llvm-symbolizer: Add a FRAME command.

This command prints a description of the referenced function's stack frame.
For each formal parameter and local variable, the tool prints:

- function name
- variable name
- file/line of declaration
- FP-relative variable location (if available)
- size in bytes
- HWASAN tag offset

This information will be used by the HWASAN runtime to identify local
variables in UAR reports.

Differential Revision: https://reviews.llvm.org/D63468

llvm-svn: 364225
diff --git a/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp b/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
index 1bfd4e8..1cb8a7a 100644
--- a/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
+++ b/llvm/lib/DebugInfo/Symbolize/Symbolize.cpp
@@ -133,6 +133,29 @@
   return Global;
 }
 
+Expected<std::vector<DILocal>>
+LLVMSymbolizer::symbolizeFrame(const std::string &ModuleName,
+                               object::SectionedAddress ModuleOffset) {
+  SymbolizableModule *Info;
+  if (auto InfoOrErr = getOrCreateModuleInfo(ModuleName))
+    Info = InfoOrErr.get();
+  else
+    return InfoOrErr.takeError();
+
+  // A null module means an error has already been reported. Return an empty
+  // result.
+  if (!Info)
+    return std::vector<DILocal>();
+
+  // If the user is giving us relative addresses, add the preferred base of
+  // the object to the offset before we do the query. It's what DIContext
+  // expects.
+  if (Opts.RelativeAddresses)
+    ModuleOffset.Address += Info->getModulePreferredBase();
+
+  return Info->symbolizeFrame(ModuleOffset);
+}
+
 void LLVMSymbolizer::flush() {
   ObjectForUBPathAndArch.clear();
   BinaryForPath.clear();