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 #define PASS_NAME "Lanai DAG->DAG Pattern Instruction Selection"
38
39 //===----------------------------------------------------------------------===//
40 // Instruction Selector Implementation
41 //===----------------------------------------------------------------------===//
42
43 //===----------------------------------------------------------------------===//
44 // LanaiDAGToDAGISel - Lanai specific code to select Lanai machine
45 // instructions for SelectionDAG operations.
46 //===----------------------------------------------------------------------===//
47 namespace {
48
49 class LanaiDAGToDAGISel : public SelectionDAGISel {
50 public:
51 LanaiDAGToDAGISel() = delete;
52
LanaiDAGToDAGISel(LanaiTargetMachine & TargetMachine)53 explicit LanaiDAGToDAGISel(LanaiTargetMachine &TargetMachine)
54 : SelectionDAGISel(TargetMachine) {}
55
56 bool SelectInlineAsmMemoryOperand(const SDValue &Op,
57 InlineAsm::ConstraintCode ConstraintCode,
58 std::vector<SDValue> &OutOps) override;
59
60 private:
61 // Include the pieces autogenerated from the target description.
62 #include "LanaiGenDAGISel.inc"
63
64 // Instruction Selection not handled by the auto-generated tablgen
65 void Select(SDNode *N) override;
66
67 // Support functions for the opcodes of Instruction Selection
68 // not handled by the auto-generated tablgen
69 void selectFrameIndex(SDNode *N);
70
71 // Complex Pattern for address selection.
72 bool selectAddrRi(SDValue Addr, SDValue &Base, SDValue &Offset,
73 SDValue &AluOp);
74 bool selectAddrRr(SDValue Addr, SDValue &R1, SDValue &R2, SDValue &AluOp);
75 bool selectAddrSls(SDValue Addr, SDValue &Offset);
76 bool selectAddrSpls(SDValue Addr, SDValue &Base, SDValue &Offset,
77 SDValue &AluOp);
78
79 // getI32Imm - Return a target constant with the specified value, of type i32.
getI32Imm(unsigned Imm,const SDLoc & DL)80 inline SDValue getI32Imm(unsigned Imm, const SDLoc &DL) {
81 return CurDAG->getTargetConstant(Imm, DL, MVT::i32);
82 }
83
84 private:
85 bool selectAddrRiSpls(SDValue Addr, SDValue &Base, SDValue &Offset,
86 SDValue &AluOp, bool RiMode);
87 };
88
canBeRepresentedAsSls(const ConstantSDNode & CN)89 bool canBeRepresentedAsSls(const ConstantSDNode &CN) {
90 // Fits in 21-bit signed immediate and two low-order bits are zero.
91 return isInt<21>(CN.getSExtValue()) && ((CN.getSExtValue() & 0x3) == 0);
92 }
93
94 class LanaiDAGToDAGISelLegacy : public SelectionDAGISelLegacy {
95 public:
96 static char ID;
LanaiDAGToDAGISelLegacy(LanaiTargetMachine & TM)97 explicit LanaiDAGToDAGISelLegacy(LanaiTargetMachine &TM)
98 : SelectionDAGISelLegacy(ID, std::make_unique<LanaiDAGToDAGISel>(TM)) {}
99 };
100
101 } // namespace
102
103 char LanaiDAGToDAGISelLegacy::ID = 0;
104
INITIALIZE_PASS(LanaiDAGToDAGISelLegacy,DEBUG_TYPE,PASS_NAME,false,false)105 INITIALIZE_PASS(LanaiDAGToDAGISelLegacy, DEBUG_TYPE, PASS_NAME, false, false)
106
107 // Helper functions for ComplexPattern used on LanaiInstrInfo
108 // Used on Lanai Load/Store instructions.
109 bool LanaiDAGToDAGISel::selectAddrSls(SDValue Addr, SDValue &Offset) {
110 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr)) {
111 SDLoc DL(Addr);
112 // Loading from a constant address.
113 if (canBeRepresentedAsSls(*CN)) {
114 int32_t Imm = CN->getSExtValue();
115 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
116 return true;
117 }
118 }
119 if (Addr.getOpcode() == ISD::OR &&
120 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL) {
121 Offset = Addr.getOperand(1).getOperand(0);
122 return true;
123 }
124 return false;
125 }
126
selectAddrRiSpls(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp,bool RiMode)127 bool LanaiDAGToDAGISel::selectAddrRiSpls(SDValue Addr, SDValue &Base,
128 SDValue &Offset, SDValue &AluOp,
129 bool RiMode) {
130 SDLoc DL(Addr);
131
132 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr)) {
133 if (RiMode) {
134 // Fits in 16-bit signed immediate.
135 if (isInt<16>(CN->getSExtValue())) {
136 int16_t Imm = CN->getSExtValue();
137 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
138 Base = CurDAG->getRegister(Lanai::R0, CN->getValueType(0));
139 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
140 return true;
141 }
142 // Allow SLS to match if the constant doesn't fit in 16 bits but can be
143 // represented as an SLS.
