From fa4fbaefde8569ca64594fc3845340536ec8eb02 Mon Sep 17 00:00:00 2001
From: Jan Voung <jvoung@gmail.com>
Date: Tue, 27 Aug 2024 13:53:25 -0400
Subject: Reapply: Use an abbrev to reduce size of VALUE_GUID records in
 ThinLTO summaries (#106165)

This retries #90692 which was reverted previously due to issues with
lld-available being set, even if the copy of lld is not built from
source.

This does not change any code compared to #90692 to address the
lld-available issue.
The main change w.r.t, lld-available is xfailing tests in PR #99056
(until a longer term fix is available).
---
 llvm/lib/Bitcode/Writer/BitcodeWriter.cpp | 30 ++++++++++++++++++++++++++----
 1 file changed, 26 insertions(+), 4 deletions(-)

(limited to 'llvm/lib/Bitcode/Writer/BitcodeWriter.cpp')

diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index d21ff10d51d0..3c5097f4af7c 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -4350,9 +4350,20 @@ void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
     return;
   }
 
+  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv->Add(BitCodeAbbrevOp(bitc::FS_VALUE_GUID));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  // GUIDS often use up most of 64-bits, so encode as two Fixed 32.
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  unsigned ValueGuidAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+
   for (const auto &GVI : valueIds()) {
     Stream.EmitRecord(bitc::FS_VALUE_GUID,
-                      ArrayRef<uint64_t>{GVI.second, GVI.first});
+                      ArrayRef<uint32_t>{GVI.second,
+                                         static_cast<uint32_t>(GVI.first >> 32),
+                                         static_cast<uint32_t>(GVI.first)},
+                      ValueGuidAbbrev);
   }
 
   if (!Index->stackIds().empty()) {
@@ -4366,7 +4377,7 @@ void ModuleBitcodeWriterBase::writePerModuleGlobalValueSummary() {
   }
 
   // Abbrev for FS_PERMODULE_PROFILE.
-  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv = std::make_shared<BitCodeAbbrev>();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_PERMODULE_PROFILE));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // flags
@@ -4520,9 +4531,20 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   // Write the index flags.
   Stream.EmitRecord(bitc::FS_FLAGS, ArrayRef<uint64_t>{Index.getFlags()});
 
+  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv->Add(BitCodeAbbrevOp(bitc::FS_VALUE_GUID));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6));
+  // GUIDS often use up most of 64-bits, so encode as two Fixed 32.
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Fixed, 32));
+  unsigned ValueGuidAbbrev = Stream.EmitAbbrev(std::move(Abbv));
+
   for (const auto &GVI : valueIds()) {
     Stream.EmitRecord(bitc::FS_VALUE_GUID,
-                      ArrayRef<uint64_t>{GVI.second, GVI.first});
+                      ArrayRef<uint32_t>{GVI.second,
+                                         static_cast<uint32_t>(GVI.first >> 32),
+                                         static_cast<uint32_t>(GVI.first)},
+                      ValueGuidAbbrev);
   }
 
   // Write the stack ids used by this index, which will be a subset of those in
@@ -4538,7 +4560,7 @@ void IndexBitcodeWriter::writeCombinedGlobalValueSummary() {
   }
 
   // Abbrev for FS_COMBINED_PROFILE.
-  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  Abbv = std::make_shared<BitCodeAbbrev>();
   Abbv->Add(BitCodeAbbrevOp(bitc::FS_COMBINED_PROFILE));
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // valueid
   Abbv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8));   // modid
-- 
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