[PGO] Reduce IO in profile dumping with merging

Differential Revision: http://reviews.llvm.org/D34709




git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@306561 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 39 insertions, 25 deletions

diff --git a/lib/profile/InstrProfilingBuffer.c b/lib/profile/InstrProfilingBuffer.c
index 548f92205..a7e852f53 100644
--- a/lib/profile/InstrProfilingBuffer.c
+++ b/lib/profile/InstrProfilingBuffer.c
@@ -54,7 +54,7 @@ void initBufferWriter(ProfDataWriter *BufferWriter, char *Buffer) {
 COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer(char *Buffer) {
   ProfDataWriter BufferWriter;
   initBufferWriter(&BufferWriter, Buffer);
-  return lprofWriteData(&BufferWriter, 0);
+  return lprofWriteData(&BufferWriter, 0, 0);
 }
 
 COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer_internal(
@@ -64,5 +64,5 @@ COMPILER_RT_VISIBILITY int __llvm_profile_write_buffer_internal(
   ProfDataWriter BufferWriter;
   initBufferWriter(&BufferWriter, Buffer);
   return lprofWriteDataImpl(&BufferWriter, DataBegin, DataEnd, CountersBegin,
-                            CountersEnd, 0, NamesBegin, NamesEnd);
+                            CountersEnd, 0, NamesBegin, NamesEnd, 0);
 }
diff --git a/lib/profile/InstrProfilingFile.c b/lib/profile/InstrProfilingFile.c
index f99f86d89..d038bb9cb 100644
--- a/lib/profile/InstrProfilingFile.c
+++ b/lib/profile/InstrProfilingFile.c
@@ -93,13 +93,17 @@ static unsigned doMerging() { return lprofCurFilename.MergePoolSize; }
 /* Return 1 if there is an error, otherwise return  0.  */
 static uint32_t fileWriter(ProfDataWriter *This, ProfDataIOVec *IOVecs,
                            uint32_t NumIOVecs) {
-
   uint32_t I;
   FILE *File = (FILE *)This->WriterCtx;
   for (I = 0; I < NumIOVecs; I++) {
-    if (fwrite(IOVecs[I].Data, IOVecs[I].ElmSize, IOVecs[I].NumElm, File) !=
-        IOVecs[I].NumElm)
-      return 1;
+    if (IOVecs[I].Data) {
+      if (fwrite(IOVecs[I].Data, IOVecs[I].ElmSize, IOVecs[I].NumElm, File) !=
+          IOVecs[I].NumElm)
+        return 1;
+    } else {
+      if (fseek(File, IOVecs[I].ElmSize * IOVecs[I].NumElm, SEEK_CUR) == -1)
+        return 1;
+    }
   }
   return 0;
 }
@@ -133,9 +137,10 @@ static void setupIOBuffer() {
 
 /* Read profile data in \c ProfileFile and merge with in-memory
    profile counters. Returns -1 if there is fatal error, otheriwse
-   0 is returned.
+   0 is returned. Returning 0 does not mean merge is actually
+   performed. If merge is actually done, *MergeDone is set to 1.
 */
-static int doProfileMerging(FILE *ProfileFile) {
+static int doProfileMerging(FILE *ProfileFile, int *MergeDone) {
   uint64_t ProfileFileSize;
   char *ProfileBuffer;
 
@@ -180,6 +185,8 @@ static int doProfileMerging(FILE *ProfileFile) {
   __llvm_profile_merge_from_buffer(ProfileBuffer, ProfileFileSize);
   (void)munmap(ProfileBuffer, ProfileFileSize);
 
+  *MergeDone = 1;
+
   return 0;
 }
 
@@ -201,7 +208,7 @@ static void createProfileDir(const char *Filename) {
  * dumper. With profile merging enabled, each executable as well as any of
  * its instrumented shared libraries dump profile data into their own data file.
 */
-static FILE *openFileForMerging(const char *ProfileFileName) {
+static FILE *openFileForMerging(const char *ProfileFileName, int *MergeDone) {
   FILE *ProfileFile;
   int rc;
 
@@ -210,8 +217,8 @@ static FILE *openFileForMerging(const char *ProfileFileName) {
   if (!ProfileFile)
     return NULL;
 
-  rc = doProfileMerging(ProfileFile);
-  if (rc || COMPILER_RT_FTRUNCATE(ProfileFile, 0L) ||
+  rc = doProfileMerging(ProfileFile, MergeDone);
+  if (rc || (!*MergeDone && COMPILER_RT_FTRUNCATE(ProfileFile, 0L)) ||
       fseek(ProfileFile, 0L, SEEK_SET) == -1) {
     PROF_ERR("Profile Merging of file %s failed: %s\n", ProfileFileName,
              strerror(errno));
@@ -226,10 +233,11 @@ static int writeFile(const char *OutputName) {
   int RetVal;
   FILE *OutputFile;
 
