[LLVMdev] How to test my pass

Chayan Sarkar chayan.ju at gmail.com
Mon Jul 5 11:01:25 PDT 2010

Thank you so much....

On Mon, Jul 5, 2010 at 11:06 PM, Nick Lewycky <nicholas at mxc.ca> wrote:
> Chayan Sarkar wrote:
>> Hi there,
>> I have written a PRE pass using LLVM. How can I test my  pass? Is
>> there any standard test-cases or bench-marks to test a pass. Please
>> suggest accordingly.
> Use the LLVM nightly test suite:
> http://llvm.org/docs/TestingGuide.html#testsuiterun
> Make a copy of an existing test like TEST.example.Makefile and modify it to
> run 'opt -yourpass -time-passes -stats', then 'make TEST=yourexample report'
> and read the report.raw.out it produces. Look for crashes first and
> foremost, then look at how many times it actually modified the user code,
> then finally make sure it didn't take show absurd compile-time problems. Fix
> all the crashers and O(n^2) behaviour.
> Now you're ready to try your pass on real code. Modify
> include/llvm/Support/StandardPasses.html to add your pass to the list of
> defaults. Go back to the nightly test suite and 'make TEST=nightly
> report.html' which will not only use your pass when building the tests, but
> actually run the resulting executables and verify their results. Most of the
> * cells in the resulting HTML will be as a result of your pass, but not all.
> Your first step in debugging them is to cd to the correct source directory
> and run 'make bugpoint-opt'[1] to get a reduced testcase. Fix all the
> crashers and miscompiles.
> If you have access to SPEC, that's also a great source of benchmarks. You
> should certainly try it out over spec if you at all possibly can, since spec
> turns up all sorts of miscompiles that the llvm test suite doesn't.
> Finally, do a run of the nightly test with your pass enabled, and a
> reference run without it. How much did you pass really speed the programs
> up? How much did it slow the compiler down? Is your pass worth it to our
> users? If so, it's time to commit!
> Nick
> [1] In MultiSource/... that does the right thing, in SingleSource/... it
> will print out a message telling you what you should really run.
>> Regards,
>> Chayan
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