[PATCH] D32647: [ELF] - Do not produce duplicate values in .gdb_index's constant pool area.

[George Rimar via Phabricator via llvm-commits]

grimar created this revision.

I found this when builded llc binary using gcc 5.4.1 + LLD.
gcc produces duplicate entries in .debug_gnu_pubtypes section, ex:

UnifyFunctionExitNodes.cpp.o has:
0x0000ac07 EXTERNAL TYPE     "std::__success_type<void*>"
0x0000ac07 EXTERNAL TYPE     "std::__success_type<void*>"

clang produces single entry here:
0x0000d291 EXTERNAL TYPE     "std::__success_type<void *>"

If we link output from gcc with LLD, that would produce excessive duplicate
entries in .gdb_index constant pool area. That does not seem affect gdb work,
but makes .gdb_index larger than it can be.

I also checked that gold filters out such duplicates too.

Patch fixes the issue and also simplifies how we store CU index + attributes,
previously they were stored separatelly, that doesn't make sense.


https://reviews.llvm.org/D32647

Files:
  ELF/SyntheticSections.cpp
  ELF/SyntheticSections.h
  test/ELF/gdb-index-dup-types.s

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