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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Make the debug info hierarchy strict"
href="http://llvm.org/bugs/show_bug.cgi?id=22777">22777</a>
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<th>Summary</th>
<td>Make the debug info hierarchy strict
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Core LLVM classes
</td>
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<th>Assignee</th>
<td>dexonsmith@apple.com
</td>
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<th>Reporter</th>
<td>dexonsmith@apple.com
</td>
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<th>CC</th>
<td>aprantl@apple.com, dblaikie@gmail.com, echristo@gmail.com, friss@apple.com, llvmbugs@cs.uiuc.edu
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<th>Blocks</th>
<td>21432
</td>
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<th>Classification</th>
<td>Unclassified
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<pre>After introducing specialized metadata nodes in <a class="bz_bug_link
bz_status_ASSIGNED "
title="ASSIGNED --- - Debug Info IR: Add specialized nodes for DIDescriptor hierarchy"
href="show_bug.cgi?id=22464">bug 22464</a>, we can take
advantage of having a real type hierarchy. There's a lot of looseness in the
debug info IR. I'll use this bug to track fixing it.
Here's a rough guide of what I think needs doing:
1. Turn on the debug info verifier by default. This will require cleaning up
some testcase bitrot; I might also have to work through some real bugs that
have crept in. (You may wonder, why was this turned off in the first place?
It's way too expensive as a function pass, since many functions transitively
reference the entire type hierarchy. But r206300 changed it to a module pass
so the overhead should be reasonable (and worth it).)
2. Check types everywhere:
(a) Add type checks to the verifier. For example, verify that `!dbg` points at
`MDLocation`s and that `MDLocation::getInlinedAt()` returns an `MDLocation`.
(There are a ton of things like this.)
(b) Change DIDescriptor accessors to `cast<>` or `cast_or_null<>`.
(c) Change the specialized nodes to `cast<>` and `cast_or_null<>` their operand
accessors.
3. Empty out the DIDescriptor wrappers.
(a) Override `operator->()` and `operator*()` for subclasses to point at the
specialized nodes.
(b) Remove wrapping accessors, forcing null checks in the users.
After that, it'll be pretty natural to remove the `DIDescriptor` wrappers
entirely (and use the specialized nodes directly).</pre>
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