src/java.base/share/classes/java/lang/invoke/InvokerBytecodeGenerator.java

rev 11254 : 8063137: Never-taken branches should be pruned when GWT LambdaForms are shared
Reviewed-by: ?
rev 11255 : [mq]: gwt.profile.1
rev 11258 : 8069591: Customize LambdaForms which are invoked using MH.invoke/invokeExact
Reviewed-by: ?

*** 54,66 ****
--- 54,68 ----
      private static final String LFN     = "java/lang/invoke/LambdaForm$Name";
      private static final String CLS     = "java/lang/Class";
      private static final String OBJ     = "java/lang/Object";
      private static final String OBJARY  = "[Ljava/lang/Object;";
  
+     private static final String MH_SIG  = "L" + MH + ";";
      private static final String LF_SIG  = "L" + LF + ";";
      private static final String LFN_SIG = "L" + LFN + ";";
      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 CLL_SIG = "(L" + CLS + ";L" + OBJ + ";)L" + OBJ + ";";
  
      /** Name of its super class*/
      private static final String superName = OBJ;
  
*** 625,634 ****
--- 627,645 ----
              }
          }
          return false;
      }
  
+     /** 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
+         mv.visitInsn(Opcodes.DUP);
+         mv.visitVarInsn(Opcodes.ALOAD, localsMap[0]);
+         mv.visitMethodInsn(Opcodes.INVOKESTATIC, MHI, "assertSame", LLV_SIG, false);
+         return true;
+     }
+ 
      /**
       * Generate an invoker method for the passed {@link LambdaForm}.
       */
      private byte[] generateCustomizedCodeBytes() {
          classFilePrologue();
*** 650,659 ****
--- 661,681 ----
              mv.visitAnnotation("Ljava/lang/invoke/ForceInline;", true);
          } else {
              mv.visitAnnotation("Ljava/lang/invoke/DontInline;", true);
          }
  
+         if (lambdaForm.customized != null) {
+             // 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.
+             mv.visitLdcInsn(constantPlaceholder(lambdaForm.customized));
+             mv.visitTypeInsn(Opcodes.CHECKCAST, MH);
+             assert(checkActualReceiver()); // expects MethodHandle on top of the stack
+             mv.visitVarInsn(Opcodes.ASTORE, localsMap[0]);
+         }
+ 
          // iterate over the form's names, generating bytecode instructions for each
          // start iterating at the first name following the arguments
          Name onStack = null;
          for (int i = lambdaForm.arity; i < lambdaForm.names.length; i++) {
              Name name = lambdaForm.names[i];