C++ optimization bug; incorrect assembly emitted

C++ optimization bug; incorrect assembly emitted by Snaar

Closed

as Fixed

Type:	Bug
ID:	643764
Opened:	2/13/2011 9:26:34 PM
Access Restriction:	Public

Workaround(s)

view

User(s) can reproduce this bug

Attached is a single C++ source file with project file and solution file. Also attached is assembly output of one of the functions as viewed from internal IDE debugger of code compiled in release mode.

Issue seems to be caused by unmatched "sub esp,0Ch" in assembly: esp register being adjusted to make space for a temporary variable on stack but then the register is never adjusted back, causing "pop esi" to put incorrect value in esi register on return, causing "this" pointer of calling function to be corrupted.

This issue happens only in release mode. Some code generation settings make this issue go away so please refer to the attached project, thought default release mode settings should be affected as well.

Details (expand)

Visual Studio 2010

Reliability

Compile and run attached code.

English

Windows 7

English

Following text printed to stdout:

Corruption detected.

Following text printed to stdout:

No corruption detected.

File Name	Submitted By	Submitted On	File Size
test01.cpp	Snaar	2/13/2011	797 bytes
test01_partial_asm.txt	Snaar	2/13/2011	2 KB
test01project.zip	Snaar	2/13/2011	2 KB

Posted by Microsoft on 6/25/2011 at 3:38 AM

Thank you for reporting this issue. We have identified the root cause of the problem as a bug in the compiler backend. The bug is due to a bad interaction between dead code elimination and structures passed by value as function arguments and return values. The bug will be fixed in the next release of the compiler.

Windows C++ Compiler Team.

Posted by Microsoft on 2/14/2011 at 1:30 AM

Thanks for your feedback.
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 2/13/2011 at 9:59 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)