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

[Fangrui Song via Phabricator via llvm-commits]

MaskRay created this revision.
MaskRay added a reviewer: ruiu.
Herald added subscribers: llvm-commits, arichardson, emaste.
Herald added a reviewer: espindola.

bfd/gold emit DF_TEXTREL/DT_TEXTREL only when text relocations are really needed.


Repository:
  rLLD LLVM Linker

https://reviews.llvm.org/D46544

Files:
  ELF/Config.h
  ELF/Relocations.cpp
  ELF/SyntheticSections.cpp


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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