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
getAnalysisUsage(AnalysisUsage & AU) const34 void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
35 AU.setPreservesAll();
36 MachineFunctionPass::getAnalysisUsage(AU);
37 }
38
runOnMachineFunction(MachineFunction & mf)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<>
WriteGraph(raw_ostream & O,const EdgeBundles & G,bool ShortNames,const Twine & Title)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.
view() const95 void EdgeBundles::view() const {
96 ViewGraph(*this, "EdgeBundles");
97 }
98