From 6ef116d9dc29990b44939bad37458bf9d7f6846f Mon Sep 17 00:00:00 2001 From: Andreas Neustifter Date: Fri, 28 Aug 2009 11:28:24 +0000 Subject: [PATCH] Preparation for Optimal Edge Profiling: This implements the maximum spanning tree algorithm on CFGs according to weights given by the ProfileEstimator. This is then used to implement Optimal Edge Profiling. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80358 91177308-0d34-0410-b5e6-96231b3b80d8 --- .../Instrumentation/MaximumSpanningTree.cpp | 121 ++++++++++++++++++ .../Instrumentation/MaximumSpanningTree.h | 50 ++++++++ 2 files changed, 171 insertions(+) create mode 100644 lib/Transforms/Instrumentation/MaximumSpanningTree.cpp create mode 100644 lib/Transforms/Instrumentation/MaximumSpanningTree.h diff --git a/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp b/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp new file mode 100644 index 00000000000..80f1a15d632 --- /dev/null +++ b/lib/Transforms/Instrumentation/MaximumSpanningTree.cpp @@ -0,0 +1,121 @@ +//===- MaximumSpanningTree.cpp - LLVM Pass to estimate profile info -------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This module privides means for calculating a maximum spanning tree for the +// CFG of a function according to a given profile. The tree does not contain +// leaf edges, since they are needed for optimal edge profiling. +// +//===----------------------------------------------------------------------===// +#define DEBUG_TYPE "maximum-spanning-tree" +#include "MaximumSpanningTree.h" +#include "llvm/Pass.h" +#include "llvm/Analysis/Passes.h" +#include "llvm/ADT/EquivalenceClasses.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/Format.h" +using namespace llvm; + +namespace { + // compare two weighted edges + struct VISIBILITY_HIDDEN EdgeWeightCompare { + bool operator()(const ProfileInfo::EdgeWeight X, + const ProfileInfo::EdgeWeight Y) const { + if (X.second > Y.second) return true; + if (X.second < Y.second) return false; +#ifndef NDEBUG + if (X.first.first != 0 && Y.first.first == 0) return true; + if (X.first.first == 0 && Y.first.first != 0) return false; + if (X.first.first == 0 && Y.first.first == 0) return false; + + if (X.first.first->size() > Y.first.first->size()) return true; + if (X.first.first->size() < Y.first.first->size()) return false; + + if (X.first.second != 0 && Y.first.second == 0) return true; + if (X.first.second == 0 && Y.first.second != 0) return false; + if (X.first.second == 0 && Y.first.second == 0) return false; + + if (X.first.second->size() > Y.first.second->size()) return true; + if (X.first.second->size() < Y.first.second->size()) return false; +#endif + return false; + } + }; +} + +static void inline printMSTEdge(ProfileInfo::EdgeWeight E, + const char *M) { + DEBUG(errs() << "--Edge " << E.first + <<" (Weight "<< format("%g",E.second) << ") " + << (M) << "\n"); +} + +// MaximumSpanningTree() - Takes a function and returns a spanning tree +// according to the currently active profiling information, the leaf edges are +// NOT in the MST. MaximumSpanningTree uses the algorithm of Kruskal. +MaximumSpanningTree::MaximumSpanningTree(Function *F, ProfileInfo *PI, + bool inverted = false) { + + // Copy edges to vector, sort them biggest first. + ProfileInfo::EdgeWeights ECs = PI->getEdgeWeights(F); + std::vector EdgeVector(ECs.begin(), ECs.end()); + std::sort(EdgeVector.begin(), EdgeVector.end(), EdgeWeightCompare()); + + // Create spanning tree, Forest contains a special data structure + // that makes checking if two nodes are already in a common (sub-)tree + // fast and cheap. + EquivalenceClasses Forest; + for (std::vector::iterator bbi = EdgeVector.begin(), + bbe = EdgeVector.end(); bbi != bbe; ++bbi) { + Forest.insert(bbi->first.first); + Forest.insert(bbi->first.second); + } + Forest.insert(0); + + // Iterate over the sorted edges, biggest first. + for (std::vector::iterator bbi = EdgeVector.begin(), + bbe = EdgeVector.end(); bbi != bbe; ++bbi) { + ProfileInfo::Edge e = (*bbi).first; + + if (Forest.findLeader(e.first) != Forest.findLeader(e.second)) { + Forest.unionSets(e.first, e.second); + // So we know now that the edge is not already in a subtree (and not + // (0,entry)), so we push the edge to the MST if it has some successors. + if (!inverted) { MST.push_back(e); } + printMSTEdge(*bbi,"in MST"); + } else { + // This edge is either (0,entry) or (BB,0) or would create a circle in a + // subtree. + if (inverted) { MST.push_back(e); } + printMSTEdge(*bbi,"*not* in MST"); + } + } + + // Sort the MST edges. + std::stable_sort(MST.begin(),MST.end()); +} + +MaximumSpanningTree::MaxSpanTree::iterator MaximumSpanningTree::begin() { + return MST.begin(); +} + +MaximumSpanningTree::MaxSpanTree::iterator MaximumSpanningTree::end() { + return MST.end(); +} + +void MaximumSpanningTree::dump() { + errs()<<"{"; + for ( MaxSpanTree::iterator ei = MST.begin(), ee = MST.end(); + ei!=ee; ++ei ) { + errs()<<"("<<((*ei).first?(*ei).first->getNameStr():"0")<<","; + errs()<<(*ei).second->getNameStr()<<")"; + } + errs()<<"}\n"; +} diff --git a/lib/Transforms/Instrumentation/MaximumSpanningTree.h b/lib/Transforms/Instrumentation/MaximumSpanningTree.h new file mode 100644 index 00000000000..fcfb3f5b9c5 --- /dev/null +++ b/lib/Transforms/Instrumentation/MaximumSpanningTree.h @@ -0,0 +1,50 @@ +//===- llvm/Analysis/MaximumSpanningTree.h - Interface ----------*- C++ -*-===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This module privides means for calculating a maximum spanning tree for the +// CFG of a function according to a given profile. +// +//===----------------------------------------------------------------------===// + +#ifndef LLVM_ANALYSIS_MAXIMUMSPANNINGTREE_H +#define LLVM_ANALYSIS_MAXIMUMSPANNINGTREE_H + +#include "llvm/Analysis/ProfileInfo.h" +#include "llvm/Support/raw_ostream.h" +#include + +namespace llvm { + class Function; + + class MaximumSpanningTree { + public: + typedef std::vector MaxSpanTree; + + protected: + MaxSpanTree MST; + + public: + static char ID; // Class identification, replacement for typeinfo + + // MaxSpanTree() - Calculates a MST for a function according to a profile. + // If inverted is true, all the edges *not* in the MST are returned. As a + // special also all leaf edges of the MST are not included, this makes it + // easier for the OptimalEdgeProfileInstrumentation to use this MST to do + // an optimal profiling. + MaximumSpanningTree(Function *F, ProfileInfo *PI, bool invert); + + virtual MaxSpanTree::iterator begin(); + virtual MaxSpanTree::iterator end(); + + virtual void dump(); + }; + +} // End llvm namespace + +#endif