1//===- PseudoLoweringEmitter.cpp - PseudoLowering Generator -----*- C++ -*-===//
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#include "Common/CodeGenInstruction.h"
10#include "Common/CodeGenTarget.h"
11#include "llvm/ADT/IndexedMap.h"
12#include "llvm/ADT/SmallVector.h"
13#include "llvm/ADT/StringMap.h"
14#include "llvm/Support/Debug.h"
15#include "llvm/Support/ErrorHandling.h"
16#include "llvm/TableGen/Error.h"
17#include "llvm/TableGen/Record.h"
18#include "llvm/TableGen/TableGenBackend.h"
19#include <vector>
20using namespace llvm;
21
22#define DEBUG_TYPE "pseudo-lowering"
23
24namespace {
25class PseudoLoweringEmitter {
26 struct OpData {
27 enum MapKind { Operand, Imm, Reg };
28 MapKind Kind;
29 union {
30 unsigned Operand; // Operand number mapped to.
31 uint64_t Imm; // Integer immedate value.
32 Record *Reg; // Physical register.
33 } Data;
34 };
35 struct PseudoExpansion {
36 CodeGenInstruction Source; // The source pseudo instruction definition.
37 CodeGenInstruction Dest; // The destination instruction to lower to.
38 IndexedMap<OpData> OperandMap;
39
40 PseudoExpansion(CodeGenInstruction &s, CodeGenInstruction &d,
41 IndexedMap<OpData> &m)
42 : Source(s), Dest(d), OperandMap(m) {}
43 };
44
45 RecordKeeper &Records;
46
47 // It's overkill to have an instance of the full CodeGenTarget object,
48 // but it loads everything on demand, not in the constructor, so it's
49 // lightweight in performance, so it works out OK.
50 CodeGenTarget Target;
51
52 SmallVector<PseudoExpansion, 64> Expansions;
53
54 unsigned addDagOperandMapping(Record *Rec, DagInit *Dag,
55 CodeGenInstruction &Insn,
56 IndexedMap<OpData> &OperandMap,
57 unsigned BaseIdx);
58 void evaluateExpansion(Record *Pseudo);
59 void emitLoweringEmitter(raw_ostream &o);
60
61public:
62 PseudoLoweringEmitter(RecordKeeper &R) : Records(R), Target(R) {}
63
64 /// run - Output the pseudo-lowerings.
65 void run(raw_ostream &o);
66};
67} // End anonymous namespace
68
69// FIXME: This pass currently can only expand a pseudo to a single instruction.
70// The pseudo expansion really should take a list of dags, not just
71// a single dag, so we can do fancier things.
72
73unsigned PseudoLoweringEmitter::addDagOperandMapping(
74 Record *Rec, DagInit *Dag, CodeGenInstruction &Insn,
75 IndexedMap<OpData> &OperandMap, unsigned BaseIdx) {
76 unsigned OpsAdded = 0;
77 for (unsigned i = 0, e = Dag->getNumArgs(); i != e; ++i) {
78 if (DefInit *DI = dyn_cast<DefInit>(Val: Dag->getArg(Num: i))) {
79 // Physical register reference. Explicit check for the special case
80 // "zero_reg" definition.
81 if (DI->getDef()->isSubClassOf(Name: "Register") ||
82 DI->getDef()->getName() == "zero_reg") {
83 OperandMap[BaseIdx + i].Kind = OpData::Reg;
84 OperandMap[BaseIdx + i].Data.Reg = DI->getDef();
85 ++OpsAdded;
86 continue;
87 }
88
89 // Normal operands should always have the same type, or we have a
90 // problem.
91 // FIXME: We probably shouldn't ever get a non-zero BaseIdx here.
92 assert(BaseIdx == 0 && "Named subargument in pseudo expansion?!");
93 // FIXME: Are the message operand types backward?
94 if (DI->getDef() != Insn.Operands[BaseIdx + i].Rec) {
95 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
96 "', operand type '" + DI->getDef()->getName() +
97 "' does not match expansion operand type '" +
98 Insn.Operands[BaseIdx + i].Rec->getName() + "'");
99 PrintFatalNote(Rec: DI->getDef(),
100 Msg: "Value was assigned at the following location:");
101 }
102 // Source operand maps to destination operand. The Data element
103 // will be filled in later, just set the Kind for now. Do it
104 // for each corresponding MachineInstr operand, not just the first.
