/Qimprecise_fwaits (Remove fwaits Inside Try Blocks)


For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

Removes the fwait commands internal to try blocks when you use the /fp:except compiler option.


This option has no effect if /fp:except is not also specified. If you specify the /fp:except option, the compiler will insert a fwait command around each line of code in a try block. In this way, the compiler can identify the specific line of code that produces an exception. /Qimprecise_fwaits removes internal fwait instructions, leaving only the waits around the try block. This improves performance, but the compiler will only be able to say which try block causes an exception, not which line.

To set this compiler option in the Visual Studio development environment

  1. Open the project's Property Pages dialog box. For details, see How to: Open Project Property Pages.

  2. Click the C/C++ folder.

  3. Click the Command Line property page.

  4. Type the compiler option in the Additional Options box.

To set this compiler option programmatically

/Q Options (Low-Level Operations)
Compiler Options
Setting Compiler Options