[llvm] [BOLT][DWARF] Refactor legacy ranges writers (PR #96006)

Sayhaan Siddiqui via llvm-commits llvm-commits at lists.llvm.org
Tue Jun 25 09:49:16 PDT 2024


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

>From c13de83600590a63a68abe4ede883eebaa6804a2 Mon Sep 17 00:00:00 2001
From: Sayhaan Siddiqui <sayhaan at meta.com>
Date: Mon, 17 Jun 2024 10:16:44 -0700
Subject: [PATCH 1/5] [BOLT][DWARF][NFC] Refactor
 updateDWARFObjectAddressRanges

Summary:

Test Plan:

Reviewers:

Subscribers:

Tasks:

Tags:

Differential Revision: https://phabricator.intern.facebook.com/D58679290
---
 bolt/include/bolt/Core/DebugData.h            |   2 +
 bolt/include/bolt/Rewrite/DWARFRewriter.h     |   9 ++
 bolt/lib/Core/DebugData.cpp                   |   6 +
 bolt/lib/Rewrite/DWARFRewriter.cpp            | 122 +++++++++++-------
 bolt/test/X86/debug-fission-single-convert.s  |   6 +-
 bolt/test/X86/dwarf4-df-dualcu.test           |  40 +++---
 .../X86/dwarf4-df-input-lowpc-ranges-cus.test |  80 ++++++------
 .../X86/dwarf4-df-input-lowpc-ranges.test     |  37 +++---
 8 files changed, 175 insertions(+), 127 deletions(-)

diff --git a/bolt/include/bolt/Core/DebugData.h b/bolt/include/bolt/Core/DebugData.h
index 585bafa088849..7364cea9c0840 100644
--- a/bolt/include/bolt/Core/DebugData.h
+++ b/bolt/include/bolt/Core/DebugData.h
@@ -211,6 +211,8 @@ class DebugRangesSectionWriter {
     return Writer->getKind() == RangesWriterKind::DebugRangesWriter;
   }
 
+  void appendToRangeBuffer(const DebugBufferVector &CUBuffer);
+
   /// Writes out range lists for a current CU being processed.
   void virtual finalizeSection(){};
 
diff --git a/bolt/include/bolt/Rewrite/DWARFRewriter.h b/bolt/include/bolt/Rewrite/DWARFRewriter.h
index 8dec32de9008e..f4754b8be8959 100644
--- a/bolt/include/bolt/Rewrite/DWARFRewriter.h
+++ b/bolt/include/bolt/Rewrite/DWARFRewriter.h
@@ -89,6 +89,15 @@ class DWARFRewriter {
   /// Store Rangelists writer for each DWO CU.
   RangeListsDWOWriers RangeListsWritersByCU;
 
+  /// Contains ranges writer and die.
+  struct RangesWriterAndDIE {
+    std::unique_ptr<DebugRangesSectionWriter> Writer;
+    DIE *Die;
+  };
+  /// Stores ranges writer and DIE for each DWO CU.
+  std::unordered_map<uint64_t, RangesWriterAndDIE>
+      LegacyRangesWritersAndDIEsByCU;
+
   std::mutex LocListDebugInfoPatchesMutex;
 
   /// Dwo id specific its RangesBase.
diff --git a/bolt/lib/Core/DebugData.cpp b/bolt/lib/Core/DebugData.cpp
index f502a50312470..08d4c45aac791 100644
--- a/bolt/lib/Core/DebugData.cpp
+++ b/bolt/lib/Core/DebugData.cpp
@@ -177,6 +177,12 @@ uint64_t DebugRangesSectionWriter::getSectionOffset() {
   return SectionOffset;
 }
 
+void DebugRangesSectionWriter::appendToRangeBuffer(
+    const DebugBufferVector &CUBuffer) {
+  *RangesStream << CUBuffer;
+  SectionOffset = RangesBuffer->size();
+}
+
 DebugAddrWriter *DebugRangeListsSectionWriter::AddrWriter = nullptr;
 
 uint64_t DebugRangeListsSectionWriter::addRanges(
diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
index 8814ebbd10aa5..701e6c94ee586 100644
--- a/bolt/lib/Rewrite/DWARFRewriter.cpp
+++ b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -646,6 +646,15 @@ void DWARFRewriter::updateDebugInfo() {
 
     } else {
       LocListWritersByCU[CUIndex] = std::make_unique<DebugLocWriter>();
+      if (std::optional<uint64_t> DWOId = CU.getDWOId()) {
+        assert(LegacyRangesWritersAndDIEsByCU.count(*DWOId) == 0 &&
+               "LegacyRangeLists writer for DWO unit already exists.");
+        auto LegacyRangesSectionWriterByCU =
+            std::make_unique<DebugRangesSectionWriter>();
+        LegacyRangesSectionWriterByCU->initSection(CU);
+        LegacyRangesWritersAndDIEsByCU[*DWOId] = {
+            std::move(LegacyRangesSectionWriterByCU), nullptr};
+      }
     }
     return LocListWritersByCU[CUIndex++].get();
   };
@@ -692,6 +701,8 @@ void DWARFRewriter::updateDebugInfo() {
       if (Unit->getVersion() >= 5) {
         TempRangesSectionWriter = RangeListsWritersByCU[*DWOId].get();
       } else {
+        TempRangesSectionWriter =
+            LegacyRangesWritersAndDIEsByCU[*DWOId].Writer.get();
         RangesBase = RangesSectionWriter->getSectionOffset();
         setDwoRangesBase(*DWOId, *RangesBase);
       }
@@ -1270,9 +1281,12 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
     }
 
