[DWARF parser] Teach DIContext to fetch short (non-linkage) function names for a given address.

Change --functions option in llvm-symbolizer tool to accept
values "none", "short" or "linkage". Update the tests and docs
accordingly.

llvm-svn: 209050
diff --git a/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp b/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
index 7018ebe..3e71111 100644
--- a/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
+++ b/llvm/tools/llvm-symbolizer/LLVMSymbolize.cpp
@@ -39,8 +39,7 @@
 getDILineInfoSpecifier(const LLVMSymbolizer::Options &Opts) {
   return DILineInfoSpecifier(
       DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath,
-      Opts.PrintFunctions ? DILineInfoSpecifier::FunctionNameKind::LinkageName
-                          : DILineInfoSpecifier::FunctionNameKind::None);
+      Opts.PrintFunctions);
 }
 
 ModuleInfo::ModuleInfo(ObjectFile *Obj, DIContext *DICtx)
@@ -117,7 +116,7 @@
         ModuleOffset, getDILineInfoSpecifier(Opts));
   }
   // Override function name from symbol table if necessary.
-  if (Opts.PrintFunctions && Opts.UseSymbolTable) {
+  if (Opts.PrintFunctions != FunctionNameKind::None && Opts.UseSymbolTable) {
     std::string FunctionName;
     uint64_t Start, Size;
     if (getNameFromSymbolTable(SymbolRef::ST_Function, ModuleOffset,
@@ -140,7 +139,7 @@
     InlinedContext.addFrame(DILineInfo());
   }
   // Override the function name in lower frame with name from symbol table.
-  if (Opts.PrintFunctions && Opts.UseSymbolTable) {
+  if (Opts.PrintFunctions != FunctionNameKind::None && Opts.UseSymbolTable) {
     DIInliningInfo PatchedInlinedContext;
     for (uint32_t i = 0, n = InlinedContext.getNumberOfFrames(); i < n; i++) {
       DILineInfo LineInfo = InlinedContext.getFrame(i);
@@ -398,7 +397,7 @@
   // cannot fetch. We replace it to "??" to make our output closer to addr2line.
   static const std::string kDILineInfoBadString = "<invalid>";
   std::stringstream Result;
-  if (Opts.PrintFunctions) {
+  if (Opts.PrintFunctions != FunctionNameKind::None) {
     std::string FunctionName = LineInfo.FunctionName;
     if (FunctionName == kDILineInfoBadString)
       FunctionName = kBadString;