<div dir="ltr"><div>FWIW, I did a BoF on the llvm binutils earlier this year at Euro LLVM, to discuss the direction of the binutils and one of the suggestions that seemed to get broad appeal was a more machine-readable output format option (e.g. JSON/XML). llvm-readobj's output is relatively human readable, but isn't quite JSON. You could possibly then write a straightforward python script to load the json and test it's properties exactly, if you're interested in the property values rather than how they are printed. I haven't got around to this yet, and probably won't for quite some time, so if anybody else is interested in the idea, I'd be happy for them to take it forward.</div><div><br></div><div>James<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, 6 Nov 2019 at 19:12, Reid Kleckner <<a href="mailto:rnk@google.com">rnk@google.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr">I think we should think about changing llvm-readobj to produce more filecheck friendly output.<div><br></div><div>This was a problem we used to have with LLVM debug info metadata: it wasn't very structured, and it was printed in some arbitrary order. Then Duncan (I think) added the DI* classes, which made it easier to match something semantic, like `DILocalVariable.*name: "foo"`, and standardized on a topological output ordering, so you could start from the variable, then match the type, and then find the type metadata number later.</div><div><br></div><div>If we printed `Section (.foo) {` for example, that would help some.</div><div><br></div><div>It still doesn't help establish delimited regions for properties printed across multiple lines for readability, though... Should we add some kind of ad-hoc delimiter balancing to FileCheck? Something like:</div><div><br></div><div>CHECK-SCOPE: Section {</div><div>CHECK: Name: asdf</div><div>CHECK: Name: asdf <br></div><div>CHECK-ENDSCOPE: }</div><div><br></div><div>A SCOPE directive line would have to end in a known delimiter, '(', '{', or '['. The ENDSCOPE directive would only match lines with delimiters that balance with the opening delimiter. It would kind of work for filechecking JSON, for example.</div><div><br></div><div>The scope idea here is pretty half-baked, but it's food for thought.</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Nov 6, 2019 at 4:18 AM James Henderson via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"> <div>Hi all,</div><div><br></div><div>Many of our lit tests use FileCheck and a tool like llvm-readobj to check properties of a section header/symbol/etc. A typical (pseudoised for brevity) output to match against might be something like the following:</div><div><br></div><div><span style="font-family:monospace">Symbols [</span></div><div><span style="font-family:monospace"> Symbol {</span></div><div><span style="font-family:monospace"> Name: foo</span></div><div><span style="font-family:monospace"> Value: 0</span></div><div><span style="font-family:monospace"> Type: Function</span></div><div><span style="font-family:monospace"> Section: .foo (1)<br></span></div><div><span style="font-family:monospace"> }</span></div><div><span style="font-family:monospace"> Symbol {</span></div><div><span style="font-family:monospace"> Name: bar</span></div><div><span style="font-family:monospace"> Value: 1</span></div><div><span style="font-family:monospace"> Type: Object</span></div><div><span style="font-family:monospace"> Section: .foo (1)<br></span></div><div><span style="font-family:monospace"> }<br></span></div><div><span style="font-family:monospace">]</span></div><div><br></div><div>and your lit test might want to check the properties of the foo symbol like so:</div><div><br></div><div><font face="monospace"># CHECK: Name: foo</font></div><div><span style="font-family:monospace"># CHECK-NEXT: Value: 0</span></div><div><span style="font-family:monospace"># CHECK-NEXT: Type: Function</span></div><div><span style="font-family:monospace"># CHECK-NEXT: Section: .foo
(1)
</span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif">This is fine. But what if you only care about the section of a symbol, and not the value or type etc? You could do the following:</font></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif"><br></font></span></div><div><span style="font-family:monospace"># CHECK: Name: foo</span></div><div><span style="font-family:monospace"># CHECK: Section: .foo (1)<br></span></div><div><br></div><div>Hopefully some of you will already notice the problem with this approach: if foo was in, say, the .baz section, the test will spuriously pass, because the Section line will match the Section line for .bar. One alternative to this is to explicitly match each field in between, using CHECK-NEXT:</div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"># CHECK: Name: foo</span></div><div><span style="font-family:monospace"># CHECK-NEXT: Value:</span></div><div><span style="font-family:monospace"># CHECK-NEXT: Type:</span></div><div><span style="font-family:monospace"># CHECK-NEXT: Section: .foo
(1)
</span></div><div><br></div><div>This works, but somewhat hides what is really being tested by adding extra noise to the checks. In reality, there are actually other fields too that need to be listed, meaning the "interesting" parts of the test are even more hidden.</div><div><br></div><div>I recently started using yet another approach:</div><div><br></div><div><span style="font-family:monospace"># CHECK: Name: foo</span></div><div><span style="font-family:monospace"># CHECK: Section:</span></div><div><span style="font-family:monospace"># CHECK-SAME: .foo (1)<br></span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:arial,sans-serif">This works because the Section: matched will be the first one found, i.e. the one belonging to foo, and then .foo will be looked for on the same line. However, I noticed today that this pattern has its own problem, namely that there could be something between the Section tag and .foo. In other words, the above pattern would match "Section: .bar.foo". A couple of solutions to this are:</span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"># CHECK: Section:</span></div><div><span style="font-family:monospace"># CHECK-NOT: {{[:graph:]}}</span></div><div><span style="font-family:monospace"># CHECK-SAME: .foo (1)</span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"># CHECK: Section:</span></div><div><span style="font-family:monospace"># CHECK-SAME: {{^}} .foo (1)<br></span></div><div><span style="font-family:monospace"><br></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif">The first one ensures that there's no non-whitespace between the end of "Section:" and the start of ".foo (1)". The second ensures that the start of the CHECK-SAME match is the "start of line", and since the first half of the line has already been consumed, it means " .foo (1)" must immediately follow "Section:". However, the first is even less readable than the current CHECK-SAME approach, whilst the second is somewhat confusing if you don't realise that FileCheck effectively consumes the things it has matched already, so that they effectively don't exist any more.<br></font></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif"><br></font></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif">Does anybody have any other suggestions/thoughts/comments? One idea I had was for a new directive something like "CHECK-IMMEDIATE" which is implicitly the same as the final approach I suggested above, but maybe adding a new directive to achieve this isn't the right approach?</font></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif"><br></font></span></div><div><span style="font-family:monospace"><font face="arial,sans-serif">James<br></font></span></div></div>
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