ProfileData: Add support for the indexed instrprof format

This adds support for an indexed instrumentation based profiling
format, which is just a small header and an on disk hash table.  This
format will be used by clang's -fprofile-instr-use= for PGO.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206656 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ProfileData/InstrProf.h

@@ -29,6 +29,7 @@ struct instrprof_error {
     bad_magic,
     bad_header,
     unsupported_version,
+    unsupported_hash_type,
     too_large,
     truncated,
     malformed,

include/llvm/ProfileData/InstrProfReader.h

@@ -16,10 +16,12 @@
 #define LLVM_PROFILEDATA_INSTRPROF_READER_H_
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ProfileData/InstrProf.h"
 #include "llvm/Support/LineIterator.h"
 #include "llvm/Support/MemoryBuffer.h"
-#include "llvm/Support/Endian.h"
+#include "llvm/Support/EndianStream.h"
+#include "llvm/Support/OnDiskHashTable.h"
 
 #include <iterator>
 
@@ -29,6 +31,9 @@ class InstrProfReader;
 
 /// Profiling information for a single function.
 struct InstrProfRecord {
+  InstrProfRecord() {}
+  InstrProfRecord(StringRef Name, uint64_t Hash, ArrayRef<uint64_t> Counts)
+      : Name(Name), Hash(Hash), Counts(Counts) {}
   StringRef Name;
   uint64_t Hash;
   ArrayRef<uint64_t> Counts;
@@ -191,6 +196,106 @@ private:
 typedef RawInstrProfReader<uint32_t> RawInstrProfReader32;
 typedef RawInstrProfReader<uint64_t> RawInstrProfReader64;
 
+namespace IndexedInstrProf {
+enum class HashT : uint32_t;
+uint64_t ComputeHash(HashT Type, StringRef K);
+}
+
+/// Trait for lookups into the on-disk hash table for the binary instrprof
+/// format.
+class InstrProfLookupTrait {
+  std::vector<uint64_t> CountBuffer;
+  IndexedInstrProf::HashT HashType;
+public:
+  InstrProfLookupTrait(IndexedInstrProf::HashT HashType) : HashType(HashType) {}
+
+  typedef InstrProfRecord data_type;
+  typedef StringRef internal_key_type;
+  typedef StringRef external_key_type;
+  typedef uint64_t hash_value_type;
+  typedef uint64_t offset_type;
+
+  static bool EqualKey(StringRef A, StringRef B) { return A == B; }
+  static StringRef GetInternalKey(StringRef K) { return K; }
+
+  hash_value_type ComputeHash(StringRef K) {
+    return IndexedInstrProf::ComputeHash(HashType, K);
+  }
+
+  static std::pair<offset_type, offset_type>
+  ReadKeyDataLength(const unsigned char *&D) {
+    using namespace support;
+    return std::make_pair(endian::readNext<offset_type, little, unaligned>(D),
+                          endian::readNext<offset_type, little, unaligned>(D));
+  }
+
+  StringRef ReadKey(const unsigned char *D, unsigned N) {
+    return StringRef((const char *)D, N);
+  }
+
+  InstrProfRecord ReadData(StringRef K, const unsigned char *D, unsigned N) {
+    if (N < 2 * sizeof(uint64_t) || N % sizeof(uint64_t)) {
+      // The data is corrupt, don't try to read it.
+      CountBuffer.clear();
+      return InstrProfRecord("", 0, CountBuffer);
+    }
+
+    using namespace support;
+
+    // The first stored value is the hash.
+    uint64_t Hash = endian::readNext<uint64_t, little, unaligned>(D);
+    // Each counter follows.
+    unsigned NumCounters = N / sizeof(uint64_t) - 1;
+    CountBuffer.clear();
+    CountBuffer.reserve(NumCounters - 1);
+    for (unsigned I = 0; I < NumCounters; ++I)
+      CountBuffer.push_back(endian::readNext<uint64_t, little, unaligned>(D));
+
+    return InstrProfRecord(K, Hash, CountBuffer);
+  }
+};
+typedef OnDiskIterableChainedHashTable<InstrProfLookupTrait>
+    InstrProfReaderIndex;
+
+/// Reader for the indexed binary instrprof format.
+class IndexedInstrProfReader : public InstrProfReader {
+private:
+  /// The profile data file contents.
+  std::unique_ptr<MemoryBuffer> DataBuffer;
+  /// The index into the profile data.
+  std::unique_ptr<InstrProfReaderIndex> Index;
+  /// Iterator over the profile data.
+  InstrProfReaderIndex::data_iterator RecordIterator;
+  /// The maximal execution count among all fucntions.
+  uint64_t MaxFunctionCount;
+
+  IndexedInstrProfReader(const IndexedInstrProfReader &) LLVM_DELETED_FUNCTION;
+  IndexedInstrProfReader &operator=(const IndexedInstrProfReader &)
+    LLVM_DELETED_FUNCTION;
+public:
+  IndexedInstrProfReader(std::unique_ptr<MemoryBuffer> DataBuffer)
+      : DataBuffer(std::move(DataBuffer)), Index(nullptr),
+        RecordIterator(InstrProfReaderIndex::data_iterator()) {}
+
+  /// Return true if the given buffer is in an indexed instrprof format.
+  static bool hasFormat(const MemoryBuffer &DataBuffer);
+
+  /// Read the file header.
+  error_code readHeader() override;
+  /// Read a single record.
+  error_code readNextRecord(InstrProfRecord &Record) override;
+
+  /// Fill Counts with the profile data for the given function name.
+  error_code getFunctionCounts(StringRef FuncName, uint64_t &FuncHash,
+                               std::vector<uint64_t> &Counts);
+  /// Return the maximum of all known function counts.
+  uint64_t getMaximumFunctionCount() { return MaxFunctionCount; }
+
+  /// Factory method to create an indexed reader.
+  static error_code create(std::string Path,
+                           std::unique_ptr<IndexedInstrProfReader> &Result);
+};
+
 } // end namespace llvm
 