     if (RangesBaseInfo) {
-      DIEBldr.replaceValue(&Die, RangesBaseInfo.getAttribute(),
-                           RangesBaseInfo.getForm(),
-                           DIEInteger(static_cast<uint32_t>(*RangesBase)));
+      if (RangesBaseInfo.getAttribute() == dwarf::DW_AT_GNU_ranges_base)
+        LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+      else
+        DIEBldr.replaceValue(&Die, RangesBaseInfo.getAttribute(),
+                             RangesBaseInfo.getForm(),
+                             DIEInteger(static_cast<uint32_t>(*RangesBase)));
       RangesBase = std::nullopt;
     }
   }
@@ -1290,20 +1304,12 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
         RangesAttrInfo.getForm() == dwarf::DW_FORM_sec_offset)
       NeedConverted = true;
 
-    uint64_t CurRangeBase = 0;
-    if (Unit.isDWOUnit()) {
-      if (std::optional<uint64_t> DWOId = Unit.getDWOId())
-        CurRangeBase = getDwoRangesBase(*DWOId);
-      else
-        errs() << "BOLT-WARNING: [internal-dwarf-error]: DWOId is not found "
-                  "for DWO Unit.";
-    }
     if (NeedConverted || RangesAttrInfo.getForm() == dwarf::DW_FORM_rnglistx)
       DIEBldr.replaceValue(&Die, dwarf::DW_AT_ranges, dwarf::DW_FORM_rnglistx,
                            DIEInteger(DebugRangesOffset));
     else
       DIEBldr.replaceValue(&Die, dwarf::DW_AT_ranges, RangesAttrInfo.getForm(),
-                           DIEInteger(DebugRangesOffset - CurRangeBase));
+                           DIEInteger(DebugRangesOffset));
 
     if (!RangesBase) {
       if (LowPCAttrInfo &&
@@ -1320,15 +1326,17 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
 
     // If we are at this point we are in the CU/Skeleton CU, and
     // DW_AT_GNU_ranges_base or DW_AT_rnglists_base doesn't exist.
-    if (Unit.getVersion() <= 4)
+    if (Unit.getVersion() <= 4) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_GNU_ranges_base, dwarf::DW_FORM_data4,
-                       DIEInteger(*RangesBase));
-    else if (Unit.getVersion() == 5)
+                       DIEInteger(INT_MAX));
+      LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+    } else if (Unit.getVersion() == 5) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_rnglists_base,
                        dwarf::DW_FORM_sec_offset, DIEInteger(*RangesBase));
-    else
+    } else {
       DIEBldr.addValue(&Die, dwarf::DW_AT_rnglists_base,
                        dwarf::DW_FORM_sec_offset, DIEInteger(*RangesBase));
+    }
     return;
   }
 
@@ -1605,6 +1613,32 @@ void DWARFRewriter::finalizeCompileUnits(DIEBuilder &DIEBlder,
                                          DIEStreamer &Streamer,
                                          CUOffsetMap &CUMap,
                                          const std::list<DWARFUnit *> &CUs) {
+  for (DWARFUnit *CU : CUs) {
+    if (CU->getVersion() != 4)
+      continue;
+    if (std::optional<uint64_t> DWOId = CU->getDWOId()) {
+      auto RangesWriterandDIEIterator =
+          LegacyRangesWritersAndDIEsByCU.find(*DWOId);
+      assert(RangesWriterandDIEIterator !=
+                 LegacyRangesWritersAndDIEsByCU.end() &&
+             "RangesWriter does not exist for DWOId");
+      RangesWriterAndDIE &RangesWriterAndDIE =
+          RangesWriterandDIEIterator->second;
+      if (RangesWriterAndDIE.Die) {
+        DIEValue DvalGNUBase =
+            RangesWriterAndDIE.Die->findAttribute(dwarf::DW_AT_GNU_ranges_base);
+        assert(DvalGNUBase &&
+               "GNU_ranges_base attribute does not exist for DWOId");
+        DIEBlder.replaceValue(
+            RangesWriterAndDIE.Die, dwarf::DW_AT_GNU_ranges_base,
+            DvalGNUBase.getForm(),
+            DIEInteger(LegacyRangesSectionWriter->getSectionOffset()));
+      }
+      std::unique_ptr<DebugBufferVector> RangesWritersContents =
+          RangesWriterAndDIE.Writer->releaseBuffer();
+      LegacyRangesSectionWriter->appendToRangeBuffer(*RangesWritersContents);
+    }
+  }
   DIEBlder.generateAbbrevs();
   DIEBlder.finish();
   // generate debug_info and CUMap
@@ -2263,7 +2297,6 @@ void DWARFRewriter::convertToRangesPatchDebugInfo(
     DWARFUnit &Unit, DIEBuilder &DIEBldr, DIE &Die,
     uint64_t RangesSectionOffset, DIEValue &LowPCAttrInfo,
     DIEValue &HighPCAttrInfo, std::optional<uint64_t> RangesBase) {
-  uint32_t BaseOffset = 0;
   dwarf::Form LowForm = LowPCAttrInfo.getForm();
   dwarf::Attribute RangeBaseAttribute = dwarf::DW_AT_GNU_ranges_base;
   dwarf::Form RangesForm = dwarf::DW_FORM_sec_offset;
@@ -2278,45 +2311,36 @@ 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));
+      LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+    }
   }
 
-  uint64_t RangeAttrVal = RangesSectionOffset - BaseOffset;
-  if (Unit.getVersion() >= 5)
-    RangeAttrVal = RangesSectionOffset;
   // HighPC was conveted into DW_AT_ranges.
   // For DWARF5 we only access ranges through index.
 
