[LLVMdev] Scheduling and alias analysis

[Amaury Pouly]

Hello,
I have recently been working on scheduling for register pressure and ran
into the issue of alias analysis when trying to integrate it with LLVM.
Looking at the code it seems that the pre register allocation scheduling
doesn't use alias analysis information. On the contrary, post-RA uses it.
I'm wondering if there is a good reason for this fact. Indeed, it seems to
me that alias analysis would be much more useful before register allocation
when the scheduler still has the opportunity to really move the memory
related instructions.
Am I missing something ? Wouldn't it be possible to use alias analysis when
building the pre-RA schedule graph ?

Regards

Amaury Pouly
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