Use MapVector to fix lld thinLTO bep issue.

When the ModuleSymbolTable is generated, the
binary consistency problem occurs due to the
unorder of the data structure when collecting
asm symbols.

Author: llvmssh

llvm/lib/Object/ModuleSymbolTable.cpp

@@ -144,7 +144,7 @@ void ModuleSymbolTable::CollectAsmSymbols(
     Streamer.flushSymverDirectives();
 
     for (auto &KV : Streamer) {
-      StringRef Key = KV.first();
+      StringRef Key = KV.first;
       RecordStreamer::State Value = KV.second;
       // FIXME: For now we just assume that all asm symbols are executable.
       uint32_t Res = BasicSymbolRef::SF_Executable;

llvm/lib/Object/RecordStreamer.h

@@ -14,6 +14,7 @@
 #include "llvm/MC/MCDirectives.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/Support/SMLoc.h"
+#include "llvm/ADT/MapVector.h"
 #include <vector>
 
 namespace llvm {
@@ -28,11 +29,11 @@ class RecordStreamer : public MCStreamer {
 
 private:
   const Module &M;
-  StringMap<State> Symbols;
+  MapVector<StringRef, State> Symbols;
   // Map of aliases created by .symver directives, saved so we can update
   // their symbol binding after parsing complete. This maps from each
   // aliasee to its list of aliases.
-  DenseMap<const MCSymbol *, std::vector<StringRef>> SymverAliasMap;
+  MapVector<const MCSymbol *, std::vector<StringRef>> SymverAliasMap;
 
   /// Get the state recorded for the given symbol.
   State getSymbolState(const MCSymbol *Sym);
@@ -70,7 +71,7 @@ class RecordStreamer : public MCStreamer {
   void flushSymverDirectives();
 
   // Symbols iterators
-  using const_iterator = StringMap<State>::const_iterator;
+  using const_iterator = MapVector<StringRef, State>::const_iterator;
   const_iterator begin();
   const_iterator end();