   DIEBldr.replaceValue(&Die, HighPCAttrInfo.getAttribute(), dwarf::DW_AT_ranges,
-                       RangesForm, DIEInteger(RangeAttrVal));
+                       RangesForm, DIEInteger(RangesSectionOffset));
 }
diff --git a/bolt/test/X86/debug-fission-single-convert.s b/bolt/test/X86/debug-fission-single-convert.s
index 28fcb6686e0a2..4cd881740b2f8 100644
--- a/bolt/test/X86/debug-fission-single-convert.s
+++ b/bolt/test/X86/debug-fission-single-convert.s
@@ -31,11 +31,11 @@
 # CHECK-DWO-DWO: 00000010
 # CHECK-DWO-DWO: 00000050
 # CHECK-DWO-DWO: DW_TAG_subprogram
-# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000000
+# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 # CHECK-DWO-DWO: DW_TAG_subprogram
-# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000020
+# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000030
 # CHECK-DWO-DWO: DW_TAG_subprogram
-# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000040
+# CHECK-DWO-DWO-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000050
 
 # CHECK-ADDR-SEC: .debug_addr contents:
 # CHECK-ADDR-SEC: 0x00000000: Addrs: [
diff --git a/bolt/test/X86/dwarf4-df-dualcu.test b/bolt/test/X86/dwarf4-df-dualcu.test
index b690623b70d83..fb328eb1872e0 100644
--- a/bolt/test/X86/dwarf4-df-dualcu.test
+++ b/bolt/test/X86/dwarf4-df-dualcu.test
@@ -37,36 +37,38 @@
 
 ; BOLT: .debug_ranges
 ; BOLT-NEXT: 00000000 <End of list>
-; BOLT-NEXT: 00000010 [[#%.16x,ADDR:]] [[#%.16x,ADDRB:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
 ; BOLT-NEXT: 00000010 <End of list>
-; BOLT-NEXT: 00000030 [[#%.16x,ADDR1:]] [[#%.16x,ADDR1B:]]
-; BOLT-NEXT: 00000030 <End of list>
-; BOLT-NEXT: 00000050 [[#%.16x,ADDR2:]] [[#%.16x,ADDR2B:]]
-; BOLT-NEXT: 00000050 [[#%.16x,ADDR3:]] [[#%.16x,ADDR3B:]]
+; BOLT-NEXT: 00000040 <End of list>
+; BOLT-NEXT: 00000050 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
 ; BOLT-NEXT: 00000050 <End of list>
-; BOLT-NEXT: 00000080 [[#%.16x,ADDR4:]] [[#%.16x,ADDR4B:]]
-; BOLT-NEXT: 00000080 <End of list>
-; BOLT-NEXT: 000000a0 [[#%.16x,ADDR5:]] [[#%.16x,ADDR5B:]]
-; BOLT-NEXT: 000000a0 <End of list>
+; BOLT-NEXT: 00000070 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
+; BOLT-NEXT: 00000070 <End of list>
+; BOLT-NEXT: 00000090 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 00000090 <End of list>
+; BOLT-NEXT: 000000b0 <End of list>
+; BOLT-NEXT: 000000c0 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 000000c0 <End of list>
 
 ; BOLT: DW_TAG_compile_unit
 ; BOLT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x00000016] = "main.dwo.dwo")
 ; BOLT-NEXT: DW_AT_GNU_dwo_id
 ; BOLT-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000050
-; BOLT-NEXT: [0x[[#ADDR2]], 0x[[#ADDR2B]])
-; BOLT-NEXT: [0x[[#ADDR3]], 0x[[#ADDR3B]]))
+; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
+; BOLT-NEXT: [0x[[#ADDR1]], 0x[[#ADDRB1]])
+; BOLT-NEXT: [0x[[#ADDR2]], 0x[[#ADDRB2]]))
 ; BOLT-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]  (0x00000000)
-; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000010)
+; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000040)
 ; BOLT-NEXT: Compile
 ; BOLT: DW_TAG_compile_unit
 ; BOLT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x00000023] = "helper.dwo.dwo")
 ; BOLT-NEXT: DW_AT_GNU_dwo_id
 ; BOLT-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x000000a0
-; BOLT-NEXT: [0x[[#ADDR5]], 0x[[#ADDR5B]])
+; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000090
+; BOLT-NEXT: [0x[[#ADDR3]], 0x[[#ADDRB3]])
 ; BOLT-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]  (0x00000010)
-; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000080)
+; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x000000b0)
 
