js/src/jit/ScalarTypeUtils.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  * vim: set ts=8 sts=2 et sw=2 tw=80:
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef jit_ScalarTypeUtils_h
   8 #define jit_ScalarTypeUtils_h
   9
  10 #include "mozilla/CheckedInt.h"
  11
  12 #include <stdint.h>
  13
  14 #include "js/ScalarType.h"
  15
  16 namespace js {
  17 namespace jit {
  18
  19 // Compute |index * Scalar::byteSize(type) + offsetAdjustment|. If this doesn't
  20 // overflow and is non-negative, return true and store the result in *offset.
  21 // If the computation overflows or the result is negative, false is returned and
  22 // *offset is left unchanged.
  23 [[nodiscard]] inline bool ArrayOffsetFitsInInt32(int32_t index,
  24                                                  Scalar::Type type,
  25                                                  int32_t offsetAdjustment,
  26                                                  int32_t* offset) {
  27   mozilla::CheckedInt<int32_t> val = index;
  28   val *= Scalar::byteSize(type);
  29   val += offsetAdjustment;
  30   if (!val.isValid() || val.value() < 0) {
  31     return false;
  32   }
  33
  34   *offset = val.value();
  35   return true;
  36 }
  37
  38 }  // namespace jit
  39 }  // namespace js
  40
  41 #endif /* jit_ScalarTypeUtils_h */