[PATCH] D10674: Value profiling - patchset 3

Betul Buyukkurt via llvm-commits llvm-commits at lists.llvm.org
Tue Sep 22 09:41:40 PDT 2015


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-----Original Message-----
From: Betul Buyukkurt [mailto:betulb at codeaurora.org] 
Sent: Friday, September 18, 2015 11:41 AM
To: Justin Bogner
Cc: Betul Buyukkurt; dnovillo at google.com; dsule at codeaurora.org;
davidxl at google.com; ibaev at codeaurora.org;
reviews+d10674+public+89cd3d23a57d43c9 at reviews.llvm.org;
llvm-commits at lists.llvm.org
Subject: Re: [PATCH] D10674: Value profiling - patchset 3


Hi Justin,

Thanks for the review comments. Please find my responses inline.

Thanks,
-Betul

> Betul Buyukkurt <betulb at codeaurora.org> writes:
>> betulb updated this revision to Diff 33963.
>> betulb added a comment.
>>
>> In this revision:
>>
>> - Turned the error to assert for "hash value not matching any known key"
>> - Used rvalue-reference semantics when passing arguments into the 
>> InstrProfWriter's addRecord routine. String table usage caused the 
>> undesirable removal of const qualifier from addRecord's argument. Now 
>> the arguments to addRecord are clearly passed using std::move()
>> - In combineInstrProfRecords, tried to account for when value 
>> profiling is not enabled for a given kind for Source vs enabled for 
>> Dest and vice versa.
>> - Used std::vector's empty() instead of comparing size() against 0
>
> This is starting to look pretty good. I have a few more comments, but 
> first, there was one suggestion I made in a previous mail that I'm not 
> entirely convinced by your answer to:
>
> Betul Buyukkurt <betulb at codeaurora.org> writes:
>>>> /// Profiling information for a single function.
>>>> struct InstrProfRecord {
>>>>    InstrProfRecord() {}
>>>> InstrProfRecord(StringRef Name, uint64_t Hash, 
>>>> std::vector<uint64_t>
> Counts)
>>>>        : Name(Name), Hash(Hash), Counts(std::move(Counts)) {}
>>>>    StringRef Name;
>>>>    uint64_t Hash;
>>>>    std::vector<uint64_t> Counts;
>>>> +  // Size of vector indicates the number of value sites for a 
>>>> + value
> kind
>>>> + std::vector<InstrProfValueSiteRecord>
> ValueSites[instrprof_value_kind::size];
>>>
>>> I don't think we're gaining much by having this be an array - I was 
>>> thinking it would be more like
>>>
>>>   std::vector<InstrProfValueSiteRecord> IndirectCalls;

Done.

