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FIX: Bitwise shift operators return incorrect results when you run a Visual C++ application that is developed in Visual Studio 2010


View products that this article applies to.

Symptoms

Consider the following scenario:
  • You use Microsoft Visual Studio 2010 Service Pack 1 (SP1) to develop a Visual C++ application.
  • The source code of the application uses bitwise shift operators (<< or >>).
  • You build the application, targeting the x64 platform.

    Note The /O2 or /Ox optimization option is enabled when you build the application.
  • You run the application.
In this scenario, the bitwise shift operators may return incorrect results.

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Resolution

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft website:Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

To apply this hotfix, you must have Visual Studio 2010 SP1 installed.

Restart requirement

You do not have to restart the computer after you install the hotfix if the affected files are not being used during the installation process. We recommend that you close all Visual Studio 2010-related components before you install the hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfix.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.
For all supported versions of Visual Studio 2010
File nameFile versionFile sizeDateTimePlatform
C2.dll16.0.40219.4022,608,19221-Jun-201219:08x86
C2.dll16.0.40219.4022,494,52822-Jun-201216:00x86
C2.dll16.0.40219.4022,593,34422-Jun-201216:00x86
C2.dll16.0.40219.4022,962,49622-Jun-201216:00x64

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Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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More Information

For more information about Visual C++ /O options, go to the following MSDN website:To reproduce this issue, run a C++ application that uses the following code:
#include "stdafx.h"

typedef unsigned long long uint64;

void print(uint64 bitBoard)
{
printf("bitboard: %llu\n", bitBoard);

for (int i = 0 ; i < 1; i++)
{
// If either of the following two statements is commented out, the running results are correct.
printf("bitBoard before shift down: %llu\n", bitBoard);
bitBoard >>= 8;
}
}



int main()
{
for (int square = 31; square <= 32; square++)
{
printf("When square is: %d\n", square);

printf("\n(Case A):\n");
uint64 temp = uint64(1) << square;
print(temp);

printf("\n(Case B): \n");
print((uint64)(uint64(1LU) << square));

printf("\n(Case C):\n");
print((uint64)(uint64(1) << square));

printf("\n(Case D): \n");
print(1ULL << square);

// Workaround method is using the following statement instead.
//print(1ULL << (uint64)square);

printf("\n");
}
}
If you are affected by this issue, you receive a result that is different from the following expected result after you run the application:

When square is: 31



(Case A):

bitboard: 2147483648

bitBoard before shift down: 2147483648



(Case B):

bitboard: 2147483648

bitBoard before shift down: 2147483648



(Case C):

bitboard: 2147483648

bitBoard before shift down: 2147483648



(Case D):

bitboard: 2147483648

bitBoard before shift down: 2147483648



When square is: 32



(Case A):

bitboard: 4294967296

bitBoard before shift down: 4294967296



(Case B):

bitboard: 4294967296

bitBoard before shift down: 4294967296



(Case C):

bitboard: 4294967296

bitBoard before shift down: 4294967296



(Case D):

bitboard: 4294967296

bitBoard before shift down: 4294967296

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Keywords: kbqfe, kbfix, kbhotfixdev, kbexpertiseadvanced, kbhotfixserver, kbsurveynew, kb

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Article Info
Article ID : 2688643
Revision : 1
Created on : 1/7/2017
Published on : 9/7/2012
Exists online : False
Views : 255