Fix cgraph_node::function_symbol availability compuattion [PR94202]

this fixes ICE in inliner cache sanity check which is caused by very old
bug in visibility calculation in cgraph_node::function_symbol and
cgraph_node::function_or_virtual_thunk_symbol.

In the testcase there is indirect call to a thunk. At begining we correctly
see that its body as AVAIL_AVAILABLE but later we inline into the thunk and
this turns it to AVAIL_INTERPOSABLE.

This is because function_symbol incorrectly overwrites availability parameter
by availability of the alias used in the call within thunk, which is a local
alias.

gcc/ChangeLog:

2020-03-19  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/94202
	* cgraph.c (cgraph_node::function_symbol): Fix availability computation.
	(cgraph_node::function_or_virtual_thunk_symbol): Likewise.

gcc/testsuite/ChangeLog:

2020-03-19  Jan Hubicka  <hubicka@ucw.cz>

	PR ipa/94202
	* g++.dg/torture/pr94202.C: New test.

gcc/ChangeLog

 2020-03-19  Jan Hubicka  <hubicka@ucw.cz>
 
+	PR ipa/94202
+	* cgraph.c (cgraph_node::function_symbol): Fix availability computation.
+	(cgraph_node::function_or_virtual_thunk_symbol): Likewise.
+
+2020-03-19  Jan Hubicka  <hubicka@ucw.cz>
+
 	PR ipa/92372
 	* cgraphunit.c (process_function_and_variable_attributes): warn
 	for flatten attribute on alias.

gcc/cgraph.c

@@ -3788,16 +3788,13 @@ cgraph_node::function_symbol (enum availability *availability,
 
   while (node->thunk.thunk_p)
     {
+      enum availability a;
+
       ref = node;
       node = node->callees->callee;
-      if (availability)
-	{
-	  enum availability a;
-	  a = node->get_availability (ref);
-	  if (a < *availability)
-	    *availability = a;
-	}
-      node = node->ultimate_alias_target (availability, ref);
+      node = node->ultimate_alias_target (availability ? &a : NULL, ref);
+      if (availability && a < *availability)
+	*availability = a;
     }
   return node;
 }
@@ -3818,16 +3815,13 @@ cgraph_node::function_or_virtual_thunk_symbol
 
   while (node->thunk.thunk_p && !node->thunk.virtual_offset_p)
     {
+      enum availability a;
+
       ref = node;
       node = node->callees->callee;
-      if (availability)
-	{
-	  enum availability a;
-	  a = node->get_availability (ref);
-	  if (a < *availability)
-	    *availability = a;
-	}
-      node = node->ultimate_alias_target (availability, ref);
+      node = node->ultimate_alias_target (availability ? &a : NULL, ref);
+      if (availability && a < *availability)
+	*availability = a;
     }
   return node;
 }

gcc/testsuite/ChangeLog

+2020-03-19  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR ipa/94202
+	* g++.dg/torture/pr94202.C: New test.
+
 2020-03-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR gcov-profile/94029

gcc/testsuite/g++.dg/torture/pr94202.C

+// { dg-additional-options "-w" }
+struct S1 {
+  virtual ~S1();
+  virtual void v();
+};
+struct S2: S1 {};
+struct S3: S1, S2 { void v(); };
+struct S4: S3 { void v(); };
+void S4::v() { S3::v(); }
+struct R {
+  S1 * m;
+  void f(S2 * x) {
+    static_cast<S1 *>(x)->v();
+    x->v();
+    m = x;
+  }
+};
+void f() {
+  R r;
+  r.f(new S4);
+  r.f(new S3);
+}