[PATCH] D46544: Set DF_TEXTREL only if text relocations are really needed.

[Fangrui Song via Phabricator via llvm-commits]

MaskRay updated this revision to Diff 145525.
MaskRay added a comment.

Update test


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D46544

Files:
  ELF/Config.h
  ELF/Relocations.cpp
  ELF/SyntheticSections.cpp
  test/ELF/ztext.s


Index: test/ELF/ztext.s
===================================================================
--- test/ELF/ztext.s
+++ test/ELF/ztext.s
@@ -1,7 +1,9 @@
 # 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.s -o %t2.o
-# RUN: ld.lld %t2.o -o %t2.so -shared
+# RUN: ld.lld -z notext %t2.o -o %t2.so -shared
+
+# RUN: llvm-readobj -dynamic-table %t2.so | FileCheck --check-prefix=UNNECESSARY %s
 
 # RUN: ld.lld -z notext %t.o %t2.so -o %t -shared
 # RUN: llvm-readobj  -dynamic-table -r %t | FileCheck %s
@@ -16,6 +18,8 @@
 
 # If the preference is to have text relocations, don't create plt of copy relocations.
 
+# UNNECESSARY-NOT: TEXTREL
+
 # CHECK:      Relocations [
 # CHECK-NEXT:   Section {{.*}} .rela.dyn {
 # CHECK-NEXT:     0x1000 R_X86_64_RELATIVE - 0x1000
Index: ELF/SyntheticSections.cpp
===================================================================
--- ELF/SyntheticSections.cpp
+++ ELF/SyntheticSections.cpp
@@ -1061,7 +1061,7 @@
     DtFlags |= DF_ORIGIN;
     DtFlags1 |= DF_1_ORIGIN;
   }
-  if (!Config->ZText)
+  if (!Config->ZText && Config->NeedTextRel)
     DtFlags |= DF_TEXTREL;
 
   if (DtFlags)
@@ -1125,7 +1125,7 @@
   addInt(DT_SYMENT, sizeof(Elf_Sym));
   addInSec(DT_STRTAB, InX::DynStrTab);
   addInt(DT_STRSZ, InX::DynStrTab->getSize());
-  if (!Config->ZText)
+  if (DtFlags & DF_TEXTREL)
     addInt(DT_TEXTREL, 0);
   if (InX::GnuHashTab)
     addInSec(DT_GNU_HASH, InX::GnuHashTab);
Index: ELF/Relocations.cpp
===================================================================
--- ELF/Relocations.cpp
+++ ELF/Relocations.cpp
@@ -788,6 +788,9 @@
   }
   bool CanWrite = (Sec.Flags & SHF_WRITE) || !Config->ZText;
   if (CanWrite) {
+    if (!(Sec.Flags & SHF_WRITE))
+      Config->NeedTextRel = true;
+
     // R_GOT refers to a position in the got, even if the symbol is preemptible.
     bool IsPreemptibleValue = Sym.IsPreemptible && Expr != R_GOT;
 
Index: ELF/Config.h
===================================================================
--- ELF/Config.h
+++ ELF/Config.h
@@ -248,6 +248,10 @@
   // True if we are creating position-independent code.
   bool Pic;
 
+  // True if non-writable segments contain dynamic relocs so that we need to
+  // emit DF_TEXTREL.
+  bool NeedTextRel = false;
+
   // 4 for ELF32, 8 for ELF64.
   int Wordsize;
 };


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