[LLVMdev] alias information in codegen

Dan Gohman gohman at apple.com
Sat Apr 5 09:13:56 PDT 2008

On Fri, April 4, 2008 12:03 am, Florian Brandner wrote:
> On Thursday 03 April 2008 22:00:34 Dan Gohman wrote:
>> However, for people just interested in post-regalloc scheduling and
>> VLIW packing and similar things, MemOperands aren't the only approach.
>> A potentially better way to do this would be to extend MachineInstrs
>> to preserve the chain dependencies from the SelectionDAG.
> the selection dag may already contain unnecessary dependencies, even with
> alias analysis turned on. it is built after codegenprepare and thus the
> lowered GEPs cause imprecise results already at this point.

Right; this idea depends on the other items being addressed,
giving the SelectiondDAG better dependence information, so it's
a somewhat longer-term strategy. But it has the nice property that
improvements to the dependence information can benefit both
pre-regalloc and post-regalloc scheduling.


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