Enable more WITH_SIZE_EXPR processing

This enables the alias machinery for WITH_SIZE_EXPR which can appear
in call LHS and arguments.  In particular this drops the NULL
return from get_base_address and it adjusts get_ref_base_and_extent
and friends to use the size information in WITH_SIZE_EXPR and
look through it for further processing.

2021-05-19  Richard Biener  <rguenther@suse.de>

	* builtins.c (get_object_alignment_1): Strip outer
	WITH_SIZE_EXPR.
	* tree-dfa.c (get_ref_base_and_extent): Handle outer
	WITH_SIZE_EXPR for size processing and process the
	containing ref.
	* tree-ssa-alias.c (ao_ref_base_alias_set): Strip
	outer WITH_SIZE_EXPR.
	(ao_ref_base_alias_ptr_type): Likewise.
	(refs_may_alias_p_2): Allow WITH_SIZE_EXPR in ref->ref
	and handle that accordingly, stripping it for the
	core alias workers.
	* tree.c (get_base_address): Handle WITH_SIZE_EXPR by
	looking through it instead of returning NULL.

1 files changed, 2 insertions, 5 deletions

diff --git a/gcc/tree.c b/gcc/tree.c
index 31ac424..bdb29b8 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -12382,6 +12382,8 @@ drop_tree_overflow (tree t)
 tree
 get_base_address (tree t)
 {
+  if (TREE_CODE (t) == WITH_SIZE_EXPR)
+    t = TREE_OPERAND (t, 0);
   while (handled_component_p (t))
     t = TREE_OPERAND (t, 0);
 
@@ -12390,11 +12392,6 @@ get_base_address (tree t)
       && TREE_CODE (TREE_OPERAND (t, 0)) == ADDR_EXPR)
     t = TREE_OPERAND (TREE_OPERAND (t, 0), 0);
 
-  /* ???  Either the alias oracle or all callers need to properly deal
-     with WITH_SIZE_EXPRs before we can look through those.  */
-  if (TREE_CODE (t) == WITH_SIZE_EXPR)
-    return NULL_TREE;
-
   return t;
 }