generate: add support DW_TAG_unspecified_type #28
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GAS 2.40 and later add return type tag to DWARF DIEs generated for
function symbols, introduced in [1]
commit 5578fbf672ee497ea19826edeb509f4cc3e825a8
Author: Nick Clifton <[email protected]>
Date: Thu Aug 25 11:48:00 2022 +0100
GAS: Add a return type tag to DWARF DIEs generated for function symbols.
This is compliant with the DWARFv5 stardard [2], Sec. 3.3.2 and Sec. 5.2.
The resulting DW_TAG_subprogram then has a DW_AT_type attribute pointing to
a DW_TAG_unspecified_type. For example,
arch/x86/entry/entry.S:
SYM_FUNC_START(entry_ibpb)
...
RET
SYM_FUNC_END(entry_ibpb)
EXPORT_SYMBOL_GPL(entry_ibpb);
emits
DW_TAG_subprogram
DW_AT_name ("entry_ibpb")
DW_AT_external (true)
DW_AT_type (0x12345678 "") -
0x12345678: DW_TAG_unspecified_type
As is, when processing DW_TAG_subprogram (print_die_subprogram), kabi-dw
calls print_die_tag to determine the return type and fail on an unsupported
DW_TAG:
print_die_tag():1845 Unexpected tag for symbol (null): 3b (unspecified_type)
Generating symbol defs from kernel-6.12.0-42.el10.x86_64/vmlinux
This commit adds a new DW_TAG_unspecified_type case to said function's
processing and treats it as a new "basetype" named "auto".
This corresponds to the following file func--entry_ibpb.txt:
Symbol:
func entry_ibpb (
)
"auto"
[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5578fbf672ee497ea19826edeb509f4cc3e825a8
[2] https://dwarfstd.org/doc/DWARF5.pdf
Signed-off-by: Čestmír Kalina <[email protected]>
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GAS 2.40 and later add return type tag to DWARF DIEs generated for function symbols, introduced in [1]
This is compliant with the DWARFv5 stardard [2], Sec. 3.3.2 and Sec. 5.2. The resulting DW_TAG_subprogram then has a DW_AT_type attribute pointing to a DW_TAG_unspecified_type. For example,
emits
As is, when processing DW_TAG_subprogram (print_die_subprogram), kabi-dw calls print_die_tag to determine the return type and fail on an unsupported DW_TAG:
This commit adds a new DW_TAG_unspecified_type case to said function's processing and treats it as a new "basetype" named "auto".
This corresponds to the following file func--entry_ibpb.txt:
[1] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=5578fbf672ee497ea19826edeb509f4cc3e825a8
[2] https://dwarfstd.org/doc/DWARF5.pdf
unspecifiedwas also considered, butautomight be more suggestive in that it is a keyword in other languages, might become a reserved C keyword, and (not that it's relevant) C++ emits the same tag for its auto return values; but I am certainly open to better naming suggestions...