Extend Range analysis to 64-bit range and mint operations

runtime/platform/utils.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef PLATFORM_UTILS_H_
 #define PLATFORM_UTILS_H_
 
 #include "platform/assert.h"
 #include "platform/globals.h"
 
@@ skipping 153 matching lines @@
   // without the risk of integer overflow.
   static inline bool RangeCheck(intptr_t offset,
                                 intptr_t count,
                                 intptr_t length) {
     return offset >= 0 &&
            count >= 0 &&
            length >= 0 &&
            count <= (length - offset);
   }
 
+  static inline bool DidAddOverflow(int64_t a, int64_t b, int64_t result) {
+    // a & b have same sign but result has a different sign.
+    return ((a < 0) && (b < 0) && (result > 0)) ||
+           ((a > 0) && (b > 0) && (result < 0));
+  }
+
+  static inline bool DidSubOverflow(int64_t a, int64_t b, int64_t result) {
+    // a & b have different signs and result has a different sign than a.
+    return ((a < 0) && (b > 0) && (result > 0)) ||
+           ((a > 0) && (b < 0) && (result < 0));
+  }
+
+
   // Utility functions for converting values from host endianess to
   // big or little endian values.
   static uint16_t HostToBigEndian16(uint16_t host_value);
   static uint32_t HostToBigEndian32(uint32_t host_value);
   static uint64_t HostToBigEndian64(uint64_t host_value);
   static uint16_t HostToLittleEndian16(uint16_t host_value);
   static uint32_t HostToLittleEndian32(uint32_t host_value);
   static uint64_t HostToLittleEndian64(uint64_t host_value);
 
   static bool DoublesBitEqual(const double a, const double b) {
     return bit_cast<int64_t, double>(a) == bit_cast<int64_t, double>(b);
   }
 };
 
 }  // namespace dart
 
 #if defined(TARGET_OS_ANDROID)
 #include "platform/utils_android.h"
 #elif defined(TARGET_OS_LINUX)
 #include "platform/utils_linux.h"
 #elif defined(TARGET_OS_MACOS)
 #include "platform/utils_macos.h"
 #elif defined(TARGET_OS_WINDOWS)
 #include "platform/utils_win.h"
 #else
 #error Unknown target os.
 #endif
 
 #endif  // PLATFORM_UTILS_H_