Incorrect code generation when optimizing and using SSE2

Incorrect code generation when optimizing and using SSE2 by yuriks

Closed

as Fixed

Type:	Bug
ID:	647064
Opened:	2/24/2011 6:07:23 PM
Access Restriction:	Public

Workaround(s)

view

User(s) can reproduce this bug

When compiling the attached program with /O1 (or, by uncommenting the marked line in the source, with /O2.) and /arch:SSE2 the compiler generates incorrect code which causes wrong results to be calculated.

Details (expand)

Visual Studio 2010

Reliability

1. Use version 16.00.30319.01 for 80x86 of the C++ Microsoft compiler;
2. Either:
a) Use commandline "cl.exe main.cpp /O1 /arch:SSE2";
b1) Uncomment line 17 on the source, and
b2) Use command line: "cl.exe main.cpp /O2 /arch:SSE2";

English

Windows 7

English

C:\Users\yuriks\projetos\vcbug>make_release.bat

C:\Users\yuriks\projetos\vcbug>cl main.cpp /EHsc /O1 /arch:SSE2
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86
Copyright (C) Microsoft Corporation. All rights reserved.

main.cpp
Microsoft (R) Incremental Linker Version 10.00.30319.01
Copyright (C) Microsoft Corporation. All rights reserved.

/out:main.exe
main.obj

C:\Users\yuriks\projetos\vcbug>main.exe
0
1
2
3
4
5
6
7
8

C:\Users\yuriks\projetos\vcbug>

C:\Users\yuriks\projetos\vcbug>make_debug.bat

C:\Users\yuriks\projetos\vcbug>cl main.cpp /EHsc /arch:SSE2
Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 16.00.30319.01 for 80x86
Copyright (C) Microsoft Corporation. All rights reserved.

main.cpp
Microsoft (R) Incremental Linker Version 10.00.30319.01
Copyright (C) Microsoft Corporation. All rights reserved.

/out:main.exe
main.obj

C:\Users\yuriks\projetos\vcbug>main.exe
8

C:\Users\yuriks\projetos\vcbug>

File Name	Submitted By	Submitted On	File Size
main.cpp	yuriks	2/24/2011	434 bytes

Posted by Microsoft on 3/1/2011 at 12:28 PM

Thank you for the bug report. We are aware of this issue and will fix this in the next major product release.
In the meantime, you may need to workaround the problem by disabling optimization for the affected function.

Mark Levine
Visual C++

Posted by Microsoft on 2/25/2011 at 1:49 AM

Thank you for submitting feedback on Visual Studio 2010 and .NET Framework. Your issue has been routed to the appropriate VS development team for review. We will contact you if we require any additional information.

Posted by Microsoft on 2/24/2011 at 6:14 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)

Posted by yuriks on 2/24/2011 at 6:12 PM

Thought I may as well post the source of the test case here:

/////////////////////////////////////
#include <iostream>
#include <cmath>

struct data
{
    float val;
};

void func(const data& origin)
{
    data tmp = origin;
    tmp.val += 1.f;
    int upz = int(tmp.val);
    int z = int(origin.val);
    for (; z < upz; ++z) {
        float value1 = std::sin(z * 2.f);
        // This needs to be added on /O2: std::cout << value << '\n';
        std::cout << z << '\n';
    }
}

int main()
{
    data origin = {8.f};
    func(origin);
    return 0;
}
/////////////////////////////////////