[lld] 1417558 - [ELF] Improve the condition to create .interp

[Reid Kleckner via llvm-commits]

I ended up reverting this because it causes some check-sanitizer nolibc
test to fail, hopefully it reproduces for you locally, let me know if it
doesn't. The "nolibc" version crashes on startup.

On Thu, Dec 26, 2019 at 1:28 PM Fangrui Song via llvm-commits <
llvm-commits at lists.llvm.org> wrote:

>
> Author: Fangrui Song
> Date: 2019-12-26T13:26:43-08:00
> New Revision: 1417558e4a61794347c6bfbafaff7cd96985b2c3
>
> URL:
> https://github.com/llvm/llvm-project/commit/1417558e4a61794347c6bfbafaff7cd96985b2c3
> DIFF:
> https://github.com/llvm/llvm-project/commit/1417558e4a61794347c6bfbafaff7cd96985b2c3.diff
>
> LOG: [ELF] Improve the condition to create .interp
>
> Similar to rL362355, but with the `!config->shared` guard.
>
> (1) {gcc,clang} -fuse-ld=bfd -pie -fPIE -nostdlib a.c => .interp created
> (2) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c => .interp not
> created
> (3) {gcc,clang} -fuse-ld=lld -pie -fPIE -nostdlib a.c a.so => .interp
> created
>
> The inconsistency of (2) is due to the condition
> `!Config->SharedFiles.empty()`.
> To make lld behave more like ld.bfd, we could change the condition to:
>
>     config->hasDynSymTab && !config->dynamicLinker.empty() &&
> script->needsInterpSection();
>
> However, that would bring another inconsistency as can be observed with:
>
> (4) {gcc,clang} -fuse-ld=bfd -no-pie -nostdlib a.c => .interp not created
>
> Added:
>
>
> Modified:
>     lld/ELF/Writer.cpp
>     lld/test/ELF/dynamic-linker.s
>     lld/test/ELF/ppc64-func-entry-points.s
>
> Removed:
>
>
>
>
> ################################################################################
> diff  --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
> index c0ad33473747..c20b74821d9c 100644
> --- a/lld/ELF/Writer.cpp
> +++ b/lld/ELF/Writer.cpp
> @@ -135,7 +135,7 @@ StringRef getOutputSectionName(const InputSectionBase
> *s) {
>  }
>
>  static bool needsInterpSection() {
> -  return !sharedFiles.empty() && !config->dynamicLinker.empty() &&
> +  return !config->shared && !config->dynamicLinker.empty() &&
>           script->needsInterpSection();
>  }
>
>
> diff  --git a/lld/test/ELF/dynamic-linker.s b/lld/test/ELF/dynamic-linker.s
> index d0da77fab295..b5e9f5f55e98 100644
> --- a/lld/test/ELF/dynamic-linker.s
> +++ b/lld/test/ELF/dynamic-linker.s
> @@ -1,6 +1,4 @@
>  # REQUIRES: x86
> -# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/shared.s
> -o %t1.o
> -# RUN: ld.lld -shared %t1.o -o %t.so
>  # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
>
>  # RUN: ld.lld --dynamic-linker foo %t.o %t.so -o %t
> @@ -11,11 +9,11 @@
>
>  # CHECK: [Requesting program interpreter: foo]
>
> -# RUN: ld.lld %t.o %t.so -o %t
> +# RUN: ld.lld %t.o -o %t
>  # RUN: llvm-readelf -program-headers %t | FileCheck --check-prefix=NO %s
>
> -# RUN: ld.lld --dynamic-linker foo --no-dynamic-linker %t.o %t.so -o %t
> -# RUN: llvm-readelf -program-headers %t | FileCheck --check-prefix=NO %s
> +# RUN: ld.lld --dynamic-linker foo --no-dynamic-linker %t.o -o %t
> +# RUN: llvm-readelf --program-headers %t | FileCheck --check-prefix=NO %s
>
>  # NO-NOT: PT_INTERP
>
>
> diff  --git a/lld/test/ELF/ppc64-func-entry-points.s
> b/lld/test/ELF/ppc64-func-entry-points.s
> index 1411cbe1c058..c322f6563426 100644
> --- a/lld/test/ELF/ppc64-func-entry-points.s
> +++ b/lld/test/ELF/ppc64-func-entry-points.s
> @@ -3,13 +3,13 @@
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux %s -o %t.o
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux
> %p/Inputs/ppc64-func-global-entry.s -o %t2.o
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64le-unknown-linux
> %p/Inputs/ppc64-func-local-entry.s -o %t3.o
> -// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.o %t3.o -o %t
> +// RUN: ld.lld %t.o %t2.o %t3.o -o %t
>  // RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
>
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux %s -o %t.o
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux
> %p/Inputs/ppc64-func-global-entry.s -o %t2.o
>  // RUN: llvm-mc -filetype=obj -triple=powerpc64-unknown-linux
> %p/Inputs/ppc64-func-local-entry.s -o %t3.o
> -// RUN: ld.lld -dynamic-linker /lib64/ld64.so.2 %t.o %t2.o %t3.o -o %t
> +// RUN: ld.lld %t.o %t2.o %t3.o -o %t
>  // RUN: llvm-objdump -d --no-show-raw-insn %t | FileCheck %s
>
>         .text
>
>
>
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