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[BOLT] Fix counts aggregation in merge-fdata (#119652)

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merge-fdata used to consider misprediction count as part of "signature",
or the aggregation key. This prevented it from collapsing profile lines
with different misprediction counts, which resulted in duplicate
`(from, to)` pairs with different misprediction and execution counts.

Fix that by splitting out misprediction count and accumulating it
separately.

Test Plan: updated bolt/test/merge-fdata-lbr-mode.test
This commit is contained in:
Amir Ayupov 2024-12-14 22:38:24 -08:00 committed by GitHub
parent 97f43364cc
commit 8652608404
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
2 changed files with 33 additions and 14 deletions
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6
bolt/test/merge-fdata-lbr-mode.test
View File

@ -7,9 +7,9 @@
# RUN: FileCheck %s --input-file %t/merged.fdata
# CHECK-NOT: no_lbr
# CHECK: main 2
# CHECK: 1 main 0 1 main 2 1 3
#--- a.fdata
main 1
1 main 0 1 main 2 0 1
#--- b.fdata
main 1
1 main 0 1 main 2 1 2

41
bolt/tools/merge-fdata/merge-fdata.cpp
View File

@ -268,7 +268,17 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
std::optional<bool> BoltedCollection;
std::optional<bool> NoLBRCollection;
std::mutex BoltedCollectionMutex;
typedef StringMap<uint64_t> ProfileTy;
struct CounterTy {
uint64_t Exec{0};
uint64_t Mispred{0};
CounterTy &operator+=(const CounterTy &O) {
Exec += O.Exec;
Mispred += O.Mispred;
return *this;
}
CounterTy operator+(const CounterTy &O) { return *this += O; }
};
typedef StringMap<CounterTy> ProfileTy;
auto ParseProfile = [&](const std::string &Filename, auto &Profiles) {
const llvm::thread::id tid = llvm::this_thread::get_id();
@ -305,13 +315,18 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
do {
StringRef Line(FdataLine);
size_t Pos = Line.rfind(" ");
if (Pos == StringRef::npos)
report_error(Filename, "Malformed / corrupted profile");
StringRef Signature = Line.substr(0, Pos);
uint64_t Count;
if (Line.substr(Pos + 1, Line.size() - Pos).getAsInteger(10, Count))
report_error(Filename, "Malformed / corrupted profile counter");
CounterTy Count;
auto [Signature, ExecCount] = Line.rsplit(' ');
if (ExecCount.getAsInteger(10, Count.Exec))
report_error(Filename, "Malformed / corrupted execution count");
// Only LBR profile has misprediction field
if (!NoLBRCollection.value_or(false)) {
auto [SignatureLBR, MispredCount] = Signature.rsplit(' ');
Signature = SignatureLBR;
if (MispredCount.getAsInteger(10, Count.Mispred))
report_error(Filename, "Malformed / corrupted misprediction count");
}
Count += Profile->lookup(Signature);
Profile->insert_or_assign(Signature, Count);
} while (std::getline(FdataFile, FdataLine));
@ -331,7 +346,7 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
ProfileTy MergedProfile;
for (const auto &[Thread, Profile] : ParsedProfiles)
for (const auto &[Key, Value] : Profile) {
uint64_t Count = MergedProfile.lookup(Key) + Value;
CounterTy Count = MergedProfile.lookup(Key) + Value;
MergedProfile.insert_or_assign(Key, Count);
}
@ -339,8 +354,12 @@ void mergeLegacyProfiles(const SmallVectorImpl<std::string> &Filenames) {
output() << "boltedcollection\n";
if (NoLBRCollection.value_or(false))
output() << "no_lbr\n";
for (const auto &[Key, Value] : MergedProfile)
output() << Key << " " << Value << "\n";
for (const auto &[Key, Value] : MergedProfile) {
output() << Key << " ";
if (!NoLBRCollection.value_or(false))
output() << Value.Mispred << " ";
output() << Value.Exec << "\n";
}
errs() << "Profile from " << Filenames.size() << " files merged.\n";
}