# HG changeset patch
# User vlivanov
# Date 1500485432 -10800
#      Wed Jul 19 20:30:32 2017 +0300
# Branch mvt
# Node ID 2760f7c563a1c9dc12297cc7da9a06a3ce4a4535
# Parent  dc6a599385189ae566bc33804123d10a063d72a7
[mq]: lfb.customize

diff --git a/src/java.base/share/classes/java/lang/invoke/LambdaFormBuilder.java b/src/java.base/share/classes/java/lang/invoke/LambdaFormBuilder.java
--- a/src/java.base/share/classes/java/lang/invoke/LambdaFormBuilder.java
+++ b/src/java.base/share/classes/java/lang/invoke/LambdaFormBuilder.java
@@ -65,6 +65,7 @@
     private static final String CLASS_PREFIX   = "java/lang/invoke/LambdaForm$Value$";
     private static final String DEFAULT_CLASS  = "MH";
     private static final String LL_SIG  = "(L" + OBJ + ";)L" + OBJ + ";";
+    private static final String LLV_SIG = "(L" + OBJ + ";L" + OBJ + ";)V";
 
     private static final String MH           = "java/lang/invoke/MethodHandle";
     private static final String MHARY2       = "[[L" + MH + ";";
@@ -94,7 +95,25 @@
         this.lambdaForm = lambdaForm;
     }
 
+    /** Generates code to check that actual receiver and LambdaForm matches */
+    private boolean checkActualReceiver() {
+        // Expects MethodHandle on the stack and actual receiver MethodHandle in slot #0
+        builder.dup().load(0).invokestatic(MethodHandleImpl.class, "assertSame", LLV_SIG, false);
+        return true;
+    }
+
     void generateLambdaFormBody() {
+        if (lambdaForm.customized != null && MethodHandleBuilder.ENABLE_POOL_PATCHES) {
+            // Since LambdaForm is customized for a particular MethodHandle, it's safe to substitute
+            // receiver MethodHandle (at slot #0) with an embedded constant and use it instead.
+            // It enables more efficient code generation in some situations, since embedded constants
+            // are compile-time constants for JIT compiler.
+            builder.ldc(lambdaForm.customized)
+                   .checkcast(MethodHandle.class);
+            assert(checkActualReceiver()); // generates runtime check
+            builder.store(0);
+        }
+
         // iterate over the form's names, generating bytecode instructions for each
         // start iterating at the first name following the arguments
         Name onStack = null;
diff --git a/src/java.base/share/classes/jdk/experimental/value/MethodHandleBuilder.java b/src/java.base/share/classes/jdk/experimental/value/MethodHandleBuilder.java
--- a/src/java.base/share/classes/jdk/experimental/value/MethodHandleBuilder.java
+++ b/src/java.base/share/classes/jdk/experimental/value/MethodHandleBuilder.java
@@ -54,7 +54,7 @@
 
     static final Unsafe UNSAFE = Unsafe.getUnsafe();
 
-    static final boolean ENABLE_POOL_PATCHES;
+    public static final boolean ENABLE_POOL_PATCHES;
 
     static {
         Properties props = GetPropertyAction.privilegedGetProperties();