1 files changed, 119 insertions, 4 deletions

diff --git a/lib/Object/RecordStreamer.cpp b/lib/Object/RecordStreamer.cpp
index e94e9cfed394..1f57867dd21a 100644
--- a/lib/Object/RecordStreamer.cpp
+++ b/lib/Object/RecordStreamer.cpp
@@ -8,6 +8,9 @@
 //===----------------------------------------------------------------------===//
 
 #include "RecordStreamer.h"
+#include "llvm/IR/Mangler.h"
+#include "llvm/IR/Module.h"
+#include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCSymbol.h"
 
 using namespace llvm;
@@ -70,7 +73,8 @@ void RecordStreamer::markUsed(const MCSymbol &Symbol) {
 
 void RecordStreamer::visitUsedSymbol(const MCSymbol &Sym) { markUsed(Sym); }
 
-RecordStreamer::RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
+RecordStreamer::RecordStreamer(MCContext &Context, const Module &M)
+    : MCStreamer(Context), M(M) {}
 
 RecordStreamer::const_iterator RecordStreamer::begin() {
   return Symbols.begin();
@@ -103,7 +107,8 @@ bool RecordStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
 }
 
 void RecordStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
-                                  uint64_t Size, unsigned ByteAlignment) {
+                                  uint64_t Size, unsigned ByteAlignment,
+                                  SMLoc Loc) {
   markDefined(*Symbol);
 }
 
@@ -112,7 +117,117 @@ void RecordStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
   markDefined(*Symbol);
 }
 
-void RecordStreamer::emitELFSymverDirective(MCSymbol *Alias,
+RecordStreamer::State RecordStreamer::getSymbolState(const MCSymbol *Sym) {
+  auto SI = Symbols.find(Sym->getName());
+  if (SI == Symbols.end())
+    return NeverSeen;
+  return SI->second;
+}
+
+void RecordStreamer::emitELFSymverDirective(StringRef AliasName,
                                             const MCSymbol *Aliasee) {
-  SymverAliasMap[Aliasee].push_back(Alias);
+  SymverAliasMap[Aliasee].push_back(AliasName);
+}
+
+iterator_range<RecordStreamer::const_symver_iterator>
+RecordStreamer::symverAliases() {
+  return {SymverAliasMap.begin(), SymverAliasMap.end()};
+}
+
+void RecordStreamer::flushSymverDirectives() {
+  // Mapping from mangled name to GV.
+  StringMap<const GlobalValue *> MangledNameMap;
+  // The name in the assembler will be mangled, but the name in the IR
+  // might not, so we first compute a mapping from mangled name to GV.
+  Mangler Mang;
+  SmallString<64> MangledName;
+  for (const GlobalValue &GV : M.global_values()) {
+    if (!GV.hasName())
+      continue;
+    MangledName.clear();
+    MangledName.reserve(GV.getName().size() + 1);
+    Mang.getNameWithPrefix(MangledName, &GV, /*CannotUsePrivateLabel=*/false);
+    MangledNameMap[MangledName] = &GV;
+  }
+
+  // Walk all the recorded .symver aliases, and set up the binding
+  // for each alias.
+  for (auto &Symver : SymverAliasMap) {
+    const MCSymbol *Aliasee = Symver.first;
+    MCSymbolAttr Attr = MCSA_Invalid;
+    bool IsDefined = false;
+
+    // First check if the aliasee binding was recorded in the asm.
+    RecordStreamer::State state = getSymbolState(Aliasee);
+    switch (state) {
+    case RecordStreamer::Global:
+    case RecordStreamer::DefinedGlobal:
+      Attr = MCSA_Global;
+      break;
+    case RecordStreamer::UndefinedWeak:
+    case RecordStreamer::DefinedWeak:
+      Attr = MCSA_Weak;
+      break;
+    default:
+      break;
+    }
+
+    switch (state) {
+    case RecordStreamer::Defined:
+    case RecordStreamer::DefinedGlobal:
+    case RecordStreamer::DefinedWeak:
+      IsDefined = true;
+      break;
+    case RecordStreamer::NeverSeen:
+    case RecordStreamer::Global:
+    case RecordStreamer::Used:
+    case RecordStreamer::UndefinedWeak:
+      break;
+    }
+
+    if (Attr == MCSA_Invalid || !IsDefined) {
+      const GlobalValue *GV = M.getNamedValue(Aliasee->getName());
+      if (!GV) {
+        auto MI = MangledNameMap.find(Aliasee->getName());
+        if (MI != MangledNameMap.end())
+          GV = MI->second;
+      }
+      if (GV) {
+        // If we don't have a symbol attribute from assembly, then check if
+        // the aliasee was defined in the IR.
+        if (Attr == MCSA_Invalid) {
+          if (GV->hasExternalLinkage())
+            Attr = MCSA_Global;
+          else if (GV->hasLocalLinkage())
+            Attr = MCSA_Local;
+          else if (GV->isWeakForLinker())
+            Attr = MCSA_Weak;
+        }
+        IsDefined = IsDefined || !GV->isDeclarationForLinker();
+      }
+    }
+
+    // Set the detected binding on each alias with this aliasee.
+    for (auto AliasName : Symver.second) {
+      std::pair<StringRef, StringRef> Split = AliasName.split("@@@");
+      SmallString<128> NewName;
+      if (!Split.second.empty() && !Split.second.startswith("@")) {
+        // Special processing for "@@@" according
+        // https://sourceware.org/binutils/docs/as/Symver.html
+        const char *Separator = IsDefined ? "@@" : "@";
+        AliasName =
+            (Split.first + Separator + Split.second).toStringRef(NewName);
+      }
+      MCSymbol *Alias = getContext().getOrCreateSymbol(AliasName);
+      // TODO: Handle "@@@". Depending on SymbolAttribute value it needs to be
+      // converted into @ or @@.
+      const MCExpr *Value = MCSymbolRefExpr::create(Aliasee, getContext());
+      if (IsDefined)
+        markDefined(*Alias);
+      // Don't use EmitAssignment override as it always marks alias as defined.
+      MCStreamer::EmitAssignment(Alias, Value);
+      if (Attr != MCSA_Invalid)
+        EmitSymbolAttribute(Alias, Attr);
+    }
+  }
 }