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

rev 52204 : 8212726: Replace some use of drop- and foldArguments with filtering argument combinator in StringConcatFactory
Reviewed-by: TBD

*** 83,93 ****
                  FOLD_ARGS = 11,
                  FOLD_ARGS_TO_VOID = 12,
                  PERMUTE_ARGS = 13,
                  LOCAL_TYPES = 14,
                  FOLD_SELECT_ARGS = 15,
!                 FOLD_SELECT_ARGS_TO_VOID = 16;
  
          private static final boolean STRESS_TEST = false; // turn on to disable most packing
          private static final int
                  PACKED_BYTE_SIZE = (STRESS_TEST ? 2 : 4),
                  PACKED_BYTE_MASK = (1 << PACKED_BYTE_SIZE) - 1,
--- 83,94 ----
                  FOLD_ARGS = 11,
                  FOLD_ARGS_TO_VOID = 12,
                  PERMUTE_ARGS = 13,
                  LOCAL_TYPES = 14,
                  FOLD_SELECT_ARGS = 15,
!                 FOLD_SELECT_ARGS_TO_VOID = 16,
!                 FILTER_SELECT_ARGS = 17;
  
          private static final boolean STRESS_TEST = false; // turn on to disable most packing
          private static final int
                  PACKED_BYTE_SIZE = (STRESS_TEST ? 2 : 4),
                  PACKED_BYTE_MASK = (1 << PACKED_BYTE_SIZE) - 1,
*** 728,768 ****
          buf.renameParameter(0, newBaseAddress);
  
          Name getCombiner = new Name(newData.getterFunction(oldData.fieldCount()), newBaseAddress);
          Object[] combinerArgs = new Object[1 + combinerArity];
          combinerArgs[0] = getCombiner;
!         Name[] newParams;
          if (keepArguments) {
-             newParams = new Name[0];
              for (int i = 0; i < combinerArity; i++) {
                  combinerArgs[i + 1] = lambdaForm.parameter(1 + argPositions[i]);
                  assert (basicType(combinerType.parameterType(i)) == lambdaForm.parameterType(1 + argPositions[i]));
              }
          } else {
!             newParams = new Name[combinerArity];
!             for (int i = 0; i < newParams.length; i++) {
!                 newParams[i] = lambdaForm.parameter(1 + argPositions[i]);
                  assert (basicType(combinerType.parameterType(i)) == lambdaForm.parameterType(1 + argPositions[i]));
              }
-             System.arraycopy(newParams, 0,
-                              combinerArgs, 1, combinerArity);
          }
          Name callCombiner = new Name(combinerType, combinerArgs);
  
          // insert the two new expressions
          int exprPos = lambdaForm.arity();
          buf.insertExpression(exprPos+0, getCombiner);
          buf.insertExpression(exprPos+1, callCombiner);
  
          // insert new arguments, if needed
          int argPos = pos + resultArity;  // skip result parameter
!         for (Name newParam : newParams) {
              buf.insertParameter(argPos++, newParam);
          }
!         assert(buf.lastIndexOf(callCombiner) == exprPos+1+newParams.length);
          if (!dropResult) {
!             buf.replaceParameterByCopy(pos, exprPos+1+newParams.length);
          }
  
          return buf.endEdit();
      }
  
--- 729,772 ----
          buf.renameParameter(0, newBaseAddress);
  
          Name getCombiner = new Name(newData.getterFunction(oldData.fieldCount()), newBaseAddress);
          Object[] combinerArgs = new Object[1 + combinerArity];
          combinerArgs[0] = getCombiner;
!         Name newParam = null;
          if (keepArguments) {
              for (int i = 0; i < combinerArity; i++) {
                  combinerArgs[i + 1] = lambdaForm.parameter(1 + argPositions[i]);
                  assert (basicType(combinerType.parameterType(i)) == lambdaForm.parameterType(1 + argPositions[i]));
              }
          } else {
!             newParam = new Name(pos, BasicType.basicType(combinerType.returnType()));
!             for (int i = 0; i < combinerArity; i++) {
!                 int argPos = 1 + argPositions[i];
!                 if (argPos == pos) {
!                     combinerArgs[i + 1] = newParam;
!                 } else {
!                     combinerArgs[i + 1] = lambdaForm.parameter(argPos);
!                 }
                  assert (basicType(combinerType.parameterType(i)) == lambdaForm.parameterType(1 + argPositions[i]));
              }
          }
          Name callCombiner = new Name(combinerType, combinerArgs);
  
          // insert the two new expressions
          int exprPos = lambdaForm.arity();
          buf.insertExpression(exprPos+0, getCombiner);
          buf.insertExpression(exprPos+1, callCombiner);
  
          // insert new arguments, if needed
          int argPos = pos + resultArity;  // skip result parameter
!         if (newParam != null) {
              buf.insertParameter(argPos++, newParam);
+             exprPos++;
          }
!         assert(buf.lastIndexOf(callCombiner) == exprPos+1);
          if (!dropResult) {
!             buf.replaceParameterByCopy(pos, exprPos+1);
          }
  
          return buf.endEdit();
      }
  
*** 843,852 ****
--- 847,870 ----
          }
          form = makeArgumentCombinationForm(foldPos, combinerType, argPositions, true, dropResult);
          return putInCache(key, form);
      }
  
+     LambdaForm filterArgumentsForm(int filterPos, MethodType combinerType, int ... argPositions) {
+         byte kind = Transform.FILTER_SELECT_ARGS;
+         int[] keyArgs = Arrays.copyOf(argPositions, argPositions.length + 1);
+         keyArgs[argPositions.length] = filterPos;
+         Transform key = Transform.of(kind, keyArgs);
+         LambdaForm form = getInCache(key);
+         if (form != null) {
+             assert(form.arity == lambdaForm.arity);
+             return form;
+         }
+         form = makeArgumentCombinationForm(filterPos, combinerType, argPositions, false, false);
+         return putInCache(key, form);
+     }
+ 
      LambdaForm permuteArgumentsForm(int skip, int[] reorder) {
          assert(skip == 1);  // skip only the leading MH argument, names[0]
          int length = lambdaForm.names.length;
          int outArgs = reorder.length;
          int inTypes = 0;