contrib/gcc/tree-ssa-loop-unswitch.c

40 /* This file implements the loop unswitching, i.e. transformation of loops like
53    where inv is the loop invariant, into
73    tree-ssa-loop-im.c ensures that all the suitable conditions are in this
76 static struct loop *tree_unswitch_loop (struct loops *, struct loop *, basic_block,
78 static bool tree_unswitch_single_loop (struct loops *, struct loop *, int);
79 static tree tree_may_unswitch_on (basic_block, struct loop *);
81 /* Main entry point.  Perform loop unswitching on all suitable LOOPS.  */
87   struct loop *loop;
95       /* Removed loop?  */
96       loop = loops->parray[i];
97       if (!loop)
100       if (loop->inner)
103       changed |= tree_unswitch_single_loop (loops, loop, 0);
115 tree_may_unswitch_on (basic_block bb, struct loop *loop)
132 	  && flow_bb_inside_loop_p (loop, def_bb))
138      but just replace tests with 0/1.  Prevent the infinite loop where we
147    simplish (sufficient to prevent us from duplicating loop in unswitching
151 simplify_using_entry_checks (struct loop *loop, tree cond)
153   edge e = loop_preheader_edge (loop);
180 tree_unswitch_single_loop (struct loops *loops, struct loop *loop, int num)
183   struct loop *nloop;
197   if (loop->inner)
200 	fprintf (dump_file, ";; Not unswitching, not innermost loop\n");
204   /* The loop should not be too large, to limit code growth.  */
205   if (tree_num_loop_insns (loop)
209 	fprintf (dump_file, ";; Not unswitching, loop too big\n");
214   bbs = get_loop_body (loop);
219       for (; i < loop->num_nodes; i++)
220 	if ((cond = tree_may_unswitch_on (bbs[i], loop)))
223       if (i == loop->num_nodes)
229       cond = simplify_using_entry_checks (loop, cond);
251     fprintf (dump_file, ";; Unswitching loop\n");
254   /* Unswitch the loop on this condition.  */
255   nloop = tree_unswitch_loop (loops, loop, bbs[i], cond);
269   tree_unswitch_single_loop (loops, loop, num + 1);
276    loop is entered -- the new loop is entered if COND is true.  Returns NULL
277    if impossible, new loop otherwise.  */
279 static struct loop *
280 tree_unswitch_loop (struct loops *loops, struct loop *loop,
286   gcc_assert (flow_bb_inside_loop_p (loop, unswitch_on));
288   gcc_assert (loop->inner == NULL);
290   return loop_version (loops, loop, unshare_expr (cond),