+  int MergeDone = 0;
   if (!doMerging())
     OutputFile = fopen(OutputName, "ab");
   else
-    OutputFile = openFileForMerging(OutputName);
+    OutputFile = openFileForMerging(OutputName, &MergeDone);
 
   if (!OutputFile)
     return -1;
@@ -238,7 +246,7 @@ static int writeFile(const char *OutputName) {
   setupIOBuffer();
   ProfDataWriter fileWriter;
   initFileWriter(&fileWriter, OutputFile);
-  RetVal = lprofWriteData(&fileWriter, lprofGetVPDataReader());
+  RetVal = lprofWriteData(&fileWriter, lprofGetVPDataReader(), MergeDone);
 
   fclose(OutputFile);
   return RetVal;
diff --git a/lib/profile/InstrProfilingInternal.h b/lib/profile/InstrProfilingInternal.h
index ee710722a..36490ef7d 100644
--- a/lib/profile/InstrProfilingInternal.h
+++ b/lib/profile/InstrProfilingInternal.h
@@ -102,7 +102,6 @@ int lprofBufferIOFlush(ProfBufferIO *BufferIO);
  * and profile data writer.  */
 uint32_t lprofBufferWriter(ProfDataWriter *This, ProfDataIOVec *IOVecs,
                            uint32_t NumIOVecs);
-
 void initBufferWriter(ProfDataWriter *BufferWriter, char *Buffer);
 
 struct ValueProfData;
@@ -139,14 +138,17 @@ typedef struct VPDataReaderType {
                                         uint32_t N);
 } VPDataReaderType;
 
-int lprofWriteData(ProfDataWriter *Writer, VPDataReaderType *VPDataReader);
+/* Write profile data to destinitation. If SkipNameDataWrite is set to 1,
+   the name data is already in destintation, we just skip over it. */
+int lprofWriteData(ProfDataWriter *Writer, VPDataReaderType *VPDataReader,
+                   int SkipNameDataWrite);
 int lprofWriteDataImpl(ProfDataWriter *Writer,
                        const __llvm_profile_data *DataBegin,
                        const __llvm_profile_data *DataEnd,
                        const uint64_t *CountersBegin,
                        const uint64_t *CountersEnd,
                        VPDataReaderType *VPDataReader, const char *NamesBegin,
-                       const char *NamesEnd);
+                       const char *NamesEnd, int SkipNameDataWrite);
 
 /* Merge value profile data pointed to by SrcValueProfData into
  * in-memory profile counters pointed by to DstData.  */
diff --git a/lib/profile/InstrProfilingWriter.c b/lib/profile/InstrProfilingWriter.c
index b6cefe049..d4c9b9bd6 100644
--- a/lib/profile/InstrProfilingWriter.c
+++ b/lib/profile/InstrProfilingWriter.c
@@ -38,7 +38,8 @@ COMPILER_RT_VISIBILITY uint32_t lprofBufferWriter(ProfDataWriter *This,
   char **Buffer = (char **)&This->WriterCtx;
   for (I = 0; I < NumIOVecs; I++) {
     size_t Length = IOVecs[I].ElmSize * IOVecs[I].NumElm;
-    memcpy(*Buffer, IOVecs[I].Data, Length);
+    if (IOVecs[I].Data)
+      memcpy(*Buffer, IOVecs[I].Data, Length);
     *Buffer += Length;
   }
   return 0;
@@ -231,7 +232,8 @@ static int writeValueProfData(ProfDataWriter *Writer,
 }
 
 COMPILER_RT_VISIBILITY int lprofWriteData(ProfDataWriter *Writer,
-                                          VPDataReaderType *VPDataReader) {
+                                          VPDataReaderType *VPDataReader,
+                                          int SkipNameDataWrite) {
   /* Match logic in __llvm_profile_write_buffer(). */
   const __llvm_profile_data *DataBegin = __llvm_profile_begin_data();
   const __llvm_profile_data *DataEnd = __llvm_profile_end_data();
@@ -240,7 +242,8 @@ COMPILER_RT_VISIBILITY int lprofWriteData(ProfDataWriter *Writer,
   const char *NamesBegin = __llvm_profile_begin_names();
   const char *NamesEnd = __llvm_profile_end_names();
   return lprofWriteDataImpl(Writer, DataBegin, DataEnd, CountersBegin,
-                            CountersEnd, VPDataReader, NamesBegin, NamesEnd);
+                            CountersEnd, VPDataReader, NamesBegin, NamesEnd,
+                            SkipNameDataWrite);
 }
 
 COMPILER_RT_VISIBILITY int
@@ -248,7 +251,7 @@ lprofWriteDataImpl(ProfDataWriter *Writer, const __llvm_profile_data *DataBegin,
                    const __llvm_profile_data *DataEnd,
                    const uint64_t *CountersBegin, const uint64_t *CountersEnd,
                    VPDataReaderType *VPDataReader, const char *NamesBegin,
-                   const char *NamesEnd) {
+                   const char *NamesEnd, int SkipNameDataWrite) {
 
   /* Calculate size of sections. */
   const uint64_t DataSize = __llvm_profile_get_data_size(DataBegin, DataEnd);
@@ -270,11 +273,12 @@ lprofWriteDataImpl(ProfDataWriter *Writer, const __llvm_profile_data *DataBegin,
 #include "InstrProfData.inc"
 
   /* Write the data. */
-  ProfDataIOVec IOVec[] = {{&Header, sizeof(__llvm_profile_header), 1},
-                           {DataBegin, sizeof(__llvm_profile_data), DataSize},
-                           {CountersBegin, sizeof(uint64_t), CountersSize},
-                           {NamesBegin, sizeof(uint8_t), NamesSize},
-                           {Zeroes, sizeof(uint8_t), Padding}};
+  ProfDataIOVec IOVec[] = {
+      {&Header, sizeof(__llvm_profile_header), 1},
+      {DataBegin, sizeof(__llvm_profile_data), DataSize},
+      {CountersBegin, sizeof(uint64_t), CountersSize},
+      {SkipNameDataWrite ? NULL : NamesBegin, sizeof(uint8_t), NamesSize},
+      {Zeroes, sizeof(uint8_t), Padding}};
   if (Writer->Write(Writer, IOVec, sizeof(IOVec) / sizeof(*IOVec)))
     return -1;