reland: [Demangle] make llvm::demangle take std::string_view rather than const std::string&

As suggested by @erichkeane in
https://reviews.llvm.org/D141451#inline-1429549

There's potential for a lot more cleanups around these APIs. This is
just a start.

Callers need to be more careful about sub-expressions producing strings
that don't outlast the expression using `llvm::demangle`. Add a
release note.

Differential Revision: https://reviews.llvm.org/D149104

1 files changed, 6 insertions, 12 deletions

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 4267ce6..7b6edb3 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -1545,7 +1545,7 @@ static void disassembleObject(const Target *TheTarget, ObjectFile &Obj,
       if (Demangle) {
         // Fetch the demangled names and store them locally.
         for (const SymbolInfoTy &Symbol : SymbolsHere)
-          DemangledSymNamesHere.push_back(demangle(Symbol.Name.str()));
+          DemangledSymNamesHere.push_back(demangle(Symbol.Name));
         // Now we've finished modifying that vector, it's safe to make
         // a vector of StringRefs pointing into it.
         SymNamesHere.insert(SymNamesHere.begin(), DemangledSymNamesHere.begin(),
@@ -1906,9 +1906,8 @@ static void disassembleObject(const Target *TheTarget, ObjectFile &Obj,
               if (TargetSym != nullptr) {
                 uint64_t TargetAddress = TargetSym->Addr;
                 uint64_t Disp = Target - TargetAddress;
-                std::string TargetName = TargetSym->Name.str();
-                if (Demangle)
-                  TargetName = demangle(TargetName);
+                std::string TargetName = Demangle ? demangle(TargetSym->Name)
+                                                  : TargetSym->Name.str();
 
                 *TargetOS << " <";
                 if (!Disp) {
@@ -2508,10 +2507,8 @@ void objdump::printSymbol(const ObjectFile &O, const SymbolRef &Symbol,
 
         if (NameOrErr) {
           outs() << " (csect:";
-          std::string SymName(NameOrErr.get());
-
-          if (Demangle)
-            SymName = demangle(SymName);
+          std::string SymName =
+              Demangle ? demangle(*NameOrErr) : NameOrErr->str();
 
           if (SymbolDescription)
             SymName = getXCOFFSymbolDescription(createSymbolInfo(O, *SymRef),
@@ -2565,10 +2562,7 @@ void objdump::printSymbol(const ObjectFile &O, const SymbolRef &Symbol,
     outs() << " .hidden";
   }
 
-  std::string SymName(Name);
-  if (Demangle)
-    SymName = demangle(SymName);
-
+  std::string SymName = Demangle ? demangle(Name) : Name.str();
   if (O.isXCOFF() && SymbolDescription)
     SymName = getXCOFFSymbolDescription(createSymbolInfo(O, Symbol), SymName);