[LLVMdev] scalar evolution to determine access functions in arays

[Jimborean Alexandra]

Hello,

How can I compute the functions on the loop iterators used as array indices? 

For example:

for i = 0, N
      for j = 0, M
            A[2*i + j - 10] = ... 

Can I obtain that this instruction A[2*i + j - 10]= .. always accesses memory using a function       f(i,j)   =   2*i + j - 10 + base_address_of_A

If I run the scalar evolution pass on this code I obtain:

%arrayidx = getelementptr inbounds [200 x i32]* @main.A, i32 0, i64 %idxprom

  -->  ((4 * (sext i32 (-10 + (2 * %tmp6) + %tmp7) to i64)) + @main.A)        

Could you please offer an insight on how can I obtain the function from the internals of the scalar evolution pass? 
Thank you.


Alexandra
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