Where can I modify detailed C# compiler optimization settings in Visual Studio?

Question

In Visual Studio C/C++ projects, it's easy to modify compiler's optimization settings in "Property Pages | C/C++ | Optimization". For example, we may give different optimization levels such as /O2 and /O3, as well as advanced optimizations like "Omit Frame Pointers".

However, I can't simply find corresponding UIs in C# project of Visual Studio. All I can find is just turning off optimizations: the "Optimize code" check box is all I've got.

Can C# users control detailed compiler's optimizations like C/C++? Do I have to give compiler options in command line?

Answer 1

AFAIK C# compiler has no such detailed optimization properties. Probably optimization is either enabled or disabled.

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http://msdn.microsoft.com/en-us/library/6s2x2bzy.aspx

I found just two:

• /filealign Specifies the size of sections in the output file.

• /optimize Enables/disables optimizations.

Answer 2

Much of the optimisation of C# code goes on at the JIT compiler level, rather than the C# compiler. Basically there are no such detailed settings as the ones available in C or C++.

There are a few performance-related elements of the runtime that can be tweaked, such as GC strategies, but not a great deal.

When I'm building benchmark tests etc from the command line I tend to just use something like this:

csc /o+ /debug- Test.cs

(I believe I have seen the presence of a matching pdb file make a difference to performance, possibly in terms of the cost of exceptions being thrown, hence the debug- switch... but I could be wrong.)

EDIT: If you want to see the difference each bit of optimization makes, there's one approach which could prove interesting:

• Compile the same code with and without optimization
• Use ildasm or Reflector in IL mode to see what the differences are
• Apply the same changes one at a time manually (using ilasm) and measure how much each one has