[PR ipa/71981] Make get_dynamic_type grok MEM_REF

2016-08-09  Martin Jambor  <mjambor@suse.cz>

        PR ipa/71981
        * ipa-polymorphic-call.c (get_dynamic_type): Bail out gracefully
        if instance is a MEM_REF.

testsuite/
        PR ipa/71981
        * gcc.dg/ipa/pr71981.c: New test.

From-SVN: r239294

gcc/ChangeLog

+2016-08-09  Martin Jambor  <mjambor@suse.cz>
+
+        PR ipa/71981
+        * ipa-polymorphic-call.c (get_dynamic_type): Bail out gracefully
+        if instance is a MEM_REF.
+
 2016-08-09  Uros Bizjak  <ubizjak@gmail.com>
 
 	PR target/72843

gcc/ipa-polymorphic-call.c

@@ -1544,6 +1544,11 @@ ipa_polymorphic_call_context::get_dynamic_type (tree instance,
   if (!maybe_in_construction && !maybe_derived_type)
     return false;
 
+  /* If we are in fact not looking at any object object or the instance is
+     some placement new into a random load, give up straight away.  */
+  if (TREE_CODE (instance) == MEM_REF)
+    return false;
+
   /* We need to obtain refernce to virtual table pointer.  It is better
      to look it up in the code rather than build our own.  This require bit
      of pattern matching, but we end up verifying that what we found is
@@ -1664,7 +1669,6 @@ ipa_polymorphic_call_context::get_dynamic_type (tree instance,
   tci.offset = instance_offset;
   tci.instance = instance;
   tci.vtbl_ptr_ref = instance_ref;
-  gcc_assert (TREE_CODE (instance) != MEM_REF);
   tci.known_current_type = NULL_TREE;
   tci.known_current_offset = 0;
   tci.otr_type = otr_type;

gcc/testsuite/ChangeLog

+2016-08-09  Martin Jambor  <mjambor@suse.cz>
+
+        PR ipa/71981
+        * gcc.dg/ipa/pr71981.c: New test.
+
 2016-08-09  Bin Cheng  <bin.cheng@arm.com>
 
 	PR tree-optimization/33707

gcc/testsuite/gcc.dg/ipa/pr71981.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -w" } */
+
+int **a;
+static void fn1(char **p1) {
+  char s = *p1, b = &s;
+  while (*fn2()[a])
+    ;
+}
+int main() { fn1(""); return 0; }