The change in https://github.com/llvm/llvm-project/commit/1ae7d83803e45f6053ec6a606f259653846926b8
makes rustc unable to read the profiles that `llvm-profdata merge` outputs,
further causing some problems (e.g. bug 1811960).

diff --git a/llvm/lib/ProfileData/InstrProfWriter.cpp b/llvm/lib/ProfileData/InstrProfWriter.cpp
index af3c27ebac76..a6da1e0f3aec 100644
--- a/llvm/lib/ProfileData/InstrProfWriter.cpp
+++ b/llvm/lib/ProfileData/InstrProfWriter.cpp
@@ -291,10 +291,6 @@ void InstrProfWriter::mergeRecordsFromWriter(InstrProfWriter &&IPW,
     for (auto &Func : I.getValue())
       addRecord(I.getKey(), Func.first, std::move(Func.second), 1, Warn);
 
-  BinaryIds.reserve(BinaryIds.size() + IPW.BinaryIds.size());
-  for (auto &I : IPW.BinaryIds)
-    addBinaryIds(I);
-
   MemProfFrameData.reserve(IPW.MemProfFrameData.size());
   for (auto &I : IPW.MemProfFrameData) {
     // If we weren't able to add the frame mappings then it doesn't make sense
@@ -339,7 +335,6 @@ static void setSummary(IndexedInstrProf::Summary *TheSummary,
 
 Error InstrProfWriter::writeImpl(ProfOStream &OS) {
   using namespace IndexedInstrProf;
-  using namespace support;
 
   OnDiskChainedHashTableGenerator<InstrProfRecordWriterTrait> Generator;
 
@@ -356,7 +351,7 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
   // Write the header.
   IndexedInstrProf::Header Header;
   Header.Magic = IndexedInstrProf::Magic;
-  Header.Version = IndexedInstrProf::ProfVersion::Version9;
+  Header.Version = IndexedInstrProf::ProfVersion::Version8;
   if (static_cast<bool>(ProfileKind & InstrProfKind::IRInstrumentation))
     Header.Version |= VARIANT_MASK_IR_PROF;
   if (static_cast<bool>(ProfileKind & InstrProfKind::ContextSensitive))
@@ -396,12 +389,6 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
   // profile contains memory profile information.
   OS.write(0);
 
-  // Save the location of binary ids section.
-  uint64_t BinaryIdSectionOffset = OS.tell();
-  // Reserve space for the BinaryIdOffset field to be patched later if this
-  // profile contains binary ids.
-  OS.write(0);
-
   // Reserve space to write profile summary data.
   uint32_t NumEntries = ProfileSummaryBuilder::DefaultCutoffs.size();
   uint32_t SummarySize = Summary::getSize(Summary::NumKinds, NumEntries);
@@ -478,43 +465,6 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
     OS.patch(PatchItems, 3);
   }
 
-  // BinaryIdSection has two parts:
-  // 1. uint64_t BinaryIdsSectionSize
-  // 2. list of binary ids that consist of:
-  //    a. uint64_t BinaryIdLength
-  //    b. uint8_t  BinaryIdData
-  //    c. uint8_t  Padding (if necessary)
-  uint64_t BinaryIdSectionStart = OS.tell();
-  // Calculate size of binary section.
-  uint64_t BinaryIdsSectionSize = 0;
-
-  // Remove duplicate binary ids.
-  llvm::sort(BinaryIds);
-  BinaryIds.erase(std::unique(BinaryIds.begin(), BinaryIds.end()),
-                  BinaryIds.end());
-
-  for (auto BI : BinaryIds) {
-    // Increment by binary id length data type size.
-    BinaryIdsSectionSize += sizeof(uint64_t);
-    // Increment by binary id data length, aligned to 8 bytes.
-    BinaryIdsSectionSize += alignToPowerOf2(BI.size(), sizeof(uint64_t));
-  }
-  // Write binary ids section size.
-  OS.write(BinaryIdsSectionSize);
-
-  for (auto BI : BinaryIds) {
-    uint64_t BILen = BI.size();
-    // Write binary id length.
-    OS.write(BILen);
-    // Write binary id data.
-    for (unsigned K = 0; K < BILen; K++)
-      OS.writeByte(BI[K]);
-    // Write padding if necessary.
-    uint64_t PaddingSize = alignToPowerOf2(BILen, sizeof(uint64_t)) - BILen;
-    for (unsigned K = 0; K < PaddingSize; K++)
-      OS.writeByte(0);
-  }
-
   // Allocate space for data to be serialized out.
   std::unique_ptr<IndexedInstrProf::Summary> TheSummary =
       IndexedInstrProf::allocSummary(SummarySize);
@@ -537,11 +487,8 @@ Error InstrProfWriter::writeImpl(ProfOStream &OS) {
   PatchItem PatchItems[] = {
       // Patch the Header.HashOffset field.
       {HashTableStartFieldOffset, &HashTableStart, 1},
-      // Patch the Header.MemProfOffset (=0 for profiles without MemProf
-      // data).
+      // Patch the Header.MemProfOffset (=0 for profiles without MemProf data).
       {MemProfSectionOffset, &MemProfSectionStart, 1},
-      // Patch the Header.BinaryIdSectionOffset.
-      {BinaryIdSectionOffset, &BinaryIdSectionStart, 1},
       // Patch the summary data.
       {SummaryOffset, reinterpret_cast<uint64_t *>(TheSummary.get()),
        (int)(SummarySize / sizeof(uint64_t))},