1 //===-- LanaiISelDAGToDAG.cpp - A dag to dag inst selector for Lanai ------===//
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 defines an instruction selector for the Lanai target.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "LanaiAluCode.h"
14 #include "LanaiMachineFunctionInfo.h"
15 #include "LanaiRegisterInfo.h"
16 #include "LanaiSubtarget.h"
17 #include "LanaiTargetMachine.h"
18 #include "llvm/CodeGen/MachineConstantPool.h"
19 #include "llvm/CodeGen/MachineFrameInfo.h"
20 #include "llvm/CodeGen/MachineFunction.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineRegisterInfo.h"
23 #include "llvm/CodeGen/SelectionDAGISel.h"
24 #include "llvm/IR/CFG.h"
25 #include "llvm/IR/GlobalValue.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/Intrinsics.h"
28 #include "llvm/IR/Type.h"
29 #include "llvm/Support/Debug.h"
30 #include "llvm/Support/ErrorHandling.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Target/TargetMachine.h"
33
34 using namespace llvm;
35
36 #define DEBUG_TYPE "lanai-isel"
37
38 //===----------------------------------------------------------------------===//
39 // Instruction Selector Implementation
40 //===----------------------------------------------------------------------===//
41
42 //===----------------------------------------------------------------------===//
43 // LanaiDAGToDAGISel - Lanai specific code to select Lanai machine
44 // instructions for SelectionDAG operations.
45 //===----------------------------------------------------------------------===//
46 namespace {
47
48 class LanaiDAGToDAGISel : public SelectionDAGISel {
49 public:
LanaiDAGToDAGISel(LanaiTargetMachine & TargetMachine)50 explicit LanaiDAGToDAGISel(LanaiTargetMachine &TargetMachine)
51 : SelectionDAGISel(TargetMachine) {}
52
runOnMachineFunction(MachineFunction & MF)53 bool runOnMachineFunction(MachineFunction &MF) override {
54 return SelectionDAGISel::runOnMachineFunction(MF);
55 }
56
57 // Pass Name
getPassName() const58 StringRef getPassName() const override {
59 return "Lanai DAG->DAG Pattern Instruction Selection";
60 }
61
62 bool SelectInlineAsmMemoryOperand(const SDValue &Op, unsigned ConstraintCode,
63 std::vector<SDValue> &OutOps) override;
64
65 private:
66 // Include the pieces autogenerated from the target description.
67 #include "LanaiGenDAGISel.inc"
68
69 // Instruction Selection not handled by the auto-generated tablgen
70 void Select(SDNode *N) override;
71
72 // Support functions for the opcodes of Instruction Selection
73 // not handled by the auto-generated tablgen
74 void selectFrameIndex(SDNode *N);
75
76 // Complex Pattern for address selection.
77 bool selectAddrRi(SDValue Addr, SDValue &Base, SDValue &Offset,
78 SDValue &AluOp);
79 bool selectAddrRr(SDValue Addr, SDValue &R1, SDValue &R2, SDValue &AluOp);
80 bool selectAddrSls(SDValue Addr, SDValue &Offset);
81 bool selectAddrSpls(SDValue Addr, SDValue &Base, SDValue &Offset,
82 SDValue &AluOp);
83
84 // getI32Imm - Return a target constant with the specified value, of type i32.
getI32Imm(unsigned Imm,const SDLoc & DL)85 inline SDValue getI32Imm(unsigned Imm, const SDLoc &DL) {
86 return CurDAG->getTargetConstant(Imm, DL, MVT::i32);
87 }
88
89 private:
90 bool selectAddrRiSpls(SDValue Addr, SDValue &Base, SDValue &Offset,
91 SDValue &AluOp, bool RiMode);
92 };
93
canBeRepresentedAsSls(const ConstantSDNode & CN)94 bool canBeRepresentedAsSls(const ConstantSDNode &CN) {
95 // Fits in 21-bit signed immediate and two low-order bits are zero.
96 return isInt<21>(CN.getSExtValue()) && ((CN.getSExtValue() & 0x3) == 0);
97 }
98
99 } // namespace
100
101 // Helper functions for ComplexPattern used on LanaiInstrInfo
102 // Used on Lanai Load/Store instructions.
selectAddrSls(SDValue Addr,SDValue & Offset)103 bool LanaiDAGToDAGISel::selectAddrSls(SDValue Addr, SDValue &Offset) {
104 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr)) {
105 SDLoc DL(Addr);
106 // Loading from a constant address.