105 for (unsigned I = 0, E = Insn.Operands[i].MINumOperands; I != E; ++I)
106 OperandMap[BaseIdx + i + I].Kind = OpData::Operand;
107 OpsAdded += Insn.Operands[i].MINumOperands;
108 } else if (IntInit *II = dyn_cast<IntInit>(Val: Dag->getArg(Num: i))) {
109 OperandMap[BaseIdx + i].Kind = OpData::Imm;
110 OperandMap[BaseIdx + i].Data.Imm = II->getValue();
111 ++OpsAdded;
112 } else if (auto *BI = dyn_cast<BitsInit>(Val: Dag->getArg(Num: i))) {
113 auto *II =
114 cast<IntInit>(Val: BI->convertInitializerTo(Ty: IntRecTy::get(RK&: Records)));
115 OperandMap[BaseIdx + i].Kind = OpData::Imm;
116 OperandMap[BaseIdx + i].Data.Imm = II->getValue();
117 ++OpsAdded;
118 } else if (DagInit *SubDag = dyn_cast<DagInit>(Val: Dag->getArg(Num: i))) {
119 // Just add the operands recursively. This is almost certainly
120 // a constant value for a complex operand (> 1 MI operand).
121 unsigned NewOps =
122 addDagOperandMapping(Rec, Dag: SubDag, Insn, OperandMap, BaseIdx: BaseIdx + i);
123 OpsAdded += NewOps;
124 // Since we added more than one, we also need to adjust the base.
125 BaseIdx += NewOps - 1;
126 } else
127 llvm_unreachable("Unhandled pseudo-expansion argument type!");
128 }
129 return OpsAdded;
130}
131
132void PseudoLoweringEmitter::evaluateExpansion(Record *Rec) {
133 LLVM_DEBUG(dbgs() << "Pseudo definition: " << Rec->getName() << "\n");
134
135 // Validate that the result pattern has the corrent number and types
136 // of arguments for the instruction it references.
137 DagInit *Dag = Rec->getValueAsDag(FieldName: "ResultInst");
138 assert(Dag && "Missing result instruction in pseudo expansion!");
139 LLVM_DEBUG(dbgs() << " Result: " << *Dag << "\n");
140
141 DefInit *OpDef = dyn_cast<DefInit>(Val: Dag->getOperator());
142 if (!OpDef) {
143 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
144 "', result operator is not a record");
145 PrintFatalNote(RecVal: Rec->getValue(Name: "ResultInst"),
146 Msg: "Result was assigned at the following location:");
147 }
148 Record *Operator = OpDef->getDef();
149 if (!Operator->isSubClassOf(Name: "Instruction")) {
150 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
151 "', result operator '" + Operator->getName() +
152 "' is not an instruction");
153 PrintFatalNote(RecVal: Rec->getValue(Name: "ResultInst"),
154 Msg: "Result was assigned at the following location:");
155 }
156
157 CodeGenInstruction Insn(Operator);
158
159 if (Insn.isCodeGenOnly || Insn.isPseudo) {
160 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
161 "', result operator '" + Operator->getName() +
162 "' cannot be a pseudo instruction");
163 PrintFatalNote(RecVal: Rec->getValue(Name: "ResultInst"),
164 Msg: "Result was assigned at the following location:");
165 }
166
167 if (Insn.Operands.size() != Dag->getNumArgs()) {
168 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
169 "', result operator '" + Operator->getName() +
170 "' has the wrong number of operands");
171 PrintFatalNote(RecVal: Rec->getValue(Name: "ResultInst"),
172 Msg: "Result was assigned at the following location:");
173 }
174
175 unsigned NumMIOperands = 0;
176 for (unsigned i = 0, e = Insn.Operands.size(); i != e; ++i)
177 NumMIOperands += Insn.Operands[i].MINumOperands;
178 IndexedMap<OpData> OperandMap;
179 OperandMap.grow(n: NumMIOperands);
180
181 addDagOperandMapping(Rec, Dag, Insn, OperandMap, BaseIdx: 0);
182
183 // If there are more operands that weren't in the DAG, they have to
184 // be operands that have default values, or we have an error. Currently,
185 // Operands that are a subclass of OperandWithDefaultOp have default values.
186
187 // Validate that each result pattern argument has a matching (by name)
188 // argument in the source instruction, in either the (outs) or (ins) list.
189 // Also check that the type of the arguments match.
190 //
191 // Record the mapping of the source to result arguments for use by
192 // the lowering emitter.
193 CodeGenInstruction SourceInsn(Rec);
194 StringMap<unsigned> SourceOperands;
195 for (unsigned i = 0, e = SourceInsn.Operands.size(); i != e; ++i)
196 SourceOperands[SourceInsn.Operands[i].Name] = i;
197
198 LLVM_DEBUG(dbgs() << " Operand mapping:\n");
199 for (unsigned i = 0, e = Insn.Operands.size(); i != e; ++i) {
200 // We've already handled constant values. Just map instruction operands
201 // here.
