[LLVMdev] MP1: Gelementptr question

[Casey Carter]

The following is legal LLVM code in which ptr, ptr2, and ptr3 are all 
aliases:

%struct = type { int, int }
implementation
int %p() {
  %ptr1 = alloca %struct
  %ptr2 = getelementptr %struct* %ptr1
  %ptr3 = getelementptr %struct* %ptr2, uint 0
  %pint = getelementptr %struct* %ptr3, uint 0, ubyte 0
  %rval = load int* %pint
   ret int %rval
}

Should our pass a) ignore this, not replace %ptr1, let copy-propagation 
fix the problem, or b) catch this obvious aliasing and replace uses of 
fields of %ptr2 and %ptr3 with the replaced scalar fields of ptr1?

-- 
Casey Carter
Casey at Carter.net
ccarter at uiuc.edu
AIM: cartec69