 #endif // LLVM_PROFILEDATA_INSTRPROF_READER_H_

include/llvm/ProfileData/InstrProfWriter.h

@@ -41,7 +41,7 @@ public:
   error_code addFunctionCounts(StringRef FunctionName, uint64_t FunctionHash,
                                ArrayRef<uint64_t> Counters);
   /// Ensure that all data is written to disk.
-  void write(raw_ostream &OS);
+  void write(raw_fd_ostream &OS);
 };
 
 } // end namespace llvm

lib/ProfileData/InstrProf.cpp

@@ -33,6 +33,8 @@ class InstrProfErrorCategoryType : public error_category {
       return "Invalid header";
     case instrprof_error::unsupported_version:
       return "Unsupported format version";
+    case instrprof_error::unsupported_hash_type:
+      return "Unsupported hash function";
     case instrprof_error::too_large:
       return "Too much profile data";
     case instrprof_error::truncated:

lib/ProfileData/InstrProfIndexed.h

@@ -0,0 +1,54 @@
+//=-- InstrProfIndexed.h - Indexed profiling format support -------*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Shared header for the instrumented profile data reader and writer.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_PROFILEDATA_INSTRPROF_INDEXED_H_
+#define LLVM_PROFILEDATA_INSTRPROF_INDEXED_H_
+
+#include "llvm/Support/MD5.h"
+
+namespace llvm {
+
+namespace IndexedInstrProf {
+enum class HashT : uint32_t {
+  MD5,
+
+  Last = MD5
+};
+
+static inline uint64_t MD5Hash(StringRef Str) {
+  MD5 Hash;
+  Hash.update(Str);
+  llvm::MD5::MD5Result Result;
+  Hash.final(Result);
+  // Return the least significant 8 bytes. Our MD5 implementation returns the
+  // result in little endian, so we may need to swap bytes.
+  using namespace llvm::support;
+  return endian::read<uint64_t, little, unaligned>(Result);
+}
+
+uint64_t ComputeHash(HashT Type, StringRef K) {
+  switch (Type) {
+  case HashT::MD5:
+    return IndexedInstrProf::MD5Hash(K);
+  }
+  llvm_unreachable("Unhandled hash type");
+}
+
+const uint64_t Magic = 0x8169666f72706cff; // "\xfflprofi\x81"
+const uint64_t Version = 1;
+const HashT HashType = HashT::MD5;
+}
+
+} // end namespace llvm
+
+#endif // LLVM_PROFILEDATA_INSTRPROF_INDEXED_H_

lib/ProfileData/InstrProfReader.cpp

@@ -15,30 +15,62 @@
 #include "llvm/ProfileData/InstrProfReader.h"
 #include "llvm/ProfileData/InstrProf.h"
 
