What is /optimize C# compiler key intended for?

Question

Is there a full list of optimizations done by the /optimize C# compiler key available anywhere?

EDIT: Why is it disabled by default? Is it worth using in a real-world app? -- it is disabled by default only in Debug configuration and Enabled in Release.

Answer 1

Scott Hanselman has a blog post that shows a few examples of what /optimize (which is enabled in Release Builds) does.

As a summary: /optimize does many things with no exact number or definition given, but one of the more visible are method inlining (If you have a Method A() which calls B() which calls C() which calls D(), the compiler may "skip" B and C and go from A to D directly), which may cause a "weird" callstack in the Release build.

Answer 2

It is disabled by default for debug builds. For Release builds it is enabled.

It is definitely worth enabling this switch as the compiler makes lots of tweaks and optimizations depending on the kind of code you have. For eg: Skipping redundant initializations, comparisons that never change etc.

Note: You might have some difficulty debugging if your turn on optimization as the code you have and the IL code that is generated may not match. This is the reason it is turned on only for Release builds.