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

rev 11254 : 8063137: Never-taken branches should be pruned when GWT LambdaForms are shared
Reviewed-by: ?
rev 11255 : [mq]: gwt.profile.1
rev 11256 : [mq]: gwt.profile.2
rev 11257 : [mq]: gwt.profile.3
rev 11258 : [mq]: gwt.profile.4

*** 595,604 ****
--- 595,605 ----
          private static final MethodHandle[] FILL_ARRAYS;
  
          static final NamedFunction NF_checkSpreadArgument;
          static final NamedFunction NF_guardWithCatch;
          static final NamedFunction NF_throwException;
+         static final NamedFunction NF_profileBoolean;
  
          static final MethodHandle MH_castReference;
          static final MethodHandle MH_selectAlternative;
          static final MethodHandle MH_copyAsPrimitiveArray;
          static final MethodHandle MH_fillNewTypedArray;
*** 612,625 ****
--- 613,628 ----
              try {
                  NF_checkSpreadArgument = new NamedFunction(MHI.getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
                  NF_guardWithCatch      = new NamedFunction(MHI.getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
                                                                                   MethodHandle.class, Object[].class));
                  NF_throwException      = new NamedFunction(MHI.getDeclaredMethod("throwException", Throwable.class));
+                 NF_profileBoolean      = new NamedFunction(MHI.getDeclaredMethod("profileBoolean", boolean.class, int[].class));
  
                  NF_checkSpreadArgument.resolve();
                  NF_guardWithCatch.resolve();
                  NF_throwException.resolve();
+                 NF_profileBoolean.resolve();
  
                  MH_castReference        = IMPL_LOOKUP.findStatic(MHI, "castReference",
                                              MethodType.methodType(Object.class, Class.class, Object.class));
                  MH_copyAsPrimitiveArray = IMPL_LOOKUP.findStatic(MHI, "copyAsPrimitiveArray",
                                              MethodType.methodType(Object.class, Wrapper.class, Object[].class));
*** 695,722 ****
      }
  
      @LambdaForm.Hidden
      static
      MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback) {
!         return testResult ? target : fallback;
      }
  
      static
      MethodHandle makeGuardWithTest(MethodHandle test,
                                     MethodHandle target,
                                     MethodHandle fallback) {
          MethodType type = target.type();
          assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
          MethodType basicType = type.basicType();
          LambdaForm form = makeGuardWithTestForm(basicType);
-         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLL();
          BoundMethodHandle mh;
- 
          try {
              mh = (BoundMethodHandle)
!                     data.constructor().invokeBasic(type, form,
                          (Object) test, (Object) profile(target), (Object) profile(fallback));
          } catch (Throwable ex) {
              throw uncaughtException(ex);
          }
          assert(mh.type() == type);
          return mh;
--- 698,749 ----
      }
  
      @LambdaForm.Hidden
      static
      MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback) {
!         if (testResult) {
!             return target;
!         } else {
!             return fallback;
!         }
!     }
! 
!     // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
!     @LambdaForm.Hidden
!     static
!     boolean profileBoolean(boolean result, int[] counters) {
!         // Profile is int[2] where [0] and [1] correspond to false and true occurrences respectively.
!         int idx = result ? 1 : 0;
!         try {
!             counters[idx] = Math.addExact(counters[idx], 1);
!         } catch (ArithmeticException e) {
!             // Avoid continuous overflow by halving the problematic count.
!             counters[idx] = counters[idx] / 2;
!         }
!         return result;
      }
  