144 if (canBeRepresentedAsSls(*CN))
145 return false;
146 } else {
147 // Fits in 10-bit signed immediate.
148 if (isInt<10>(CN->getSExtValue())) {
149 int16_t Imm = CN->getSExtValue();
150 Offset = CurDAG->getTargetConstant(Imm, DL, CN->getValueType(0));
151 Base = CurDAG->getRegister(Lanai::R0, CN->getValueType(0));
152 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
153 return true;
154 }
155 }
156 }
157
158 // if Address is FI, get the TargetFrameIndex.
159 if (FrameIndexSDNode *FIN = dyn_cast<FrameIndexSDNode>(Addr)) {
160 Base = CurDAG->getTargetFrameIndex(
161 FIN->getIndex(),
162 getTargetLowering()->getPointerTy(CurDAG->getDataLayout()));
163 Offset = CurDAG->getTargetConstant(0, DL, MVT::i32);
164 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
165 return true;
166 }
167
168 // Skip direct calls
169 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
170 Addr.getOpcode() == ISD::TargetGlobalAddress))
171 return false;
172
173 // Address of the form imm + reg
174 ISD::NodeType AluOperator = static_cast<ISD::NodeType>(Addr.getOpcode());
175 if (AluOperator == ISD::ADD) {
176 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
177 // Addresses of the form FI+const
178 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))
179 if ((RiMode && isInt<16>(CN->getSExtValue())) ||
180 (!RiMode && isInt<10>(CN->getSExtValue()))) {
181 // If the first operand is a FI, get the TargetFI Node
182 if (FrameIndexSDNode *FIN =
183 dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {
184 Base = CurDAG->getTargetFrameIndex(
185 FIN->getIndex(),
186 getTargetLowering()->getPointerTy(CurDAG->getDataLayout()));
187 } else {
188 Base = Addr.getOperand(0);
189 }
190
191 Offset = CurDAG->getTargetConstant(CN->getSExtValue(), DL, MVT::i32);
192 return true;
193 }
194 }
195
196 // Let SLS match SMALL instead of RI.
197 if (AluOperator == ISD::OR && RiMode &&
198 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL)
199 return false;
200
201 Base = Addr;
202 Offset = CurDAG->getTargetConstant(0, DL, MVT::i32);
203 AluOp = CurDAG->getTargetConstant(LPAC::ADD, DL, MVT::i32);
204 return true;
205 }
206
selectAddrRi(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp)207 bool LanaiDAGToDAGISel::selectAddrRi(SDValue Addr, SDValue &Base,
208 SDValue &Offset, SDValue &AluOp) {
209 return selectAddrRiSpls(Addr, Base, Offset, AluOp, /*RiMode=*/true);
210 }
211
selectAddrSpls(SDValue Addr,SDValue & Base,SDValue & Offset,SDValue & AluOp)212 bool LanaiDAGToDAGISel::selectAddrSpls(SDValue Addr, SDValue &Base,
213 SDValue &Offset, SDValue &AluOp) {
214 return selectAddrRiSpls(Addr, Base, Offset, AluOp, /*RiMode=*/false);
215 }
216
217 namespace llvm {
218 namespace LPAC {
isdToLanaiAluCode(ISD::NodeType Node_type)219 static AluCode isdToLanaiAluCode(ISD::NodeType Node_type) {
220 switch (Node_type) {
221 case ISD::ADD:
222 return AluCode::ADD;
223 case ISD::ADDE:
224 return AluCode::ADDC;
225 case ISD::SUB:
226 return AluCode::SUB;
227 case ISD::SUBE:
228 return AluCode::SUBB;
229 case ISD::AND:
230 return AluCode::AND;
231 case ISD::OR:
232 return AluCode::OR;
233 case ISD::XOR:
234 return AluCode::XOR;
235 case ISD::SHL:
236 return AluCode::SHL;
237 case ISD::SRL:
238 return AluCode::SRL;
239 case ISD::SRA:
240 return AluCode::SRA;
241 default:
242 return AluCode::UNKNOWN;
243 }
244 }
245 } // namespace LPAC
246 } // namespace llvm
247
selectAddrRr(SDValue Addr,SDValue & R1,SDValue & R2,SDValue & AluOp)248 bool LanaiDAGToDAGISel::selectAddrRr(SDValue Addr, SDValue &R1, SDValue &R2,
249 SDValue &AluOp) {
250 // if Address is FI, get the TargetFrameIndex.
