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

53 #include "tree-ssa-loop-niter.h"
54 #include "tree-ssa-loop.h"
61 /* This file implements the loop unswitching, i.e. transformation of loops like
74    where inv is the loop invariant, into
94    tree-ssa-loop-im.c ensures that all the suitable conditions are in this
97 static struct loop *tree_unswitch_loop (struct loop *, basic_block, tree);
98 static bool tree_unswitch_single_loop (struct loop *, int);
99 static tree tree_may_unswitch_on (basic_block, struct loop *);
101 /* Main entry point.  Perform loop unswitching on all suitable loops.  */
106   struct loop *loop;
111   FOR_EACH_LOOP (loop, LI_ONLY_INNERMOST)
114         fprintf (dump_file, ";; Considering loop %d\n", loop->num);
117       if (optimize_loop_for_size_p (loop))
124       /* The loop should not be too large, to limit code growth. */
125       if (tree_num_loop_insns (loop, &eni_size_weights)
129             fprintf (dump_file, ";; Not unswitching, loop too big\n");
133       /* If the loop is not expected to iterate, there is no need
135       iterations = estimated_loop_iterations_int (loop);
139             fprintf (dump_file, ";; Not unswitching, loop is not expected to iterate\n");
143       changed |= tree_unswitch_single_loop (loop, 0);
155 tree_may_unswitch_on (basic_block bb, struct loop *loop)
171      loop where we would unswitch again on such a condition.  */
181 	  && flow_bb_inside_loop_p (loop, def_bb))
192    simplish (sufficient to prevent us from duplicating loop in unswitching
196 simplify_using_entry_checks (struct loop *loop, tree cond)
198   edge e = loop_preheader_edge (loop);
229 tree_unswitch_single_loop (struct loop *loop, int num)
232   struct loop *nloop;
239   bbs = get_loop_body (loop);
240   found = loop->num_nodes;
245       for (; i < loop->num_nodes; i++)
246 	if ((cond = tree_may_unswitch_on (bbs[i], loop)))
249       if (i == loop->num_nodes)
256 	  if (found == loop->num_nodes)
264       cond = simplify_using_entry_checks (loop, cond);
288 	 loop and find the condition only among those still reachable bbs.  */
291 	  if (found == loop->num_nodes)
313       tos = worklist = XNEWVEC (basic_block, loop->num_nodes);
315       for (i = 0; i < loop->num_nodes; i++)
323 	 within the same innermost loop.  Don't look through false edges
351 	      if (dest->loop_father == loop
364       for (; found < loop->num_nodes; found++)
366 	    && (cond = tree_may_unswitch_on (bbs[found], loop)))
369       if (found == loop->num_nodes)
377     fprintf (dump_file, ";; Unswitching loop\n");
380   /* Unswitch the loop on this condition.  */
381   nloop = tree_unswitch_loop (loop, bbs[found], cond);
395   tree_unswitch_single_loop (loop, num + 1);
402    loop is entered -- the new loop is entered if COND is true.  Returns NULL
403    if impossible, new loop otherwise.  */
405 static struct loop *
406 tree_unswitch_loop (struct loop *loop,
413   gcc_assert (flow_bb_inside_loop_p (loop, unswitch_on));
415   gcc_assert (loop->inner == NULL);
419   return loop_version (loop, unshare_expr (cond),