src/llvm/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->getNumBlockIDs());
  43
  44   for (const auto &MBB : *MF) {
  45     unsigned OutE = 2 * MBB.getNumber() + 1;
  46     // Join the outgoing bundle with the ingoing bundles of all successors.
  47     for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
  48            SE = MBB.succ_end(); SI != SE; ++SI)
  49       EC.join(OutE, 2 * (*SI)->getNumber());
  50   }
  51   EC.compress();
  52   if (ViewEdgeBundles)
  53     view();
  54
  55   // Compute the reverse mapping.
  56   Blocks.clear();
  57   Blocks.resize(getNumBundles());
  58
  59   for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
  60     unsigned b0 = getBundle(i, 0);
  61     unsigned b1 = getBundle(i, 1);
  62     Blocks[b0].push_back(i);
  63     if (b1 != b0)
  64       Blocks[b1].push_back(i);
  65   }
  66
  67   return false;
  68 }
  69
  70 /// Specialize WriteGraph, the standard implementation won't work.
  71 namespace llvm {
  72 template<>
  73 raw_ostream &WriteGraph<>(raw_ostream &O, const EdgeBundles &G,
  74                           bool ShortNames,
  75                           const Twine &Title) {
  76   const MachineFunction *MF = G.getMachineFunction();
  77
  78   O << "digraph {\n";
  79   for (const auto &MBB : *MF) {
  80     unsigned BB = MBB.getNumber();
  81     O << "\t\"BB#" << BB << "\" [ shape=box ]\n"
  82       << '\t' << G.getBundle(BB, false) << " -> \"BB#" << BB << "\"\n"
  83       << "\t\"BB#" << BB << "\" -> " << G.getBundle(BB, true) << '\n';
  84     for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
  85            SE = MBB.succ_end(); SI != SE; ++SI)
  86       O << "\t\"BB#" << BB << "\" -> \"BB#" << (*SI)->getNumber()
  87         << "\" [ color=lightgray ]\n";
  88   }
  89   O << "}\n";
  90   return O;
  91 }
  92 }
  93
  94 /// view - Visualize the annotated bipartite CFG with Graphviz.
  95 void EdgeBundles::view() const {
  96   ViewGraph(*this, "EdgeBundles");
  97 }