8336003: [lworld] TestLWorld::test151 triggers "Should have been buffered" assert

Reviewed-by: thartmann

Author: Quan Anh Mai

src/hotspot/share/opto/cfgnode.cpp

@@ -1476,6 +1476,10 @@ Node* PhiNode::Identity(PhaseGVN* phase) {
   if (uin != nullptr) {
     return uin;
   }
+  uin = unique_input_recursive(phase);
+  if (uin != nullptr) {
+    return uin;
+  }
 
   int true_path = is_diamond_phi();
   // Delay CMove'ing identity if Ideal has not had the chance to handle unsafe cases, yet.
@@ -1575,6 +1579,39 @@ Node* PhiNode::unique_input(PhaseValues* phase, bool uncast) {
   return nullptr;
 }
 
+// Find the unique input, try to look recursively through input Phis
+Node* PhiNode::unique_input_recursive(PhaseGVN* phase) {
+  if (!phase->is_IterGVN()) {
+    return nullptr;
+  }
+
+  ResourceMark rm;
+  Node* unique = nullptr;
+  Unique_Node_List visited;
+  visited.push(this);
+
+  for (uint visited_idx = 0; visited_idx < visited.size(); visited_idx++) {
+    Node* current = visited.at(visited_idx);
+    for (uint i = 1; i < current->req(); i++) {
+      Node* phi_in = current->in(i);
+      if (phi_in == nullptr) {
+        continue;
+      }
+
+      if (phi_in->is_Phi()) {
+        visited.push(phi_in);
+      } else {
+        if (unique == nullptr) {
+          unique = phi_in;
+        } else if (unique != phi_in) {
+          return nullptr;
+        }
+      }
+    }
+  }
+  return unique;
+}
+
 //------------------------------is_x2logic-------------------------------------
 // Check for simple convert-to-boolean pattern
 // If:(C Bool) Region:(IfF IfT) Phi:(Region 0 1)

src/hotspot/share/opto/cfgnode.hpp

@@ -232,6 +232,7 @@ class PhiNode : public TypeNode {
     }
     return uin;
   }
+  Node* unique_input_recursive(PhaseGVN* phase);
 
   // Check for a simple dead loop.
   enum LoopSafety { Safe = 0, Unsafe, UnsafeLoop };

test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestLWorld.java

@@ -4156,13 +4156,14 @@ public void test150_verifier() {
         Asserts.assertEquals(test150(), testValue2.hash());
     }
 
-// TODO 8336003 This triggers #  assert(false) failed: Should have been buffered
-/*
-    // Same as test150 but with val not being allocated in the scope of the method
+    // Same as test150 but with a real loop and val not being allocated in the scope of the method
     @Test
+    // Dynamic call does not null check the receiver, so it cannot be strength reduced to a static
+    // call without an explicit null check
     @IR(failOn = {compiler.lib.ir_framework.IRNode.DYNAMIC_CALL_OF_METHOD, "MyValue2::hash"},
         counts = {compiler.lib.ir_framework.IRNode.STATIC_CALL_OF_METHOD, "MyValue2::hash", "= 1"})
     public long test151(MyValue2 val) {
+        val = Objects.requireNonNull(val);
         MyAbstract receiver = MyValue1.createWithFieldsInline(rI, rL);
 
         for (int i = 0; i < 100; i++) {
@@ -4180,7 +4181,6 @@ public long test151(MyValue2 val) {
     public void test151_verifier() {
         Asserts.assertEquals(test151(testValue2), testValue2.hash());
     }
-*/
 
     static interface MyInterface2 {
         public int val();