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

42    in the loop body are always executed when the loop is entered.  This
44    for loop preconditioning.  */
51 should_duplicate_loop_header_p (basic_block header, struct loop *loop,
58      loop peeling here).  */
65   if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest)
66       && flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 1)->dest))
69   /* If this is not the original loop header, we want it to have just
71   if (header != loop->header && !single_pred_p (header))
98 /* Checks whether LOOP is a do-while style loop.  */
101 do_while_loop_p (struct loop *loop)
103   tree stmt = last_stmt (loop->latch);
105   /* If the latch of the loop is not empty, it is not a do-while loop.  */
110   /* If the header contains just a condition, it is not a do-while loop.  */
111   stmt = last_and_only_stmt (loop->header);
119 /* For all loops, copy the condition at the end of the loop body in front
120    of the loop.  This is beneficial since it increases efficiency of
121    code motion optimizations.  It also saves one jump on entry to the loop.  */
128   struct loop *loop;
153       loop = loops->parray[i];
154       if (!loop)
156       header = loop->header;
158       /* If the loop is already a do-while style one (either because it was
160 	 we might be in fact peeling the first iteration of the loop.  This
162       if (do_while_loop_p (loop))
173       while (should_duplicate_loop_header_p (header, loop, &limit))
175 	  /* Find a successor of header that is inside a loop; i.e. the new
177 	  if (flow_bb_inside_loop_p (loop, EDGE_SUCC (header, 0)->dest))
191 		 "Duplicating header of the loop %d up to edge %d->%d.\n",
192 		 loop->num, exit->src->index, exit->dest->index);
195 	 inside the loop.  */
199       entry = loop_preheader_edge (loop);
207       /* If the loop has the form "for (i = j; i < j + 10; i++)" then
229 	 are not now, since there was the loop exit condition.  */
230       loop_split_edge_with (loop_preheader_edge (loop), NULL);
231       loop_split_edge_with (loop_latch_edge (loop), NULL);