Add basic support for .debug_ranges section to LLVM's DebugInfo library.

This section (introduced in DWARF-3) is used to define instruction address
ranges for functions that are not contiguous and can't be described
by low_pc/high_pc attributes (this is the usual case for inlined subroutines).
The patch is the first step to support fetching complete inlining info from DWARF.

Reviewed by Benjamin Kramer.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162657 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 58 insertions, 0 deletions

diff --git a/lib/DebugInfo/DWARFDebugRangeList.cpp b/lib/DebugInfo/DWARFDebugRangeList.cpp
new file mode 100644
index 0000000000..10f51b4aa0
--- /dev/null
+++ b/lib/DebugInfo/DWARFDebugRangeList.cpp
@@ -0,0 +1,58 @@
+//===-- DWARFDebugRangesList.cpp ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "DWARFDebugRangeList.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+void DWARFDebugRangeList::clear() {
+  Offset = -1U;
+  AddressSize = 0;
+  Entries.clear();
+}
+
+bool DWARFDebugRangeList::extract(DataExtractor data, uint32_t *offset_ptr) {
+  clear();
+  if (!data.isValidOffset(*offset_ptr))
+    return false;
+  AddressSize = data.getAddressSize();
+  if (AddressSize != 4 && AddressSize != 8)
+    return false;
+  Offset = *offset_ptr;
+  while (true) {
+    RangeListEntry entry;
+    uint32_t prev_offset = *offset_ptr;
+    entry.StartAddress = data.getAddress(offset_ptr);
+    entry.EndAddress = data.getAddress(offset_ptr);
+    // Check that both values were extracted correctly.
+    if (*offset_ptr != prev_offset + 2 * AddressSize) {
+      clear();
+      return false;
+    }
+    // The end of any given range 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 (entry.StartAddress == 0 && entry.EndAddress == 0)
+      break;
+    Entries.push_back(entry);
+  }
+  return true;
+}
+
+void DWARFDebugRangeList::dump(raw_ostream &OS) const {
+  for (int i = 0, n = Entries.size(); i != n; ++i) {
+    const char *format_str = (AddressSize == 4) ? "%08x %08x %08x\n"
+                                                : "%08x %016x %016x\n";
+    OS << format(format_str, Offset, Entries[i].StartAddress,
+                                     Entries[i].EndAddress);
+  }
+  OS << format("%08x <End of list>\n", Offset);
+}