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[ELF] Simplify the condition to create .interp 

(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

So instead, use `!Config->DynamicLinker.empty() && Script->needsInterpSection()`,
which is both simple and consistent in these cases.

The inconsistency of (4) likely originated from ld.bfd and gold's choice to have a default --dynamic-linker.
Their condition to create .interp is ANDed with (not -shared).
Since lld doesn't have a default --dynamic-linker,
compiler drivers (gcc/clang) don't pass --dynamic-linker for -shared,
and direct ld users are not supposed to specify --dynamic-linker for -shared,
we do not need the condition !Config->Shared.

Reviewed By: ruiu

Differential Revision: https://reviews.llvm.org/D62765

llvm-svn: 362355
This commit is contained in:
Fangrui Song 2019-06-03 05:25:03 +00:00
parent 471f11805f
commit c78c999a9c
2 changed files with 8 additions and 11 deletions
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3
lld/ELF/Writer.cpp
View File

@ -138,8 +138,7 @@ StringRef elf::getOutputSectionName(const InputSectionBase *S) {
}
static bool needsInterpSection() {
return !SharedFiles.empty() && !Config->DynamicLinker.empty() &&
Script->needsInterpSection();
return !Config->DynamicLinker.empty() && Script->needsInterpSection();
}
template <class ELFT> void elf::writeResult() { Writer<ELFT>().run(); }

16
lld/test/ELF/dynamic-linker.s
View File

@ -1,21 +1,19 @@
# 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
# RUN: llvm-readelf -program-headers %t | FileCheck %s
# RUN: ld.lld --dynamic-linker foo %t.o -o %t
# RUN: llvm-readelf --program-headers %t | FileCheck %s
# RUN: ld.lld --dynamic-linker=foo %t.o %t.so -o %t
# RUN: llvm-readelf -program-headers %t | FileCheck %s
# RUN: ld.lld --dynamic-linker=foo %t.o -o %t
# RUN: llvm-readelf --program-headers %t | FileCheck %s
# 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