llvm dev - Oct 2016 - Getting the symbolic expression for an address calculation

How do you generate a SCEVAddRecExpr from a SCEV? It tried dyn_casting and
it seems like that the SCEV returned by getSCEV is not a SCEVAddRecExpr.

Thanks

On Fri, Sep 30, 2016 at 4:16 PM, Friedman, Eli <efriedma at
codeaurora.org>
wrote:
> On 9/30/2016 12:16 PM, Charith Mendis via llvm-dev wrote:
>
>>
>> Hi all,
>>
>> What is the best way to get the symbolic expression for an address
>> calculation in llvm specially when  memory addresses are calculated
within
>> a loop.
>>
>
> ScalarEvolution works with pointers as well as integers; if you call
> getSCEV on an address based on an induction variable, you'll get a
> SCEVAddRecExpr.
>
> -Eli
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project
>
>

-- 
Kind regards,
Charith Mendis

Graduate Student,
CSAIL,
Massachusetts Institute of Technology
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On 10/4/2016 11:13 AM, Charith Mendis wrote:
> How do you generate a SCEVAddRecExpr from a SCEV? It tried dyn_casting 
> and it seems like that the SCEV returned by getSCEV is not a 
> SCEVAddRecExpr.
You can dyn_cast if it's actually an AddRec... but not all expressions 
can be represented as an AddRec.

SCEV has a dump() method which can be helpful for debugging.  What does 
E->dump() on the SCEV in question look like?  What does the IR look like?

-Eli

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
Foundation Collaborative Project

(((15 + %add144.sink230.i) * (%blocksize /u %bytesoftype)) +
{%_dest,+,16}<%for.cond1.preheader.i59>)<nsw>

On Tue, Oct 4, 2016 at 2:24 PM, Friedman, Eli <efriedma at codeaurora.org>
wrote:
> On 10/4/2016 11:13 AM, Charith Mendis wrote:
>
>> How do you generate a SCEVAddRecExpr from a SCEV? It tried dyn_casting
>> and it seems like that the SCEV returned by getSCEV is not a
SCEVAddRecExpr.
>>
>
> You can dyn_cast if it's actually an AddRec... but not all expressions
can
> be represented as an AddRec.
>
> SCEV has a dump() method which can be helpful for debugging.  What does
> E->dump() on the SCEV in question look like?  What does the IR look
like?
>
>
> -Eli
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> Foundation Collaborative Project
>
>

-- 
Kind regards,
Charith Mendis

Graduate Student,
CSAIL,
Massachusetts Institute of Technology
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