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 (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
57  // Compute the reverse mapping.
58  Blocks.clear();
59  Blocks.resize(getNumBundles());
60
61  for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
62    unsigned b0 = getBundle(i, 0);
63    unsigned b1 = getBundle(i, 1);
64    Blocks[b0].push_back(i);
65    if (b1 != b0)
66      Blocks[b1].push_back(i);
67  }
68
69  return false;
70}
71
72/// view - Visualize the annotated bipartite CFG with Graphviz.
73void EdgeBundles::view() const {
74  ViewGraph(*this, "EdgeBundles");
75}
76
77/// Specialize WriteGraph, the standard implementation won't work.
78raw_ostream &llvm::WriteGraph(raw_ostream &O, const EdgeBundles &G,
79                              bool ShortNames,
80                              const Twine &Title) {
81  const MachineFunction *MF = G.getMachineFunction();
82
83  O << "digraph {\n";
84  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
85       I != E; ++I) {
86    unsigned BB = I->getNumber();
87    O << "\t\"BB#" << BB << "\" [ shape=box ]\n"
88      << '\t' << G.getBundle(BB, false) << " -> \"BB#" << BB << "\"\n"
89      << "\t\"BB#" << BB << "\" -> " << G.getBundle(BB, true) << '\n';
90    for (MachineBasicBlock::const_succ_iterator SI = I->succ_begin(),
91           SE = I->succ_end(); SI != SE; ++SI)
92      O << "\t\"BB#" << BB << "\" -> \"BB#" << (*SI)->getNumber()
93        << "\" [ color=lightgray ]\n";
94  }
95  O << "}\n";
96  return O;
97}
98