[LLVMdev] Assert in LiveInterval update

Jakob Stoklund Olesen stoklund at 2pi.dk
Tue Sep 4 11:07:12 PDT 2012

On Sep 2, 2012, at 11:52 PM, Lang Hames <lhames at gmail.com> wrote:

> Hi Sergei,
> I just fixed the broken test case for PR13719 with r163107, but from the debugging output you've posted it suspect it won't fix your test case.
> Your analysis looks good - findLastUseBefore(..) doesn't appear to be handling physregs. I'm surprised that isn't causing more failures. I'll see if I can find a failing case in the LLVM test-suite (it's been a while since I ran live-interval-update over all of it) and try out your modifications to findLastUseBefore.

I think Sergei's analysis is correct, but you probably don't want to be scanning use-def chains for physregs. You are pretty much guaranteed to visit the entire function.

Physreg live ranges are usually short. It would be better to scan instructions instead of use-def chains for physregs.


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