Exceptions raised when generating SSA against native functions
Apologies in advance if these issues have been discussed before. I did a brief search but wasn't able to come up with anything obvious on the forum or in the documentation. The issue I'm having centers around trying to construct SSA information against native functions. I have a feeling these issues are fairly easy to solve, but thus far I haven't come across a solution.
The tool I'm working on takes care of loading assemblies and does not execute as part of a phase. Part of the analysis it performs requires constructing SSA information to analyze data flow. Function units are raised to the SymbolicFunctionUnitState (is this correct?) and then SSA information is constructed as followed:
Code Snippet
if (funit.SsaInfo ==null)
{
funit.SsaInfo = Phx.SSA.Info.New(funit.Lifetime, funit, Phx.SSA.Attribute.Aliased);
funit.SsaInfo.Build();
}
Judging from the other examples I've seen, this seems to be the correct approach to take. However, as a result of the call to Build, an exception is generated:
Object reference not set to an instance of an object.
at Phx.Alias.Info.GetAliasType(Int32 tag)
at Phx.Alias.FactorAnalyzer.ComputeProxyClosure(FunctionUnit functionUnit)
at Phx.SSA.Info.CollectBaseFlowInfo(Attribute ssaAttribute)
at Phx.SSA.Info.Build()
This same code works perfectly fine with managed assemblies. However, it seems to fail consistently on the native module that I'm attempting to analyze (it also fails on the testapp.exe included in the RDK). I've played around with a few things, such as changing the Phx.SSA.Attribute enumeration value, but this seems to result in additional exceptions. Is there some alias state that isn't being generated before hand that I need to take care of?
Thanks in advance for any insight.
Matt
[2305 byte] By [
mmiller] at [2008-2-26]
As far as I can tell I'm taking almost the exact same steps as what you outline above. The one major distinction has to do with how I'm obtaining the FunctionUnit. In the context of my code, I'm only working with a FunctionSymbol. I'm not iterating over all of the function units. Instead, I acquire a function symbol's associated function unit by doing the following:
Code Snippet
functionUnit =
module.Raise(functionSymbol, FunctionUnit.SymbolicFunctionUnitState); I then use the function unit to try to build SSA information and so on. I'm guessing that acquiring a function unit in this fashion isn't fully supported (or is just plain wrong). HasSymbolicIR is always false for native code when I run the above code against it. Is there a correct way to obtain a function unit when all you have is a function symbol (which is a restriction related to how my current code is laid out)?
I'll keep messing with it and see what I can find out in the mean time.
Tangent: When enumerating the functions contained within a module, would you recommend enumerating function symbols or function units? Currently, I'm enumerating function symbols, hence the limitation described above.
Good catch. Guess I should read the comment more closely next time 
I added this to my phoenix initialization code and it seems to work fine now. Are there any side effects that I should be concious of as a result of setting this flag? I guess a better question would be, why doesn't phoenix have this flag enabled by default (memory consumption)?
Thanks.
