4 Commits

Author SHA1 Message Date
Fangrui Song
7c7702b318 [ELF] Move section assignment from initializeSymbols to postParse
https://discourse.llvm.org/t/parallel-input-file-parsing/60164

initializeSymbols currently sets Defined::section and handles non-prevailing
COMDAT groups. Move the code to the parallel postParse to reduce work from the
single-threading code path and make parallel section initialization infeasible.

Postpone reporting duplicate symbol errors so that the messages have the
section information. (`Defined::section` is assigned in postParse and another
thread may not have the information).

* duplicated-synthetic-sym.s: BinaryFile duplicate definition (very rare) now
  has no section information
* comdat-binding: `%t/w.o %t/g.o` leads to an undesired undefined symbol. This
  is not ideal but we report a diagnostic to inform that this is unsupported.
  (See release note)
* comdat-discarded-lazy.s: %tdef.o is unextracted. The new behavior (discarded
  section error) makes more sense
* i386-comdat.s: switched to a better approach working around
  .gnu.linkonce.t.__x86.get_pc_thunk.bx in glibc<2.32 for x86-32.
  Drop the ancient no-longer-relevant workaround for __i686.get_pc_thunk.bx

Depends on D120640

Differential Revision: https://reviews.llvm.org/D120626
2022-03-15 19:24:41 -07:00
Fangrui Song
9b61fff0eb Revert D120626 "[ELF] Move section assignment from initializeSymbols to postParse"
This reverts commit c30e6447c0225f675773d07f2b6d4e3c2b962155.
It exposed brittle support for __x86.get_pc_thunk.bx.
Need to think a bit how to support __x86.get_pc_thunk.bx.
2022-03-15 19:00:54 -07:00
Fangrui Song
c30e6447c0 [ELF] Move section assignment from initializeSymbols to postParse
https://discourse.llvm.org/t/parallel-input-file-parsing/60164

initializeSymbols currently sets Defined::section and handles non-prevailing
COMDAT groups. Move the code to the parallel postParse to reduce work from the
single-threading code path and make parallel section initialization infeasible.

Postpone reporting duplicate symbol errors so that the messages have the
section information. (`Defined::section` is assigned in postParse and another
thread may not have the information).

* duplicated-synthetic-sym.s: BinaryFile duplicate definition (very rare) now
  has no section information
* comdat-binding: `%t/w.o %t/g.o` leads to an undesired undefined symbol. This
  is not ideal but we report a diagnostic to inform that this is unsupported.
  (See release note)
* comdat-discarded-lazy.s: %tdef.o is unextracted. The new behavior (discarded
  section error) makes more sense

Depends on D120640

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D120626
2022-03-14 14:13:41 -07:00
Fangrui Song
c7cf960d85 [ELF] Set the priority of STB_GNU_UNIQUE the same as STB_WEAK
In GCC -fgnu-unique output, STB_GNU_UNIQUE symbols are always defined relative
to a section in a COMDAT group. Currently `other` cannot be STB_GNU_UNIQUE for
valid input, so this patch is NFC.

If we switch to the model that ignores COMDAT resolution when performing symbol
resolution (D120626), this will fix bogus `relocation refers to a symbol in a
discarded section` errors when mixing -fno-gnu-unique objects with -fgnu-unique
objects.

Differential Revision: https://reviews.llvm.org/D120640
2022-03-14 12:00:15 -07:00