dblaikie added subscribers: JDevlieghere, aprantl.
dblaikie added a comment.
Yeah, GCC's debug info for this is... not good. I don't think it's anything
we'd need to be inspired by. Here's the tags and names:
DW_TAG_compile_unit
DW_AT_name ("templ2.cpp")
DW_TAG_structure_type
DW_AT_name ("type")
DW_TAG_variable
DW_AT_name ("variable")
DW_TAG_base_type
DW_AT_name ("int")
DW_TAG_variable
DW_AT_name ("variable")
DW_TAG_base_type
DW_AT_name ("float")
DW_TAG_subprogram
DW_AT_name ("main")
DW_TAG_variable
DW_AT_name ("t")
DW_TAG_variable
DW_AT_name ("i")
DW_TAG_variable
DW_AT_name ("f")
The structure_type has no child DIEs and no mention of the variable template
instantiations - the global variables are both called "global" but with
different types. No mention of the scope they were actually declared in. I
guess maybe at least this "works" for free in some ways, but probably makes it
impossible to refer to one or the other variable or with the right name.
@aprantl @probinson @echristo @JDevlieghere - So my proposal is that the
'right' DWARF for this is:
DW_TAG_structure_type
DW_AT_name ("type")
DW_TAG_member
DW_AT_name ("variable<int>")
DW_AT_declaration (true)
DW_TAG_member
DW_AT_name ("variable<float>")
DW_AT_declaration (true)
DW_TAG_variable
DW_AT_specification (0x.... "variable<int>")
DW_AT_location
DW_AT_linkage_name ("_ZN4type1iE")
DW_TAG_base_type
DW_AT_name ("int")
DW_TAG_variable
DW_AT_specification (0x.... "variable<float>")
DW_AT_location
DW_AT_linkage_name ("_ZN4type1fE")
DW_TAG_base_type
DW_AT_name ("float")
And the LLVM IR should be done the same way as member function templates -
never appear in the member list, but appear otherwise the same - a
DIGlobalVariable named "variable<int>" for the definition with a 'declaration:'
attribute that refers to a DIDerivedType DW_TAG_member for the declaration of
"variable<int>" where the 'scope:' attribute of the DW_TAG_member refers to the
DW_TAG_structure_type, but that structure_type's member list does not contain
this member. (same as functions - DISubprogram definition -declaration->
DISubprogram declaration -scope-> DW_TAG_structure_type but doesn't appear in
the member list of the structure_type)
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D70537/new/
https://reviews.llvm.org/D70537
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