      static
      MethodHandle makeGuardWithTest(MethodHandle test,
                                     MethodHandle target,
                                     MethodHandle fallback) {
          MethodType type = target.type();
          assert(test.type().equals(type.changeReturnType(boolean.class)) && fallback.type().equals(type));
          MethodType basicType = type.basicType();
          LambdaForm form = makeGuardWithTestForm(basicType);
          BoundMethodHandle mh;
          try {
+             if (PROFILE_GWT) {
+                 int[] counts = new int[2];
+                 mh = (BoundMethodHandle)
+                         BoundMethodHandle.speciesData_LLLL().constructor().invokeBasic(type, form,
+                                 (Object) test, (Object) profile(target), (Object) profile(fallback), counts);
+             } else {
                  mh = (BoundMethodHandle)
!                         BoundMethodHandle.speciesData_LLL().constructor().invokeBasic(type, form,
                                  (Object) test, (Object) profile(target), (Object) profile(fallback));
+             }
          } catch (Throwable ex) {
              throw uncaughtException(ex);
          }
          assert(mh.type() == type);
          return mh;
*** 854,893 ****
          final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
          int nameCursor = ARG_LIMIT;
          final int GET_TEST     = nameCursor++;
          final int GET_TARGET   = nameCursor++;
          final int GET_FALLBACK = nameCursor++;
          final int CALL_TEST    = nameCursor++;
          final int SELECT_ALT   = nameCursor++;
          final int CALL_TARGET  = nameCursor++;
          assert(CALL_TARGET == SELECT_ALT+1);  // must be true to trigger IBG.emitSelectAlternative
  
          MethodType lambdaType = basicType.invokerType();
          Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
  
!         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLL();
          names[THIS_MH] = names[THIS_MH].withConstraint(data);
          names[GET_TEST]     = new Name(data.getterFunction(0), names[THIS_MH]);
          names[GET_TARGET]   = new Name(data.getterFunction(1), names[THIS_MH]);
          names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
! 
          Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
  
          // call test
          MethodType testType = basicType.changeReturnType(boolean.class).basicType();
          invokeArgs[0] = names[GET_TEST];
          names[CALL_TEST] = new Name(testType, invokeArgs);
  
          // call selectAlternative
!         names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[CALL_TEST],
!                                      names[GET_TARGET], names[GET_FALLBACK]);
  
          // call target or fallback
          invokeArgs[0] = names[SELECT_ALT];
          names[CALL_TARGET] = new Name(basicType, invokeArgs);
  
!         lform = new LambdaForm("guard", lambdaType.parameterCount(), names);
  
          return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
      }
  
      /**
--- 881,930 ----
          final int ARG_LIMIT    = ARG_BASE + basicType.parameterCount();
          int nameCursor = ARG_LIMIT;
          final int GET_TEST     = nameCursor++;
          final int GET_TARGET   = nameCursor++;
          final int GET_FALLBACK = nameCursor++;
+         final int GET_COUNTERS = PROFILE_GWT ? nameCursor++ : -1;
          final int CALL_TEST    = nameCursor++;
+         final int PROFILE      = (GET_COUNTERS != -1) ? nameCursor++ : -1;
+         final int TEST         = nameCursor-1; // previous statement: either PROFILE or CALL_TEST
          final int SELECT_ALT   = nameCursor++;
          final int CALL_TARGET  = nameCursor++;
          assert(CALL_TARGET == SELECT_ALT+1);  // must be true to trigger IBG.emitSelectAlternative
  
          MethodType lambdaType = basicType.invokerType();
          Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);
  
!         BoundMethodHandle.SpeciesData data =
!                 (GET_COUNTERS != -1) ? BoundMethodHandle.speciesData_LLLL()
!                                      : BoundMethodHandle.speciesData_LLL();
          names[THIS_MH] = names[THIS_MH].withConstraint(data);
          names[GET_TEST]     = new Name(data.getterFunction(0), names[THIS_MH]);
          names[GET_TARGET]   = new Name(data.getterFunction(1), names[THIS_MH]);
          names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
!         if (GET_COUNTERS != -1) {
!             names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
!         }
          Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);
  
          // call test
          MethodType testType = basicType.changeReturnType(boolean.class).basicType();
          invokeArgs[0] = names[GET_TEST];
          names[CALL_TEST] = new Name(testType, invokeArgs);
  
+         // profile branch
+         if (PROFILE != -1) {
+             names[PROFILE] = new Name(Lazy.NF_profileBoolean, names[CALL_TEST], names[GET_COUNTERS]);
+         }
          // call selectAlternative
!         names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[TEST], names[GET_TARGET], names[GET_FALLBACK]);
  
          // call target or fallback
          invokeArgs[0] = names[SELECT_ALT];
          names[CALL_TARGET] = new Name(basicType, invokeArgs);
  
!         lform = new LambdaForm("guard", lambdaType.parameterCount(), names, /*forceInline=*/true);
  
          return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
      }
  
      /**