[PATCH] D36499: If --dynamic-list is given, only those symbols are preemptible

[Rafael Avila de Espindola via llvm-commits]

Shoaib Meenai via Phabricator <reviews at reviews.llvm.org> writes:

> smeenai added a comment.
>
> Thank you!
>
> One issue I have is that this still conflates version scripts and dynamic lists, whereas they're orthogonal concepts in my mind; a version script controls dynamic symbol table population, while a dynamic list (for a shared library) controls preemptibility. The test case  below demonstrates this; it passes with ld.bfd and ld.gold.

I first thought of just disallowing the combination of -dynamic-list and
-version-scirpt, but I think I now realize it is a realistic use
case. One can want a few symbols exported, but only a subset of those
preemptible.

I will try to fix this to handle your testcase.

Thanks,
Rafael


>   # REQUIRES: x86
>   
>   # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
>   # RUN: echo "{ foo; };" > %t.list
>   # RUN: echo "{ global: foo; bar; };" > %t.vers
>   # RUN: ld.lld -fatal-warnings -dynamic-list %t.list -version-script %t.vers -shared %t.o -o %t.so
>   # RUN: llvm-readobj -r %t.so | FileCheck --check-prefix=RELOCS %s
>   # RUN: llvm-nm -DU %t.so | FileCheck --check-prefix=DYNSYMS %s
>   
>   # RELOCS:      Relocations [
>   # RELOCS-NEXT:   Section ({{.*}}) .rela.plt {
>   # RELOCS-NEXT:     R_X86_64_JUMP_SLOT foo 0x0
>   # RELOCS-NEXT:   }
>   # RELOCS-NEXT: ]
>   
>   # DYNSYMS:      bar
>   # DYNSYMS-NEXT: foo
>   
>   	.globl	foo
>   foo:
>   	ret
>   
>   	.globl	bar
>   bar:
>   	ret
>   
>   	call	foo at PLT
>   	call	bar at PLT
>
>
> https://reviews.llvm.org/D36499