107 if (canBeRepresentedAsSls(*CN)) {
108 int32_t Imm = CN->getSExtValue();
109 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
110 return true;
111 }
112 }
113 if (Addr.getOpcode() == ISD::OR &&
114 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL) {
115 Offset = Addr.getOperand(1).getOperand(0);
116 return true;
117 }
118 return false;
119 }
120
selectAddrRiSpls(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp,bool RiMode)121 bool LanaiDAGToDAGISel::selectAddrRiSpls(SDValue Addr, SDValue &Base,
122 SDValue &Offset, SDValue &AluOp,
123 bool RiMode) {
124 SDLoc DL(Addr);
125
126 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr)) {
127 if (RiMode) {
128 // Fits in 16-bit signed immediate.
129 if (isInt<16>(CN->getSExtValue())) {
130 int16_t Imm = CN->getSExtValue();
131 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
132 Base = CurDAG->getRegister(Lanai::R0, CN->getValueType(0));
133 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
134 return true;
135 }
136 // Allow SLS to match if the constant doesn't fit in 16 bits but can be
137 // represented as an SLS.
138 if (canBeRepresentedAsSls(*CN))
139 return false;
140 } else {
141 // Fits in 10-bit signed immediate.
142 if (isInt<10>(CN->getSExtValue())) {
143 int16_t Imm = CN->getSExtValue();
144 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
145 Base = CurDAG->getRegister(Lanai::R0, CN->getValueType(0));
146 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
147 return true;
148 }
149 }
150 }
151
152 // if Address is FI, get the TargetFrameIndex.
153 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
154 Base = CurDAG->getTargetFrameIndex(
155 FIN->getIndex(),
156 getTargetLowering()->getPointerTy(CurDAG->getDataLayout()));
157 Offset = CurDAG->getTargetConstant(0, DL, MVT::i32);
158 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
159 return true;
160 }
161
162 // Skip direct calls
163 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
164 Addr.getOpcode() == ISD::TargetGlobalAddress))
165 return false;
166
167 // Address of the form imm + reg
168 ISD::NodeType AluOperator = static_cast<ISD::NodeType>(Addr.getOpcode());
169 if (AluOperator == ISD::ADD) {
170 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
171 // Addresses of the form FI+const
172 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))
173 if ((RiMode && isInt<16>(CN->getSExtValue())) ||
174 (!RiMode && isInt<10>(CN->getSExtValue()))) {
175 // If the first operand is a FI, get the TargetFI Node
176 if (FrameIndexSDNode *FIN =
177 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {
178 Base = CurDAG->getTargetFrameIndex(
179 FIN->getIndex(),
180 getTargetLowering()->getPointerTy(CurDAG->getDataLayout()));
181 } else {
182 Base = Addr.getOperand(0);
183 }
184
185 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i32);
186 return true;
187 }
188 }
189
190 // Let SLS match SMALL instead of RI.
191 if (AluOperator == ISD::OR && RiMode &&
192 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL)
193 return false;
194
195 Base = Addr;
196 Offset = CurDAG->getTargetConstant(0, DL, MVT::i32);
197 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
198 return true;
199 }
200
selectAddrRi(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp)201 bool LanaiDAGToDAGISel::selectAddrRi(SDValue Addr, SDValue &Base,
202 SDValue &Offset, SDValue &AluOp) {
203 return selectAddrRiSpls(Addr, Base, Offset, AluOp, /*RiMode=*/true);
204 }
205
selectAddrSpls(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp)206 bool LanaiDAGToDAGISel::selectAddrSpls(SDValue Addr, SDValue &Base,
207 SDValue &Offset, SDValue &AluOp) {
208 return selectAddrRiSpls(Addr, Base, Offset, AluOp, /*RiMode=*/false);
209 }
210
selectAddrRr(SDValue Addr,SDValue & R1,SDValue & R2,SDValue & AluOp)211 bool LanaiDAGToDAGISel::selectAddrRr(SDValue Addr, SDValue &R1, SDValue &R2,
212 SDValue &AluOp) {
213 // if Address is FI, get the TargetFrameIndex.
