re PR rtl-optimization/29924 (pr24626-4.c fails on powerpc-aix and others)

	PR rtl-optimization/29924
	* loop-unroll.c (split_edge_and_insert): Handle the case insns is NULL.
	(unroll_loop_runtime_iterations): Assert that the argument passed to
	split_edge_and_insert is not NULL.
	* loop-doloop.c (add_test): Ditto.

From-SVN: r119078

1 files changed, 13 insertions, 3 deletions

diff --git a/gcc/loop-unroll.c b/gcc/loop-unroll.c
index 7d230fb..2f6f3ba 100644
--- a/gcc/loop-unroll.c
+++ b/gcc/loop-unroll.c
@@ -899,13 +899,18 @@ decide_unroll_runtime_iterations (struct loop *loop, int flags)
 	     loop->lpt_decision.times);
 }
 
-/* Splits edge E and inserts INSNS on it.  */
+/* Splits edge E and inserts the sequence of instructions INSNS on it, and
+   returns the newly created block.  If INSNS is NULL_RTX, nothing is changed
+   and NULL is returned instead.  */
 
 basic_block
 split_edge_and_insert (edge e, rtx insns)
 {
-  basic_block bb = split_edge (e); 
-  gcc_assert (insns != NULL_RTX);
+  basic_block bb;
+
+  if (!insns)
+    return NULL;
+  bb = split_edge (e); 
   emit_insn_after (insns, BB_END (bb));
   bb->flags |= BB_SUPERBLOCK;
   return bb;
@@ -1069,6 +1074,10 @@ unroll_loop_runtime_iterations (struct loops *loops, struct loop *loop)
 					  block_label (preheader), p,
 					  NULL_RTX);
 
+      /* We rely on the fact that the compare and jump cannot be optimized out,
+	 and hence the cfg we create is correct.  */
+      gcc_assert (branch_code != NULL_RTX);
+
       swtch = split_edge_and_insert (single_pred_edge (swtch), branch_code);
       set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);
       single_pred_edge (swtch)->probability = REG_BR_PROB_BASE - p;
@@ -1086,6 +1095,7 @@ unroll_loop_runtime_iterations (struct loops *loops, struct loop *loop)
       branch_code = compare_and_jump_seq (copy_rtx (niter), const0_rtx, EQ,
 					  block_label (preheader), p,
 					  NULL_RTX);
+      gcc_assert (branch_code != NULL_RTX);
 
       swtch = split_edge_and_insert (single_succ_edge (swtch), branch_code);
       set_immediate_dominator (CDI_DOMINATORS, preheader, swtch);