 ; PRE-BOLT-DWO-MAIN: version = 0x0004
 ; PRE-BOLT-DWO-MAIN: DW_TAG_compile_unit
@@ -113,13 +115,13 @@
 ; BOLT-DWO-MAIN-NEXT: DW_AT_decl_line
 ; BOLT-DWO-MAIN-NEXT: DW_AT_location [DW_FORM_exprloc]	(DW_OP_GNU_addr_index 0x1)
 ; BOLT-DWO-MAIN: DW_TAG_subprogram [4]
-; BOLT-DWO-MAIN-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000000
+; BOLT-DWO-MAIN-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000010
 ; BOLT-DWO-MAIN-NEXT: )
 ; BOLT-DWO-MAIN-NEXT: DW_AT_frame_base
 ; BOLT-DWO-MAIN-NEXT: DW_AT_linkage_name [DW_FORM_GNU_str_index]	(indexed (00000003) string = "_Z3usePiS_")
 ; BOLT-DWO-MAIN-NEXT: DW_AT_name [DW_FORM_GNU_str_index]	(indexed (00000004) string = "use")
 ; BOLT-DWO-MAIN: DW_TAG_subprogram [6]
-; BOLT-DWO-MAIN-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000020
+; BOLT-DWO-MAIN-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000030
 ; BOLT-DWO-MAIN-NEXT: )
 ; BOLT-DWO-MAIN-NEXT: DW_AT_frame_base [DW_FORM_exprloc]	(DW_OP_reg6 RBP)
 ; BOLT-DWO-MAIN-NEXT: DW_AT_name [DW_FORM_GNU_str_index]	(indexed (00000005) string = "main")
@@ -160,4 +162,4 @@
 ; BOLT-DWO-HELPER-NEXT: DW_AT_decl_line
 ; BOLT-DWO-HELPER-NEXT: DW_AT_location [DW_FORM_exprloc]	(DW_OP_GNU_addr_index 0x1)
 ; BOLT-DWO-HELPER: DW_TAG_subprogram [4]
-; BOLT-DWO-HELPER-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000000
+; BOLT-DWO-HELPER-NEXT: DW_AT_ranges [DW_FORM_sec_offset]	(0x00000010
diff --git a/bolt/test/X86/dwarf4-df-input-lowpc-ranges-cus.test b/bolt/test/X86/dwarf4-df-input-lowpc-ranges-cus.test
index c9abd02bbb7d9..cf9357d5f3c59 100644
--- a/bolt/test/X86/dwarf4-df-input-lowpc-ranges-cus.test
+++ b/bolt/test/X86/dwarf4-df-input-lowpc-ranges-cus.test
@@ -17,45 +17,47 @@
 
 ; BOLT: .debug_ranges
 ; BOLT-NEXT: 00000000 <End of list>
-; BOLT-NEXT: 00000010
-; BOLT-NEXT: 00000010
-; BOLT-NEXT: 00000010
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR4:]] [[#%.16x,ADDRB4:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
 ; BOLT-NEXT: 00000010 <End of list>
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050 <End of list>
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR4:]] [[#%.16x,ADDRB4:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
 ; BOLT-NEXT: 00000090 <End of list>
-; BOLT-NEXT: 00000110
-; BOLT-NEXT: 00000110
-; BOLT-NEXT: 00000110
-; BOLT-NEXT: 00000110 <End of list>
-; BOLT-NEXT: 00000150
-; BOLT-NEXT: 00000150
-; BOLT-NEXT: 00000150
-; BOLT-NEXT: 00000150 <End of list>
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR8:]] [[#%.16x,ADDRB8:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR9:]] [[#%.16x,ADDRB9:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR10:]] [[#%.16x,ADDRB10:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR11:]] [[#%.16x,ADDRB11:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR12:]] [[#%.16x,ADDRB12:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR13:]] [[#%.16x,ADDRB13:]]
-; BOLT-NEXT: 00000190 [[#%.16x,ADDR14:]] [[#%.16x,ADDRB14:]]
-; BOLT-NEXT: 00000190 <End of list>
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 000000a0 <End of list>
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
+; BOLT-NEXT: 000000e0 <End of list>
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR8:]] [[#%.16x,ADDRB8:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR9:]] [[#%.16x,ADDRB9:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR10:]] [[#%.16x,ADDRB10:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR11:]] [[#%.16x,ADDRB11:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR12:]] [[#%.16x,ADDRB12:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR13:]] [[#%.16x,ADDRB13:]]
+; BOLT-NEXT: 00000120 [[#%.16x,ADDR14:]] [[#%.16x,ADDRB14:]]
+; BOLT-NEXT: 00000120 <End of list>
+; BOLT-NEXT: 000001a0 <End of list>
+; BOLT-NEXT: 000001b0 [[#%.16x,ADDR8:]] [[#%.16x,ADDRB8:]]
+; BOLT-NEXT: 000001b0 [[#%.16x,ADDR9:]] [[#%.16x,ADDRB9:]]
+; BOLT-NEXT: 000001b0 [[#%.16x,ADDR10:]] [[#%.16x,ADDRB10:]]
+; BOLT-NEXT: 000001b0 <End of list>
+; BOLT-NEXT: 000001f0 [[#%.16x,ADDR12:]] [[#%.16x,ADDRB12:]]
+; BOLT-NEXT: 000001f0 [[#%.16x,ADDR13:]] [[#%.16x,ADDRB13:]]
+; BOLT-NEXT: 000001f0 [[#%.16x,ADDR14:]] [[#%.16x,ADDRB14:]]
+; BOLT-NEXT: 000001f0 <End of list>
 
