[all-commits] [llvm/llvm-project] 65a15a: [ELF] Respect orders of symbol assignments and DEF...

[Fangrui Song via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 65a15a56d5ca0d26ca6d34c31a617f5b26e3cfee
      https://github.com/llvm/llvm-project/commit/65a15a56d5ca0d26ca6d34c31a617f5b26e3cfee
  Author: Fangrui Song <i at maskray.me>
  Date:   2023-09-11 (Mon, 11 Sep 2023)

  Changed paths:
    M lld/ELF/Config.h
    M lld/ELF/Driver.cpp
    M lld/ELF/LinkerScript.cpp
    M lld/ELF/LinkerScript.h
    M lld/ELF/ScriptParser.cpp
    R lld/test/ELF/linkerscript/define.test
    A lld/test/ELF/linkerscript/defined.test

  Log Message:
  -----------
  [ELF] Respect orders of symbol assignments and DEFINED (#65866)

Fix #64600: the currently implementation is minimal (see
https://reviews.llvm.org/D83758), and an assignment like
`__TEXT_REGION_ORIGIN__ = DEFINED(__TEXT_REGION_ORIGIN__) ? __TEXT_REGION_ORIGIN__ : 0;`
(used by avr-ld[1]) leads to a value of zero (default value in `declareSymbol`),
which is unexpected.

Assign orders to symbol assignments and references so that
for a script-defined symbol, the `DEFINED` results match users'
expectation. I am unclear about GNU ld's exact behavior, but this hopefully
matches its behavior in the majority of cases.

[1]: https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=ld/scripttempl/avr.sc