re PR tree-optimization/41857 (Loop optimizer breaks __ea pointers with -mea64)

gcc/
	PR tree-optimization/41857
	* tree-flow.h (rewrite_use_address): Add BASE_HINT argument.
	* tree-ssa-loop-ivopts.c (rewrite_use_address): Pass base hint
	to create_mem_ref.
	* tree-ssa-address.c (move_hint_to_base): New function.
	(most_expensive_mult_to_index): Add TYPE argument.  Use mode and
	address space associated with TYPE.
	(addr_to_parts): Add TYPE and BASE_HINT arguments.  Pass TYPE to
	most_expensive_mult_to_index.  Call move_hint_to_base.
	(create_mem_ref): Add BASE_HINT argument.  Pass BASE_HINT and
	TYPE to addr_to_parts.

gcc/testsuite/
	PR tree-optimization/41857
	* gcc.target/spu/ea/pr41857.c: New file.

From-SVN: r153810

1 files changed, 17 insertions, 1 deletions

diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c
index 82e45d2..e89ee0e 100644
--- a/gcc/tree-ssa-loop-ivopts.c
+++ b/gcc/tree-ssa-loop-ivopts.c
@@ -5510,6 +5510,7 @@ rewrite_use_address (struct ivopts_data *data,
 {
   aff_tree aff;
   gimple_stmt_iterator bsi = gsi_for_stmt (use->stmt);
+  tree base_hint = NULL_TREE;
   tree ref;
   bool ok;
 
@@ -5517,7 +5518,22 @@ rewrite_use_address (struct ivopts_data *data,
   gcc_assert (ok);
   unshare_aff_combination (&aff);
 
-  ref = create_mem_ref (&bsi, TREE_TYPE (*use->op_p), &aff, data->speed);
+  /* To avoid undefined overflow problems, all IV candidates use unsigned
+     integer types.  The drawback is that this makes it impossible for
+     create_mem_ref to distinguish an IV that is based on a memory object
+     from one that represents simply an offset.
+
+     To work around this problem, we pass a hint to create_mem_ref that
+     indicates which variable (if any) in aff is an IV based on a memory
+     object.  Note that we only consider the candidate.  If this is not
+     based on an object, the base of the reference is in some subexpression
+     of the use -- but these will use pointer types, so they are recognized
+     by the create_mem_ref heuristics anyway.  */
+  if (cand->iv->base_object)
+    base_hint = var_at_stmt (data->current_loop, cand, use->stmt);
+
+  ref = create_mem_ref (&bsi, TREE_TYPE (*use->op_p), &aff, base_hint,
+			data->speed);
   copy_ref_info (ref, *use->op_p);
   *use->op_p = ref;
 }