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 EdgeBundles::ID = 0;
30
31 INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
32 /* cfg = */true, /* is_analysis = */ true)
33
34 char &llvm::EdgeBundlesID = EdgeBundles::ID;
35
getAnalysisUsage(AnalysisUsage & AU) const36 void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
37 AU.setPreservesAll();
38 MachineFunctionPass::getAnalysisUsage(AU);
39 }
40
runOnMachineFunction(MachineFunction & mf)41 bool EdgeBundles::runOnMachineFunction(MachineFunction &mf) {
42 MF = &mf;
43 EC.clear();
44 EC.grow(2 * MF->getNumBlockIDs());
45
46 for (const auto &MBB : *MF) {
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, false);
63 unsigned b1 = getBundle(i, true);
64 Blocks[b0].push_back(i);
65 if (b1 != b0)
66 Blocks[b1].push_back(i);
67 }
68
69 return false;
70 }
71
72 /// Specialize WriteGraph, the standard implementation won't work.
73 namespace llvm {
74
75 template<>
WriteGraph(raw_ostream & O,const EdgeBundles & G,bool ShortNames,const Twine & Title)76 raw_ostream &WriteGraph<>(raw_ostream &O, const EdgeBundles &G,
77 bool ShortNames,
78 const Twine &Title) {
79 const MachineFunction *MF = G.getMachineFunction();
80
81 O << "digraph {\n";
82 for (const auto &MBB : *MF) {
83 unsigned BB = MBB.getNumber();
84 O << "\t\"" << printMBBReference(MBB) << "\" [ shape=box ]\n"
85 << '\t' << G.getBundle(BB, false) << " -> \"" << printMBBReference(MBB)
86 << "\"\n"
87 << "\t\"" << printMBBReference(MBB) << "\" -> " << G.getBundle(BB, true)
88 << '\n';
89 for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
90 SE = MBB.succ_end(); SI != SE; ++SI)
91 O << "\t\"" << printMBBReference(MBB) << "\" -> \""
92 << printMBBReference(**SI) << "\" [ color=lightgray ]\n";
93 }
94 O << "}\n";
95 return O;
96 }
97
98 } // end namespace llvm
99
100 /// view - Visualize the annotated bipartite CFG with Graphviz.
view() const101 void EdgeBundles::view() const {
102 ViewGraph(*this, "EdgeBundles");
103 }
104