 ; BOLT: DW_TAG_compile_unit
 ; BOLT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x{{[0-9a-fA-F]+}}] = "main.dwo.dwo")
 ; BOLT-NEXT: DW_AT_GNU_dwo_id
-; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000010)
+; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000090)
 ; BOLT-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000090
+; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 ; BOLT-NEXT: [0x[[#ADDR1]], 0x[[#ADDRB1]])
 ; BOLT-NEXT: [0x[[#ADDR2]], 0x[[#ADDRB2]])
 ; BOLT-NEXT: [0x[[#ADDR3]], 0x[[#ADDRB3]])
@@ -64,13 +66,14 @@
 ; BOLT-NEXT: [0x[[#ADDR6]], 0x[[#ADDRB6]])
 ; BOLT-NEXT: [0x[[#ADDR7]], 0x[[#ADDRB7]])
 ; BOLT-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]  (0x00000000)
+; BOLT-NEXT: Compile Unit
 
 ; BOLT: DW_TAG_compile_unit
 ; BOLT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x{{[0-9a-fA-F]+}}] = "mainOther.dwo.dwo")
 ; BOLT-NEXT: DW_AT_GNU_dwo_id
-; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000110)
+; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x000001a0)
 ; BOLT-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000190
+; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000120
 ; BOLT-NEXT: [0x[[#ADDR8]], 0x[[#ADDRB8]])
 ; BOLT-NEXT: [0x[[#ADDR9]], 0x[[#ADDRB9]])
 ; BOLT-NEXT: [0x[[#ADDR10]], 0x[[#ADDRB10]])
@@ -79,19 +82,20 @@
 ; BOLT-NEXT: [0x[[#ADDR13]], 0x[[#ADDRB13]])
 ; BOLT-NEXT: [0x[[#ADDR14]], 0x[[#ADDRB14]])
 ; BOLT-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]  (0x00000018)
+; BOLT: {{^$}}
 
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000000
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000040
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000050
 
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000000
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000040
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000050
diff --git a/bolt/test/X86/dwarf4-df-input-lowpc-ranges.test b/bolt/test/X86/dwarf4-df-input-lowpc-ranges.test
index 276bea4ba0c1c..ab4353a282475 100644
--- a/bolt/test/X86/dwarf4-df-input-lowpc-ranges.test
+++ b/bolt/test/X86/dwarf4-df-input-lowpc-ranges.test
@@ -15,29 +15,30 @@
 
 ; BOLT: .debug_ranges
 ; BOLT-NEXT: 00000000 <End of list>
-; BOLT-NEXT: 00000010
-; BOLT-NEXT: 00000010
-; BOLT-NEXT: 00000010
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR4:]] [[#%.16x,ADDRB4:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
+; BOLT-NEXT: 00000010 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
 ; BOLT-NEXT: 00000010 <End of list>
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050
-; BOLT-NEXT: 00000050 <End of list>
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR4:]] [[#%.16x,ADDRB4:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
-; BOLT-NEXT: 00000090 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
 ; BOLT-NEXT: 00000090 <End of list>
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR1:]] [[#%.16x,ADDRB1:]]
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR2:]] [[#%.16x,ADDRB2:]]
+; BOLT-NEXT: 000000a0 [[#%.16x,ADDR3:]] [[#%.16x,ADDRB3:]]
+; BOLT-NEXT: 000000a0 <End of list>
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR5:]] [[#%.16x,ADDRB5:]]
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR6:]] [[#%.16x,ADDRB6:]]
+; BOLT-NEXT: 000000e0 [[#%.16x,ADDR7:]] [[#%.16x,ADDRB7:]]
+; BOLT-NEXT: 000000e0 <End of list>
 
 ; BOLT: DW_TAG_compile_unit
 ; BOLT: DW_AT_GNU_dwo_name [DW_FORM_strp] ( .debug_str[0x{{[0-9a-fA-F]+}}] = "main.dwo.dwo")
 ; BOLT-NEXT: DW_AT_GNU_dwo_id
-; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000010)
+; BOLT-NEXT: DW_AT_GNU_ranges_base [DW_FORM_sec_offset]  (0x00000090)
 ; BOLT-NEXT: DW_AT_low_pc [DW_FORM_addr] (0x0000000000000000)
-; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000090
+; BOLT-NEXT: DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 ; BOLT-NEXT: [0x[[#ADDR1]], 0x[[#ADDRB1]])
 ; BOLT-NEXT: [0x[[#ADDR2]], 0x[[#ADDRB2]])
 ; BOLT-NEXT: [0x[[#ADDR3]], 0x[[#ADDRB3]])
@@ -48,9 +49,9 @@
 ; BOLT-NEXT: DW_AT_GNU_addr_base [DW_FORM_sec_offset]  (0x00000000)
 
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000000
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000010
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
 ; BOLT-DWO-MAIN:        DW_TAG_subprogram
-; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000040
+; BOLT-DWO-MAIN-NEXT:   DW_AT_ranges [DW_FORM_sec_offset] (0x00000050

