Cleanup the handling of MustBeInDynSym and IsUsedInRegularObj.

Now MustBeInDynSym is only true if the symbol really must be in the
dynamic symbol table.

IsUsedInRegularObj is only true if the symbol is used in a .o or -u. Not
a .so or a .bc.

A benefit is that this is now done almost entirilly during symbol
resolution. The only exception is copy relocations because of aliases.

This includes a small fix in that protected symbols in .so don't force
executable symbols to be exported.

This also opens the way for implementing internalize for -shared.

llvm-svn: 265826

7 files changed, 45 insertions, 22 deletions

diff --git a/lld/ELF/LTO.cpp b/lld/ELF/LTO.cpp
index a9196567c4c..2fdf94a6c5f 100644
--- a/lld/ELF/LTO.cpp
+++ b/lld/ELF/LTO.cpp
@@ -116,7 +116,8 @@ void BitcodeCompiler::add(BitcodeFile &F) {
     // Shared libraries need to be handled slightly differently.
     // For now, let's be conservative and just never internalize
     // symbols when creating a shared library.
-    if (!Config->Shared && !Config->ExportDynamic && !B->isUsedInRegularObj())
+    if (!Config->Shared && !Config->ExportDynamic && !B->isUsedInRegularObj() &&
+        !B->MustBeInDynSym)
       if (!Used.count(GV))
         InternalizedSyms.insert(GV->getName());
 
diff --git a/lld/ELF/OutputSections.cpp b/lld/ELF/OutputSections.cpp
index 24258fe40cc..753960447fa 100644
--- a/lld/ELF/OutputSections.cpp
+++ b/lld/ELF/OutputSections.cpp
@@ -138,9 +138,6 @@ template <class ELFT> void GotSection<ELFT>::addEntry(SymbolBody &Sym) {
       ++MipsLocalEntries;
       return;
     }
-    // All preemptible symbols with MIPS GOT entries should be represented
-    // in the dynamic symbols table.
-    Sym.MustBeInDynSym = true;
   }
   Sym.GotIndex = Entries.size();
   Entries.push_back(&Sym);
@@ -299,9 +296,6 @@ RelocationSection<ELFT>::RelocationSection(StringRef Name)
 
 template <class ELFT>
 void RelocationSection<ELFT>::addReloc(const DynamicReloc<ELFT> &Reloc) {
-  SymbolBody *Sym = Reloc.Sym;
-  if (!Reloc.UseSymVA && Sym)
-    Sym->MustBeInDynSym = true;
   Relocs.push_back(Reloc);
 }
 
diff --git a/lld/ELF/SymbolTable.cpp b/lld/ELF/SymbolTable.cpp
index 2348f9a6fb4..c1f01c10da8 100644
--- a/lld/ELF/SymbolTable.cpp
+++ b/lld/ELF/SymbolTable.cpp
@@ -119,10 +119,12 @@ template <class ELFT> void SymbolTable<ELFT>::addCombinedLtoObject() {
   for (SymbolBody *Body : Obj->getNonLocalSymbols()) {
     Symbol *Sym = insert(Body);
     Sym->Body->setUsedInRegularObj();
-    if (!Sym->Body->isUndefined() && Body->isUndefined())
-      continue;
+    if (Sym->Body->isShared())
+      Sym->Body->MustBeInDynSym = true;
     if (Sym->Body->MustBeInDynSym)
       Body->MustBeInDynSym = true;
+    if (!Sym->Body->isUndefined() && Body->isUndefined())
+      continue;
     Sym->Body = Body;
   }
   ObjectFiles.emplace_back(Obj);
diff --git a/lld/ELF/Symbols.cpp b/lld/ELF/Symbols.cpp
index 9def17c6dbb..a0d07690da6 100644
--- a/lld/ELF/Symbols.cpp
+++ b/lld/ELF/Symbols.cpp
@@ -218,6 +218,18 @@ int SymbolBody::compare(SymbolBody *Other) {
   if (L > R)
     return -Other->compare(this);
 
