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
  21 using namespace llvm;
  22
  23 static cl::opt<bool>
  24 ViewEdgeBundles("view-edge-bundles", cl::Hidden,
  25                 cl::desc("Pop up a window to show edge bundle graphs"));
  26
  27 char EdgeBundles::ID = 0;
  28
  29 INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
  30                 /* cfg = */true, /* analysis = */ true)
  31
  32 char &llvm::EdgeBundlesID = EdgeBundles::ID;
  33
  34 void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
  35   AU.setPreservesAll();
  36   MachineFunctionPass::getAnalysisUsage(AU);
  37 }
  38
  39 bool EdgeBundles::runOnMachineFunction(MachineFunction &mf) {
  40   MF = &mf;
  41   EC.clear();
  42   EC.grow(2 * MF->size());
  43
  44   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end(); I != E;
  45        ++I) {
  46     const MachineBasicBlock &MBB = *I;
  47     unsigned OutE = 2 * MBB.getNumber() + 1;
  48     // Join the outgoing bundle with the ingoing bundles of all successors.
  49     for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
  50            SE = MBB.succ_end(); SI != SE; ++SI)
  51       EC.join(OutE, 2 * (*SI)->getNumber());
  52   }
  53   EC.compress();
  54   if (ViewEdgeBundles)
  55     view();
  56   return false;
  57 }
  58
  59 /// view - Visualize the annotated bipartite CFG with Graphviz.
  60 void EdgeBundles::view() const {
  61   ViewGraph(*this, "EdgeBundles");
  62 }
  63
  64 /// Specialize WriteGraph, the standard implementation won't work.
  65 raw_ostream &llvm::WriteGraph(raw_ostream &O, const EdgeBundles &G,
  66                               bool ShortNames,
  67                               const std::string &Title) {
  68   const MachineFunction *MF = G.getMachineFunction();
  69
  70   O << "digraph {\n";
  71   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
  72        I != E; ++I) {
  73     unsigned BB = I->getNumber();
  74     O << "\t\"BB#" << BB << "\" [ shape=box ]\n"
  75       << '\t' << G.getBundle(BB, false) << " -> \"BB#" << BB << "\"\n"
  76       << "\t\"BB#" << BB << "\" -> " << G.getBundle(BB, true) << '\n';
  77     for (MachineBasicBlock::const_succ_iterator SI = I->succ_begin(),
  78            SE = I->succ_end(); SI != SE; ++SI)
  79       O << "\t\"BB#" << BB << "\" -> \"BB#" << (*SI)->getNumber()
  80         << "\" [ color=lightgray ]\n";
  81   }
  82   O << "}\n";
  83   return O;
  84 }
  85
  86