>>>
>>> Then when we add more value types, they can have their own variables
> and
>>> be accessed directly. Most of the code that works with these will 
>>> have
> a
>>> particular kind in mind, and since the value data is dependent on 
>>> kind looping over these isn't generally that useful. That is, the 
>>> looping we have now is only in the reader and writer, and I can't 
>>> see the users of the data ever doing that.
>>
>> I think, I'm leaning towards keeping an array of kinds here.
>
> Why?
>
>>> For the reader and writer, a switch statement over the kinds will 
>>> allow us to warn if someone doesn't update somewhere when they add a 
>>> new kind. For the users of profile data, Data->IndirectCalls reads a 
>>> lot better than
> Data->ValueSites[instrprof_value_kind::indirect_call_target].
>>
>> I'll revisit my latest patch to allow for that.
>
> Obviously, you didn't do this, since the comment above said you 
> weren't going to.
>
> A few more things on the latest patch:
>
> Betul Buyukkurt <betulb at codeaurora.org> writes:
>> Index: unittests/ProfileData/InstrProfTest.cpp
>> ===================================================================
>> --- unittests/ProfileData/InstrProfTest.cpp
>> +++ unittests/ProfileData/InstrProfTest.cpp
>> @@ -50,7 +50,8 @@
>>  }
>>
>>  TEST_F(InstrProfTest, write_and_read_one_function) {
>> -  Writer.addFunctionCounts("foo", 0x1234, {1, 2, 3, 4});
>> +  InstrProfRecord Record("foo", 0x1234, {1, 2, 3, 4});  
>> + Writer.addRecord(std::move(Record));
>>    auto Profile = Writer.writeBuffer();
>>    readProfile(std::move(Profile));
>>
>> @@ -67,8 +68,10 @@
>>  }
>>
>>  TEST_F(InstrProfTest, get_function_counts) {
>> -  Writer.addFunctionCounts("foo", 0x1234, {1, 2});
>> -  Writer.addFunctionCounts("foo", 0x1235, {3, 4});
>> +  InstrProfRecord Record1("foo", 0x1234, {1, 2});  InstrProfRecord 
>> + Record2("foo", 0x1235, {3, 4});  
>> + Writer.addRecord(std::move(Record1));
>> +  Writer.addRecord(std::move(Record2));
>>    auto Profile = Writer.writeBuffer();
>>    readProfile(std::move(Profile));
>>
>> @@ -92,9 +95,12 @@
>>  }
>>
>>  TEST_F(InstrProfTest, get_max_function_count) {
>> -  Writer.addFunctionCounts("foo", 0x1234, {1ULL << 31, 2});
>> -  Writer.addFunctionCounts("bar", 0, {1ULL << 63});
>> -  Writer.addFunctionCounts("baz", 0x5678, {0, 0, 0, 0});
>> +  InstrProfRecord Record1("foo", 0x1234, {1ULL << 31, 2});  
>> + InstrProfRecord Record2("bar", 0, {1ULL << 63});  InstrProfRecord 
>> + Record3("baz", 0x5678, {0, 0, 0, 0});  
>> + Writer.addRecord(std::move(Record1));
>> +  Writer.addRecord(std::move(Record2));
>> +  Writer.addRecord(std::move(Record3));
>>    auto Profile = Writer.writeBuffer();
>>    readProfile(std::move(Profile));
>>
>> Index: unittests/ProfileData/CoverageMappingTest.cpp
>> ===================================================================
>> --- unittests/ProfileData/CoverageMappingTest.cpp
>> +++ unittests/ProfileData/CoverageMappingTest.cpp
>> @@ -188,7 +188,8 @@
>>  }
>>
>>  TEST_F(CoverageMappingTest, basic_coverage_iteration) {
>> -  ProfileWriter.addFunctionCounts("func", 0x1234, {30, 20, 10, 0});
>> +  InstrProfRecord Record("func", 0x1234, {30, 20, 10, 0});  
>> + ProfileWriter.addRecord(std::move(Record));
>>    readProfCounts();
>>
>>    addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9); @@ -238,7 
>> +239,8 @@  }
>>
>>  TEST_F(CoverageMappingTest, combine_regions) {
>> -  ProfileWriter.addFunctionCounts("func", 0x1234, {10, 20, 30});
>> +  InstrProfRecord Record("func", 0x1234, {10, 20, 30});  
>> + ProfileWriter.addRecord(std::move(Record));
>>    readProfCounts();
>>
>>    addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9); @@ -256,7 
>> +258,8 @@  }
>>
>>  TEST_F(CoverageMappingTest, dont_combine_expansions) {
>> -  ProfileWriter.addFunctionCounts("func", 0x1234, {10, 20});
>> +  InstrProfRecord Record("func", 0x1234, {10, 20});  
>> + ProfileWriter.addRecord(std::move(Record));
>>    readProfCounts();
>>
>>    addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9); @@ -275,7 
>> +278,8 @@  }
>>
>>  TEST_F(CoverageMappingTest, strip_filename_prefix) {
>> -  ProfileWriter.addFunctionCounts("file1:func", 0x1234, {10});
>> +  InstrProfRecord Record("file1:func", 0x1234, {10});  
>> + ProfileWriter.addRecord(std::move(Record));
>>    readProfCounts();
>>
>>    addCMR(Counter::getCounter(0), "file1", 1, 1, 9, 9);
>> Index: tools/llvm-profdata/llvm-profdata.cpp
>> ===================================================================
>> --- tools/llvm-profdata/llvm-profdata.cpp
>> +++ tools/llvm-profdata/llvm-profdata.cpp
>> @@ -58,9 +58,8 @@
>>        exitWithError(ec.message(), Filename);
>>
>>      auto Reader = std::move(ReaderOrErr.get());
>> -    for (const auto &I : *Reader)
>> -      if (std::error_code EC =
>> -              Writer.addFunctionCounts(I.Name, I.Hash, I.Counts))
>> +    for (auto &I : *Reader)
>> +      if (std::error_code EC = Writer.addRecord(std::move(I)))
>>          errs() << Filename << ": " << I.Name << ": " << EC.message() 
>> <<
> "\n";
>>      if (Reader->hasError())
>>        exitWithError(Reader->getError().message(), Filename); @@ 
>> -134,8 +133,8 @@  }
>>
>>  static int showInstrProfile(std::string Filename, bool ShowCounts,
>> -                            bool ShowAllFunctions, std::string
> ShowFunction,
>> -                            raw_fd_ostream &OS) {
>> +                            bool ShowIndirectCallTargets, bool
> ShowAllFunctions,
>> +                            std::string ShowFunction, raw_fd_ostream
> &OS) {
>>    auto ReaderOrErr = InstrProfReader::create(Filename);
>>    if (std::error_code EC = ReaderOrErr.getError())
>>      exitWithError(EC.message(), Filename); @@ -162,6 +161,10 @@
>>           << "    Hash: " << format("0x%016" PRIx64, Func.Hash) << "\n"
>>           << "    Counters: " << Func.Counts.size() << "\n"
>>           << "    Function count: " << Func.Counts[0] << "\n";
>> +      if (ShowIndirectCallTargets)
>> +        OS << "    Indirect Call Site Count: "
>> +           <<
> Func.ValueSites[instrprof_value_kind::indirect_call_target].size()
>> +           << "\n";
>>      }
>>
>>      if (Show && ShowCounts)
>> @@ -174,6 +177,17 @@
>>      }
>>      if (Show && ShowCounts)
>>        OS << "]\n";
>> +
>> +    if (Show && ShowIndirectCallTargets) {
>> +      OS << "    Indirect Target Results: \n";
>> +      uint32_t ValueKind = instrprof_value_kind::indirect_call_target;
>> +      for (size_t I = 0, E = Func.ValueSites[ValueKind].size(); I < 
>> + E;
> ++I) {
>> +        for (auto V : Func.ValueSites[ValueKind][I].ValueData) {
>> +          OS << "\t[ " << I << ", ";
>> +          OS << (const char *)V.first << ", " << V.second << " ]\n";
>> +        }
>> +      }
>> +    }
>>    }
>>    if (Reader->hasError())
>>      exitWithError(Reader->getError().message(), Filename); @@ -210,6 
>> +224,8 @@
>>
>>    cl::opt<bool> ShowCounts("counts", cl::init(false),
>>                             cl::desc("Show counter values for shown
> functions"));
>> +  cl::opt<bool> ShowIndirectCallTargets("ic-targets", cl::init(false),
>> +      cl::desc("Show indirect call site target values for shown
> functions"));
>>    cl::opt<bool> ShowAllFunctions("all-functions", cl::init(false),
>>                                   cl::desc("Details for every
> function"));
>>    cl::opt<std::string> ShowFunction("function", @@ -238,8 +254,8 @@
>>      errs() << "warning: -function argument ignored: showing all
> functions\n";
>>
>>    if (ProfileKind == instr)
>> -    return showInstrProfile(Filename, ShowCounts, ShowAllFunctions,
>> -                            ShowFunction, OS);
>> +    return showInstrProfile(Filename, ShowCounts,
> ShowIndirectCallTargets,
>> +                            ShowAllFunctions, ShowFunction, OS);
>>    else
>>      return showSampleProfile(Filename, ShowCounts, ShowAllFunctions,
>>                               ShowFunction, OS);
>> Index: lib/ProfileData/InstrProfWriter.cpp
>> ===================================================================
>> --- lib/ProfileData/InstrProfWriter.cpp
>> +++ lib/ProfileData/InstrProfWriter.cpp
>> @@ -26,8 +26,8 @@
>>    typedef StringRef key_type;
>>    typedef StringRef key_type_ref;
>>
>> -  typedef const InstrProfWriter::CounterData *const data_type;
>> -  typedef const InstrProfWriter::CounterData *const data_type_ref;
>> +  typedef const InstrProfWriter::ProfilingData *const data_type;
>> +  typedef const InstrProfWriter::ProfilingData *const data_type_ref;
>>
>>    typedef uint64_t hash_value_type;
>>    typedef uint64_t offset_type;
>> @@ -45,8 +45,30 @@
>>      LE.write<offset_type>(N);
>>
>>      offset_type M = 0;
>> -    for (const auto &Counts : *V)
>> -      M += (2 + Counts.second.size()) * sizeof(uint64_t);
>> +    for (const auto &ProfileData : *V) {
>> +      M += sizeof(uint64_t); // size of function hash
>> +      M += sizeof(uint64_t); // size of
> ProfileData.second.Counts.size()
>
> I'd write this as "The function hash", and "The number of profile counts".

