[llvm] [BOLT] Add extra staleness logging (PR #80225)

[Amir Ayupov via llvm-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/80225

Report two extra metrics:
- # of stale functions with matching block count,
- # of stale blocks with matching instruction count.


>From d3a928ef919a9d9ed3be5a207f89356532ae184f Mon Sep 17 00:00:00 2001
From: Amir Ayupov <aaupov at fb.com>
Date: Sat, 27 Jan 2024 19:00:42 -0800
Subject: [PATCH] [BOLT] Add extra staleness logging

Report two extra metrics:
- # of stale functions with matching block count,
- # of stale blocks with matching instruction count.
---
 bolt/include/bolt/Core/BinaryContext.h    |  5 +++++
 bolt/lib/Passes/BinaryPasses.cpp          | 16 ++++++++++++++++
 bolt/lib/Profile/StaleProfileMatching.cpp |  3 +++
 bolt/lib/Profile/YAMLProfileReader.cpp    | 20 ++++++++++----------
 4 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/bolt/include/bolt/Core/BinaryContext.h b/bolt/include/bolt/Core/BinaryContext.h
index f0e7a8272ad0e..d6849cb8cc0eb 100644
--- a/bolt/include/bolt/Core/BinaryContext.h
+++ b/bolt/include/bolt/Core/BinaryContext.h
@@ -665,6 +665,11 @@ class BinaryContext {
     uint64_t StaleSampleCount{0};
     ///   the count of matched samples
     uint64_t MatchedSampleCount{0};
+    ///   the number of stale functions that have matching number of blocks in
+    ///   the profile
+    uint64_t NumStaleFuncsWithEqualBlockCount{0};
+    ///   the number of blocks that have matching size but a differing hash
+    uint64_t NumStaleBlocksWithEqualIcount{0};
   } Stats;
 
   // Address of the first allocated segment.
diff --git a/bolt/lib/Passes/BinaryPasses.cpp b/bolt/lib/Passes/BinaryPasses.cpp
index 955cd3726ad41..8505d37491415 100644
--- a/bolt/lib/Passes/BinaryPasses.cpp
+++ b/bolt/lib/Passes/BinaryPasses.cpp
@@ -1420,6 +1420,12 @@ void PrintProgramStats::runOnFunctions(BinaryContext &BC) {
   if (NumAllStaleFunctions) {
     const float PctStale =
         NumAllStaleFunctions / (float)NumAllProfiledFunctions * 100.0f;
+    const float PctStaleFuncsWithEqualBlockCount =
+        (float)BC.Stats.NumStaleFuncsWithEqualBlockCount /
+        NumAllStaleFunctions * 100.0f;
+    const float PctStaleBlocksWithEqualIcount =
+        (float)BC.Stats.NumStaleBlocksWithEqualIcount /
+        BC.Stats.NumStaleBlocks * 100.0f;
     auto printErrorOrWarning = [&]() {
       if (PctStale > opts::StaleThreshold)
         errs() << "BOLT-ERROR: ";
@@ -1442,6 +1448,16 @@ void PrintProgramStats::runOnFunctions(BinaryContext &BC) {
              << "%) belong to functions with invalid"
                 " (possibly stale) profile.\n";
     }
+    outs() << "BOLT-INFO: " << BC.Stats.NumStaleFuncsWithEqualBlockCount
+           << " stale function"
+           << (BC.Stats.NumStaleFuncsWithEqualBlockCount == 1 ? "" : "s")
+           << format(" (%.1f%% of all stale)", PctStaleFuncsWithEqualBlockCount)
+           << " have matching block count.\n";
+    outs() << "BOLT-INFO: " << BC.Stats.NumStaleBlocksWithEqualIcount
+           << " stale block"
+           << (BC.Stats.NumStaleBlocksWithEqualIcount == 1 ? "" : "s")
+           << format(" (%.1f%% of all stale)", PctStaleBlocksWithEqualIcount)
+           << " have matching icount.\n";
     if (PctStale > opts::StaleThreshold) {
       errs() << "BOLT-ERROR: stale functions exceed specified threshold of "
              << opts::StaleThreshold << "%. Exiting.\n";
diff --git a/bolt/lib/Profile/StaleProfileMatching.cpp b/bolt/lib/Profile/StaleProfileMatching.cpp
index 26180f1321477..631ccaec6ae61 100644
--- a/bolt/lib/Profile/StaleProfileMatching.cpp
+++ b/bolt/lib/Profile/StaleProfileMatching.cpp
@@ -418,6 +418,7 @@ void matchWeightsByHashes(BinaryContext &BC,
     if (MatchedBlock == nullptr && YamlBB.Index == 0)
       MatchedBlock = Blocks[0];
     if (MatchedBlock != nullptr) {
+      const BinaryBasicBlock *BB = BlockOrder[MatchedBlock->Index - 1];
       MatchedBlocks[YamlBB.Index] = MatchedBlock;
       BlendedBlockHash BinHash = BlendedHashes[MatchedBlock->Index - 1];
       LLVM_DEBUG(dbgs() << "Matched yaml block (bid = " << YamlBB.Index << ")"
@@ -433,6 +434,8 @@ void matchWeightsByHashes(BinaryContext &BC,
       } else {
         LLVM_DEBUG(dbgs() << "  loose match\n");
       }
+      if (YamlBB.NumInstructions == BB->size())
+        ++BC.Stats.NumStaleBlocksWithEqualIcount;
     } else {
       LLVM_DEBUG(
           dbgs() << "Couldn't match yaml block (bid = " << YamlBB.Index << ")"
diff --git a/bolt/lib/Profile/YAMLProfileReader.cpp b/bolt/lib/Profile/YAMLProfileReader.cpp
index a4a401fd3cabf..e4673f6e3c301 100644
--- a/bolt/lib/Profile/YAMLProfileReader.cpp
+++ b/bolt/lib/Profile/YAMLProfileReader.cpp
@@ -246,20 +246,20 @@ bool YAMLProfileReader::parseFunctionProfile(
 
   ProfileMatched &= !MismatchedBlocks && !MismatchedCalls && !MismatchedEdges;
 
-  if (ProfileMatched)
-    BF.markProfiled(YamlBP.Header.Flags);
+  if (!ProfileMatched) {
+    if (opts::Verbosity >= 1)
+      errs() << "BOLT-WARNING: " << MismatchedBlocks << " blocks, "
+             << MismatchedCalls << " calls, and " << MismatchedEdges
+             << " edges in profile did not match function " << BF << '\n';
 
-  if (!ProfileMatched && opts::Verbosity >= 1)
-    errs() << "BOLT-WARNING: " << MismatchedBlocks << " blocks, "
-           << MismatchedCalls << " calls, and " << MismatchedEdges
-           << " edges in profile did not match function " << BF << '\n';
+    if (YamlBF.NumBasicBlocks != BF.size())
+      ++BC.Stats.NumStaleFuncsWithEqualBlockCount;
 
-  if (!ProfileMatched && opts::InferStaleProfile) {
-    if (inferStaleProfile(BF, YamlBF)) {
+    if (opts::InferStaleProfile && inferStaleProfile(BF, YamlBF))
       ProfileMatched = true;
-      BF.markProfiled(YamlBP.Header.Flags);
-    }
   }
+  if (ProfileMatched)
+    BF.markProfiled(YamlBP.Header.Flags);
 
   return ProfileMatched;
 }