[es6] Optimize TypedArray.subarray()

src/macros.py

 # Copyright 2006-2009 the V8 project authors. All rights reserved.
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 #       notice, this list of conditions and the following disclaimer.
 #     * Redistributions in binary form must reproduce the above
 #       copyright notice, this list of conditions and the following
 #       disclaimer in the documentation and/or other materials provided
@@ skipping 139 matching lines @@
 macro TO_STRING_INLINE(arg) = (IS_STRING(%IS_VAR(arg)) ? arg : $nonStringToString(arg));
 macro TO_NUMBER_INLINE(arg) = (IS_NUMBER(%IS_VAR(arg)) ? arg : $nonNumberToNumber(arg));
 macro TO_OBJECT(arg) = (%_ToObject(arg));
 macro TO_PRIMITIVE(arg) = (%_ToPrimitive(arg));
 macro TO_PRIMITIVE_NUMBER(arg) = (%_ToPrimitive_Number(arg));
 macro TO_PRIMITIVE_STRING(arg) = (%_ToPrimitive_String(arg));
 macro TO_NAME(arg) = (%_ToName(arg));
 macro JSON_NUMBER_TO_STRING(arg) = ((%_IsSmi(%IS_VAR(arg)) || arg - arg == 0) ? %_NumberToString(arg) : "null");
 macro HAS_OWN_PROPERTY(arg, index) = (%_CallFunction(arg, index, ObjectHasOwnProperty));
 macro HAS_INDEX(array, index, is_array) = ((is_array && %_HasFastPackedElements(%IS_VAR(array))) ? (index < array.length) : (index in array));
+macro MAX_SIMPLE(argA, argB) = (argA < argB ? argB : argA);

[Michael Starzinger, 2015/10/07 18:49:07]

Please be aware that this macro will expand "MAX_SIMPLE(a + b, 0)" to "a + b < 0
? a + b : 0" which will evaluate the addition twice in the baseline compiler
(which is the only compiler where this macro makes any sense in the first
place).

If you wanted to guard against that, then the %IS_VAR marker would be the right
thing. But then you would need to adapt the use-sites accordingly. And I see
that this is now being used left and right in the builtin JavaScript files and
almost all use-sites are affected.

+macro MIN_SIMPLE(argA, argB) = (argA < argB ? argA : argB);
 
 # Private names.
 macro IS_PRIVATE(sym) = (%SymbolIsPrivate(sym));
 macro HAS_PRIVATE(obj, sym) = (%HasOwnProperty(obj, sym));
 macro HAS_DEFINED_PRIVATE(obj, sym) = (!IS_UNDEFINED(obj[sym]));
 macro GET_PRIVATE(obj, sym) = (obj[sym]);
 macro SET_PRIVATE(obj, sym, val) = (obj[sym] = val);
 
 # Constants.  The compiler constant folds them.
 define NAN = $NaN;
@@ skipping 131 matching lines @@
 define NOT_FOUND = -1;
 
 # Check whether debug is active.
 define DEBUG_IS_ACTIVE = (%_DebugIsActive() != 0);
 macro DEBUG_IS_STEPPING(function) = (%_DebugIsActive() != 0 && %DebugCallbackSupportsStepping(function));
 macro DEBUG_PREPARE_STEP_IN_IF_STEPPING(function) = if (DEBUG_IS_STEPPING(function)) %DebugPrepareStepInIfStepping(function);
 
 # SharedFlag equivalents
 define kNotShared = false;
 define kShared = true;