[llvm] [BOLT][NFC] Set NeedsConvertRetProfileToCallCont for pre-aggregated profile (PR #126997)

[Amir Ayupov via llvm-commits]

https://github.com/aaupov created https://github.com/llvm/llvm-project/pull/126997

Instead of passing `IsPreagg` to decide whether or not return profile
needs to be converted into call to continuation fallthrough, set
`NeedsConvertRetProfileToCallCont` based on whether pre-aggregated
profile has a certain format (B, F, or f).

Test Plan: ninja check-bolt


>From 95ae44fbfd439b447c22687178581737cc960126 Mon Sep 17 00:00:00 2001
From: Amir Ayupov <aaupov at fb.com>
Date: Wed, 12 Feb 2025 18:07:03 -0800
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Created using spr 1.3.4
---
 bolt/include/bolt/Profile/DataAggregator.h |  7 +++++--
 bolt/lib/Profile/DataAggregator.cpp        | 15 ++++++++++-----
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/bolt/include/bolt/Profile/DataAggregator.h b/bolt/include/bolt/Profile/DataAggregator.h
index aa83d7f9b13ab..dc8b7d21447b7 100644
--- a/bolt/include/bolt/Profile/DataAggregator.h
+++ b/bolt/include/bolt/Profile/DataAggregator.h
@@ -197,6 +197,10 @@ class DataAggregator : public DataReader {
 
   BoltAddressTranslation *BAT{nullptr};
 
+  /// Whether pre-aggregated profile needs to convert branch profile into call
+  /// to continuation fallthrough profile.
+  bool NeedsConvertRetProfileToCallCont{false};
+
   /// Update function execution profile with a recorded trace.
   /// A trace is region of code executed between two LBR entries supplied in
   /// execution order.
@@ -268,8 +272,7 @@ class DataAggregator : public DataReader {
                      uint64_t Mispreds);
 
   /// Register a \p Branch.
-  bool doBranch(uint64_t From, uint64_t To, uint64_t Count, uint64_t Mispreds,
-                bool IsPreagg);
+  bool doBranch(uint64_t From, uint64_t To, uint64_t Count, uint64_t Mispreds);
 
   /// Register a trace between two LBR entries supplied in execution order.
   bool doTrace(const LBREntry &First, const LBREntry &Second,
diff --git a/bolt/lib/Profile/DataAggregator.cpp b/bolt/lib/Profile/DataAggregator.cpp
index de9ec6c1723d5..704c8847df413 100644
--- a/bolt/lib/Profile/DataAggregator.cpp
+++ b/bolt/lib/Profile/DataAggregator.cpp
@@ -711,7 +711,7 @@ bool DataAggregator::doInterBranch(BinaryFunction *FromFunc,
 }
 
 bool DataAggregator::doBranch(uint64_t From, uint64_t To, uint64_t Count,
-                              uint64_t Mispreds, bool IsPreagg) {
+                              uint64_t Mispreds) {
   // Returns whether \p Offset in \p Func contains a return instruction.
   auto checkReturn = [&](const BinaryFunction &Func, const uint64_t Offset) {
     auto isReturn = [&](auto MI) { return MI && BC->MIB->isReturn(*MI); };
@@ -772,7 +772,8 @@ bool DataAggregator::doBranch(uint64_t From, uint64_t To, uint64_t Count,
     return false;
 
   // Record call to continuation trace.
-  if (IsPreagg && FromFunc != ToFunc && (IsReturn || IsCallCont)) {
+  if (NeedsConvertRetProfileToCallCont && FromFunc != ToFunc &&
+      (IsReturn || IsCallCont)) {
     LBREntry First{ToOrig - 1, ToOrig - 1, false};
     LBREntry Second{ToOrig, ToOrig, false};
     return doTrace(First, Second, Count);
@@ -1224,12 +1225,17 @@ DataAggregator::parseAggregatedLBREntry() {
   ErrorOr<StringRef> TypeOrErr = parseString(FieldSeparator);
   if (std::error_code EC = TypeOrErr.getError())
     return EC;
+  // Pre-aggregated profile with branches and fallthroughs needs to convert
+  // return profile into call to continuation fall-through.
   auto Type = AggregatedLBREntry::BRANCH;
   if (TypeOrErr.get() == "B") {
+    NeedsConvertRetProfileToCallCont = true;
     Type = AggregatedLBREntry::BRANCH;
   } else if (TypeOrErr.get() == "F") {
+    NeedsConvertRetProfileToCallCont = true;
     Type = AggregatedLBREntry::FT;
   } else if (TypeOrErr.get() == "f") {
+    NeedsConvertRetProfileToCallCont = true;
     Type = AggregatedLBREntry::FT_EXTERNAL_ORIGIN;
   } else {
     reportError("expected B, F or f");
@@ -1585,8 +1591,7 @@ void DataAggregator::processBranchEvents() {
   for (const auto &AggrLBR : BranchLBRs) {
     const Trace &Loc = AggrLBR.first;
     const TakenBranchInfo &Info = AggrLBR.second;
-    doBranch(Loc.From, Loc.To, Info.TakenCount, Info.MispredCount,
-             /*IsPreagg*/ false);
+    doBranch(Loc.From, Loc.To, Info.TakenCount, Info.MispredCount);
   }
 }
 
@@ -1747,7 +1752,7 @@ void DataAggregator::processPreAggregated() {
     switch (AggrEntry.EntryType) {
     case AggregatedLBREntry::BRANCH:
       doBranch(AggrEntry.From.Offset, AggrEntry.To.Offset, AggrEntry.Count,
-               AggrEntry.Mispreds, /*IsPreagg*/ true);
+               AggrEntry.Mispreds);
       break;
     case AggregatedLBREntry::FT:
     case AggregatedLBREntry::FT_EXTERNAL_ORIGIN: {