patch: remove PseudoSourceValue from Value.

[Nick Lewycky]

+cc Evan Cheng

Evan, I'm not sure whether you're still the right person to review this. I
consider it a substantive change to how the backend works, even though the
line count of the patch is small. If nothing else, I figure you want to be
aware of this patch before it lands.

Nick

On 24 February 2014 17:01, Nick Lewycky <nlewycky at google.com> wrote:

> On 24 February 2014 16:45, Hal Finkel <hfinkel at anl.gov> wrote:
>
>> ----- Original Message -----
>> > From: "Nick Lewycky" <nlewycky at google.com>
>> > To: "Hal Finkel" <hfinkel at anl.gov>
>> > Cc: "Commit Messages and Patches for LLVM" <llvm-commits at cs.uiuc.edu>
>> > Sent: Monday, February 24, 2014 6:31:34 PM
>> > Subject: Re: patch: remove PseudoSourceValue from Value.
>> >
>> >
>> >
>> >
>> > On 24 February 2014 16:20, Hal Finkel < hfinkel at anl.gov > wrote:
>> >
>> >
>> > What is the underlying motivation for doing this?
>> >
>> >
>> >
>> > The proximate cause is that I'm trying to remove the vtable from
>> > llvm::Value, and in order to do that I'm going to write dispatch
>> > functions that switch on the ValueID and call the appropriate
>> > function from the most-derived-type. If I do that, then we have
>> > lib/IR placing calls to lib/CodeGen, which is a layering violation.
>> >
>> >
>> > At a higher level, PSV does not belong there. It is not part of the
>> > IR. No IR passes use or understand it. It's not documented in the
>> > LangRef. Frankly, it's a hack -- and it's a great hack that and I
>> > understand its utility for lib/CodeGen -- but that doesn't change
>> > the fact that it's not part of llvm's IR. I've just never been
>> > motivated to do something about it until now.
>>
>> Thanks for explaining!
>>
>>    AliasAnalysis::AliasResult AAResult = AA->alias(
>> -  AliasAnalysis::Location(MMOa->getValue(), Overlapa,
>> -                          UseTBAA ? MMOa->getTBAAInfo() : 0),
>> -  AliasAnalysis::Location(MMOb->getValue(), Overlapb,
>> -                          UseTBAA ? MMOb->getTBAAInfo() : 0));
>> +      AliasAnalysis::Location(MMOa->getValue(), Overlapa,
>> +                              UseTBAA ? MMOa->getTBAAInfo() : 0),
>> +      AliasAnalysis::Location(MMOb->getValue(), Overlapb,
>> +                              UseTBAA ? MMOb->getTBAAInfo() : 0));
>>
>> This is purely an indentation change, can you please commit this
>> separately?
>>
>
> Done.
>
>
>> -        MapVector<const Value *, std::vector<SUnit *> >::iterator IE =
>> +        MapVector<PointerUnion<const Value *, const PseudoSourceValue *>,
>> +            std::vector<SUnit *> >::iterator IE =
>>
>> These are starting to get really ugly. Can you please do something so
>> that we don't have to use these really long local types in many places
>> (like make a local typedef)?
>>
>
> Done. Updated patch attached.
>
> Nick
>
>
>
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