[llvm-dev] Skip redundant checks in AliasSet::aliasesUnknownInst

[Roman Gareev via llvm-dev]

Dear llvm contributors,

Could you please advise me how to skip
checks, which are performed in AliasSet::aliasesUnknownInst, of
unknown instructions from different alias sets of an alias set tracker
that is a parameter of ‘AliasSetTracker::add(const AliasSetTracker
&AST)’?

If this wasn’t available at the moment and someone could review me, I
would try to implement it. A temporary patch can be found attached
(for example, ViewedInst can become a second parameter of
AliasSetTracker::addUnknown ). It
passes the LLVM regression tests and helps to reduce the runtime of
'opt -basicaa -licm out.opt.ll’ from 130ms to 67ms and the runtime of
'opt -basicaa -licm out.opt2.ll’ from 117ms to 62ms (out.opt.ll and
out.opt2.ll can be found on the following link
https://llvm.org/bugs/show_bug.cgi?id=23077).

Thank you for the attention!

-- 
                                    Cheers, Roman Gareev.
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