Done. I used a different text for the latter suggestion.

>
>> +      M += ProfileData.second.Counts.size() * sizeof(uint64_t);
>> +
>> +      // Value data
>> +      M += sizeof(uint64_t); // Number of value kinds with value sites.
>> +      for (uint32_t Kind = instrprof_value_kind::first;
>> +           Kind < instrprof_value_kind::size; ++Kind) {
>> +        if (ProfileData.second.ValueSites[Kind].empty())
>> +          continue;
>> +        M += sizeof(uint64_t); // Value kind
>> +        // Number of value sites for current value kind
>> +        M += sizeof(uint64_t); //
> ProfileData.second.ValuesSites[Kind].size()
>
> "The number of value kinds"

Done.

>
>> +        for (InstrProfValueSiteRecord I :
> ProfileData.second.ValueSites[Kind]) {
>> +          // Number of value data pairs at a value site
>> +          M += sizeof(uint64_t); // I.ValueData.size()
>> +          for (auto V : I.ValueData) {
>> +            M += sizeof(uint64_t); // size of TargetValue
>> +            M += sizeof(uint64_t); // size of NumTaken
>> +          }
>
> Either way's fine, but would it read better to do
>
>   M += 2 * sizeof(uint64_t) * I.ValueData.size();
>
> ?

Done.


