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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">re-add llvm-dev…<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></a></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> Robinson, Paul
<br>
<b>Sent:</b> Thursday, March 30, 2017 2:50 PM<br>
<b>To:</b> 'Keane, Erich'; Reid Kleckner<br>
<b>Subject:</b> RE: [llvm-dev] FileCheck feature request- by default ignore IR-"headers"<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in">I think the most practical thing to do would be to make FileCheck reject test cases that consist only CHECK-NOT directives, unless a flag is passed to disable this behavior.<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">That might help a certain class of tests, but I'm not so sure that's such a common case. It's about as easy to write a positive CHECK[-LABEL] that will unexpectedly
match something that you didn't expect. At least the test with only CHECK-NOT in it *will* fail if you get it wrong, which is certainly better than passing when it should fail.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">So, I am reluctant to encourage yet another wart/hack on how FileCheck works.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">--paulr<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> llvm-dev [<a href="mailto:llvm-dev-bounces@lists.llvm.org">mailto:llvm-dev-bounces@lists.llvm.org</a>]
<b>On Behalf Of </b>Keane, Erich via llvm-dev<br>
<b>Sent:</b> Thursday, March 30, 2017 11:18 AM<br>
<b>To:</b> Reid Kleckner<br>
<b>Cc:</b> <a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> Re: [llvm-dev] FileCheck feature request- by default ignore IR-"headers"<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Alright, I guess it isn’t just my pain then, it makes it feel better
</span><span style="font-size:11.0pt;font-family:Wingdings;color:#1F497D">J</span><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"> I think that proposed feature would be really nice, since it would encourage people to write
tests that have a //CHECK: some-thing-after-header first!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> Reid Kleckner [<a href="mailto:rnk@google.com">mailto:rnk@google.com</a>]
<br>
<b>Sent:</b> Thursday, March 30, 2017 11:15 AM<br>
<b>To:</b> Keane, Erich <<a href="mailto:erich.keane@intel.com">erich.keane@intel.com</a>><br>
<b>Cc:</b> <a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a><br>
<b>Subject:</b> Re: [llvm-dev] FileCheck feature request- by default ignore IR-"headers"<o:p></o:p></span></p>
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<p class="MsoNormal">Yeah, this is a documented shortcoming of FileCheck:<o:p></o:p></p>
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<p class="MsoNormal"><a href="http://llvm.org/docs/TestingGuide.html#fragile-tests">http://llvm.org/docs/TestingGuide.html#fragile-tests</a><o:p></o:p></p>
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<p class="MsoNormal">I think the most practical thing to do would be to make FileCheck reject test cases that consist only CHECK-NOT directives, unless a flag is passed to disable this behavior.<o:p></o:p></p>
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<p class="MsoNormal">On Thu, Mar 30, 2017 at 8:57 AM, Keane, Erich via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi all-<br>
I hope this is the right place for this.<br>
<br>
Anyway, the primary usage for the utility "FileCheck" is to pattern match for specific values in a stream. This is perfectly consistent and deterministic for the most part! However, when validating clang's LLVM-IR generation, it is possible to make an invalid
match against the top few generated lines (the LLVM-IR Headers), which are inconsistent.<br>
<br>
For example (from my personal pain), we have a test: clang/test/CodeGen/debug-info-macro.c that has a 'check-not' on the word "macros". Unfortunately, my SVN workspace name was "ms_macros", which gave me a false match. I'm a bit ashamed to say how long this
took me to figure out :)<br>
<br>
Anywya, to my feature request: to prevent someone else from going through this pain again, would it be possible to have FileCheck ignore these first 4 lines as default behavior? I suspect there might be a few tests that would want to validate those headers,
though I expect those are the vast minority, so I would think this should be opt in.<br>
<br>
-Erich<br>
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