Add function to DWARFContext to get all line addresses

[sque-google]

Summary

Get all addresses that appear in the line tables of all compile units within the DWARF context.

[probinson]

We generally don't want to introduce unused code. What is the use-case for this API?

[probinson]

Seems like there should be an in-tree unit test, if it's not super complicated. Up to Eric though.

[echristo]

I think this is going to turn out to be not necessary yes Simon?

[sque-google]

Yeah it seems that way. I'll close this once I make the internal changes to verify that this is no longer needed.

include/llvm/DebugInfo/DWARF/DWARFContext.h

 #include "llvm/DebugInfo/DWARF/DWARFTypeUnit.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnit.h"
 #include "llvm/DebugInfo/DWARF/DWARFUnitIndex.h"
 #include "llvm/Object/ObjectFile.h"
 #include <cstdint>
 #include <deque>
 #include <map>
 #include <memory>
+#include <set>
 #include <utility>
 
 namespace llvm {
 
 // In place of applying the relocations to the data we've read from disk we use
 // a separate mapping table to the side and checking that at locations in the
 // dwarf where we expect relocated values. This adds a bit of complexity to the
 // dwarf parsing/extraction at the benefit of not allocating memory for the
public:
   const DWARFDebugFrame *getEHFrame();
 
   /// Get a pointer to the parsed DebugMacro object.
   const DWARFDebugMacro *getDebugMacro();
 
   /// Get a pointer to a parsed line table corresponding to a compile unit.
   const DWARFDebugLine::LineTable *getLineTableForUnit(DWARFUnit *cu);
 
+  /// Get a set of all addresses that appear in the line tables of the compile
+  /// units in this DWARF context.
+  std::set<uint64_t> getAllLineAddresses();
+
   DILineInfo getLineInfoForAddress(uint64_t Address,
       DILineInfoSpecifier Specifier = DILineInfoSpecifier()) override;
   DILineInfoTable getLineInfoForAddressRange(uint64_t Address, uint64_t Size,
       DILineInfoSpecifier Specifier = DILineInfoSpecifier()) override;
   DIInliningInfo getInliningInfoForAddress(uint64_t Address,
       DILineInfoSpecifier Specifier = DILineInfoSpecifier()) override;
 
   virtual bool isLittleEndian() const = 0;

lib/DebugInfo/DWARF/DWARFContext.cpp

if (const DWARFLineTable *lt = Line->getLineTable(stmtOffset))
     return lt;
 
   // We have to parse it first.
   DataExtractor lineData(U->getLineSection(), isLittleEndian(),
                          U->getAddressByteSize());
   return Line->getOrParseLineTable(lineData, stmtOffset);
 }
 
+std::set<uint64_t> DWARFContext::getAllLineAddresses() {
+  parseCompileUnits();
+
+  std::set<uint64_t> Result;
+  for (const auto &CU : CUs) {
+    const DWARFLineTable* table = getLineTableForUnit(CU.get());
+    for (const DWARFDebugLine::Row &row : table->Rows) {
+      Result.insert(row.Address);
+    }
+  }
+  return Result;
+}
+
 void DWARFContext::parseCompileUnits() {
   CUs.parse(*this, getInfoSection());
 }
 
 void DWARFContext::parseTypeUnits() {
   if (!TUs.empty())
     return;
   for (const auto &I : getTypesSections()) {