Profile: set branch weight metadata with data generated from profiling.

This patch implements ProfileDataLoader which loads profile data generated by
-insert-edge-profiling and updates branch weight metadata accordingly.

Patch by Alastair Murray.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162799 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 148 insertions, 0 deletions

diff --git a/include/llvm/Analysis/ProfileDataLoader.h b/include/llvm/Analysis/ProfileDataLoader.h
new file mode 100644
index 0000000000..3d15bda364
--- /dev/null
+++ b/include/llvm/Analysis/ProfileDataLoader.h
@@ -0,0 +1,148 @@
+//===- ProfileDataLoader.h - Load & convert profile info ----*- C++ -*-===//
+//
+//                      The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The ProfileDataLoader class is used to load profiling data from a dump file.
+// The ProfileDataT<FType, BType> class is used to store the mapping of this
+// data to control flow edges.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_PROFILEDATALOADER_H
+#define LLVM_ANALYSIS_PROFILEDATALOADER_H
+
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <vector>
+#include <string>
+#include <map>
+
+namespace llvm {
+
+class ModulePass;
+class Function;
+class BasicBlock;
+
+// Helpers for dumping edges to dbgs().
+raw_ostream& operator<<(raw_ostream &O, std::pair<const BasicBlock *,
+                                                  const BasicBlock *> E);
+raw_ostream& operator<<(raw_ostream &O, const BasicBlock *BB);
+raw_ostream& operator<<(raw_ostream &O, const Function *F);
+
+/// \brief The ProfileDataT<FType, BType> class is used to store the mapping of
+/// profiling data to control flow edges.
+///
+/// An edge is defined by its source and sink basic blocks.
+template<class FType, class BType>
+class ProfileDataT {
+  public:
+  // The profiling information defines an Edge by its source and sink basic
+  // blocks.
+  typedef std::pair<const BType*, const BType*> Edge;
+
+  private:
+  typedef std::map<Edge, unsigned> EdgeWeights;
+
+  /// \brief Count the number of times a transition between two blocks is
+  /// executed.
+  ///
+  /// As a special case, we also hold an edge from the null BasicBlock to the
+  /// entry block to indicate how many times the function was entered.
+  std::map<const FType*, EdgeWeights> EdgeInformation;
+
+  public:
+  static char ID; // Class identification, replacement for typeinfo
+  ProfileDataT() {};
+  ~ProfileDataT() {};
+
+  /// getFunction() - Returns the Function for an Edge.
+  static const FType* getFunction(Edge e) {
+    // e.first may be NULL
+    assert(   ((!e.first) || (e.first->getParent() == e.second->getParent()))
+           && "A ProfileData::Edge can not be between two functions");
+    assert(e.second && "A ProfileData::Edge must have a real sink");
+    return e.second->getParent();
+  }
+
+  /// getEdge() - Creates an Edge between two BasicBlocks.
+  static Edge getEdge(const BType *Src, const BType *Dest) {
+    return std::make_pair(Src, Dest);
+  }
+
+  /// getEdgeWeight - Return the number of times that a given edge was
+  /// executed.
+  unsigned getEdgeWeight(Edge e) const {
+    const FType *f = getFunction(e);
+    assert(   (EdgeInformation.find(f) != EdgeInformation.end())
+           && "No profiling information for function");
+    EdgeWeights weights = EdgeInformation.find(f)->second;
+
+    assert(   (weights.find(e) != weights.end())
+           && "No profiling information for edge");
+    return weights.find(e)->second;
+  }
+
+  /// addEdgeWeight - Add 'weight' to the already stored execution count for
+  /// this edge.
+  void addEdgeWeight(Edge e, unsigned weight) {
+      EdgeInformation[getFunction(e)][e] += weight;
+  }
+};
+
+typedef ProfileDataT<Function, BasicBlock> ProfileData;
+//typedef ProfileDataT<MachineFunction, MachineBasicBlock> MachineProfileData;
+
+/// The ProfileDataLoader class is used to load raw profiling data from the
+/// dump file.
+class ProfileDataLoader {
+private:
+  /// The name of the file where the raw profiling data is stored.
+  const std::string &Filename;
+
+  /// A vector of the command line arguments used when the target program was
+  /// run to generate profiling data.  One entry per program run.
+  std::vector<std::string> CommandLines;
+
+  /// The raw values for how many times each edge was traversed, values from
+  /// multiple program runs are accumulated.
+  std::vector<unsigned> EdgeCounts;
+
+public:
+  /// ProfileDataLoader ctor - Read the specified profiling data file, exiting
+  /// the program if the file is invalid or broken.
+  ProfileDataLoader(const char *ToolName, const std::string &Filename);
+
+  /// A special value used to represent the weight of an edge which has not
+  /// been counted yet.
+  static const unsigned Uncounted;
+
+  /// The maximum value that can be stored in a profiling counter.
+  static const unsigned MaxCount;
+
+  /// getNumExecutions - Return the number of times the target program was run
+  /// to generate this profiling data.
+  unsigned getNumExecutions() const { return CommandLines.size(); }
+
+  /// getExecution - Return the command line parameters used to generate the
+  /// i'th set of profiling data.
+  const std::string& getExecution(unsigned i) const { return CommandLines[i]; }
+
+  const std::string& getFileName() const { return Filename; }
+
+  /// getRawEdgeCounts - Return the raw profiling data, this is just a list of
+  /// numbers with no mappings to edges.
+  const std::vector<unsigned>& getRawEdgeCounts() const { return EdgeCounts; }
+};
+
+/// createProfileMetadataLoaderPass - This function returns a Pass that loads
+/// the profiling information for the module from the specified filename.
+ModulePass *createProfileMetadataLoaderPass(const std::string &Filename);
+
+} // End llvm namespace
+
+#endif