Subject: Re: rep questions
From: Craig Chambers (chambers@cs.washington.edu)
Date: Mon Oct 30 2000 - 16:47:03 PST
Yes. The idea is that, when we're not doing optimizations, we don't build the
DFG (to make compilation as fast as possible). When we care about dataflow
links, we consult the AST as a coarse approximation of the DFG. You can ask a
WindIR for its dfg_kind, which is either WindDataflowKind or WindASTKind,
depending on which slice is representing the dataflow links. You then access
your dataflow arguments using node.arg1(kind), where kind was computed from
ir.dfg_kind. See wil-codegen-c.cecil for lots of examples of accessing dataflow
predecessors indexed by analysis.kind (which is a cached copy of ir.dfg_kind).
ast-helpers, by the way, defines a bunch of functions to give convenient names
to particular dataflow predecessors, including the functions indexed by the
dataflow slice to access. (These functions should probably be moved to ir-node,
since they're generally useful, not just when manipulating ASTs. The
constructors, on the other hand, should stay, since they're explicitly building
up AST links.)
-- Craig
Keunwoo Lee wrote:
>
> Craig: (cc'd to list for benefit of all)
>
> Is there any particular reason method lower(ir:WindIR) in lower.cecil
> takes either a CFG or a CDFG? It seems the lowering pass needs data flow
> information. Certainly, DFG info would be useful for the lower_ops I'm
> working on now.
>
> ~k
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