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

*** 630,640 ****
                  MH_fillNewTypedArray    = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
                                              MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
  
                  MH_selectAlternative    = makeIntrinsic(
                          IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
!                                 MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class)),
                          Intrinsic.SELECT_ALTERNATIVE);
              } catch (ReflectiveOperationException ex) {
                  throw newInternalError(ex);
              }
          }
--- 630,640 ----
                  MH_fillNewTypedArray    = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
                                              MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));
  
                  MH_selectAlternative    = makeIntrinsic(
                          IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
!                                 MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class, MethodHandle.class, int[].class)),
                          Intrinsic.SELECT_ALTERNATIVE);
              } catch (ReflectiveOperationException ex) {
                  throw newInternalError(ex);
              }
          }
*** 694,722 ****
          return SimpleMethodHandle.make(srcType, form);
      }
  
      @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;
--- 694,751 ----
          return SimpleMethodHandle.make(srcType, form);
      }
  
      @LambdaForm.Hidden
      static
!     MethodHandle selectAlternative(boolean testResult, MethodHandle target, MethodHandle fallback, int[] counters) {
!         if (counters != null) {
!             updateCounters(counters, testResult);
!         }
!         if (testResult) {
!             return target;
!         } else {
!             return fallback;
!         }
!     }
! 
!     // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
!     @LambdaForm.Hidden
!     static
!     boolean profileBranch(boolean result, int[] counters) {
!         updateCounters(counters, result);
!         return result;
!     }
! 
!     @LambdaForm.Hidden
!     @ForceInline
!     static
!     void updateCounters(int[] counters, boolean result) {
!         int idx = result ? 0 : 1;
!         try {
!             counters[idx] = Math.addExact(counters[idx], 1);
!         } catch (ArithmeticException e) {
!             // Avoid continuous overflow by halving the problematic count.
!             counters[idx] = counters[idx] / 2;
!         }
      }
  
      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();
+         int[] counters = PROFILE_GWT ? new int[2] : null;
          LambdaForm form = makeGuardWithTestForm(basicType);
!         BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLL();
          BoundMethodHandle mh;
  
          try {
              mh = (BoundMethodHandle)
                      data.constructor().invokeBasic(type, form,
!                         (Object) test, (Object) profile(target), (Object) profile(fallback), counters);
          } 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);
      }
  
      /**
--- 883,923 ----
          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 = 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_LLLL();
          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]);
!         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);
  
          // call selectAlternative
          names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[CALL_TEST],
!                                      names[GET_TARGET], names[GET_FALLBACK], names[GET_COUNTERS]);
  
          // 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);
      }
  
      /**