>> +        }
>> +      }
>> +    }
>>      LE.write<offset_type>(M);
>>
>>      return std::make_pair(N, M);
>> @@ -60,52 +82,106 @@
>>                         offset_type) {
>>      using namespace llvm::support;
>>      endian::Writer<little> LE(Out);
>> -
>> -    for (const auto &Counts : *V) {
>> -      LE.write<uint64_t>(Counts.first);
>> -      LE.write<uint64_t>(Counts.second.size());
>> -      for (uint64_t I : Counts.second)
>> +    for (const auto &ProfileData : *V) {
>> +      LE.write<uint64_t>(ProfileData.first); // Function hash
>> +      LE.write<uint64_t>(ProfileData.second.Counts.size());
>> +      for (uint64_t I : ProfileData.second.Counts)
>>          LE.write<uint64_t>(I);
>> +
>> +      // Compute the number of value kinds with value sites.
>> +      uint64_t NumValueKinds = 0;
>> +      for (uint32_t Kind = instrprof_value_kind::first;
>> +           Kind < instrprof_value_kind::size; ++Kind)
>> +        NumValueKinds +=
> !(ProfileData.second.ValueSites[Kind].empty());
>> +      LE.write<uint64_t>(NumValueKinds);
>> +
>> +      // Write value data
>> +      for (uint32_t Kind = instrprof_value_kind::first;
>> +           Kind < instrprof_value_kind::size; ++Kind) {
>> +        if (ProfileData.second.ValueSites[Kind].empty())
>> +          continue;
>> +        LE.write<uint64_t>(Kind); // Write value kind
>> +        // Write number of value sites for current value kind
>> +        LE.write<uint64_t>(ProfileData.second.ValueSites[Kind].size());
>> +        for (InstrProfValueSiteRecord I :
> ProfileData.second.ValueSites[Kind]) {
>> +          // Write number of value data pairs at this value site
>> +          LE.write<uint64_t>(I.ValueData.size());
>> +          for (auto V : I.ValueData) {
>> +            if (Kind == instrprof_value_kind::indirect_call_target)
>> +              LE.write<uint64_t>(ComputeHash((const char *)V.first));
>> +            else
>> +              LE.write<uint64_t>(V.first);
>
> This should just assert(Kind ==
> instrprof_value_kind::indirect_call_target).
> We don't want to be writing out data we don't understand. That said, if
> you get rid of the array that doesn't come up.

I'm doing the llvm_unreachable in InstrProf.h. I've defined two new
methods for the InstrProfRecord. These are:
  const std::vector<InstrProfValueSiteRecord>& getValueSitesForKind(
      uint32_t ValueKind) const;
and
  std::vector<InstrProfValueSiteRecord>& getValueSitesForKind(uint32_t
ValueKind);.

These methods use switch/case to pick the appropriate value site vector
for the given value kind. If no value site vector was defined for the
passed argument, the methods use llvm_unreachable instead of an explicit
assert. Please check and let know if this still makes sense for you. To me
this was a clean implementation.

