On Jun 19, 2007, at 10:31 AM, Chris Lattner wrote:
It seems that simple remat works for things that:
1. have no side effects
2. have no register inputs
Is there another condition?
Can't think of any.
If so, simple remat can check #2 today, just by itself looking at
the
machineinstr. Given that, it comes down to how we want to
represent #1.
I don't see a better way so I guess this will be a targetinstrinfo
bit (true for those with side-effects).
Okay, the tricky thing here is instructions that have "conditional
side effects". For example, all instructions marked isload/isstore/
iscall etc should be considered to have side effects (as would
anything with implicit definitions), but loads from constant pools
and other special cases should not be considered to have side effects.
And on some specialized architectures there are other types of loads/
stores that are not side affecting as well. It would be good to have
this be open to customization.
--
Christopher Lamb
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