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

[Fangrui Song via llvm-commits]

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
 
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