[PGO] Make indexed value profile data more compact

- Make indexed value profile data more compact by peeling out 
  the per-site value count field into its own smaller sized array.
- Introduced formal data structure definitions to specify value 
  profile data layout in indexed format. Previously the layout 
  of the data is only assumed in the client code (scattered in 
  three different places : size computation, EmitData, and ReadData
- The new data structure  serves as a central place for layout documentation.
- Add interfaces to force BE output for value profile data (testing purpose)
- Add byte swap unit tests

Differential Revision: http://reviews.llvm.org/D14401

llvm-svn: 252563

1 files changed, 14 insertions, 43 deletions

diff --git a/llvm/lib/ProfileData/InstrProfWriter.cpp b/llvm/lib/ProfileData/InstrProfWriter.cpp
index b073d8d..b6725df 100644
--- a/llvm/lib/ProfileData/InstrProfWriter.cpp
+++ b/llvm/lib/ProfileData/InstrProfWriter.cpp
@@ -20,6 +20,8 @@
 using namespace llvm;
 
 namespace {
+static support::endianness ValueProfDataEndianness = support::little;
+
 class InstrProfRecordTrait {
 public:
   typedef StringRef key_type;
@@ -51,20 +53,7 @@ public:
       M += ProfRecord.Counts.size() * sizeof(uint64_t);
 
       // Value data
-      M += sizeof(uint64_t); // Number of value kinds with value sites.
-      for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind) {
-        uint32_t NumValueSites = ProfRecord.getNumValueSites(Kind);
-        if (NumValueSites == 0)
-          continue;
-        M += sizeof(uint64_t); // Value kind
-        M += sizeof(uint64_t); // The number of value sites for given value kind
-        for (uint32_t I = 0; I < NumValueSites; I++) {
-          M += sizeof(uint64_t); // Number of value data pairs at a value site
-          uint64_t NumValueDataForSite =
-              ProfRecord.getNumValueDataForSite(Kind, I);
-          M += 2 * sizeof(uint64_t) * NumValueDataForSite; // Value data pairs
-        }
-      }
+      M += IndexedInstrProf::ValueProfData::getSize(ProfileData.second);
     }
     LE.write<offset_type>(M);
 
@@ -87,36 +76,12 @@ public:
       for (uint64_t I : ProfRecord.Counts)
         LE.write<uint64_t>(I);
 
-      // Compute the number of value kinds with value sites.
-      uint64_t NumValueKinds = ProfRecord.getNumValueKinds();
-      LE.write<uint64_t>(NumValueKinds);
-
       // Write value data
-      for (uint32_t Kind = IPVK_First; Kind <= IPVK_Last; ++Kind) {
-        uint32_t NumValueSites = ProfRecord.getNumValueSites(Kind);
-        if (NumValueSites == 0)
-          continue;
-        LE.write<uint64_t>(Kind); // Write value kind
-        // Write number of value sites for current value kind
-        LE.write<uint64_t>(NumValueSites);
-
-        for (uint32_t I = 0; I < NumValueSites; I++) {
-          // Write number of value data pairs at this value site
-          uint64_t NumValueDataForSite =
-              ProfRecord.getNumValueDataForSite(Kind, I);
-          LE.write<uint64_t>(NumValueDataForSite);
-          std::unique_ptr<InstrProfValueData[]> VD =
-              ProfRecord.getValueForSite(Kind, I);
-
-          for (uint32_t V = 0; V < NumValueDataForSite; V++) {
-            if (Kind == IPVK_IndirectCallTarget)
-              LE.write<uint64_t>(ComputeHash((const char *)VD[V].Value));
-            else
-              LE.write<uint64_t>(VD[V].Value);
-            LE.write<uint64_t>(VD[V].Count);
-          }
-        }
-      }
+      std::unique_ptr<IndexedInstrProf::ValueProfData> VDataPtr =
+          IndexedInstrProf::ValueProfData::serializeFrom(ProfileData.second);
+      uint32_t S = VDataPtr->getSize();
+      VDataPtr->swapBytesFromHost(ValueProfDataEndianness);
+      Out.write((const char *)VDataPtr.get(), S);
     }
   }
 };
@@ -148,6 +113,12 @@ static std::error_code combineInstrProfRecords(InstrProfRecord &Dest,
   return instrprof_error::success;
 }
 
+// Internal interface for testing purpose only.
+void InstrProfWriter::setValueProfDataEndianness(
+    support::endianness Endianness) {
+  ValueProfDataEndianness = Endianness;
+}
+
 void InstrProfWriter::updateStringTableReferences(InstrProfRecord &I) {
   I.updateStrings(&StringTable);
 }