single_edge);
+
+ /* Find the successor edge which is not the latch edge. */
+ FOR_EACH_EDGE (e, ei, b_loop->succs)
+ if (e->dest != b_loop)
+ break;
+
+ b_exit = e->dest;
+
+ /* Check that the exit block has only the loop as a predecessor,
+ and that there are no pending stmts on that edge as well. */
+ if (EDGE_COUNT (b_exit->preds) != 1 || PENDING_STMT (e))
+ return false;
+
+ /* Find the predecessor edge which is not the latch edge. */
+ FOR_EACH_EDGE (e, ei, b_loop->preds)
+ if (e->src != b_loop)
+ break;
+
+ b_pheader = e->src;
+
+ if (b_exit == b_pheader || b_exit == b_loop || b_pheader == b_loop)
+ return false;
+
+ bsi_exit = bsi_after_labels (b_exit);
+
+ /* Get the last stmt in the loop body. */
+ bsi = bsi_last (single_edge->src);
+ stmt = bsi_stmt (bsi);
+
+ if (TREE_CODE (stmt) != COND_EXPR)
+ return false;
+
+ expr = COND_EXPR_COND (stmt);
+ /* Iterate over the insns on the latch and count them. */
+ for (tsi = tsi_start (stmts); !tsi_end_p (tsi); tsi_next (&tsi))
+ {
+ tree stmt1 = tsi_stmt (tsi);
+ tree var;
+
+ count++;
+ /* Check that the condition does not contain any new definition
+ created in the latch as the stmts from the latch intended
+ to precede it. */
+ if (TREE_CODE (stmt1) != GIMPLE_MODIFY_STMT)
+ return false;
+ var = GIMPLE_STMT_OPERAND (stmt1, 0);
+ if (TREE_THIS_VOLATILE (var)
+ || TYPE_VOLATILE (TREE_TYPE (var))
+ || walk_tree (&expr, contains_tree_r, var, NULL))
+ return false;
+ }
+ /* Check that the latch does not contain more than MAX_STMTS_IN_LATCH
+ insns. The purpose of this restriction is to prevent blowing the
+ loop with too many copies from the latch. */
+ if (count > MAX_STMTS_IN_LATCH)
+ return false;
+
+ /* Apply the transformation - clean up the latch block:
+
+ var = something;
+ L1:
+ x1 = expr;
+ if (cond) goto L2 else goto L3;
+ L2:
+ var = x1;
+ goto L1
+ L3:
+ ...
+
+ ==>
+
+ var = something;
+ L1:
+ x1 = expr;
+ tmp_var = var;
+ var = x1;
+ if (cond) goto L1 else goto L2;
+ L2:
+ var = tmp_var;
+ ...
+ */
+ for (tsi = tsi_start (stmts); !tsi_end_p (tsi); tsi_next (&tsi))
+ {
+ tree stmt1 = tsi_stmt (tsi);
+ tree var, tmp_var, copy;
+
+ /* Create a new variable to load back the value of var in case
+ we exit the loop. */
+ var = GIMPLE_STMT_OPERAND (stmt1, 0);
+ tmp_var = create_temp (var);
+ copy = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (tmp_var), tmp_var, var);
+ set_is_used (tmp_var);
+ bsi_insert_before (&bsi, copy, BSI_SAME_STMT);
+ copy = build2 (GIMPLE_MODIFY_STMT, TREE_TYPE (tmp_var), var, tmp_var);
+ bsi_insert_before (&bsi_exit, copy, BSI_SAME_STMT);
+ }
+
+ PENDING_STMT (single_edge) = 0;
+ /* Insert the new stmts to the loop body. */
+ bsi_insert_before (&bsi, stmts, BSI_NEW_STMT);
+
+ if (dump_file)
+ fprintf (dump_file,
+ "\nCleaned-up latch block of loop with single BB: %d\n\n",
+ single_edge->dest->index);
+
+ return true;
+}
/* Look at all the incoming edges to block BB, and decide where the best place
to insert the stmts on each edge are, and perform those insertions. */
if (count < 2)
{
if (single_edge)
- bsi_commit_one_edge_insert (single_edge, NULL);
+ {
+ /* Add stmts to the edge unless processed specially as a
+ single-block loop latch edge. */
+ if (!process_single_block_loop_latch (single_edge))
+ bsi_commit_one_edge_insert (single_edge, NULL);
+ }
return;
}
/* Define the parameters of the out of SSA pass. */
-struct tree_opt_pass pass_del_ssa =
+struct gimple_opt_pass pass_del_ssa =
{
+ {
+ GIMPLE_PASS,
"optimized", /* name */
NULL, /* gate */
rewrite_out_of_ssa, /* execute */
| TODO_verify_stmts, /* todo_flags_start */
TODO_dump_func
| TODO_ggc_collect
- | TODO_remove_unused_locals, /* todo_flags_finish */
- 0 /* letter */
+ | TODO_remove_unused_locals /* todo_flags_finish */
+ }
};
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