>From d9759abe710d963fc733e1e29cb836eb0e3c8b71 Mon Sep 17 00:00:00 2001
From: Sayhaan Siddiqui <sayhaan at meta.com>
Date: Mon, 24 Jun 2024 16:20:07 -0700
Subject: [PATCH 2/5] Updates and formatting changes

---
 bolt/include/bolt/Core/DebugData.h        |  6 +++
 bolt/include/bolt/Rewrite/DWARFRewriter.h |  9 +---
 bolt/lib/Rewrite/DWARFRewriter.cpp        | 60 +++++++++++------------
 3 files changed, 38 insertions(+), 37 deletions(-)

diff --git a/bolt/include/bolt/Core/DebugData.h b/bolt/include/bolt/Core/DebugData.h
index 7364cea9c0840..f78123b3a59b4 100644
--- a/bolt/include/bolt/Core/DebugData.h
+++ b/bolt/include/bolt/Core/DebugData.h
@@ -213,6 +213,10 @@ class DebugRangesSectionWriter {
 
   void appendToRangeBuffer(const DebugBufferVector &CUBuffer);
 
+  void setDie(std::optional<DIE *> Die) { this->Die = Die; }
+
+  std::optional<DIE *> getDie() const { return Die; }
+
   /// Writes out range lists for a current CU being processed.
   void virtual finalizeSection(){};
 
@@ -234,6 +238,8 @@ class DebugRangesSectionWriter {
   static constexpr uint64_t EmptyRangesOffset{0};
 
 private:
+  std::optional<DIE *> Die;
+
   RangesWriterKind Kind;
 };
 
diff --git a/bolt/include/bolt/Rewrite/DWARFRewriter.h b/bolt/include/bolt/Rewrite/DWARFRewriter.h
index f4754b8be8959..8c17ccbf57380 100644
--- a/bolt/include/bolt/Rewrite/DWARFRewriter.h
+++ b/bolt/include/bolt/Rewrite/DWARFRewriter.h
@@ -89,14 +89,9 @@ class DWARFRewriter {
   /// Store Rangelists writer for each DWO CU.
   RangeListsDWOWriers RangeListsWritersByCU;
 
-  /// Contains ranges writer and die.
-  struct RangesWriterAndDIE {
-    std::unique_ptr<DebugRangesSectionWriter> Writer;
-    DIE *Die;
-  };
   /// Stores ranges writer and DIE for each DWO CU.
-  std::unordered_map<uint64_t, RangesWriterAndDIE>
-      LegacyRangesWritersAndDIEsByCU;
+  std::unordered_map<uint64_t, std::unique_ptr<DebugRangesSectionWriter>>
+      LegacyRangesWritersByCU;
 
   std::mutex LocListDebugInfoPatchesMutex;
 
diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
index 701e6c94ee586..534cc1793429d 100644
--- a/bolt/lib/Rewrite/DWARFRewriter.cpp
+++ b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -647,13 +647,13 @@ void DWARFRewriter::updateDebugInfo() {
     } else {
       LocListWritersByCU[CUIndex] = std::make_unique<DebugLocWriter>();
       if (std::optional<uint64_t> DWOId = CU.getDWOId()) {
-        assert(LegacyRangesWritersAndDIEsByCU.count(*DWOId) == 0 &&
+        assert(LegacyRangesWritersByCU.count(*DWOId) == 0 &&
                "LegacyRangeLists writer for DWO unit already exists.");
         auto LegacyRangesSectionWriterByCU =
             std::make_unique<DebugRangesSectionWriter>();
         LegacyRangesSectionWriterByCU->initSection(CU);
-        LegacyRangesWritersAndDIEsByCU[*DWOId] = {
-            std::move(LegacyRangesSectionWriterByCU), nullptr};
+        LegacyRangesWritersByCU[*DWOId] =
+            std::move(LegacyRangesSectionWriterByCU);
       }
     }
     return LocListWritersByCU[CUIndex++].get();
@@ -701,8 +701,7 @@ void DWARFRewriter::updateDebugInfo() {
       if (Unit->getVersion() >= 5) {
         TempRangesSectionWriter = RangeListsWritersByCU[*DWOId].get();
       } else {
-        TempRangesSectionWriter =
-            LegacyRangesWritersAndDIEsByCU[*DWOId].Writer.get();
+        TempRangesSectionWriter = LegacyRangesWritersByCU[*DWOId].get();
         RangesBase = RangesSectionWriter->getSectionOffset();
         setDwoRangesBase(*DWOId, *RangesBase);
       }
@@ -1282,7 +1281,8 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
 
