[PATCH] D62317: [llvm-objcopy] - Strip undefined symbols if they are no longer referenced following --only-section

[George Rimar via Phabricator via llvm-commits]

grimar added a comment.

In D62317#1515541 <https://reviews.llvm.org/D62317#1515541>, @jhenderson wrote:

> I think you should do that before landing this, because it might mean the implementation is a little simpler (e.g. we simply always remove unreferenced undefined globals, regardless of the switch).


Ok, done: imagine we have

  .globl bar
  .globl foo
  .section .text,"ax"
    movl $bar, %edx

I.e. file with `.text`, `.rela.text`,
undefined `bar`, referenced by `.rela.text` and
undefined unreferenced `foo`.
(also, GNU `as` creates zero sized `.data` section, it is used below)

> as in.s -o as.o

GNU objdump behavior:

1. objcopy in.o out.o:

both `foo` and `bar` are in the output.

2. objcopy in.o out.o -R .text

`.text` and `.rela.text` are removed, both symbols are there.

3. objcopy in.o out.o -j .text -j .rela.text

reports error: objcopy: out.o: symbol `bar` required but not present
(looks like a bug to me)

4. objcopy in.o out.o -j .data

`.text` and `.rela.text` are removed, both symbols are removed.

I.e. the behavior of this patch matches GNU now,
which does not removes undefined unreferenced symbols when `-R` is used and
does not remove them regardless of the switch.

Is there anything else you think worth to check?


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https://reviews.llvm.org/D62317