[PATCH] D79592: [DebugInfo] support for DW_AT_data_location in llvm

[Adrian Prantl via Phabricator via llvm-commits]

aprantl added a comment.

Thanks, we're almost there!



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Comment at: llvm/docs/LangRef.rst:4796
 level of indexing. The ``DIFlagVector`` flag to ``flags:`` indicates that an
-array type is a native packed vector.
+array type is a native packed vector. the ``dataLocation:`` is location
+description, representing location of the data for an object. When this is
----------------
the -> The

LLVM IR doesn't know the term location description. Let's call it what it is:

```
The ``dataLocation`` is a DIExpression that describes how to get from an object's address to the actual raw data, if they aren't equivalent. This is only supported for array types, particularly to describe Fortran arrays, which have an array descriptor in addition to the array data.
```


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Comment at: llvm/lib/IR/Verifier.cpp:1018
+             "dataLocation can only appear in array type ");
+  }
 }
----------------
Thanks! Can you add a tiny testcase to tests/Verifier that covers this check?


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Comment at: llvm/test/Bitcode/dataLocation.ll:7
+; CHECK:  !DICompositeType(tag: DW_TAG_array_type, baseType: !{{[0-9]+}}, size: 32, align: 32, elements: !{{[0-9]+}}, dataLocation: !{{[0-9]+}})
+; CHECK:  !DICompositeType(tag: DW_TAG_array_type, baseType: !{{[0-9]+}}, size: 32, align: 32, elements: !{{[0-9]+}}, dataLocation: !DIExpression(DW_OP_constu, 3412))
+
----------------
Out of curiosity: This is a placeholder, right? I would have expected something like `!DIExpression(DW_OP_constu, 32, DW_OP_plus)` here.


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https://reviews.llvm.org/D79592