[llvm-dev] Getting the symbolic expression for an address calculation

[Friedman, Eli via llvm-dev]

On 10/4/2016 11:26 AM, Charith Mendis wrote:
> (((15 + %add144.sink230.i) * (%blocksize /u %bytesoftype)) + 
> {%_dest,+,16}<%for.cond1.preheader.i59>)<nsw>

This is a SCEVAddExpr with two operands.  The first is a SCEVMulExpr, 
the second is a SCEVAddRecExpr.  You're ending up with an expression 
like this because one of "%add144.sink230.i", "%blocksize", or 
"%bytesoftype" isn't loop-invariant.  Maybe a load wasn't hoisted where 
you expected it to be.

If you're confused about what kind of expression you're looking at, you 
can use the getSCEVType() method on a SCEV, which returns a member of 
the SCEVTypes enum.

-Eli

-- 
Employee of Qualcomm Innovation Center, Inc.
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