[PEA] mark monitor inputs as escaped (openjdk#64)

PEA/MatInMonitor.java

@@ -0,0 +1,17 @@
+class MatInMonitor {
+    private Object _cache;
+    public void test() {
+        Object x = new Object();
+        synchronized (x) {
+            _cache = x;
+        }
+    }
+
+    public static void main(String[] args)  {
+        MatInMonitor kase = new MatInMonitor();
+
+        for (int i = 0; i < 2; ++i) {
+            kase.test();
+        }
+    }
+}

PEA/run_mat_in_monitor.sh

@@ -0,0 +1,2 @@
+#!/usr/bin/bash
+java -Xcomp -Xms32M -Xmx32M -XX:+AlwaysPreTouch -XX:+UnlockExperimentalVMOptions -XX:-UseOnStackReplacement -XX:+StressRecompilation -XX:+UseTLAB -XX:CompileCommand='compileOnly,MatInMonitor.test*' $* MatInMonitor

src/hotspot/share/opto/locknode.cpp

@@ -189,6 +189,16 @@ void Parse::do_monitor_enter() {
   // the monitor object is not part of debug info expression stack
   pop();
 
+  if (DoPartialEscapeAnalysis) {
+    // TODO: PEA can support monitors
+    PartialEscapeAnalysis* pea = PEA();
+    PEAState& state = jvms()->alloc_state();
+
+    if (state.as_virtual(pea, obj) != nullptr) {
+      state.escape(pea->is_alias(obj), obj, false);
+    }
+  }
+
   // Insert a FastLockNode which takes as arguments the current thread pointer,
   // the obj pointer & the address of the stack slot pair used for the lock.
   shared_lock(obj);