     if (RangesBaseInfo) {
       if (RangesBaseInfo.getAttribute() == dwarf::DW_AT_GNU_ranges_base)
-        LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+        LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
+            std::optional<DIE *>(&Die));
       else
         DIEBldr.replaceValue(&Die, RangesBaseInfo.getAttribute(),
                              RangesBaseInfo.getForm(),
@@ -1329,7 +1329,8 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
     if (Unit.getVersion() <= 4) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_GNU_ranges_base, dwarf::DW_FORM_data4,
                        DIEInteger(INT_MAX));
-      LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+      LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
+          std::optional<DIE *>(&Die));
     } else if (Unit.getVersion() == 5) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_rnglists_base,
                        dwarf::DW_FORM_sec_offset, DIEInteger(*RangesBase));
@@ -1616,28 +1617,26 @@ void DWARFRewriter::finalizeCompileUnits(DIEBuilder &DIEBlder,
   for (DWARFUnit *CU : CUs) {
     if (CU->getVersion() != 4)
       continue;
-    if (std::optional<uint64_t> DWOId = CU->getDWOId()) {
-      auto RangesWriterandDIEIterator =
-          LegacyRangesWritersAndDIEsByCU.find(*DWOId);
-      assert(RangesWriterandDIEIterator !=
-                 LegacyRangesWritersAndDIEsByCU.end() &&
-             "RangesWriter does not exist for DWOId");
-      RangesWriterAndDIE &RangesWriterAndDIE =
-          RangesWriterandDIEIterator->second;
-      if (RangesWriterAndDIE.Die) {
-        DIEValue DvalGNUBase =
-            RangesWriterAndDIE.Die->findAttribute(dwarf::DW_AT_GNU_ranges_base);
-        assert(DvalGNUBase &&
-               "GNU_ranges_base attribute does not exist for DWOId");
-        DIEBlder.replaceValue(
-            RangesWriterAndDIE.Die, dwarf::DW_AT_GNU_ranges_base,
-            DvalGNUBase.getForm(),
-            DIEInteger(LegacyRangesSectionWriter->getSectionOffset()));
-      }
-      std::unique_ptr<DebugBufferVector> RangesWritersContents =
-          RangesWriterAndDIE.Writer->releaseBuffer();
-      LegacyRangesSectionWriter->appendToRangeBuffer(*RangesWritersContents);
-    }
+    std::optional<uint64_t> DWOId = CU->getDWOId();
+    if (!DWOId)
+      continue;
+    auto RangesWriterIterator = LegacyRangesWritersByCU.find(*DWOId);
+    assert(RangesWriterIterator != LegacyRangesWritersByCU.end() &&
+           "RangesWriter does not exist for DWOId");
+    std::unique_ptr<DebugRangesSectionWriter> &LegacyRangesWriter =
+        RangesWriterIterator->second;
+    std::optional<DIE *> Die = LegacyRangesWriter->getDie();
+    if (!Die)
+      continue;
+    DIEValue DvalGNUBase =
+        Die.value()->findAttribute(dwarf::DW_AT_GNU_ranges_base);
+    assert(DvalGNUBase && "GNU_ranges_base attribute does not exist for DWOId");
+    DIEBlder.replaceValue(
+        Die.value(), dwarf::DW_AT_GNU_ranges_base, DvalGNUBase.getForm(),
+        DIEInteger(LegacyRangesSectionWriter->getSectionOffset()));
+    std::unique_ptr<DebugBufferVector> RangesWritersContents =
+        LegacyRangesWriter->releaseBuffer();
+    LegacyRangesSectionWriter->appendToRangeBuffer(*RangesWritersContents);
   }
   DIEBlder.generateAbbrevs();
   DIEBlder.finish();
@@ -2334,7 +2333,8 @@ void DWARFRewriter::convertToRangesPatchDebugInfo(
     } else {
       DIEBldr.addValue(&Die, RangeBaseAttribute, dwarf::DW_FORM_sec_offset,
                        DIEInteger(INT_MAX));
-      LegacyRangesWritersAndDIEsByCU[*Unit.getDWOId()].Die = &Die;
+      LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
+          std::optional<DIE *>(&Die));
     }
   }
 

>From 5aca87bd9f31838fc5dcccc6965e8c93b9e2da4b Mon Sep 17 00:00:00 2001
From: Sayhaan Siddiqui <sayhaan at meta.com>
Date: Mon, 24 Jun 2024 16:23:28 -0700
Subject: [PATCH 3/5] Formatting changes

---
 bolt/include/bolt/Rewrite/DWARFRewriter.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bolt/include/bolt/Rewrite/DWARFRewriter.h b/bolt/include/bolt/Rewrite/DWARFRewriter.h
index 8c17ccbf57380..1776f9efd137f 100644
--- a/bolt/include/bolt/Rewrite/DWARFRewriter.h
+++ b/bolt/include/bolt/Rewrite/DWARFRewriter.h
@@ -89,7 +89,7 @@ class DWARFRewriter {
   /// Store Rangelists writer for each DWO CU.
   RangeListsDWOWriers RangeListsWritersByCU;
 
-  /// Stores ranges writer and DIE for each DWO CU.
+  /// Stores ranges writer for each DWO CU.
   std::unordered_map<uint64_t, std::unique_ptr<DebugRangesSectionWriter>>
       LegacyRangesWritersByCU;
 

>From 051025bd92ac34bf6da620f4e062ed1a06b559f7 Mon Sep 17 00:00:00 2001
From: Sayhaan Siddiqui <sayhaan at meta.com>
Date: Tue, 25 Jun 2024 09:44:26 -0700
Subject: [PATCH 4/5] Updates and formatting changes

---
 bolt/include/bolt/Core/DebugData.h |  6 +++---
 bolt/lib/Rewrite/DWARFRewriter.cpp | 28 +++++++++++++++++++---------
 2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/bolt/include/bolt/Core/DebugData.h b/bolt/include/bolt/Core/DebugData.h
index f78123b3a59b4..a9a0200c7c4b7 100644
--- a/bolt/include/bolt/Core/DebugData.h
+++ b/bolt/include/bolt/Core/DebugData.h
@@ -213,9 +213,9 @@ class DebugRangesSectionWriter {
 
   void appendToRangeBuffer(const DebugBufferVector &CUBuffer);
 
