[LLVMdev] questions

[Bill? Wendling]

Also sprach xli3 at uiuc.edu:
} Sorry I got really overwhelmed by so many classes and member
} functions in LLVM.  So would you please clarify some problems
} I have?
} 
} 1. If I see this instruction in the function.
} 
} %S.i = alloca %struct.SimpleStruct
} 
} Suppose SimpleStruct is as following:
} struct.SimpleStruct = type { int, double }
} 
} When I read the instruction, how can I know the type of
} simplstruct, should I use 'getType' member function like
} Inst.getType()? If I use that, I will get a PointerType, how
} can I use it?
} 
I used the "dyn_cast<>" method to dynamically check whether something is
of a given type. dyn_cast<> helpfully returns 0 if it's not of that type.
So, you can do something like:

  if (const PointerType *PT = dyn_cast<PointerType>(Inst.getType()))
    if (const StructType *ST = dyn_cast<StructType>(PT->getType()))
      // Work with ST...

and it'll work.

} 2. Another question is that since we do the scalar replacement
} on each function. If the program look like this.
} 
} struct s {
}    int a;
}    float b;
} }
} fun1( struct s *ps) {
}    ps->a = 1;
}    ps->b = 2;
} }
} main( )
} {
}         struct s mystru;
} 
} 	fun1( &mystru );
} }
} 
} When we process the function 'fun1', should we change fun1 to
} something like
} fun1( int *a, float *b )
} then change fun1(&mystru) in main to something like
} fun1( &mystru.a, &mystru.b)?
} 
I assume that, since "mystru" isn't being used as specified in rules
U1-U3, that we shouldn't have to handle it...

But I could be wrong...

*crosses fingers, hoping he's not wrong*

-- 
|| Bill? Wendling			wendling at isanbard.org