>
>> +            LE.write<uint64_t>(V.second);
>> +          }
>> +        }
>> +      }
>>      }
>>    }
>>  };
>>  }
>>
>> -std::error_code
>> -InstrProfWriter::addFunctionCounts(StringRef FunctionName,
>> -                                   uint64_t FunctionHash,
>> -                                   ArrayRef<uint64_t> Counters) {
>> -  auto &CounterData = FunctionData[FunctionName];
>> -
>> -  auto Where = CounterData.find(FunctionHash);
>> -  if (Where == CounterData.end()) {
>> -    // We've never seen a function with this name and hash, add it.
>> -    CounterData[FunctionHash] = Counters;
>> -    // We keep track of the max function count as we go for simplicity.
>> -    if (Counters[0] > MaxFunctionCount)
>> -      MaxFunctionCount = Counters[0];
>> -    return instrprof_error::success;
>> -  }
>> -
>> -  // We're updating a function we've seen before.
>> -  auto &FoundCounters = Where->second;
>> -  // If the number of counters doesn't match we either have bad data or
> a hash
>> -  // collision.
>> -  if (FoundCounters.size() != Counters.size())
>> +static std::error_code combineInstrProfRecords(InstrProfRecord &Dest,
>> +                                               InstrProfRecord &Source,
>> +                                               uint64_t
> &MaxFunctionCount) {
>> +  // If the number of counters doesn't match we either have bad data
>> +  // or a hash collision.
>> +  if (Dest.Counts.size() != Source.Counts.size())
>>      return instrprof_error::count_mismatch;
>>
>> -  for (size_t I = 0, E = Counters.size(); I < E; ++I) {
>> -    if (FoundCounters[I] + Counters[I] < FoundCounters[I])
>> +  for (size_t I = 0, E = Source.Counts.size(); I < E; ++I) {
>> +    if (Dest.Counts[I] + Source.Counts[I] < Dest.Counts[I])
>>        return instrprof_error::counter_overflow;
>> -    FoundCounters[I] += Counters[I];
>> +    Dest.Counts[I] += Source.Counts[I];
>> +  }
>> +
>> +  for (uint32_t Kind = instrprof_value_kind::first;
>> +       Kind < instrprof_value_kind::size; ++Kind) {
>> +    if (Source.ValueSites[Kind].empty())
>> +      continue;
>> +    if (Dest.ValueSites[Kind].empty()) {
>> +      Dest.ValueSites[Kind].swap(Source.ValueSites[Kind]);
>> +      continue;
>> +    }
>
> Why do we allow combining data that has no value sites with data that
> does? Does that actually make sense?
>
>> +    if (Dest.ValueSites[Kind].size() != Source.ValueSites[Kind].size())
>> +      return instrprof_error::value_site_count_mismatch;
>> +    for (size_t I = 0, E = Source.ValueSites[Kind].size(); I < E; ++I)
>> +
> Dest.ValueSites[Kind][I].mergeValueData(Source.ValueSites[Kind][I]);
>>    }
>> +
>>    // We keep track of the max function count as we go for simplicity.
>> -  if (FoundCounters[0] > MaxFunctionCount)
>> -    MaxFunctionCount = FoundCounters[0];
>> +  if (Dest.Counts[0] > MaxFunctionCount)
>> +    MaxFunctionCount = Dest.Counts[0];
>>
>>    return instrprof_error::success;
>>  }
>>
>> +void InstrProfWriter::updateStringTableReferences(InstrProfRecord &I) {
>> +  I.Name = StringTable.insertString(I.Name);
>> +  for (auto& VSite :
> I.ValueSites[instrprof_value_kind::indirect_call_target])
>> +    for (auto& VData : VSite.ValueData)
>> +      VData.first =
>> +          (uint64_t)StringTable.insertString((const char
> *)VData.first);
>
> I'm a little uncomfortable that we need to modify the Name in the
> iterators here. Can't the data structure backing the string table just
> work in StringRefs instead?
>
>> +}
>> +
>> +std::error_code InstrProfWriter::addRecord(InstrProfRecord &&I) {
>> +  updateStringTableReferences(I);
>> +  auto &ProfileDataMap = FunctionData[I.Name];
>> +
>> +  auto Where = ProfileDataMap.find(I.Hash);
>> +  if (Where == ProfileDataMap.end()) {
>> +    // We've never seen a function with this name and hash, add it.
>> +    ProfileDataMap[I.Hash] = I;
>> +
>> +    // We keep track of the max function count as we go for simplicity.
>> +    if (I.Counts[0] > MaxFunctionCount)
>> +      MaxFunctionCount = I.Counts[0];
>> +    return instrprof_error::success;
>> +  }
>> +
>> +  // We're updating a function we've seen before.
>> +  return combineInstrProfRecords(Where->second, I, MaxFunctionCount);
>> +}
>> +
>>  std::pair<uint64_t, uint64_t> InstrProfWriter::writeImpl(raw_ostream
> &OS) {
>>    OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
>>
>> Index: lib/ProfileData/InstrProfReader.cpp
>> ===================================================================
>> --- lib/ProfileData/InstrProfReader.cpp
>> +++ lib/ProfileData/InstrProfReader.cpp
>> @@ -15,8 +15,12 @@
>>  #include "llvm/ProfileData/InstrProfReader.h"
>>  #include "InstrProfIndexed.h"
>>  #include "llvm/ADT/STLExtras.h"
>> +#include "llvm/Support/Debug.h"
>> +#include "llvm/Support/raw_ostream.h"
>>  #include <cassert>
>>
>> +#define DEBUG_TYPE "InstrProfReader"
>> +
>>  using namespace llvm;
>>
>>  static ErrorOr<std::unique_ptr<MemoryBuffer>>
>> @@ -302,42 +306,94 @@
>>  typedef InstrProfLookupTrait::data_type data_type;
>>  typedef InstrProfLookupTrait::offset_type offset_type;
>>
>> +bool InstrProfLookupTrait::ReadValueProfilingData(
>> +    const unsigned char *&D, const unsigned char *const End) {
>> +
>> +  using namespace support;
>> +  // Read number of value kinds with value sites.
>> +  if (D + sizeof(uint64_t) > End)
>> +    return false;
>> +  uint64_t ValueKindCount = endian::readNext<uint64_t, little,
> unaligned>(D);
>> +
>> +  for (uint32_t Kind = 0; Kind < ValueKindCount; ++Kind) {
>> +
>> +    // Read value kind and number of value sites for kind.
>> +    if (D + 2*sizeof(uint64_t) > End)
>> +      return false;
>> +    uint64_t ValueKind = endian::readNext<uint64_t, little,
> unaligned>(D);
>> +    uint64_t ValueSiteCount = endian::readNext<uint64_t, little,
> unaligned>(D);
>> +
>> +    DataBuffer.back().ValueSites[ValueKind].reserve(ValueSiteCount);
>> +    for (uint64_t VSite = 0; VSite < ValueSiteCount; ++VSite) {
>> +      // Read number of value data pairs at value site.
>> +      if (D + sizeof(uint64_t) > End)
>> +        return false;
>> +      uint64_t ValueDataCount =
>> +          endian::readNext<uint64_t, little, unaligned>(D);
>> +
>> +      // Check if there are as many ValueDataPairs as ValueDataCount in
> memory.
>> +      if (D + (ValueDataCount<<1)*sizeof(uint64_t) > End)
>> +        return false;
>> +
>> +      InstrProfValueSiteRecord VSiteRecord;
>> +      for (uint64_t VCount = 0; VCount < ValueDataCount; ++VCount) {
>> +        uint64_t Value = endian::readNext<uint64_t, little,
> unaligned>(D);
>> +        uint64_t NumTaken = endian::readNext<uint64_t, little,
> unaligned>(D);
>> +        if (ValueKind == instrprof_value_kind::indirect_call_target) {
>
> If we see anything other than indirect_call_target we should return
> false - we don't know how to interpret that data.

The assert is placed in the getValueSitesForKind method.