-  void setDie(std::optional<DIE *> Die) { this->Die = Die; }
+  void setDie(DIE *Die) { this->Die = Die; }
 
-  std::optional<DIE *> getDie() const { return Die; }
+  DIE *getDie() const { return Die; }
 
   /// Writes out range lists for a current CU being processed.
   void virtual finalizeSection(){};
@@ -238,7 +238,7 @@ class DebugRangesSectionWriter {
   static constexpr uint64_t EmptyRangesOffset{0};
 
 private:
-  std::optional<DIE *> Die;
+  DIE *Die{0};
 
   RangesWriterKind Kind;
 };
diff --git a/bolt/lib/Rewrite/DWARFRewriter.cpp b/bolt/lib/Rewrite/DWARFRewriter.cpp
index 534cc1793429d..be7bab9359839 100644
--- a/bolt/lib/Rewrite/DWARFRewriter.cpp
+++ b/bolt/lib/Rewrite/DWARFRewriter.cpp
@@ -1280,13 +1280,17 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
     }
 
     if (RangesBaseInfo) {
-      if (RangesBaseInfo.getAttribute() == dwarf::DW_AT_GNU_ranges_base)
-        LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
-            std::optional<DIE *>(&Die));
-      else
+      if (RangesBaseInfo.getAttribute() == dwarf::DW_AT_GNU_ranges_base) {
+        auto RangesWriterIterator =
+            LegacyRangesWritersByCU.find(*Unit.getDWOId());
+        assert(RangesWriterIterator != LegacyRangesWritersByCU.end() &&
+               "RangesWriter does not exist for DWOId");
+        RangesWriterIterator->second->setDie(&Die);
+      } else {
         DIEBldr.replaceValue(&Die, RangesBaseInfo.getAttribute(),
                              RangesBaseInfo.getForm(),
                              DIEInteger(static_cast<uint32_t>(*RangesBase)));
+      }
       RangesBase = std::nullopt;
     }
   }
@@ -1329,8 +1333,11 @@ void DWARFRewriter::updateDWARFObjectAddressRanges(
     if (Unit.getVersion() <= 4) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_GNU_ranges_base, dwarf::DW_FORM_data4,
                        DIEInteger(INT_MAX));
-      LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
-          std::optional<DIE *>(&Die));
+      auto RangesWriterIterator =
+          LegacyRangesWritersByCU.find(*Unit.getDWOId());
+      assert(RangesWriterIterator != LegacyRangesWritersByCU.end() &&
+             "RangesWriter does not exist for DWOId");
+      RangesWriterIterator->second->setDie(&Die);
     } else if (Unit.getVersion() == 5) {
       DIEBldr.addValue(&Die, dwarf::DW_AT_rnglists_base,
                        dwarf::DW_FORM_sec_offset, DIEInteger(*RangesBase));
@@ -1626,7 +1633,7 @@ void DWARFRewriter::finalizeCompileUnits(DIEBuilder &DIEBlder,
     std::unique_ptr<DebugRangesSectionWriter> &LegacyRangesWriter =
         RangesWriterIterator->second;
     std::optional<DIE *> Die = LegacyRangesWriter->getDie();
-    if (!Die)
+    if (!Die || !Die.value())
       continue;
     DIEValue DvalGNUBase =
         Die.value()->findAttribute(dwarf::DW_AT_GNU_ranges_base);
@@ -2333,8 +2340,11 @@ void DWARFRewriter::convertToRangesPatchDebugInfo(
     } else {
       DIEBldr.addValue(&Die, RangeBaseAttribute, dwarf::DW_FORM_sec_offset,
                        DIEInteger(INT_MAX));
-      LegacyRangesWritersByCU[*Unit.getDWOId()]->setDie(
-          std::optional<DIE *>(&Die));
+      auto RangesWriterIterator =
+          LegacyRangesWritersByCU.find(*Unit.getDWOId());
+      assert(RangesWriterIterator != LegacyRangesWritersByCU.end() &&
+             "RangesWriter does not exist for DWOId");
+      RangesWriterIterator->second->setDie(&Die);
     }
   }
 

>From 2d16ac1032bf24288df7a3d5bf44a132c74aa451 Mon Sep 17 00:00:00 2001
From: Sayhaan Siddiqui <sayhaan at meta.com>
Date: Tue, 25 Jun 2024 09:48:57 -0700
Subject: [PATCH 5/5] Add comment describing DIE

---
 bolt/include/bolt/Core/DebugData.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/bolt/include/bolt/Core/DebugData.h b/bolt/include/bolt/Core/DebugData.h
index a9a0200c7c4b7..b0a8d9c1db87b 100644
--- a/bolt/include/bolt/Core/DebugData.h
+++ b/bolt/include/bolt/Core/DebugData.h
@@ -238,6 +238,7 @@ class DebugRangesSectionWriter {
   static constexpr uint64_t EmptyRangesOffset{0};
 
 private:
+  /// Stores DIE to be updated for CU.
   DIE *Die{0};
 
   RangesWriterKind Kind;



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