[DWARF parser] Use distinction between DW_AT_ranges_base and DW_AT_GNU_ranges_base instead of DWARF version

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210945 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 17 insertions, 8 deletions

diff --git a/lib/DebugInfo/DWARFDebugInfoEntry.cpp b/lib/DebugInfo/DWARFDebugInfoEntry.cpp
index b811ed7064..2e7a54aeb8 100644
--- a/lib/DebugInfo/DWARFDebugInfoEntry.cpp
+++ b/lib/DebugInfo/DWARFDebugInfoEntry.cpp
@@ -210,6 +210,16 @@ uint64_t DWARFDebugInfoEntryMinimal::getAttributeValueAsSectionOffset(
   return Result.hasValue() ? Result.getValue() : FailValue;
 }
 
+uint64_t
+DWARFDebugInfoEntryMinimal::getRangesBaseAttribute(const DWARFUnit *U,
+                                                   uint64_t FailValue) const {
+  uint64_t Result =
+      getAttributeValueAsSectionOffset(U, DW_AT_ranges_base, -1ULL);
+  if (Result != -1ULL)
+    return Result;
+  return getAttributeValueAsSectionOffset(U, DW_AT_GNU_ranges_base, FailValue);
+}
+
 bool DWARFDebugInfoEntryMinimal::getLowAndHighPC(const DWARFUnit *U,
                                                  uint64_t &LowPC,
                                                  uint64_t &HighPC) const {
diff --git a/lib/DebugInfo/DWARFDebugInfoEntry.h b/lib/DebugInfo/DWARFDebugInfoEntry.h
index 916e1ed340..cc58eb652a 100644
--- a/lib/DebugInfo/DWARFDebugInfoEntry.h
+++ b/lib/DebugInfo/DWARFDebugInfoEntry.h
@@ -106,6 +106,8 @@ public:
                                             const uint16_t Attr,
                                             uint64_t FailValue) const;
 
+  uint64_t getRangesBaseAttribute(const DWARFUnit *U, uint64_t FailValue) const;
+
   /// Retrieves DW_AT_low_pc and DW_AT_high_pc from CU.
   /// Returns true if both attributes are present.
   bool getLowAndHighPC(const DWARFUnit *U, uint64_t &LowPC,
diff --git a/lib/DebugInfo/DWARFUnit.cpp b/lib/DebugInfo/DWARFUnit.cpp
index 027827735c..39d0a0ff5a 100644
--- a/lib/DebugInfo/DWARFUnit.cpp
+++ b/lib/DebugInfo/DWARFUnit.cpp
@@ -225,12 +225,10 @@ size_t DWARFUnit::extractDIEsIfNeeded(bool CUDieOnly) {
     setBaseAddress(BaseAddr);
     AddrOffsetSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
         this, DW_AT_GNU_addr_base, 0);
-    // Users of old DWARF may not know about DW_AT_ranges_base, so it is ignored
-    // for skeleton CU DIE (e.g. DW_AT_ranges are *not* relative to it).
-    if (Version > 4) {
-      RangeSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
-          this, DW_AT_GNU_ranges_base, 0);
-    }
+    RangeSectionBase = DieArray[0].getAttributeValueAsSectionOffset(
+        this, DW_AT_ranges_base, 0);
+    // Don't fall back to DW_AT_GNU_ranges_base: it should be ignored for
+    // skeleton CU DIE, so that DWARF users not aware of it are not broken.
   }
 
   setDIERelations();
@@ -276,8 +274,7 @@ bool DWARFUnit::parseDWO() {
   }
   // Share .debug_addr and .debug_ranges section with compile unit in .dwo
   DWOCU->setAddrOffsetSection(AddrOffsetSection, AddrOffsetSectionBase);
-  uint32_t DWORangesBase = DieArray[0].getAttributeValueAsSectionOffset(
-      this, DW_AT_GNU_ranges_base, 0);
+  uint32_t DWORangesBase = DieArray[0].getRangesBaseAttribute(this, 0);
   DWOCU->setRangesSection(RangeSection, DWORangesBase);
   return true;
 }