[all-commits] [llvm/llvm-project] 6e1fe7: [ELF][test] Reorganize "TLS attribute mismatch" tests

[Fangrui Song via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 6e1fe7856970f468e1c8ffdbd62ba4aeff4d47e1
      https://github.com/llvm/llvm-project/commit/6e1fe7856970f468e1c8ffdbd62ba4aeff4d47e1
  Author: Fangrui Song <maskray at google.com>
  Date:   2020-04-21 (Tue, 21 Apr 2020)

  Changed paths:
    R lld/test/ELF/Inputs/tls-mismatch.s
    R lld/test/ELF/tls-archive.s
    M lld/test/ELF/tls-mismatch.s

  Log Message:
  -----------
  [ELF][test] Reorganize "TLS attribute mismatch" tests


  Commit: 58207d6fe1e507c6fc94ae16b0306a99dd51fdbd
      https://github.com/llvm/llvm-project/commit/58207d6fe1e507c6fc94ae16b0306a99dd51fdbd
  Author: Fangrui Song <maskray at google.com>
  Date:   2020-04-21 (Tue, 21 Apr 2020)

  Changed paths:
    M lld/ELF/Symbols.h
    M lld/test/ELF/tls-mismatch.s

  Log Message:
  -----------
  [ELF] Fix "TLS attribute mismatch" false positives for STT_NOTYPE undefined symbols

D13550 added the diagnostic to address/work around a crash.
The rule was refined by D19836 (test/ELF/tls-archive.s) to exclude Lazy symbols.

https://bugs.llvm.org/show_bug.cgi?id=45598 reported another case where the current logic has a false positive:

Bitcode does not record undefined module-level inline assembly symbols
(`IRSymtab.cpp:Builder::addSymbol`). Such an undefined symbol does not
have the FB_tls bit and lld will not consider it STT_TLS. When the symbol is
later replaced by a STT_TLS Defined, lld will error "TLS attribute mismatch".

This patch fixes this false positive by allowing a STT_NOTYPE undefined
symbol to be replaced by a STT_TLS.

Considered alternative:

Moving the diagnostics to scanRelocs() can improve the diagnostics (PR36049)
but that requires a fair amount of refactoring. We will need more
RelExpr members. It requires more thoughts whether it is worthwhile.

See `test/ELF/tls-mismatch.s` for behavior differences. We will fail to
diagnose a likely runtime bug (STT_NOTYPE non-TLS relocation referencing
a TLS definition). This is probably acceptable because compiler
generated code sets symbol types properly.

Reviewed By: grimar, psmith

Differential Revision: https://reviews.llvm.org/D78438


Compare: https://github.com/llvm/llvm-project/compare/c475856d0532...58207d6fe1e5