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
21using namespace llvm;
22
23static cl::opt<bool>
24ViewEdgeBundles("view-edge-bundles", cl::Hidden,
25                cl::desc("Pop up a window to show edge bundle graphs"));
26
27char EdgeBundles::ID = 0;
28
29INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
30                /* cfg = */true, /* analysis = */ true)
31
32char &llvm::EdgeBundlesID = EdgeBundles::ID;
33
34void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
35  AU.setPreservesAll();
36  MachineFunctionPass::getAnalysisUsage(AU);
37}
38
39bool 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.
71namespace llvm {
72template<>
73raw_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.
95void EdgeBundles::view() const {
96  ViewGraph(*this, "EdgeBundles");
97}
98