+  if (isShared() != Other->isShared()) {
+    SymbolBody *Shared = isShared() ? this : Other;
+    Shared->MustBeInDynSym = true;
+    if (Shared->getVisibility() == STV_DEFAULT) {
+      // We want to export all symbols that exist in the executable and are
+      // preemptable in DSOs, so that the symbols in the executable can
+      // preempt symbols in the DSO at runtime.
+      SymbolBody *NonShared = isShared() ? Other : this;
+      NonShared->MustBeInDynSym = true;
+    }
+  }
+
   if (!isShared() && !Other->isShared()) {
     uint8_t V = getMinVisibility(getVisibility(), Other->getVisibility());
     setVisibility(V);
@@ -227,15 +239,6 @@ int SymbolBody::compare(SymbolBody *Other) {
   if (IsUsedInRegularObj || Other->IsUsedInRegularObj)
     IsUsedInRegularObj = Other->IsUsedInRegularObj = true;
 
-  // We want to export all symbols that exist both in the executable
-  // and in DSOs, so that the symbols in the executable can interrupt
-  // symbols in the DSO at runtime.
-  if (isShared() != Other->isShared())
-    if (isa<Defined>(isShared() ? Other : this)) {
-      IsUsedInRegularObj = Other->IsUsedInRegularObj = true;
-      MustBeInDynSym = Other->MustBeInDynSym = true;
-    }
-
   if (L != R)
     return -1;
   if (!isDefined() || isShared() || isWeak())
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index b19627e8c03..02627cc9d1f 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -826,12 +826,14 @@ template <class ELFT> static bool includeInSymtab(const SymbolBody &B) {
 }
 
 static bool includeInDynsym(const SymbolBody &B) {
+  if (B.MustBeInDynSym)
+    return true;
   uint8_t V = B.getVisibility();
   if (V != STV_DEFAULT && V != STV_PROTECTED)
     return false;
   if (Config->ExportDynamic || Config->Shared)
     return true;
-  return B.MustBeInDynSym;
+  return false;
 }
 
 // This class knows how to create an output section for a given
diff --git a/lld/test/ELF/mips-dynamic.s b/lld/test/ELF/mips-dynamic.s
index 7dcc247e536..cc5f233163c 100644
--- a/lld/test/ELF/mips-dynamic.s
+++ b/lld/test/ELF/mips-dynamic.s
@@ -47,8 +47,8 @@
 # EXE-DAG:    0x70000005 MIPS_FLAGS           NOTPOT
 # EXE-DAG:    0x70000006 MIPS_BASE_ADDRESS
 # EXE-DAG:    0x7000000A MIPS_LOCAL_GOTNO     2
-# EXE-DAG:    0x70000011 MIPS_SYMTABNO        2
-# EXE-DAG:    0x70000013 MIPS_GOTSYM          0x2
+# EXE-DAG:    0x70000011 MIPS_SYMTABNO        3
+# EXE-DAG:    0x70000013 MIPS_GOTSYM          0x3
 # EXE-DAG:    0x70000016 MIPS_RLD_MAP         [[RLDMAPADDR]]
 # EXE:      ]
 
diff --git a/lld/test/ELF/protected-shared.s b/lld/test/ELF/protected-shared.s
index ee931831b30..e1391a1320f 100644
--- a/lld/test/ELF/protected-shared.s
+++ b/lld/test/ELF/protected-shared.s
@@ -3,7 +3,7 @@
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %p/Inputs/protected-shared.s -o %t2.o
 // RUN: ld.lld -shared %t2.o -o %t2.so
 // RUN: ld.lld %t.o %t2.so -o %t
-// RUN: llvm-readobj -t %t | FileCheck %s
+// RUN: llvm-readobj -t --dyn-symbols %t | FileCheck %s
 
         .global  _start
 _start:
@@ -27,3 +27,24 @@ bar:
 // CHECK-NEXT: Type: None
 // CHECK-NEXT: Other: 0
 // CHECK-NEXT: Section: Undefined
+
+// CHECK:      DynamicSymbols [
+// CHECK-NEXT:   Symbol {
+// CHECK-NEXT:     Name: @
+// CHECK-NEXT:     Value: 0x0
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Local (0x0)
+// CHECK-NEXT:     Type: None (0x0)
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: Undefined (0x0)
+// CHECK-NEXT:   }
+// CHECK-NEXT:   Symbol {
+// CHECK-NEXT:     Name: foo@
+// CHECK-NEXT:     Value: 0x0
+// CHECK-NEXT:     Size: 0
+// CHECK-NEXT:     Binding: Global
+// CHECK-NEXT:     Type: None
+// CHECK-NEXT:     Other: 0
+// CHECK-NEXT:     Section: Undefined
+// CHECK-NEXT:   }
+// CHECK-NEXT: ]