[LLVMdev] Why change "sub x, 5" to "add x, -5" ?

[Frédéric Heitzmann]

2015-07-10 16:53 GMT+02:00 escha <escha at apple.com>:

>
> If you write a target-specific combine that conflicts with a
> canonicalization, it’ll infinite loop because it’ll oscillate between the
> two forms.
>
>
I saw that ;-)
However, I used DAGCombinerInfo::CombineTo(oldNode, newNode, false) to
prevent DAGCombiner to add the returned SDValue to worklist and recombine
it back to the canical form.
Did I miss the purpose of CombineTo ?

fred
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