>
>> +          auto Result = HashKeyMap.find(Value);
>> +          assert(Result != HashKeyMap.end() &&
>> +                 "Hash does not match any known keys\n");
>> +          Value = (uint64_t)Result->second;
>> +        }
>> +        VSiteRecord.ValueData.push_back(std::make_pair(Value,
> NumTaken));
>> +      }
>> +
> DataBuffer.back().ValueSites[ValueKind].push_back(std::move(VSiteRecord));
>> +    }
>> +  }
>> +  return true;
>> +}
>> +
>>  data_type InstrProfLookupTrait::ReadData(StringRef K, const unsigned
> char *D,
>>                                           offset_type N) {
>> -
>>    // Check if the data is corrupt. If so, don't try to read it.
>>    if (N % sizeof(uint64_t))
>>      return data_type();
>>
>>    DataBuffer.clear();
>> -  uint64_t NumCounts;
>> -  uint64_t NumEntries = N / sizeof(uint64_t);
>>    std::vector<uint64_t> CounterBuffer;
>> -  for (uint64_t I = 0; I < NumEntries; I += NumCounts) {
>> -    using namespace support;
>> -    // The function hash comes first.
>> -    uint64_t Hash = endian::readNext<uint64_t, little, unaligned>(D);
>>
>> -    if (++I >= NumEntries)
>> +  using namespace support;
>> +  const unsigned char *End = D + N;
>> +  while (D < End) {
>> +    // Read hash
>> +    if (D + sizeof(uint64_t) >= End)
>>        return data_type();
>> +    uint64_t Hash = endian::readNext<uint64_t, little, unaligned>(D);
>>
>> -    // In v1, we have at least one count.
>> -    // Later, we have the number of counts.
>> -    NumCounts = (1 == FormatVersion)
>> -                    ? NumEntries - I
>> -                    : endian::readNext<uint64_t, little, unaligned>(D);
>> -    if (1 != FormatVersion)
>> -      ++I;
>> -
>> -    // If we have more counts than data, this is bogus.
>> -    if (I + NumCounts > NumEntries)
>> +    // Initialize number of counters for FormatVersion == 1
>> +    uint64_t CountsSize = N / sizeof(uint64_t) - 1;
>> +    // If format version is different then read number of counters
>> +    if (FormatVersion != 1) {
>> +      if (D + sizeof(uint64_t) > End)
>> +        return data_type();
>> +      CountsSize = endian::readNext<uint64_t, little, unaligned>(D);
>> +    }
>> +    // Read counter values
>> +    if (D + CountsSize * sizeof(uint64_t) > End)
>>        return data_type();
>>
>>      CounterBuffer.clear();
>> -    for (unsigned J = 0; J < NumCounts; ++J)
>> +    CounterBuffer.reserve(CountsSize);
>> +    for (uint64_t J = 0; J < CountsSize; ++J)
>>        CounterBuffer.push_back(endian::readNext<uint64_t, little,
> unaligned>(D));
>>
>>      DataBuffer.push_back(InstrProfRecord(K, Hash,
> std::move(CounterBuffer)));
>> +
>> +    // Read value profiling data
>> +    if (FormatVersion == 3 && !ReadValueProfilingData(D, End)) {
>
> This should be "FormatVersion > 2".

Done.

>
>> +      DataBuffer.clear();
>> +      return data_type();
>> +    }
>>    }
>>    return DataBuffer;
>>  }
>> @@ -383,7 +439,19 @@
>>    // The rest of the file is an on disk hash table.
>>    Index.reset(InstrProfReaderIndex::Create(
>>        Start + HashOffset, Cur, Start,
>> -      InstrProfLookupTrait(HashType, FormatVersion)));
>> +      InstrProfLookupTrait(HashType, FormatVersion, HashKeyMap)));
>> +  for (auto Key : Index->keys()) {
>> +    const char *KeyTableRef = StringTable.insertString(Key);
>> +    auto Result =
> HashKeyMap.insert(std::make_pair(ComputeHash(HashType, Key),
>> +                                                   KeyTableRef));
>
> The way the HashKeyMap works here seems a little off. Why does the
> Reader own it? Only the trait uses it. Also, since it follows a strict
> "fill then query" pattern, it's probably better to just use a vector
> that we sort after filling and then binary search later.

Done.