+#include "InstrProfIndexed.h"
+
 #include <cassert>
 
 using namespace llvm;
 
-error_code InstrProfReader::create(std::string Path,
-                                   std::unique_ptr<InstrProfReader> &Result) {
-  std::unique_ptr<MemoryBuffer> Buffer;
+static error_code setupMemoryBuffer(std::string Path,
+                                    std::unique_ptr<MemoryBuffer> &Buffer) {
   if (error_code EC = MemoryBuffer::getFileOrSTDIN(Path, Buffer))
     return EC;
 
   // Sanity check the file.
   if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max())
     return instrprof_error::too_large;
+  return instrprof_error::success;
+}
+
+static error_code initializeReader(InstrProfReader &Reader) {
+  return Reader.readHeader();
+}
+
+error_code InstrProfReader::create(std::string Path,
+                                   std::unique_ptr<InstrProfReader> &Result) {
+  // Set up the buffer to read.
+  std::unique_ptr<MemoryBuffer> Buffer;
+  if (error_code EC = setupMemoryBuffer(Path, Buffer))
+    return EC;
 
   // Create the reader.
-  if (RawInstrProfReader64::hasFormat(*Buffer))
+  if (IndexedInstrProfReader::hasFormat(*Buffer))
+    Result.reset(new IndexedInstrProfReader(std::move(Buffer)));
+  else if (RawInstrProfReader64::hasFormat(*Buffer))
     Result.reset(new RawInstrProfReader64(std::move(Buffer)));
   else if (RawInstrProfReader32::hasFormat(*Buffer))
     Result.reset(new RawInstrProfReader32(std::move(Buffer)));
   else
     Result.reset(new TextInstrProfReader(std::move(Buffer)));
 
-  // Read the header and return the result.
-  return Result->readHeader();
+  // Initialize the reader and return the result.
+  return initializeReader(*Result);
+}
+
+error_code IndexedInstrProfReader::create(
+    std::string Path, std::unique_ptr<IndexedInstrProfReader> &Result) {
+  // Set up the buffer to read.
+  std::unique_ptr<MemoryBuffer> Buffer;
+  if (error_code EC = setupMemoryBuffer(Path, Buffer))
+    return EC;
+
+  // Create the reader.
+  if (!IndexedInstrProfReader::hasFormat(*Buffer))
+    return instrprof_error::bad_magic;
+  Result.reset(new IndexedInstrProfReader(std::move(Buffer)));
+
+  // Initialize the reader and return the result.
+  return initializeReader(*Result);
 }
 
