ipa/96291: don't crash on unoptimized lto functions

In PR ipa/96291 the test contained an SCC with one
unoptimized function. This tricked ipa-cp into NULL dereference.

has_undead_caller_from_outside_scc_p() did not take into account
that unoptimized funtions don't have IPA summary analysis. And
dereferenced NULL pointer causing an ICE.

gcc/
	PR ipa/96291
	* ipa-cp.c (has_undead_caller_from_outside_scc_p): Consider
	unoptimized callers as undead.

gcc/testsuite/
	PR ipa/96291
	* gcc.dg/lto/pr96291_0.c: New testcase.
	* gcc.dg/lto/pr96291_1.c: Support file.
	* gcc.dg/lto/pr96291_2.c: Likewise.
	* gcc.dg/lto/pr96291.h: Likewise.

gcc/ipa-cp.c

@@ -5667,8 +5667,9 @@ has_undead_caller_from_outside_scc_p (struct cgraph_node *node,
 	  (has_undead_caller_from_outside_scc_p, NULL, true))
       return true;
     else if (!ipa_edge_within_scc (cs)
-	     && !IPA_NODE_REF (cs->caller)->node_dead)
-      return true;
+	     && (!IPA_NODE_REF (cs->caller) /* Unoptimized caller.  */
+		 || !IPA_NODE_REF (cs->caller)->node_dead))
+	  return true;
   return false;
 }
 

gcc/testsuite/gcc.dg/lto/pr96291.h

@@ -0,0 +1,4 @@
+void e(void);
+void f(void);
+void a(void *, void *);
+void c(int);

gcc/testsuite/gcc.dg/lto/pr96291_0.c

@@ -0,0 +1,11 @@
+/* { dg-lto-do link } */
+
+#include "pr96291.h"
+
+static void * b;
+void c(int d) {
+  f();
+  a(b, b);
+}
+
+void e(void) { c(0); }

gcc/testsuite/gcc.dg/lto/pr96291_1.c

@@ -0,0 +1,3 @@
+#include "pr96291.h"
+
+void f(void) { c(0); }

gcc/testsuite/gcc.dg/lto/pr96291_2.c

@@ -0,0 +1,7 @@
+/* { dg-options {-O0} } */
+
+#include "pr96291.h"
+
+void a(void * a1, void * a2) { e(); }
+
+int main(){}