llvm-dwarfdump: Add support for dumping the .debug_loc section

This is a basic implementation - we still don't have any support (that I
know of) for dumping DWARF expressions in a meaningful way, so the
location information itself is just printed as a sequence of bytes as we
do elsewhere.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184361 91177308-0d34-0410-b5e6-96231b3b80d8

lib/DebugInfo/DWARFDebugLoc.cpp

@@ -0,0 +1,74 @@
+//===-- DWARFDebugLoc.cpp -------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFDebugLoc.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+void DWARFDebugLoc::dump(raw_ostream &OS) const {
+  for (LocationLists::const_iterator I = Locations.begin(), E = Locations.end(); I != E; ++I) {
+    OS << format("0x%8.8x: ", I->Offset);
+    const unsigned Indent = 12;
+    for (SmallVectorImpl<Entry>::const_iterator I2 = I->Entries.begin(), E2 = I->Entries.end(); I2 != E2; ++I2) {
+      if (I2 != I->Entries.begin())
+        OS.indent(Indent);
+      OS << "Begining address offset: " << format("0x%016" PRIx64, I2->Begin)
+         << '\n';
+      OS.indent(Indent) << "  Ending address offset: "
+                        << format("0x%016" PRIx64, I2->End) << '\n';
+      OS.indent(Indent) << "   Location description: ";
+      for (SmallVectorImpl<unsigned char>::const_iterator I3 = I2->Loc.begin(), E3 = I2->Loc.end(); I3 != E3; ++I3) {
+        OS << format("%2.2x ", *I3);
+      }
+      OS << "\n\n";
+    }
+  }
+}
+
+void DWARFDebugLoc::parse(DataExtractor data, unsigned AddressSize) {
+  uint32_t Offset = 0;
+  while (data.isValidOffset(Offset)) {
+    Locations.resize(Locations.size() + 1);
+    LocationList &Loc = Locations.back();
+    Loc.Offset = Offset;
+    // 2.6.2 Location Lists
+    // A location list entry consists of:
+    while (true) {
+      Entry E;
+      RelocAddrMap::const_iterator AI = RelocMap.find(Offset);
+      // 1. A beginning address offset. ...
+      E.Begin = data.getUnsigned(&Offset, AddressSize);
+      if (AI != RelocMap.end())
+        E.Begin += AI->second.second;
+
+      AI = RelocMap.find(Offset);
+      // 2. An ending address offset. ...
+      E.End = data.getUnsigned(&Offset, AddressSize);
+      if (AI != RelocMap.end())
+        E.End += AI->second.second;
+
+      // The end of any given location list is marked by an end of list entry,
+      // which consists of a 0 for the beginning address offset and a 0 for the
+      // ending address offset.
+      if (E.Begin == 0 && E.End == 0)
+        break;
+
+      unsigned Bytes = data.getU16(&Offset);
+      // A single location description describing the location of the object...
+      StringRef str = data.getData().substr(Offset, Bytes);
+      Offset += Bytes;
+      E.Loc.reserve(str.size());
+      std::copy(str.begin(), str.end(), std::back_inserter(E.Loc));
+      Loc.Entries.push_back(llvm_move(E));
+    }
+  }
+}