 void InstrProfIterator::Increment() {
@@ -210,3 +242,77 @@ namespace llvm {
 template class RawInstrProfReader<uint32_t>;
 template class RawInstrProfReader<uint64_t>;
 }
+
+bool IndexedInstrProfReader::hasFormat(const MemoryBuffer &DataBuffer) {
+  if (DataBuffer.getBufferSize() < 8)
+    return false;
+  using namespace support;
+  uint64_t Magic =
+      endian::read<uint64_t, little, aligned>(DataBuffer.getBufferStart());
+  return Magic == IndexedInstrProf::Magic;
+}
+
+error_code IndexedInstrProfReader::readHeader() {
+  const unsigned char *Start = (unsigned char *)DataBuffer->getBufferStart();
+  const unsigned char *Cur = Start;
+  if ((unsigned char *)DataBuffer->getBufferEnd() - Cur < 24)
+    return error(instrprof_error::truncated);
+
+  using namespace support;
+
+  // Check the magic number.
+  uint64_t Magic = endian::readNext<uint64_t, little, unaligned>(Cur);
+  if (Magic != IndexedInstrProf::Magic)
+    return error(instrprof_error::bad_magic);
+
+  // Read the version.
+  uint64_t Version = endian::readNext<uint64_t, little, unaligned>(Cur);
+  if (Version != IndexedInstrProf::Version)
+    return error(instrprof_error::unsupported_version);
+
+  // Read the maximal function count.
+  MaxFunctionCount = endian::readNext<uint64_t, little, unaligned>(Cur);
+
+  // Read the hash type and start offset.
+  IndexedInstrProf::HashT HashType = static_cast<IndexedInstrProf::HashT>(
+      endian::readNext<uint64_t, little, unaligned>(Cur));
+  if (HashType > IndexedInstrProf::HashT::Last)
+    return error(instrprof_error::unsupported_hash_type);
+  uint64_t HashOffset = endian::readNext<uint64_t, little, unaligned>(Cur);
+
+  // The rest of the file is an on disk hash table.
+  Index.reset(InstrProfReaderIndex::Create(Start + HashOffset, Cur, Start,
+                                           InstrProfLookupTrait(HashType)));
+  // Set up our iterator for readNextRecord.
+  RecordIterator = Index->data_begin();
+
+  return success();
+}
+
+error_code IndexedInstrProfReader::getFunctionCounts(
+    StringRef FuncName, uint64_t &FuncHash, std::vector<uint64_t> &Counts) {
+  const auto &Iter = Index->find(FuncName);
+  if (Iter == Index->end())
+    return error(instrprof_error::unknown_function);
+
+  // Found it. Make sure it's valid before giving back a result.
+  const InstrProfRecord &Record = *Iter;
+  if (Record.Name.empty())
+    return error(instrprof_error::malformed);
+  FuncHash = Record.Hash;
+  Counts = Record.Counts;
+  return success();
+}
+
+error_code IndexedInstrProfReader::readNextRecord(InstrProfRecord &Record) {
+  // Are we out of records?
+  if (RecordIterator == Index->data_end())
+    return error(instrprof_error::eof);
+
+  // Read the next one.
+  Record = *RecordIterator;
+  ++RecordIterator;
+  if (Record.Name.empty())
+    return error(instrprof_error::malformed);
+  return success();
+}

lib/ProfileData/InstrProfWriter.cpp

@@ -13,10 +13,59 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/ProfileData/InstrProfWriter.h"
-#include "llvm/Support/Endian.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/EndianStream.h"
+#include "llvm/Support/OnDiskHashTable.h"
+
+#include "InstrProfIndexed.h"
 
 using namespace llvm;
 
+namespace {
+class InstrProfRecordTrait {
+public:
+  typedef StringRef key_type;
+  typedef StringRef key_type_ref;
+
+  typedef InstrProfWriter::CounterData data_type;
+  typedef const InstrProfWriter::CounterData &data_type_ref;
+
+  typedef uint64_t hash_value_type;
+  typedef uint64_t offset_type;
+
+  static hash_value_type ComputeHash(key_type_ref K) {
+    return IndexedInstrProf::ComputeHash(IndexedInstrProf::HashType, K);
+  }
+
+  static std::pair<offset_type, offset_type>
+  EmitKeyDataLength(raw_ostream &Out, key_type_ref K, data_type_ref V) {
+    using namespace llvm::support;
+    endian::Writer<little> LE(Out);
+
+    unsigned N = K.size();
+    LE.write<offset_type>(N);
+
+    unsigned M = (1 + V.Counts.size()) * sizeof(uint64_t);
+    LE.write<offset_type>(M);
+
+    return std::make_pair(N, M);
+  }
+
+  static void EmitKey(raw_ostream &Out, key_type_ref K, unsigned N){
+    Out.write(K.data(), N);
+  }
+
+  static void EmitData(raw_ostream &Out, key_type_ref, data_type_ref V,
+                       unsigned) {
+    using namespace llvm::support;
+    endian::Writer<little> LE(Out);
+    LE.write<uint64_t>(V.Hash);
+    for (uint64_t I : V.Counts)
+      LE.write<uint64_t>(I);
+  }
+};
+}
+
 error_code InstrProfWriter::addFunctionCounts(StringRef FunctionName,
                                               uint64_t FunctionHash,
                                               ArrayRef<uint64_t> Counters) {
@@ -45,16 +94,33 @@ error_code InstrProfWriter::addFunctionCounts(StringRef FunctionName,
   return instrprof_error::success;
 }
 
