[llvm-commits] building a Dependence Graph

[Hal Finkel]

----- Original Message -----
> From: "Preston Briggs" <preston.briggs at gmail.com>
> To: llvm-commits at cs.uiuc.edu
> Sent: Wednesday, October 17, 2012 7:04:20 PM
> Subject: [llvm-commits] building a Dependence Graph
> 
> 
> Attached is a small patch that begins the definition of a new
> function pass, DependenceGraph, that will build a dependence graph
> for an entire function.

What will time time/space complexity of this be?

Thanks again,
Hal

> I'm trying to sneak up on the problem in
> stages, rather than blatting out one big chunk of code, hoping to
> make it easier to review.
> 
> 
> This new pass depends on the DependenceAnalysis pass to answer
> questions about the dependence between pairs of instructions. There
> are two separate passes because there's a useful separation of
> concerns. A dependence exists if two conditions are met:
> 
> 
>     1. Two instructions reference the same memory location, and
>     2. There is a flow of control leading from one instruction to the
>     other.
> 
> 
> DependenceAnalysis attacks the first condition; DependenceGraph
> attacks the second.
> 
> 
> Someday it may be useful to write a different pass, called something
> like LoopDependenceGraph, that would build a dependence graph for a
> single loop nest. Such a pass could still rely on the
> DependenceAnalysis pass.
> 
> 
> Thanks,
> Preston
> 
> 
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-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory