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->size());
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   return false;
57 }
58 
59 /// view - Visualize the annotated bipartite CFG with Graphviz.
60 void EdgeBundles::view() const {
61   ViewGraph(*this, "EdgeBundles");
62 }
63 
64 /// Specialize WriteGraph, the standard implementation won't work.
65 raw_ostream &llvm::WriteGraph(raw_ostream &O, const EdgeBundles &G,
66                               bool ShortNames,
67                               const std::string &Title) {
68   const MachineFunction *MF = G.getMachineFunction();
69 
70   O << "digraph {\n";
71   for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
72        I != E; ++I) {
73     unsigned BB = I->getNumber();
74     O << "\t\"BB#" << BB << "\" [ shape=box ]\n"
75       << '\t' << G.getBundle(BB, false) << " -> \"BB#" << BB << "\"\n"
76       << "\t\"BB#" << BB << "\" -> " << G.getBundle(BB, true) << '\n';
77     for (MachineBasicBlock::const_succ_iterator SI = I->succ_begin(),
78            SE = I->succ_end(); SI != SE; ++SI)
79       O << "\t\"BB#" << BB << "\" -> \"BB#" << (*SI)->getNumber()
80         << "\" [ color=lightgray ]\n";
81   }
82   O << "}\n";
83   return O;
84 }
85 
86 
87