-void InstrProfWriter::write(raw_ostream &OS) {
-  // Write out the counts for each function.
-  for (const auto &I : FunctionData) {
-    StringRef Name = I.getKey();
-    uint64_t Hash = I.getValue().Hash;
-    const std::vector<uint64_t> &Counts = I.getValue().Counts;
+void InstrProfWriter::write(raw_fd_ostream &OS) {
+  OnDiskChainedHashTableGenerator<InstrProfRecordTrait> Generator;
+  uint64_t MaxFunctionCount = 0;
 
-    OS << Name << "\n" << Hash << "\n" << Counts.size() << "\n";
-    for (uint64_t Count : Counts)
-      OS << Count << "\n";
-    OS << "\n";
+  // Populate the hash table generator.
+  for (const auto &I : FunctionData) {
+    Generator.insert(I.getKey(), I.getValue());
+    if (I.getValue().Counts[0] > MaxFunctionCount)
+      MaxFunctionCount = I.getValue().Counts[0];
   }
+
+  using namespace llvm::support;
+  endian::Writer<little> LE(OS);
+
+  // Write the header.
+  LE.write<uint64_t>(IndexedInstrProf::Magic);
+  LE.write<uint64_t>(IndexedInstrProf::Version);
+  LE.write<uint64_t>(MaxFunctionCount);
+  LE.write<uint64_t>(static_cast<uint64_t>(IndexedInstrProf::HashType));
+
+  // Save a space to write the hash table start location.
+  uint64_t HashTableStartLoc = OS.tell();
+  LE.write<uint64_t>(0);
+  // Write the hash table.
+  uint64_t HashTableStart = Generator.Emit(OS);
+
+  // Go back and fill in the hash table start.
+  OS.seek(HashTableStartLoc);
+  LE.write<uint64_t>(HashTableStart);
 }

test/tools/llvm-profdata/errors.test

@@ -5,9 +5,9 @@ RUN: llvm-profdata merge %p/Inputs/overflow.profdata %p/Inputs/overflow.profdata
 OVERFLOW: overflow.profdata: overflow: Counter overflow
 
 RUN: not llvm-profdata show %p/Inputs/invalid-count-later.profdata 2>&1 | FileCheck %s --check-prefix=INVALID-COUNT-LATER
-RUN: not llvm-profdata merge %p/Inputs/invalid-count-later.profdata %p/Inputs/invalid-count-later.profdata 2>&1 | FileCheck %s --check-prefix=INVALID-COUNT-LATER
+RUN: not llvm-profdata merge %p/Inputs/invalid-count-later.profdata %p/Inputs/invalid-count-later.profdata -o /dev/null 2>&1 | FileCheck %s --check-prefix=INVALID-COUNT-LATER
 INVALID-COUNT-LATER: error: {{.*}}invalid-count-later.profdata: Malformed profile data
 
 RUN: not llvm-profdata show %p/Inputs/bad-hash.profdata 2>&1 | FileCheck %s --check-prefix=BAD-HASH
-RUN: not llvm-profdata merge %p/Inputs/bad-hash.profdata %p/Inputs/bad-hash.profdata 2>&1 | FileCheck %s --check-prefix=BAD-HASH
+RUN: not llvm-profdata merge %p/Inputs/bad-hash.profdata %p/Inputs/bad-hash.profdata -o /dev/null 2>&1 | FileCheck %s --check-prefix=BAD-HASH
 BAD-HASH: error: {{.*}}bad-hash.profdata: Malformed profile data

test/tools/llvm-profdata/simple.test

@@ -1,5 +1,7 @@
-RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/foo3-2.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3
-RUN: llvm-profdata merge %p/Inputs/foo3-2.profdata %p/Inputs/foo3-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3
+RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/foo3-2.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3
+RUN: llvm-profdata merge %p/Inputs/foo3-2.profdata %p/Inputs/foo3-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3
 FOO3: foo:
 FOO3: Counters: 3
 FOO3: Function count: 8
@@ -8,8 +10,10 @@ FOO3: Total functions: 1
 FOO3: Maximum function count: 8
 FOO3: Maximum internal block count: 7
 
