[Symbolize] Keep SymbolDescs with the same address and improve getNam…

…eFromSymbolTable heuristic

I'll follow up with better heuristics or tests.

llvm-svn: 357683

llvm/lib/DebugInfo/Symbolize/SymbolizableObjectFile.cpp

@@ -198,7 +198,10 @@ bool SymbolizableObjectFile::getNameFromSymbolTable(SymbolRef::Type Type,
   const auto &SymbolMap = Type == SymbolRef::ST_Function ? Functions : Objects;
   if (SymbolMap.empty())
     return false;
-  SymbolDesc SD = { Address, Address };
+  SymbolDesc SD = {Address, UINT64_C(-1)};
+  // SymbolDescs are sorted by (Addr,Size), if several SymbolDescs share the
+  // same Addr, pick the one with the largest Size. This helps us avoid symbols
+  // with no size information (Size=0).
   auto SymbolIterator = SymbolMap.upper_bound(SD);
   if (SymbolIterator == SymbolMap.begin())
     return false;

llvm/lib/DebugInfo/Symbolize/SymbolizableObjectFile.h

@@ -75,8 +75,8 @@ class SymbolizableObjectFile : public SymbolizableModule {
     // the following symbol.
     uint64_t Size;
 
-    friend bool operator<(const SymbolDesc &s1, const SymbolDesc &s2) {
-      return s1.Addr < s2.Addr;
+    bool operator<(const SymbolDesc &RHS) const {
+      return Addr != RHS.Addr ? Addr < RHS.Addr : Size < RHS.Size;
     }
   };
   std::map<SymbolDesc, StringRef> Functions;