[PATCH] D43920: Set DF_TEXTREL instead of creating an empty DT_TEXTREL.

[Rui Ueyama via Phabricator via llvm-commits]

ruiu created this revision.
ruiu added a reviewer: rafael.
Herald added subscribers: arichardson, emaste.

Generic ABI as of 2000 [1] mentioned that "Its [DT_TEXTREL's] use
has been superseded by the DF_TEXTREL flag". We currently create only
DT_TEXTREL and don't set the DF_TEXTREL flag.

This patch is to let the linker to set the flag instead of creating
a DT_TEXTREL marker segment.

With this patch, lld no longer emits DT_TEXTREL. I believe that's not
an issue because it is a very old option and text relocation is rare.
If you want to keep it, we can set both DT_TEXTREL and DF_TEXTREL though.
But I'm not comfortable with supporting only the old way.

[1] http://www.sco.com/developers/gabi/2000-07-17/ch5.dynamic.html


https://reviews.llvm.org/D43920

Files:
  lld/ELF/SyntheticSections.cpp
  lld/test/ELF/Inputs/ztext-text-notext.s
  lld/test/ELF/Inputs/ztext.s
  lld/test/ELF/ztext-text-notext.s
  lld/test/ELF/ztext.s


Index: lld/test/ELF/ztext.s
===================================================================
--- lld/test/ELF/ztext.s
+++ lld/test/ELF/ztext.s
@@ -1,13 +1,13 @@
 # REQUIRES: x86
 # RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %s -o %t.o
-# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/ztext-text-notext.s -o %t2.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/ztext.s -o %t2.o
 # RUN: ld.lld %t2.o -o %t2.so -shared
 # RUN: ld.lld -z notext %t.o %t2.so -o %t -shared
-# RUN: llvm-readobj  -dynamic-table -r %t | FileCheck %s
+# RUN: llvm-readobj -dynamic-table -r %t | FileCheck %s
 # RUN: ld.lld -z notext %t.o %t2.so -o %t2 -pie
-# RUN: llvm-readobj  -dynamic-table -r %t2 | FileCheck %s
+# RUN: llvm-readobj -dynamic-table -r %t2 | FileCheck %s
 # RUN: ld.lld -z notext %t.o %t2.so -o %t3
-# RUN: llvm-readobj  -dynamic-table -r %t3 | FileCheck --check-prefix=STATIC %s
+# RUN: llvm-readobj -dynamic-table -r %t3 | FileCheck --check-prefix=STATIC %s
 
 # If the preference is to have text relocations, don't create plt of copy relocations.
 
@@ -19,16 +19,16 @@
 # CHECK-NEXT:    }
 # CHECK-NEXT:  ]
 # CHECK: DynamicSection [
-# CHECK: 0x0000000000000016 TEXTREL 0x0
+# CHECK: FLAGS TEXTREL
 
 # STATIC:      Relocations [
 # STATIC-NEXT:    Section {{.*}} .rela.dyn {
 # STATIC-NEXT:      0x201008 R_X86_64_64 bar 0x0
 # STATIC-NEXT:      0x201010 R_X86_64_PC64 zed 0x0
 # STATIC-NEXT:    }
 # STATIC-NEXT:  ]
 # STATIC: DynamicSection [
-# STATIC: 0x0000000000000016 TEXTREL 0x0
+# STATIC: FLAGS TEXTREL
 
 foo:
 .quad foo
Index: lld/test/ELF/Inputs/ztext-text-notext.s
===================================================================
--- /dev/null
+++ lld/test/ELF/Inputs/ztext-text-notext.s
@@ -1,10 +0,0 @@
-        .global bar
-        .type bar, @object
-        .size bar, 8
-bar:
-        .quad 0
-
-        .global zed
-        .type zed, @function
-zed:
-        nop
Index: lld/ELF/SyntheticSections.cpp
===================================================================
--- lld/ELF/SyntheticSections.cpp
+++ lld/ELF/SyntheticSections.cpp
@@ -1046,6 +1046,8 @@
     DtFlags |= DF_ORIGIN;
     DtFlags1 |= DF_1_ORIGIN;
   }
+  if (!Config->ZText)
+    DtFlags |= DF_TEXTREL;
 
   if (DtFlags)
     addInt(DT_FLAGS, DtFlags);
@@ -1108,8 +1110,6 @@
   addInt(DT_SYMENT, sizeof(Elf_Sym));
   addInSec(DT_STRTAB, InX::DynStrTab);
   addInt(DT_STRSZ, InX::DynStrTab->getSize());
-  if (!Config->ZText)
-    addInt(DT_TEXTREL, 0);
   if (InX::GnuHashTab)
     addInSec(DT_GNU_HASH, InX::GnuHashTab);
   if (InX::HashTab)


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