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
23using namespace llvm;
24
25static cl::opt<bool>
26ViewEdgeBundles("view-edge-bundles", cl::Hidden,
27 cl::desc("Pop up a window to show edge bundle graphs"));
28
29char EdgeBundles::ID = 0;
30
31INITIALIZE_PASS(EdgeBundles, "edge-bundles", "Bundle Machine CFG Edges",
32 /* cfg = */true, /* is_analysis = */ true)
33
34char &llvm::EdgeBundlesID = EdgeBundles::ID;
35
36void EdgeBundles::getAnalysisUsage(AnalysisUsage &AU) const {
37 AU.setPreservesAll();
38 MachineFunctionPass::getAnalysisUsage(AU);
39}
40
41bool EdgeBundles::runOnMachineFunction(MachineFunction &mf) {
42 MF = &mf;
43 EC.clear();
44 EC.grow(N: 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 (const MachineBasicBlock *Succ : MBB.successors())
50 EC.join(a: OutE, b: 2 * Succ->getNumber());
51 }
52 EC.compress();
53 if (ViewEdgeBundles)
54 view();
55
56 // Compute the reverse mapping.
57 Blocks.clear();
58 Blocks.resize(N: getNumBundles());
59
60 for (unsigned i = 0, e = MF->getNumBlockIDs(); i != e; ++i) {
61 unsigned b0 = getBundle(N: i, Out: false);
62 unsigned b1 = getBundle(N: i, Out: true);
63 Blocks[b0].push_back(Elt: i);
64 if (b1 != b0)
65 Blocks[b1].push_back(Elt: i);
66 }
67
68 return false;
69}
70
71namespace llvm {
72
73/// Specialize WriteGraph, the standard implementation won't work.
74template<>
75raw_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(N: BB, Out: false) << " -> \"" << printMBBReference(MBB)
85 << "\"\n"
86 << "\t\"" << printMBBReference(MBB) << "\" -> " << G.getBundle(N: BB, Out: true)
87 << '\n';
88 for (const MachineBasicBlock *Succ : MBB.successors())
89 O << "\t\"" << printMBBReference(MBB) << "\" -> \""
90 << printMBBReference(MBB: *Succ) << "\" [ color=lightgray ]\n";
91 }
92 O << "}\n";
93 return O;
94}
95
96} // end namespace llvm
97
98/// view - Visualize the annotated bipartite CFG with Graphviz.
99void EdgeBundles::view() const {
100 ViewGraph(G: *this, Name: "EdgeBundles");
101}
102