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

[Fangrui Song via llvm-commits]

Do you have a reproduce command line?

I am at commit c3dbd782f1e0578c7ebc342f2e92f54d9644cff7 (your revert).
With it rolled forward locally, check-sanitizer works here. (-DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=on)

Running projects/compiler-rt/lib/sanitizer_common/tests/Sanitizer-x86_64-Test-Nolibc directly is also fine.

On 2019-12-27, Reid Kleckner wrote:
>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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