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/CodeGen/MachineBasicBlock.h"
15 #include "llvm/CodeGen/MachineFunction.h"
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/InitializePasses.h"
18 #include "llvm/Support/CommandLine.h"
19 #include "llvm/Support/GraphWriter.h"
20 #include "llvm/Support/raw_ostream.h"
21
22 using namespace llvm;
23
24 static cl::opt<bool>
25 ViewEdgeBundles("view-edge-bundles", cl::Hidden,
26 cl::desc("Pop up a window to show edge bundle graphs"));
27
28 char EdgeBundles::ID = 0;
29
30 INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
31 /* cfg = */true, /* is_analysis = */ true)
32
33 char &llvm::EdgeBundlesID = EdgeBundles::ID;
34
getAnalysisUsage(AnalysisUsage & AU) const35 void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
36 AU.setPreservesAll();
37 MachineFunctionPass::getAnalysisUsage(AU);
38 }
39
runOnMachineFunction(MachineFunction & mf)40 bool EdgeBundles::runOnMachineFunction(MachineFunction &mf) {
41 MF = &mf;
42 EC.clear();
43 EC.grow(2 * MF->getNumBlockIDs());
44
45 for (const auto &MBB : *MF) {
46 unsigned OutE = 2 * MBB.getNumber() + 1;
47 // Join the outgoing bundle with the ingoing bundles of all successors.
48 for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
49 SE = MBB.succ_end(); SI != SE; ++SI)
50 EC.join(OutE, 2 * (*SI)->getNumber());
51 }
52 EC.compress();
53 if (ViewEdgeBundles)
54 view();
55
56 // Compute the reverse mapping.
57 Blocks.clear();
58 Blocks.resize(getNumBundles());
59
60 for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
61 unsigned b0 = getBundle(i, false);
62 unsigned b1 = getBundle(i, true);
63 Blocks[b0].push_back(i);
64 if (b1 != b0)
65 Blocks[b1].push_back(i);
66 }
67
68 return false;
69 }
70
71 /// Specialize WriteGraph, the standard implementation won't work.
72 namespace llvm {
73
74 template<>
WriteGraph(raw_ostream & O,const EdgeBundles & G,bool ShortNames,const Twine & Title)75 raw_ostream &WriteGraph<>(raw_ostream &O, const EdgeBundles &G,
76 bool ShortNames,
77 const Twine &Title) {
78 const MachineFunction *MF = G.getMachineFunction();
79
80 O << "digraph {\n";
81 for (const auto &MBB : *MF) {
82 unsigned BB = MBB.getNumber();
83 O << "\t\"" << printMBBReference(MBB) << "\" [ shape=box ]\n"
84 << '\t' << G.getBundle(BB, false) << " -> \"" << printMBBReference(MBB)
85 << "\"\n"
86 << "\t\"" << printMBBReference(MBB) << "\" -> " << G.getBundle(BB, true)
87 << '\n';
88 for (MachineBasicBlock::const_succ_iterator SI = MBB.succ_begin(),
89 SE = MBB.succ_end(); SI != SE; ++SI)
90 O << "\t\"" << printMBBReference(MBB) << "\" -> \""
91 << printMBBReference(**SI) << "\" [ color=lightgray ]\n";
92 }
93 O << "}\n";
94 return O;
95 }
96
97 } // end namespace llvm
98
99 /// view - Visualize the annotated bipartite CFG with Graphviz.
view() const100 void EdgeBundles::view() const {
101 ViewGraph(*this, "EdgeBundles");
102 }
103