8257632: C2: Late inlining attempt on a call with a dead memory crashes

Reviewed-by: neliasso, kvn, thartmann

src/hotspot/share/opto/callGenerator.cpp

@@ -363,6 +363,12 @@ void LateInlineCallGenerator::do_late_inline() {
     assert(Compile::current()->inlining_incrementally(), "shouldn't happen during parsing");
     return;
   }
+  if (call->in(TypeFunc::Memory)->is_MergeMem()) {
+    MergeMemNode* merge_mem = call->in(TypeFunc::Memory)->as_MergeMem();
+    if (merge_mem->base_memory() == merge_mem->empty_memory()) {
+      return; // dead path
+    }
+  }
 
   // check for unreachable loop
   CallProjections callprojs;

src/hotspot/share/opto/graphKit.cpp

@@ -1460,6 +1460,7 @@ void GraphKit::replace_in_map(Node* old, Node* neww) {
 Node* GraphKit::memory(uint alias_idx) {
   MergeMemNode* mem = merged_memory();
   Node* p = mem->memory_at(alias_idx);
+  assert(p != mem->empty_memory(), "empty");
   _gvn.set_type(p, Type::MEMORY);  // must be mapped
   return p;
 }