CodeGen: Include a function hash in instrumentation based profiling

The hash itself is still the number of counters, which isn't all that
useful, but this separates the API changes from the actual
implementation of the hash and will make it easier to transition to
the ProfileData library once it's implemented.

llvm-svn: 204186

2 files changed, 29 insertions, 13 deletions

diff --git a/clang/lib/CodeGen/CodeGenPGO.cpp b/clang/lib/CodeGen/CodeGenPGO.cpp
index 207cb665b0f..1f2fe38c40e 100644
--- a/clang/lib/CodeGen/CodeGenPGO.cpp
+++ b/clang/lib/CodeGen/CodeGenPGO.cpp
@@ -58,10 +58,15 @@ PGOProfileData::PGOProfileData(CodeGenModule &CGM, std::string Path)
       ReportBadPGOData(CGM, "pgo data file has malformed function entry");
       return;
     }
-    while (*--CurPtr != ' ')
-      ;
     StringRef FuncName(FuncStart, CurPtr - FuncStart);
 
+    // Skip over the function hash.
+    CurPtr = strchr(++CurPtr, '\n');
+    if (!CurPtr) {
+      ReportBadPGOData(CGM, "pgo data file is missing the function hash");
+      return;
+    }
+
     // Read the number of counters.
     char *EndPtr;
     unsigned NumCounters = strtol(++CurPtr, &EndPtr, 10);
@@ -99,7 +104,7 @@ PGOProfileData::PGOProfileData(CodeGenModule &CGM, std::string Path)
   MaxFunctionCount = MaxCount;
 }
 
-bool PGOProfileData::getFunctionCounts(StringRef FuncName,
+bool PGOProfileData::getFunctionCounts(StringRef FuncName, uint64_t &FuncHash,
                                        std::vector<uint64_t> &Counts) {
   // Find the relevant section of the pgo-data file.
   llvm::StringMap<unsigned>::const_iterator OffsetIter =
@@ -111,11 +116,15 @@ bool PGOProfileData::getFunctionCounts(StringRef FuncName,
   // Skip over the function name.
   CurPtr = strchr(CurPtr, '\n');
   assert(CurPtr && "pgo-data has corrupted function entry");
-  while (*--CurPtr != ' ')
-    ;
 
-  // Read the number of counters.
   char *EndPtr;
+  // Read the function hash.
+  FuncHash = strtoll(++CurPtr, &EndPtr, 10);
+  assert(EndPtr != CurPtr && *EndPtr == '\n' &&
+         "pgo-data file has corrupted function hash");
+  CurPtr = EndPtr;
+
+  // Read the number of counters.
   unsigned NumCounters = strtol(++CurPtr, &EndPtr, 10);
   assert(EndPtr != CurPtr && *EndPtr == '\n' && NumCounters > 0 &&
          "pgo-data file has corrupted number of counters");
@@ -246,15 +255,17 @@ llvm::GlobalVariable *CodeGenPGO::buildDataVar() {
 
   // Create data variable.
   auto *Int32Ty = llvm::Type::getInt32Ty(Ctx);
+  auto *Int64Ty = llvm::Type::getInt64Ty(Ctx);
   auto *Int8PtrTy = llvm::Type::getInt8PtrTy(Ctx);
   auto *Int64PtrTy = llvm::Type::getInt64PtrTy(Ctx);
   llvm::Type *DataTypes[] = {
-    Int32Ty, Int32Ty, Int8PtrTy, Int64PtrTy
+    Int32Ty, Int32Ty, Int64Ty, Int8PtrTy, Int64PtrTy
   };
   auto *DataTy = llvm::StructType::get(Ctx, makeArrayRef(DataTypes));
   llvm::Constant *DataVals[] = {
     llvm::ConstantInt::get(Int32Ty, getFuncName().size()),
     llvm::ConstantInt::get(Int32Ty, NumRegionCounters),
+    llvm::ConstantInt::get(Int64Ty, FunctionHash),
     llvm::ConstantExpr::getBitCast(Name, Int8PtrTy),
     llvm::ConstantExpr::getBitCast(RegionCounters, Int64PtrTy)
   };
@@ -847,6 +858,8 @@ void CodeGenPGO::mapRegionCounters(const Decl *D) {
   else if (const BlockDecl *BD = dyn_cast_or_null<BlockDecl>(D))
     Walker.VisitBlockDecl(BD);
   NumRegionCounters = Walker.NextCounter;
+  // FIXME: The number of counters isn't sufficient for the hash
+  FunctionHash = NumRegionCounters;
 }
 
 void CodeGenPGO::computeRegionCounts(const Decl *D) {
@@ -905,8 +918,9 @@ void CodeGenPGO::loadRegionCounts(PGOProfileData *PGOData) {
   // ignore counts when the input changes in various ways, e.g., by comparing a
   // hash value based on some characteristics of the input.
   RegionCounts = new std::vector<uint64_t>();
-  if (PGOData->getFunctionCounts(getFuncName(), *RegionCounts) ||
-      RegionCounts->size() != NumRegionCounters) {
+  uint64_t Hash;
+  if (PGOData->getFunctionCounts(getFuncName(), Hash, *RegionCounts) ||
+      Hash != FunctionHash || RegionCounts->size() != NumRegionCounters) {
     delete RegionCounts;
     RegionCounts = 0;
   }
diff --git a/clang/lib/CodeGen/CodeGenPGO.h b/clang/lib/CodeGen/CodeGenPGO.h
index 2f1fe5dba8a..e859324ae08 100644
--- a/clang/lib/CodeGen/CodeGenPGO.h
+++ b/clang/lib/CodeGen/CodeGenPGO.h
@@ -42,7 +42,8 @@ public:
   PGOProfileData(CodeGenModule &CGM, std::string Path);
   /// Fill Counts with the profile data for the given function name. Returns
   /// false on success.
-  bool getFunctionCounts(StringRef FuncName, std::vector<uint64_t> &Counts);
+  bool getFunctionCounts(StringRef FuncName, uint64_t &FuncHash,
+                         std::vector<uint64_t> &Counts);
   /// Return the maximum of all known function counts.
   uint64_t getMaximumFunctionCount() { return MaxFunctionCount; }
 };
@@ -57,6 +58,7 @@ private:
   llvm::GlobalValue::LinkageTypes FuncLinkage;
 
   unsigned NumRegionCounters;
+  uint64_t FunctionHash;
   llvm::GlobalVariable *RegionCounters;
   llvm::DenseMap<const Stmt*, unsigned> *RegionCounterMap;
   llvm::DenseMap<const Stmt*, uint64_t> *StmtCountMap;
@@ -65,9 +67,9 @@ private:
 
 public:
   CodeGenPGO(CodeGenModule &CGM)
-    : CGM(CGM), PrefixedFuncName(0), NumRegionCounters(0), RegionCounters(0),
-      RegionCounterMap(0), StmtCountMap(0), RegionCounts(0),
-      CurrentRegionCount(0) {}
+      : CGM(CGM), PrefixedFuncName(0), NumRegionCounters(0), FunctionHash(0),
+        RegionCounters(0), RegionCounterMap(0), StmtCountMap(0),
+        RegionCounts(0), CurrentRegionCount(0) {}
   ~CodeGenPGO() {
     if (PrefixedFuncName) delete PrefixedFuncName;
   }