lib/CodeGen/EdgeBundles.cpp

   1 //===-------- EdgeBundles.cpp - Bundles of CFG edges ----------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file provides the implementation of the EdgeBundles analysis.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/CodeGen/EdgeBundles.h"
  15 #include "llvm/CodeGen/MachineBasicBlock.h"
  16 #include "llvm/CodeGen/MachineFunction.h"
  17 #include "llvm/CodeGen/Passes.h"
  18 #include "llvm/Support/CommandLine.h"
  19 #include "llvm/Support/GraphWriter.h"
  20 #include "llvm/Support/raw_ostream.h"
  21
  22 using namespace llvm;
  23
  24 static cl::opt<bool>
  25 ViewEdgeBundles("view-edge-bundles", cl::Hidden,
  26                 cl::desc("Pop up a window to show edge bundle graphs"));
  27
  28 char EdgeBundles::ID = 0;
  29
  30 INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
  31                 /* cfg = */true, /* analysis = */ true)
  32
  33 char &llvm::EdgeBundlesID = EdgeBundles::ID;
  34
  35 void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
  36   AU.setPreservesAll();
  37   MachineFunctionPass::getAnalysisUsage(AU);
  38 }
  39
  40 bool EdgeBundles::runOnMachineFunction(MachineFunction &mf) {
  41   MF = &mf;
  42   EC.clear();
  43   EC.grow(2 * MF->getNumBlockIDs());
  44
  45   for (const auto &MBB : *MF) {
  46     unsigned OutE = 2 * MBB.getNumber() + 1;
  47     // Join the outgoing bundle with the ingoing bundles of all successors.
  48     for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
  49            SE = MBB.succ_end(); SI != SE; ++SI)
  50       EC.join(OutE, 2 * (*SI)->getNumber());
  51   }
  52   EC.compress();
  53   if (ViewEdgeBundles)
  54     view();
  55
  56   // Compute the reverse mapping.
  57   Blocks.clear();
  58   Blocks.resize(getNumBundles());
  59
  60   for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
  61     unsigned b0 = getBundle(i, false);
  62     unsigned b1 = getBundle(i, true);
  63     Blocks[b0].push_back(i);
  64     if (b1 != b0)
  65       Blocks[b1].push_back(i);
  66   }
  67
  68   return false;
  69 }
  70
  71 /// Specialize WriteGraph, the standard implementation won't work.
  72 namespace llvm {
  73
  74 template<>
  75 raw_ostream &WriteGraph<>(raw_ostream &O, const EdgeBundles &G,
  76                           bool ShortNames,
  77                           const Twine &Title) {
  78   const MachineFunction *MF = G.getMachineFunction();
  79
  80   O << "digraph {\n";
  81   for (const auto &MBB : *MF) {
  82     unsigned BB = MBB.getNumber();
  83     O << "\t\"" << printMBBReference(MBB) << "\" [ shape=box ]\n"
  84       << '\t' << G.getBundle(BB, false) << " -> \"" << printMBBReference(MBB)
  85       << "\"\n"
  86       << "\t\"" << printMBBReference(MBB) << "\" -> " << G.getBundle(BB, true)
  87       << '\n';
  88     for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
  89            SE = MBB.succ_end(); SI != SE; ++SI)
  90       O << "\t\"" << printMBBReference(MBB) << "\" -> \""
  91         << printMBBReference(**SI) << "\" [ color=lightgray ]\n";
  92   }
  93   O << "}\n";
  94   return O;
  95 }
  96
  97 } // end namespace llvm
  98
  99 /// view - Visualize the annotated bipartite CFG with Graphviz.
 100 void EdgeBundles::view() const {
 101   ViewGraph(*this, "EdgeBundles");
 102 }