llvm/lib/CodeGen/EdgeBundles.cpp

   1 //===-------- EdgeBundles.cpp - Bundles of CFG edges ----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file provides the implementation of the EdgeBundles analysis.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/CodeGen/EdgeBundles.h"
  14 #include "llvm/ADT/Twine.h"
  15 #include "llvm/CodeGen/MachineBasicBlock.h"
  16 #include "llvm/CodeGen/MachineFunction.h"
  17 #include "llvm/CodeGen/Passes.h"
  18 #include "llvm/InitializePasses.h"
  19 #include "llvm/Support/CommandLine.h"
  20 #include "llvm/Support/GraphWriter.h"
  21 #include "llvm/Support/raw_ostream.h"
  22
  23 using namespace llvm;
  24
  25 static cl::opt<bool>
  26 ViewEdgeBundles("view-edge-bundles", cl::Hidden,
  27                 cl::desc("Pop up a window to show edge bundle graphs"));
  28
  29 char EdgeBundlesWrapperLegacy::ID = 0;
  30
  31 INITIALIZE_PASS(EdgeBundlesWrapperLegacy, "edge-bundles",
  32                 "Bundle Machine CFG Edges",
  33                 /* cfg = */ true, /* is_analysis = */ true)
  34
  35 char &llvm::EdgeBundlesWrapperLegacyID = EdgeBundlesWrapperLegacy::ID;
  36
  37 void EdgeBundlesWrapperLegacy::getAnalysisUsage(AnalysisUsage &AU) const {
  38   AU.setPreservesAll();
  39   MachineFunctionPass::getAnalysisUsage(AU);
  40 }
  41
  42 AnalysisKey EdgeBundlesAnalysis::Key;
  43
  44 EdgeBundles EdgeBundlesAnalysis::run(MachineFunction &MF,
  45                                      MachineFunctionAnalysisManager &MFAM) {
  46   EdgeBundles Impl(MF);
  47   return Impl;
  48 }
  49
  50 bool EdgeBundlesWrapperLegacy::runOnMachineFunction(MachineFunction &MF) {
  51   Impl.reset(new EdgeBundles(MF));
  52   return false;
  53 }
  54
  55 EdgeBundles::EdgeBundles(MachineFunction &MF) : MF(&MF) { init(); }
  56
  57 void EdgeBundles::init() {
  58   EC.clear();
  59   EC.grow(2 * MF->getNumBlockIDs());
  60
  61   for (const auto &MBB : *MF) {
  62     unsigned OutE = 2 * MBB.getNumber() + 1;
  63     // Join the outgoing bundle with the ingoing bundles of all successors.
  64     for (const MachineBasicBlock *Succ : MBB.successors())
  65       EC.join(OutE, 2 * Succ->getNumber());
  66   }
  67   EC.compress();
  68   if (ViewEdgeBundles)
  69     view();
  70
  71   // Compute the reverse mapping.
  72   Blocks.clear();
  73   Blocks.resize(getNumBundles());
  74
  75   for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
  76     unsigned b0 = getBundle(i, false);
  77     unsigned b1 = getBundle(i, true);
  78     Blocks[b0].push_back(i);
  79     if (b1 != b0)
  80       Blocks[b1].push_back(i);
  81   }
  82 }
  83
  84 namespace llvm {
  85
  86 /// Specialize WriteGraph, the standard implementation won't work.
  87 template<>
  88 raw_ostream &WriteGraph<>(raw_ostream &O, const EdgeBundles &G,
  89                           bool ShortNames,
  90                           const Twine &Title) {
  91   const MachineFunction *MF = G.getMachineFunction();
  92
  93   O << "digraph {\n";
  94   for (const auto &MBB : *MF) {
  95     unsigned BB = MBB.getNumber();
  96     O << "\t\"" << printMBBReference(MBB) << "\" [ shape=box, label=\""
  97       << printMBBReference(MBB) << "\" ]\n"
  98       << '\t' << G.getBundle(BB, false) << " -> \"" << printMBBReference(MBB)
  99       << "\"\n"
 100       << "\t\"" << printMBBReference(MBB) << "\" -> " << G.getBundle(BB, true)
 101       << '\n';
 102     for (const MachineBasicBlock *Succ : MBB.successors())
 103       O << "\t\"" << printMBBReference(MBB) << "\" -> \""
 104         << printMBBReference(*Succ) << "\" [ color=lightgray ]\n";
 105   }
 106   O << "}\n";
 107   return O;
 108 }
 109
 110 } // end namespace llvm
 111
 112 /// view - Visualize the annotated bipartite CFG with Graphviz.
 113 void EdgeBundles::view() const {
 114   ViewGraph(*this, "EdgeBundles");
 115 }
 116
 117 bool EdgeBundles::invalidate(MachineFunction &MF, const PreservedAnalyses &PA,
 118                              MachineFunctionAnalysisManager::Invalidator &Inv) {
 119   // Invalidated when CFG is not preserved
 120   auto PAC = PA.getChecker<EdgeBundlesAnalysis>();
 121   return !PAC.preserved() && !PAC.preservedSet<CFGAnalyses>() &&
 122          !PAC.preservedSet<AllAnalysesOn<MachineFunction>>();
 123 }