1 //===-- BPFISelDAGToDAG.cpp - A dag to dag inst selector for BPF ----------===//
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 defines a DAG pattern matching instruction selector for BPF,
11 // converting from a legalized dag to a BPF dag.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "BPF.h"
16 #include "BPFRegisterInfo.h"
17 #include "BPFSubtarget.h"
18 #include "BPFTargetMachine.h"
19 #include "llvm/CodeGen/MachineConstantPool.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineInstrBuilder.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 #include "llvm/CodeGen/SelectionDAGISel.h"
25 #include "llvm/IR/IntrinsicInst.h"
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/Target/TargetMachine.h"
30 using namespace llvm;
31
32 #define DEBUG_TYPE "bpf-isel"
33
34 // Instruction Selector Implementation
35 namespace {
36
37 class BPFDAGToDAGISel : public SelectionDAGISel {
38 public:
BPFDAGToDAGISel(BPFTargetMachine & TM)39 explicit BPFDAGToDAGISel(BPFTargetMachine &TM) : SelectionDAGISel(TM) {}
40
getPassName() const41 const char *getPassName() const override {
42 return "BPF DAG->DAG Pattern Instruction Selection";
43 }
44
45 private:
46 // Include the pieces autogenerated from the target description.
47 #include "BPFGenDAGISel.inc"
48
49 void Select(SDNode *N) override;
50
51 // Complex Pattern for address selection.
52 bool SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
53 bool SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset);
54 };
55 }
56
57 // ComplexPattern used on BPF Load/Store instructions
SelectAddr(SDValue Addr,SDValue & Base,SDValue & Offset)58 bool BPFDAGToDAGISel::SelectAddr(SDValue Addr, SDValue &Base, SDValue &Offset) {
59 // if Address is FI, get the TargetFrameIndex.
60 SDLoc DL(Addr);
61 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
62 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
63 Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
64 return true;
65 }
66
67 if (Addr.getOpcode() == ISD::TargetExternalSymbol ||
68 Addr.getOpcode() == ISD::TargetGlobalAddress)
69 return false;
70
71 // Addresses of the form Addr+const or Addr|const
72 if (CurDAG->isBaseWithConstantOffset(Addr)) {
73 ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
74 if (isInt<32>(CN->getSExtValue())) {
75
76 // If the first operand is a FI, get the TargetFI Node
77 if (FrameIndexSDNode *FIN =
78 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
79 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
80 else
81 Base = Addr.getOperand(0);
82
83 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64);
84 return true;
85 }
86 }
87
88 Base = Addr;
89 Offset = CurDAG->getTargetConstant(0, DL, MVT::i64);
90 return true;
91 }
92
93 // ComplexPattern used on BPF FI instruction
SelectFIAddr(SDValue Addr,SDValue & Base,SDValue & Offset)94 bool BPFDAGToDAGISel::SelectFIAddr(SDValue Addr, SDValue &Base, SDValue &Offset) {
95 SDLoc DL(Addr);
96
97 if (!CurDAG->isBaseWithConstantOffset(Addr))
98 return false;
99
100 // Addresses of the form Addr+const or Addr|const
101 ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1));
102 if (isInt<32>(CN->getSExtValue())) {
103
104 // If the first operand is a FI, get the TargetFI Node
105 if (FrameIndexSDNode *FIN =
106 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0)))
107 Base = CurDAG->getTargetFrameIndex(FIN->getIndex(), MVT::i64);
108 else
109 return false;
110
111 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i64);
112 return true;
113 }
114
115 return false;
116 }
117
Select(SDNode * Node)118 void BPFDAGToDAGISel::Select(SDNode *Node) {
119 unsigned Opcode = Node->getOpcode();
120
121 // Dump information about the Node being selected
122 DEBUG(dbgs() << "Selecting: "; Node->dump(CurDAG); dbgs() << '\n');
123
124 // If we have a custom node, we already have selected!
125 if (Node->isMachineOpcode()) {
126 DEBUG(dbgs() << "== "; Node->dump(CurDAG); dbgs() << '\n');
127 return;
128 }
129
130 // tablegen selection should be handled here.
131 switch (Opcode) {
132 default: break;
133 case ISD::SDIV: {
134 DebugLoc Empty;
135 const DebugLoc &DL = Node->getDebugLoc();
136 if (DL != Empty)
137 errs() << "Error at line " << DL.getLine() << ": ";
138 else
139 errs() << "Error: ";
140 errs() << "Unsupport signed division for DAG: ";
141 Node->dump(CurDAG);
142 errs() << "Please convert to unsigned div/mod.\n";
143 break;
144 }
145 case ISD::INTRINSIC_W_CHAIN: {
146 unsigned IntNo = cast<ConstantSDNode>(Node->getOperand(1))->getZExtValue();
147 switch (IntNo) {
148 case Intrinsic::bpf_load_byte:
149 case Intrinsic::bpf_load_half:
150 case Intrinsic::bpf_load_word: {
151 SDLoc DL(Node);
152 SDValue Chain = Node->getOperand(0);
153 SDValue N1 = Node->getOperand(1);
154 SDValue Skb = Node->getOperand(2);
155 SDValue N3 = Node->getOperand(3);
156
157 SDValue R6Reg = CurDAG->getRegister(BPF::R6, MVT::i64);
158 Chain = CurDAG->getCopyToReg(Chain, DL, R6Reg, Skb, SDValue());
159 Node = CurDAG->UpdateNodeOperands(Node, Chain, N1, R6Reg, N3);
160 break;
161 }
162 }
163 break;
164 }
165
166 case ISD::FrameIndex: {
167 int FI = cast<FrameIndexSDNode>(Node)->getIndex();
168 EVT VT = Node->getValueType(0);
169 SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
170 unsigned Opc = BPF::MOV_rr;
171 if (Node->hasOneUse()) {
172 CurDAG->SelectNodeTo(Node, Opc, VT, TFI);
173 return;
174 }
175 ReplaceNode(Node, CurDAG->getMachineNode(Opc, SDLoc(Node), VT, TFI));
176 return;
177 }
178 }
179
180 // Select the default instruction
181 SelectCode(Node);
182 }
183
createBPFISelDag(BPFTargetMachine & TM)184 FunctionPass *llvm::createBPFISelDag(BPFTargetMachine &TM) {
185 return new BPFDAGToDAGISel(TM);
186 }
187