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| author | Roman Lebedev <lebedev.ri@gmail.com> | 2021-10-27 16:05:09 +0300 |
|---|---|---|
| committer | Roman Lebedev <lebedev.ri@gmail.com> | 2021-10-27 18:01:05 +0300 |
| commit | ab1dbcecd6f0969976fafd62af34730436ad5944 (patch) | |
| tree | e3dcee662ec34be617f534e4c9bb6971cd114564 /lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp | |
| parent | 5a8a7b3bf807b3c8c2b3772eb70386846a72013f (diff) | |
[IR] `IRBuilderBase::CreateSelect()`: if cond is a constant i1, short-circuit
While we could emit such a tautological `select`,
it will stick around until the next instsimplify invocation,
which may happen after we count the cost of this redundant `select`.
Which is precisely what happens with loop vectorization legality checks,
and that artificially increases the cost of said checks,
which is bad.
There is prior art for this in `IRBuilderBase::CreateAnd()`/`IRBuilderBase::CreateOr()`.
Refs. https://reviews.llvm.org/D109368#3089809
Diffstat (limited to 'lldb/source/Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.cpp')
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