251 if (Addr.getOpcode() == ISD::FrameIndex)
252 return false;
253
254 // Skip direct calls
255 if ((Addr.getOpcode() == ISD::TargetExternalSymbol ||
256 Addr.getOpcode() == ISD::TargetGlobalAddress))
257 return false;
258
259 // Address of the form OP + OP
260 ISD::NodeType AluOperator = static_cast<ISD::NodeType>(Addr.getOpcode());
261 LPAC::AluCode AluCode = LPAC::isdToLanaiAluCode(AluOperator);
262 if (AluCode != LPAC::UNKNOWN) {
263 // Skip addresses of the form FI OP const
264 if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Addr.getOperand(1)))
265 if (isInt<16>(CN->getSExtValue()))
266 return false;
267
268 // Skip addresses with hi/lo operands
269 if (Addr.getOperand(0).getOpcode() == LanaiISD::HI ||
270 Addr.getOperand(0).getOpcode() == LanaiISD::LO ||
271 Addr.getOperand(0).getOpcode() == LanaiISD::SMALL ||
272 Addr.getOperand(1).getOpcode() == LanaiISD::HI ||
273 Addr.getOperand(1).getOpcode() == LanaiISD::LO ||
274 Addr.getOperand(1).getOpcode() == LanaiISD::SMALL)
275 return false;
276
277 // Addresses of the form register OP register
278 R1 = Addr.getOperand(0);
279 R2 = Addr.getOperand(1);
280 AluOp = CurDAG->getTargetConstant(AluCode, SDLoc(Addr), MVT::i32);
281 return true;
282 }
283
284 // Skip addresses with zero offset
285 return false;
286 }
287
SelectInlineAsmMemoryOperand(const SDValue & Op,InlineAsm::ConstraintCode ConstraintCode,std::vector<SDValue> & OutOps)288 bool LanaiDAGToDAGISel::SelectInlineAsmMemoryOperand(
289 const SDValue &Op, InlineAsm::ConstraintCode ConstraintCode,
290 std::vector<SDValue> &OutOps) {
291 SDValue Op0, Op1, AluOp;
292 switch (ConstraintCode) {
293 default:
294 return true;
295 case InlineAsm::ConstraintCode::m: // memory
296 if (!selectAddrRr(Op, Op0, Op1, AluOp) &&
297 !selectAddrRi(Op, Op0, Op1, AluOp))
298 return true;
299 break;
300 }
301
302 OutOps.push_back(Op0);
303 OutOps.push_back(Op1);
304 OutOps.push_back(AluOp);
305 return false;
306 }
307
308 // Select instructions not customized! Used for
309 // expanded, promoted and normal instructions
Select(SDNode * Node)310 void LanaiDAGToDAGISel::Select(SDNode *Node) {
311 unsigned Opcode = Node->getOpcode();
312
313 // If we have a custom node, we already have selected!
314 if (Node->isMachineOpcode()) {
315 LLVM_DEBUG(errs() << "== "; Node->dump(CurDAG); errs() << "\n");
316 return;
317 }
318
319 // Instruction Selection not handled by the auto-generated tablegen selection
320 // should be handled here.
321 EVT VT = Node->getValueType(0);
322 switch (Opcode) {
323 case ISD::Constant:
324 if (VT == MVT::i32) {
325 ConstantSDNode *ConstNode = cast<ConstantSDNode>(Node);
326 // Materialize zero constants as copies from R0. This allows the coalescer
327 // to propagate these into other instructions.
328 if (ConstNode->isZero()) {
329 SDValue New = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
330 SDLoc(Node), Lanai::R0, MVT::i32);
331 return ReplaceNode(Node, New.getNode());
332 }
333 // Materialize all ones constants as copies from R1. This allows the
334 // coalescer to propagate these into other instructions.
335 if (ConstNode->isAllOnes()) {
336 SDValue New = CurDAG->getCopyFromReg(CurDAG->getEntryNode(),
337 SDLoc(Node), Lanai::R1, MVT::i32);
338 return ReplaceNode(Node, New.getNode());
339 }
340 }
341 break;
342 case ISD::FrameIndex:
343 selectFrameIndex(Node);
344 return;
345 default:
346 break;
347 }
348
349 // Select the default instruction
350 SelectCode(Node);
351 }
352
selectFrameIndex(SDNode * Node)353 void LanaiDAGToDAGISel::selectFrameIndex(SDNode *Node) {
354 SDLoc DL(Node);
355 SDValue Imm = CurDAG->getTargetConstant(0, DL, MVT::i32);
356 int FI = cast<FrameIndexSDNode>(Node)->getIndex();
357 EVT VT = Node->getValueType(0);
358 SDValue TFI = CurDAG->getTargetFrameIndex(FI, VT);
359 unsigned Opc = Lanai::ADD_I_LO;
360 if (Node->hasOneUse()) {
361 CurDAG->SelectNodeTo(Node, Opc, VT, TFI, Imm);
362 return;
363 }
364 ReplaceNode(Node, CurDAG->getMachineNode(Opc, DL, VT, TFI, Imm));
365 }
366
367 // createLanaiISelDag - This pass converts a legalized DAG into a
368 // Lanai-specific DAG, ready for instruction scheduling.
createLanaiISelDag(LanaiTargetMachine & TM)369 FunctionPass *llvm::createLanaiISelDag(LanaiTargetMachine &TM) {
370 return new LanaiDAGToDAGISelLegacy(TM);
371 }
372