Use modref summaries for byte-wise dead store elimination.

gcc/ChangeLog:

	* ipa-modref.c (get_modref_function_summary): Declare.
	* ipa-modref.h (get_modref_function_summary): New function.
	* tree-ssa-dse.c (clear_live_bytes_for_ref): Break out from ...
	(clear_bytes_written_by): ... here; also clear memory killed by
	calls.

gcc/testsuite/ChangeLog:

	* gcc.dg/tree-ssa/modref-dse-4.c: New test.

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c
index 5783430..a70575bc 100644
--- a/gcc/ipa-modref.c
+++ b/gcc/ipa-modref.c
@@ -740,6 +740,28 @@ get_modref_function_summary (cgraph_node *func)
   return r;
 }
 
+/* Get function summary for CALL if it exists, return NULL otherwise.
+   If non-null set interposed to indicate whether function may not
+   bind to current def.  In this case sometimes loads from function
+   needs to be ignored.  */
+
+modref_summary *
+get_modref_function_summary (gcall *call, bool *interposed)
+{
+  tree callee = gimple_call_fndecl (call);
+  if (!callee)
+    return NULL;
+  struct cgraph_node *node = cgraph_node::get (callee);
+  if (!node)
+    return NULL;
+  modref_summary *r = get_modref_function_summary (node);
+  if (interposed && r)
+    *interposed = r->calls_interposable
+	    	  || !node->binds_to_current_def_p ();
+  return r;
+}
+
+
 namespace {
 
 /* Construct modref_access_node from REF.  */