[DWARF parser] Refactor fetching DIE address ranges.

Add a helper method to get address ranges specified in a DIE
(either by DW_AT_low_pc/DW_AT_high_pc, or by DW_AT_ranges). Use it
to untangle and simplify the code.

No functionality change.

llvm-svn: 206624
diff --git a/llvm/lib/DebugInfo/DWARFDebugRangeList.cpp b/llvm/lib/DebugInfo/DWARFDebugRangeList.cpp
index aa2a2be..07b23b3 100644
--- a/llvm/lib/DebugInfo/DWARFDebugRangeList.cpp
+++ b/llvm/lib/DebugInfo/DWARFDebugRangeList.cpp
@@ -54,13 +54,16 @@
   OS << format("%08x <End of list>\n", Offset);
 }
 
-bool DWARFDebugRangeList::containsAddress(uint64_t BaseAddress,
-                                          uint64_t Address) const {
+DWARFAddressRangesVector
+DWARFDebugRangeList::getAbsoluteRanges(uint64_t BaseAddress) const {
+  DWARFAddressRangesVector Res;
   for (const RangeListEntry &RLE : Entries) {
-    if (RLE.isBaseAddressSelectionEntry(AddressSize))
+    if (RLE.isBaseAddressSelectionEntry(AddressSize)) {
       BaseAddress = RLE.EndAddress;
-    else if (RLE.containsAddress(BaseAddress, Address))
-      return true;
+    } else {
+      Res.push_back(std::make_pair(BaseAddress + RLE.StartAddress,
+                                   BaseAddress + RLE.EndAddress));
+    }
   }
-  return false;
+  return Res;
 }