>
>> +    // Emit warning if a hash collision is detected.
>> +    if (Result.second == false)
>> +      DEBUG(dbgs() << "IndexedInstrProfReader: hash collision detected:
> \n"
>> +                   << "\t Map Entry(Hash, Key): " <<
> Result.first->first
>> +                   << ", " << Result.first->second << "\n"
>> +                   << "\t New Entry(Hash, Key): " <<
> ComputeHash(HashType, Key)
>> +                   << ", " << Key << "\n");
>
> This is not "emitting a warning". This will only be printed if the host
> compiler is built in debug mode, so it seems pretty pointless. Actually
> emitting a proper warning from this point in the compiler might be kind
> of tricky though.
>
>> +  }
>>    // Set up our iterator for readNextRecord.
>>    RecordIterator = Index->data_begin();
>>
>> Index: lib/ProfileData/InstrProfIndexed.h
>> ===================================================================
>> --- lib/ProfileData/InstrProfIndexed.h
>> +++ lib/ProfileData/InstrProfIndexed.h
>> @@ -47,7 +47,7 @@
>>  }
>>
>>  const uint64_t Magic = 0x8169666f72706cff; // "\xfflprofi\x81"
>> -const uint64_t Version = 2;
>> +const uint64_t Version = 3;
>>  const HashT HashType = HashT::MD5;
>>  }
>>
>> Index: lib/ProfileData/InstrProf.cpp
>> ===================================================================
>> --- lib/ProfileData/InstrProf.cpp
>> +++ lib/ProfileData/InstrProf.cpp
>> @@ -50,6 +50,8 @@
>>        return "Function count mismatch";
>>      case instrprof_error::counter_overflow:
>>        return "Counter overflow";
>> +    case instrprof_error::value_site_count_mismatch:
>> +      return "Function's value site counts mismatch";
>>      }
>>      llvm_unreachable("A value of instrprof_error has no message.");
>>    }
>> Index: include/llvm/ProfileData/InstrProfWriter.h
>> ===================================================================
>> --- include/llvm/ProfileData/InstrProfWriter.h
>> +++ include/llvm/ProfileData/InstrProfWriter.h
>> @@ -15,33 +15,32 @@
>>  #ifndef LLVM_PROFILEDATA_INSTRPROFWRITER_H
>>  #define LLVM_PROFILEDATA_INSTRPROFWRITER_H
>>
>> -#include "llvm/ADT/ArrayRef.h"
>>  #include "llvm/ADT/DenseMap.h"
>> -#include "llvm/ADT/StringMap.h"
>>  #include "llvm/ProfileData/InstrProf.h"
>>  #include "llvm/Support/DataTypes.h"
>>  #include "llvm/Support/MemoryBuffer.h"
>>  #include "llvm/Support/raw_ostream.h"
>> -#include <vector>
>>
>>  namespace llvm {
>>
>>  /// Writer for instrumentation based profile data.
>>  class InstrProfWriter {
>>  public:
>> -  typedef SmallDenseMap<uint64_t, std::vector<uint64_t>, 1>
> CounterData;
>> +  typedef SmallDenseMap<uint64_t, InstrProfRecord, 1> ProfilingData;
>> +
>>  private:
>> -  StringMap<CounterData> FunctionData;
>> +  InstrProfStringTable StringTable;
>> +  StringMap<ProfilingData> FunctionData;
>>    uint64_t MaxFunctionCount;
>>  public:
>>    InstrProfWriter() : MaxFunctionCount(0) {}
>>
>> +  /// Update string entries in profile data with references to
> StringTable.
>> +  void updateStringTableReferences(InstrProfRecord &I);
>>    /// Add function counts for the given function. If there are already
> counts
>>    /// for this function and the hash and number of counts match, each
> counter is
>>    /// summed.
>> -  std::error_code addFunctionCounts(StringRef FunctionName,
>> -                                    uint64_t FunctionHash,
>> -                                    ArrayRef<uint64_t> Counters);
>> +  std::error_code addRecord(InstrProfRecord &&I);
>>    /// Write the profile to \c OS
>>    void write(raw_fd_ostream &OS);
>>    /// Write the profile, returning the raw data. For testing.
>> Index: include/llvm/ProfileData/InstrProfReader.h
>> ===================================================================
>> --- include/llvm/ProfileData/InstrProfReader.h
>> +++ include/llvm/ProfileData/InstrProfReader.h
>> @@ -24,6 +24,7 @@
>>  #include "llvm/Support/MemoryBuffer.h"
>>  #include "llvm/Support/OnDiskHashTable.h"
>>  #include <iterator>
>> +#include <map>
>>
>>  namespace llvm {
>>
>> @@ -65,6 +66,9 @@
>>    InstrProfIterator end() { return InstrProfIterator(); }
>>
>>  protected:
>> +  /// String table for holding a unique copy of all the strings in the
> profile.
>> +  InstrProfStringTable StringTable;
>> +
>>    /// Set the current std::error_code and return same.
>>    std::error_code error(std::error_code EC) {
>>      LastError = EC;
>> @@ -195,10 +199,13 @@
>>    std::vector<InstrProfRecord> DataBuffer;
>>    IndexedInstrProf::HashT HashType;
>>    unsigned FormatVersion;
>> +  const std::map<uint64_t, const char *> &HashKeyMap;
>>
>>  public:
>> -  InstrProfLookupTrait(IndexedInstrProf::HashT HashType, unsigned
> FormatVersion)
>> -      : HashType(HashType), FormatVersion(FormatVersion) {}
>> +  InstrProfLookupTrait(IndexedInstrProf::HashT HashType, unsigned
> FormatVersion,
>> +                       std::map<uint64_t, const char *> &HashKeyMap)
>> +      : HashType(HashType), FormatVersion(FormatVersion),
>> +        HashKeyMap(HashKeyMap) {}
>>
>>    typedef ArrayRef<InstrProfRecord> data_type;
>>
>> @@ -209,6 +216,7 @@
>>
>>    static bool EqualKey(StringRef A, StringRef B) { return A == B; }
>>    static StringRef GetInternalKey(StringRef K) { return K; }
>> +  static StringRef GetExternalKey(StringRef K) { return K; }
>
> What do you need GetExternalKey for?

If you want to be able to iterate over the keys of the
OnDiskChainedIterableHashTable, then you have to have this method defined.
We're iterating over the keys in the reader to form the HashKeyMap, so
this had to be defined.

