[llvm-dev] llvm PeepholeOptimizer + optimizeLoadInstr question

[Hal Finkel via llvm-dev]

Hi Andrew, 

Is this still an open question? I took a quick look at the code and I think the change you're proposing makes sense. If you'd like to pursue this, I recommend posting a patch for review. 

-Hal 

----- Original Message -----

> From: "Andrew Zhogin via llvm-dev" <llvm-dev at lists.llvm.org>
> To: lhames at gmail.com
> Cc: llvm-dev at lists.llvm.org
> Sent: Sunday, July 17, 2016 1:29:34 PM
> Subject: [llvm-dev] llvm PeepholeOptimizer + optimizeLoadInstr
> question

> Hello Lang,

> PeepholeOptimizer allows backend to provide optimizeLoadInstr
> function to fold memory-load operand.

> But it doesn't work for folding load operand into store instruction
> (combine into memory-to-memory instruction).
> It is rare case, but some backends have such instructions (like
> SystemZ MVC).

> It doesn't work because "FoldAsLoadDefCandidates.clear()" occurs too
> early, before current instruction "optimizeLoadInstr" check.

> Could "FoldAsLoadDefCandidates.clear()" be moved later?

> After "!isLoadFoldable(...) && !FoldAsLoadDefCandidates.empty()"
> condition check.

> --

> Thanks,
> Andrew
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> llvm-dev at lists.llvm.org
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-- 

Hal Finkel 
Assistant Computational Scientist 
Leadership Computing Facility 
Argonne National Laboratory 
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