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