3 files changed, 19 insertions, 3 deletions
diff --git a/lld/ELF/InputFiles.cpp b/lld/ELF/InputFiles.cpp
index 71d7a585583..bccbddf5058 100644
--- a/lld/ELF/InputFiles.cpp
+++ b/lld/ELF/InputFiles.cpp
@@ -12,6 +12,7 @@
 #include "InputSection.h"
 #include "Symbols.h"
 #include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/Analysis.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Object/IRObjectFile.h"
@@ -498,8 +499,11 @@ BitcodeFile::createSymbolBody(const DenseSet<const Comdat *> &KeptComdats,
     Body = new (Alloc) DefinedBitcode(NameRef, IsWeak, Visibility);
   }
   // FIXME: Expose a thread-local flag for module asm symbols.
-  if (GV && GV->isThreadLocal())
-    Body->Type = STT_TLS;
+  if (GV) {
+    if (GV->isThreadLocal())
+      Body->Type = STT_TLS;
+    Body->CanOmitFromDynSym = canBeOmittedFromSymbolTable(GV);
+  }
   return Body;
 }
 
diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp
index 747161efe8b..e6f8842b80d 100644
--- a/lld/ELF/Symbols.cpp
+++ b/lld/ELF/Symbols.cpp
@@ -109,6 +109,7 @@ void SymbolBody::init() {
                        K == DefinedSyntheticKind || K == UndefinedElfKind;
   CanKeepUndefined = false;
   MustBeInDynSym = false;
+  CanOmitFromDynSym = false;
   NeedsCopyOrPltAddr = false;
 }
 
@@ -241,6 +242,9 @@ int SymbolBody::compare(SymbolBody *Other) {
   if (IsUsedInRegularObj || Other->IsUsedInRegularObj)
     IsUsedInRegularObj = Other->IsUsedInRegularObj = true;
 
+  if (!CanOmitFromDynSym || !Other->CanOmitFromDynSym)
+    CanOmitFromDynSym = Other->CanOmitFromDynSym = false;
+
   if (L != R)
     return -1;
   if (!isDefined() || isShared() || isWeak())
@@ -360,7 +364,9 @@ bool SymbolBody::includeInDynsym() const {
   uint8_t V = getVisibility();
   if (V != STV_DEFAULT && V != STV_PROTECTED)
     return false;
-  return Config->ExportDynamic || Config->Shared;
+  if (!Config->ExportDynamic && !Config->Shared)
+    return false;
+  return !CanOmitFromDynSym;
 }
 
 template uint32_t SymbolBody::template getVA<ELF32LE>(uint32_t) const;
diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h
index 11fcdcb5a45..da2ab59a72c 100644
--- a/lld/ELF/Symbols.h
+++ b/lld/ELF/Symbols.h
@@ -147,6 +147,12 @@ protected:
   unsigned IsUsedInRegularObj : 1;
 
 public:
+  // True if this symbol can be omitted from the symbol table if nothing else
+  // requires it to be there. Right now this is only used for linkonce_odr in
+  // LTO, but we could add the feature to ELF. It would be similar to
+  // MachO's .weak_def_can_be_hidden.
+  unsigned CanOmitFromDynSym : 1;
+
   // If true, the symbol is added to .dynsym symbol table.
   unsigned MustBeInDynSym : 1;