[llvm] [BOLT][DWARF] Refactor updateDWARFObjectAddressRanges (PR #96006)

[Alexander Yermolovich via llvm-commits]

================
@@ -2278,42 +2310,34 @@ void DWARFRewriter::convertToRangesPatchDebugInfo(
                    Die.getTag() == dwarf::DW_TAG_skeleton_unit;
   if (!IsUnitDie)
     DIEBldr.deleteValue(&Die, LowPCAttrInfo.getAttribute());
-  // In DWARF4 for DW_AT_low_pc in binary DW_FORM_addr is used. In the DWO
-  // section DW_FORM_GNU_addr_index is used. So for if we are converting
-  // DW_AT_low_pc/DW_AT_high_pc and see DW_FORM_GNU_addr_index. We are
-  // converting in DWO section, and DW_AT_ranges [DW_FORM_sec_offset] is
-  // relative to DW_AT_GNU_ranges_base.
-  if (LowForm == dwarf::DW_FORM_GNU_addr_index) {
-    // Ranges are relative to DW_AT_GNU_ranges_base.
-    uint64_t CurRangeBase = 0;
-    if (std::optional<uint64_t> DWOId = Unit.getDWOId()) {
-      CurRangeBase = getDwoRangesBase(*DWOId);
-    }
-    BaseOffset = CurRangeBase;
-  } else {
-    // In DWARF 5 we can have DW_AT_low_pc either as DW_FORM_addr, or
-    // DW_FORM_addrx. Former is when DW_AT_rnglists_base is present. Latter is
-    // when it's absent.
-    if (IsUnitDie) {
-      if (LowForm == dwarf::DW_FORM_addrx) {
-        const uint32_t Index = AddrWriter->getIndexFromAddress(0, Unit);
-        DIEBldr.replaceValue(&Die, LowPCAttrInfo.getAttribute(),
-                             LowPCAttrInfo.getForm(), DIEInteger(Index));
-      } else {
-        DIEBldr.replaceValue(&Die, LowPCAttrInfo.getAttribute(),
-                             LowPCAttrInfo.getForm(), DIEInteger(0));
-      }
+
+  // In DWARF 5 we can have DW_AT_low_pc either as DW_FORM_addr, or
+  // DW_FORM_addrx. Former is when DW_AT_rnglists_base is present. Latter is
+  // when it's absent.
+  if (IsUnitDie) {
+    if (LowForm == dwarf::DW_FORM_addrx) {
+      const uint32_t Index = AddrWriter->getIndexFromAddress(0, Unit);
+      DIEBldr.replaceValue(&Die, LowPCAttrInfo.getAttribute(),
+                           LowPCAttrInfo.getForm(), DIEInteger(Index));
+    } else {
+      DIEBldr.replaceValue(&Die, LowPCAttrInfo.getAttribute(),
+                           LowPCAttrInfo.getForm(), DIEInteger(0));
     }
-    // Original CU didn't have DW_AT_*_base. We converted it's children (or
-    // dwo), so need to insert it into CU.
-    if (RangesBase)
+  }
+  // Original CU didn't have DW_AT_*_base. We converted it's children (or
+  // dwo), so need to insert it into CU.
+  if (RangesBase) {
+    if (Unit.getVersion() >= 5) {
       DIEBldr.addValue(&Die, RangeBaseAttribute, dwarf::DW_FORM_sec_offset,
                        DIEInteger(*RangesBase));
+    } else {
+      DIEBldr.addValue(&Die, RangeBaseAttribute, dwarf::DW_FORM_sec_offset,
+                       DIEInteger(INT_MAX));
+      UpdatedDIEsByDWO[*Unit.getDWOId()] = &Die;
+    }
   }
 
-  uint64_t RangeAttrVal = RangesSectionOffset - BaseOffset;
-  if (Unit.getVersion() >= 5)
-    RangeAttrVal = RangesSectionOffset;
+  uint64_t RangeAttrVal = RangesSectionOffset;
----------------
ayermolo wrote:

can just use RangesSectionOffset directly

https://github.com/llvm/llvm-project/pull/96006