VB.NET and .maxstack

[Kjetil Kristoffer Solberg]

Why is it that the VB.NET compiler outputs an incorrect .maxstack CIL
directive? It
seems like they always set it to 8. Even though the correct value should be
1 or 2 for
example.


regards
Kjetil Kristoffer Solberg

 

[Alex Clark]

Hi
It's a "feature", and I recall it's mentioned somewhere on the Microsoft
site. I have a feeling that the C# compiler actually determines the correct
..maxstack value, whereas vbc just defaults to 8 unless a deeper stack is
required. I'm not sure this makes any difference to performance though, but
I'm sure someone will correct me on this

Cheers,
Alex Clark

 

[Kjetil Kristoffer Solberg]

But this could become a problem. I can see that since you know how the
MS-CLR-JIT compiler
and verifier works, you can do this. But, lets say you're on a different
platform that has a different
implementation of the JIT-Compiler and verifier. This implementation could
throw an exception
when the .maxstack directive is incorrect, leaving your application useless
on that platform.

regards
Kjetil Kristoffer Solberg

 

[Alex Clark]

Hi,

I suspect MS probably included a clause in the CLS of something like "To be
fully CLR compliant, the JIT-Compiler should not check to see if the
..maxstack value is accurate." This would cover their back in that type of
scenario.

;-)

Cheers,
Alex

 

[JD]

Its used for analysis and verification of the program, not for runtime. As
long as the .Maxstack is greater than actual stack size, the program is
verifiable, so it doesn't hurt with default of 8. If it was less than the
actual stack size then the program is unverifiable and can be rejected by
the runtime implementation in the verification process.

Its discussed in the specifications of CLI.