-RUN: llvm-profdata merge %p/Inputs/foo4-1.profdata %p/Inputs/foo4-2.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO4
-RUN: llvm-profdata merge %p/Inputs/foo4-2.profdata %p/Inputs/foo4-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO4
+RUN: llvm-profdata merge %p/Inputs/foo4-1.profdata %p/Inputs/foo4-2.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO4
+RUN: llvm-profdata merge %p/Inputs/foo4-2.profdata %p/Inputs/foo4-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO4
 FOO4: foo:
 FOO4: Counters: 4
 FOO4: Function count: 18
@@ -18,8 +22,10 @@ FOO4: Total functions: 1
 FOO4: Maximum function count: 18
 FOO4: Maximum internal block count: 48
 
-RUN: llvm-profdata merge %p/Inputs/foo3bar3-1.profdata %p/Inputs/foo3bar3-2.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3BAR3
-RUN: llvm-profdata merge %p/Inputs/foo3bar3-2.profdata %p/Inputs/foo3bar3-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3BAR3
+RUN: llvm-profdata merge %p/Inputs/foo3bar3-1.profdata %p/Inputs/foo3bar3-2.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3BAR3
+RUN: llvm-profdata merge %p/Inputs/foo3bar3-2.profdata %p/Inputs/foo3bar3-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3BAR3
 FOO3BAR3: foo:
 FOO3BAR3: Counters: 3
 FOO3BAR3: Function count: 19
@@ -32,7 +38,8 @@ FOO3BAR3: Total functions: 2
 FOO3BAR3: Maximum function count: 36
 FOO3BAR3: Maximum internal block count: 50
 
-RUN: llvm-profdata merge %p/Inputs/empty.profdata %p/Inputs/foo3-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3EMPTY
+RUN: llvm-profdata merge %p/Inputs/empty.profdata %p/Inputs/foo3-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3EMPTY
 FOO3EMPTY: foo:
 FOO3EMPTY: Counters: 3
 FOO3EMPTY: Function count: 1
@@ -41,7 +48,8 @@ FOO3EMPTY: Total functions: 1
 FOO3EMPTY: Maximum function count: 1
 FOO3EMPTY: Maximum internal block count: 3
 
-RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/foo3bar3-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=FOO3FOO3BAR3
+RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/foo3bar3-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=FOO3FOO3BAR3
 FOO3FOO3BAR3: foo:
 FOO3FOO3BAR3: Counters: 3
 FOO3FOO3BAR3: Function count: 3
@@ -54,7 +62,8 @@ FOO3FOO3BAR3: Total functions: 2
 FOO3FOO3BAR3: Maximum function count: 7
 FOO3FOO3BAR3: Maximum internal block count: 13
 
-RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/bar3-1.profdata | llvm-profdata show - -all-functions -counts | FileCheck %s --check-prefix=DISJOINT
+RUN: llvm-profdata merge %p/Inputs/foo3-1.profdata %p/Inputs/bar3-1.profdata -o %t
+RUN: llvm-profdata show %t -all-functions -counts | FileCheck %s --check-prefix=DISJOINT
 DISJOINT: foo:
 DISJOINT: Counters: 3
 DISJOINT: Function count: 1

tools/llvm-profdata/llvm-profdata.cpp

@@ -39,16 +39,15 @@ int merge_main(int argc, const char *argv[]) {
   cl::opt<std::string> OutputFilename("output", cl::value_desc("output"),
                                       cl::init("-"),
                                       cl::desc("Output file"));
-  cl::alias OutputFilenameA("o", cl::desc("Alias for --output"),
-                                 cl::aliasopt(OutputFilename));
+  cl::alias OutputFilenameA("o", cl::desc("Alias for --output"), cl::Required,
+                            cl::aliasopt(OutputFilename));
 
   cl::ParseCommandLineOptions(argc, argv, "LLVM profile data merger\n");
 
-  if (OutputFilename.empty())
-    OutputFilename = "-";
+  if (OutputFilename.compare("-") == 0)
+    exitWithError("Cannot write indexed profdata format to stdout.");
 
   std::string ErrorInfo;
-  // FIXME: F_Text would be available if line_iterator could accept CRLF.
   raw_fd_ostream Output(OutputFilename.data(), ErrorInfo, sys::fs::F_None);
   if (!ErrorInfo.empty())
     exitWithError(ErrorInfo, OutputFilename);