>
>>
>>    hash_value_type ComputeHash(StringRef K);
>>
>> @@ -224,6 +232,8 @@
>>      return StringRef((const char *)D, N);
>>    }
>>
>> +  bool ReadValueProfilingData(const unsigned char *&D,
>> +                              const unsigned char *const End);
>>    data_type ReadData(StringRef K, const unsigned char *D, offset_type
> N);
>>  };
>>
>> @@ -243,6 +253,8 @@
>>    uint64_t FormatVersion;
>>    /// The maximal execution count among all functions.
>>    uint64_t MaxFunctionCount;
>> +  /// Map of hash values to const char* keys in profiling data.
>> +  std::map<uint64_t, const char *> HashKeyMap;
>>
>>    IndexedInstrProfReader(const IndexedInstrProfReader &) = delete;
>>    IndexedInstrProfReader &operator=(const IndexedInstrProfReader &) =
> delete;
>> Index: include/llvm/ProfileData/InstrProf.h
>> ===================================================================
>> --- include/llvm/ProfileData/InstrProf.h
>> +++ include/llvm/ProfileData/InstrProf.h
>> @@ -16,42 +16,102 @@
>>  #ifndef LLVM_PROFILEDATA_INSTRPROF_H_
>>  #define LLVM_PROFILEDATA_INSTRPROF_H_
>>
>> -#include "llvm/ADT/StringRef.h"
>> +#include "llvm/ADT/StringSet.h"
>>  #include <cstdint>
>> +#include <list>
>>  #include <system_error>
>>  #include <vector>
>>
>>  namespace llvm {
>>  const std::error_category &instrprof_category();
>>
>>  enum class instrprof_error {
>> -    success = 0,
>> -    eof,
>> -    bad_magic,
>> -    bad_header,
>> -    unsupported_version,
>> -    unsupported_hash_type,
>> -    too_large,
>> -    truncated,
>> -    malformed,
>> -    unknown_function,
>> -    hash_mismatch,
>> -    count_mismatch,
>> -    counter_overflow
>> +  success = 0,
>> +  eof,
>> +  bad_magic,
>> +  bad_header,
>> +  unsupported_version,
>> +  unsupported_hash_type,
>> +  too_large,
>> +  truncated,
>> +  malformed,
>> +  unknown_function,
>> +  hash_mismatch,
>> +  count_mismatch,
>> +  counter_overflow,
>> +  value_site_count_mismatch
>>  };
>>
>>  inline std::error_code make_error_code(instrprof_error E) {
>>    return std::error_code(static_cast<int>(E), instrprof_category());
>>  }
>>
>> +enum instrprof_value_kind : uint32_t {
>> +  first = 0,
>> +  indirect_call_target = 0,
>> +  size = 1
>> +};
>> +
>> +struct InstrProfStringTable {
>> +  // Set of string values in profiling data.
>> +  StringSet<> StringValueSet;
>> +  InstrProfStringTable() { StringValueSet.clear(); }
>> +  // Get a pointer to internal storage of a string in set
>> +  const char *getStringData(StringRef Str) {
>> +    auto Result = StringValueSet.find(Str);
>> +    return (Result == StringValueSet.end()) ? nullptr :
> Result->first().data();
>> +  }
>> +  // Insert a string to StringTable
>> +  const char *insertString(StringRef Str) {
>> +    auto Result = StringValueSet.insert(Str);
>> +    return Result.first->first().data();
>> +  }
>> +};
>> +
>> +struct InstrProfValueSiteRecord {
>> +  // Typedef for a single TargetValue-NumTaken pair.
>> +  typedef std::pair<uint64_t, uint64_t> ValueDataPair;
>> +  // Value profiling data pairs at a given value site.
>> +  std::list<ValueDataPair> ValueData;
>> +
>> +  InstrProfValueSiteRecord() { ValueData.clear(); }
>> +
>> +  // Sort ValueData ascending by TargetValue
>> +  void sortByTargetValues() {
>> +    ValueData.sort([](const ValueDataPair &left, const ValueDataPair
> &right) {
>> +      return left.first < right.first;
>> +    });
>> +  }
>> +  // Merge data from another InstrProfValueSiteRecord
>> +  void mergeValueData(InstrProfValueSiteRecord &Input) {
>> +    this->sortByTargetValues();
>> +    Input.sortByTargetValues();
>> +    auto I = ValueData.begin();
>> +    auto IE = ValueData.end();
>> +    for (auto J = Input.ValueData.begin(), JE = Input.ValueData.end();
> J != JE;
>> +         ++J) {
>> +      while (I != IE && I->first < J->first)
>> +        ++I;
>> +      if (I != IE && I->first == J->first) {
>> +        I->second += J->second;
>> +        ++I;
>> +        continue;
>> +      }
>> +      ValueData.insert(I, *J);
>> +    }
>> +  }
>> +};
>> +
>>  /// Profiling information for a single function.
>>  struct InstrProfRecord {
>>    InstrProfRecord() {}
>>    InstrProfRecord(StringRef Name, uint64_t Hash, std::vector<uint64_t>
> Counts)
>>        : Name(Name), Hash(Hash), Counts(std::move(Counts)) {}
>>    StringRef Name;
>>    uint64_t Hash;
>>    std::vector<uint64_t> Counts;
>> +  // Size of vector indicates the number of value sites for a value
> kind
>> +  std::vector<InstrProfValueSiteRecord>
> ValueSites[instrprof_value_kind::size];
>>  };
>>
>>  } // end namespace llvm
>
>




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