Global variables of __m128i type behave incorrectly with global optimization.

Global variables of __m128i type behave incorrectly with global optimization. by Arseny Kapoulkine

Closed

as Fixed

Type:	Bug
ID:	615374
Opened:	10/20/2010 12:39:16 PM
Access Restriction:	Public

Workaround(s)

view

User(s) can reproduce this bug

When using a global variable of __m128i type from several translation units (via extern), the size of the variable differs if global optimizations are enabled.

Details (expand)

Visual Studio 2010

Reliability

1. Create file a.cpp with the following contents:

#include <emmintrin.h>

extern __m128i g_value;

int main()
{
return g_value.m128i_i32[0];
}

2. Create file b.cpp with the following contents:

#include <emmintrin.h>

__m128i g_value;

3. Compile them together with the following options:

cl /GL a.cpp b.cpp

English

Windows 7

English

There is a compilation warning:

warning C4743: 'union __m128i g_value' has different size in 'E:\work\misc\bugs\m128i_bug\b.cpp' and 'E:\work\misc\bugs\m128i_bug\a.cpp': 18 and 16 bytes

Code compiles without any warnings.

0 attachments

Posted by Microsoft on 11/22/2010 at 5:53 PM

Hi.

This warning is actually a false positive in your case. We plan to fix this issue in the next release of Visual Studio.

If you are currently blocked by this warning, you can add /wd4743 to the command line.

Posted by Microsoft on 10/21/2010 at 2:02 AM

Thank you for reporting the issue.
We are routing this issue to the appropriate group within the Visual Studio Product Team for triage and resolution.These specialized experts will follow-up with your issue.

Posted by Microsoft on 10/20/2010 at 6:35 PM

Thank you for your feedback, we are currently reviewing the issue you have submitted. If this issue is urgent, please contact support directly(http://support.microsoft.com)