214 if (Addr.getOpcode() == ISD::FrameIndex)
215 return false;
216
217 // Skip direct calls
218 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
219 Addr.getOpcode() == ISD::TargetGlobalAddress))
220 return false;
221
222 // Address of the form OP + OP
223 ISD::NodeType AluOperator = static_cast<ISD::NodeType>(Addr.getOpcode());
224 LPAC::AluCode AluCode = LPAC::isdToLanaiAluCode(AluOperator);
225 if (AluCode != LPAC::UNKNOWN) {
226 // Skip addresses of the form FI OP const
227 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))
228 if (isInt<16>(CN->getSExtValue()))
229 return false;
230
231 // Skip addresses with hi/lo operands
232 if (Addr.getOperand(0).getOpcode() == LanaiISD::HI ||
233 Addr.getOperand(0).getOpcode() == LanaiISD::LO ||
234 Addr.getOperand(0).getOpcode() == LanaiISD::SMALL ||
235 Addr.getOperand(1).getOpcode() == LanaiISD::HI ||
236 Addr.getOperand(1).getOpcode() == LanaiISD::LO ||
237 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL)
238 return false;
239
240 // Addresses of the form register OP register
241 R1 = Addr.getOperand(0);
242 R2 = Addr.getOperand(1);
243 AluOp = CurDAG->getTargetConstant(AluCode, SDLoc(Addr), MVT::i32);
244 return true;
245 }
246
247 // Skip addresses with zero offset
248 return false;
249 }
250
SelectInlineAsmMemoryOperand(const SDValue & Op,unsigned ConstraintCode,std::vector<SDValue> & OutOps)251 bool LanaiDAGToDAGISel::SelectInlineAsmMemoryOperand(
252 const SDValue &Op, unsigned ConstraintCode, std::vector<SDValue> &OutOps) {
253 SDValue Op0, Op1, AluOp;
254 switch (ConstraintCode) {
255 default:
256 return true;
257 case InlineAsm::Constraint_m: // memory
258 if (!selectAddrRr(Op, Op0, Op1, AluOp) &&
259 !selectAddrRi(Op, Op0, Op1, AluOp))
260 return true;
261 break;
262 }
263
264 OutOps.push_back(Op0);
265 OutOps.push_back(Op1);
266 OutOps.push_back(AluOp);
267 return false;
268 }
269
270 // Select instructions not customized! Used for
271 // expanded, promoted and normal instructions
Select(SDNode * Node)272 void LanaiDAGToDAGISel::Select(SDNode *Node) {
273 unsigned Opcode = Node->getOpcode();
274
275 // If we have a custom node, we already have selected!
276 if (Node->isMachineOpcode()) {
277 LLVM_DEBUG(errs() << "== "; Node->dump(CurDAG); errs() << "\n");
278 return;
279 }
280
281 // Instruction Selection not handled by the auto-generated tablegen selection
282 // should be handled here.
283 EVT VT = Node->getValueType(0);
284 switch (Opcode) {
285 case ISD::Constant:
286 if (VT == MVT::i32) {
287 ConstantSDNode *ConstNode = cast<ConstantSDNode>(Node);
288 // Materialize zero constants as copies from R0. This allows the coalescer
289 // to propagate these into other instructions.
290 if (ConstNode->isNullValue()) {
291 SDValue New = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
292 SDLoc(Node), Lanai::R0, MVT::i32);
293 return ReplaceNode(Node, New.getNode());
294 }
295 // Materialize all ones constants as copies from R1. This allows the
296 // coalescer to propagate these into other instructions.
297 if (ConstNode->isAllOnesValue()) {
298 SDValue New = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
299 SDLoc(Node), Lanai::R1, MVT::i32);
300 return ReplaceNode(Node, New.getNode());
301 }
302 }
303 break;
304 case ISD::FrameIndex:
305 selectFrameIndex(Node);
306 return;
307 default:
308 break;
309 }
310
311 // Select the default instruction
312 SelectCode(Node);
313 }
314
selectFrameIndex(SDNode * Node)315 void LanaiDAGToDAGISel::selectFrameIndex(SDNode *Node) {
316 SDLoc DL(Node);
317 SDValue Imm = CurDAG->getTargetConstant(0, DL, MVT::i32);
318 int FI = cast<FrameIndexSDNode>(Node)->getIndex();
319 EVT VT = Node->getValueType(0);
320 SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
321 unsigned Opc = Lanai::ADD_I_LO;
322 if (Node->hasOneUse()) {
323 CurDAG->SelectNodeTo(Node, Opc, VT, TFI, Imm);
324 return;
325 }
326 ReplaceNode(Node, CurDAG->getMachineNode(Opc, DL, VT, TFI, Imm));
327 }
328
329 // createLanaiISelDag - This pass converts a legalized DAG into a
330 // Lanai-specific DAG, ready for instruction scheduling.
createLanaiISelDag(LanaiTargetMachine & TM)331 FunctionPass *llvm::createLanaiISelDag(LanaiTargetMachine &TM) {
332 return new LanaiDAGToDAGISel(TM);
333 }
334