202 if (OperandMap[Insn.Operands[i].MIOperandNo].Kind != OpData::Operand)
203 continue;
204 StringMap<unsigned>::iterator SourceOp =
205 SourceOperands.find(Key: Dag->getArgNameStr(Num: i));
206 if (SourceOp == SourceOperands.end()) {
207 PrintError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
208 "', output operand '" + Dag->getArgNameStr(Num: i) +
209 "' has no matching source operand");
210 PrintFatalNote(RecVal: Rec->getValue(Name: "ResultInst"),
211 Msg: "Value was assigned at the following location:");
212 }
213 // Map the source operand to the destination operand index for each
214 // MachineInstr operand.
215 for (unsigned I = 0, E = Insn.Operands[i].MINumOperands; I != E; ++I)
216 OperandMap[Insn.Operands[i].MIOperandNo + I].Data.Operand =
217 SourceOp->getValue();
218
219 LLVM_DEBUG(dbgs() << " " << SourceOp->getValue() << " ==> " << i
220 << "\n");
221 }
222
223 Expansions.push_back(Elt: PseudoExpansion(SourceInsn, Insn, OperandMap));
224}
225
226void PseudoLoweringEmitter::emitLoweringEmitter(raw_ostream &o) {
227 // Emit file header.
228 emitSourceFileHeader(Desc: "Pseudo-instruction MC lowering Source Fragment", OS&: o);
229
230 o << "bool " << Target.getName() + "AsmPrinter"
231 << "::\n"
232 << "emitPseudoExpansionLowering(MCStreamer &OutStreamer,\n"
233 << " const MachineInstr *MI) {\n";
234
235 if (!Expansions.empty()) {
236 o << " switch (MI->getOpcode()) {\n"
237 << " default: return false;\n";
238 for (auto &Expansion : Expansions) {
239 CodeGenInstruction &Source = Expansion.Source;
240 CodeGenInstruction &Dest = Expansion.Dest;
241 o << " case " << Source.Namespace << "::" << Source.TheDef->getName()
242 << ": {\n"
243 << " MCInst TmpInst;\n"
244 << " MCOperand MCOp;\n"
245 << " TmpInst.setOpcode(" << Dest.Namespace
246 << "::" << Dest.TheDef->getName() << ");\n";
247
248 // Copy the operands from the source instruction.
249 // FIXME: Instruction operands with defaults values (predicates and cc_out
250 // in ARM, for example shouldn't need explicit values in the
251 // expansion DAG.
252 unsigned MIOpNo = 0;
253 for (const auto &DestOperand : Dest.Operands) {
254 o << " // Operand: " << DestOperand.Name << "\n";
255 for (unsigned i = 0, e = DestOperand.MINumOperands; i != e; ++i) {
256 switch (Expansion.OperandMap[MIOpNo + i].Kind) {
257 case OpData::Operand:
258 o << " lowerOperand(MI->getOperand("
259 << Source.Operands[Expansion.OperandMap[MIOpNo].Data.Operand]
260 .MIOperandNo +
261 i
262 << "), MCOp);\n"
263 << " TmpInst.addOperand(MCOp);\n";
264 break;
265 case OpData::Imm:
266 o << " TmpInst.addOperand(MCOperand::createImm("
267 << Expansion.OperandMap[MIOpNo + i].Data.Imm << "));\n";
268 break;
269 case OpData::Reg: {
270 Record *Reg = Expansion.OperandMap[MIOpNo + i].Data.Reg;
271 o << " TmpInst.addOperand(MCOperand::createReg(";
272 // "zero_reg" is special.
273 if (Reg->getName() == "zero_reg")
274 o << "0";
275 else
276 o << Reg->getValueAsString(FieldName: "Namespace") << "::" << Reg->getName();
277 o << "));\n";
278 break;
279 }
280 }
281 }
282 MIOpNo += DestOperand.MINumOperands;
283 }
284 if (Dest.Operands.isVariadic) {
285 MIOpNo = Source.Operands.size() + 1;
286 o << " // variable_ops\n";
287 o << " for (unsigned i = " << MIOpNo
288 << ", e = MI->getNumOperands(); i != e; ++i)\n"
289 << " if (lowerOperand(MI->getOperand(i), MCOp))\n"
290 << " TmpInst.addOperand(MCOp);\n";
291 }
292 o << " EmitToStreamer(OutStreamer, TmpInst);\n"
293 << " break;\n"
294 << " }\n";
295 }
296 o << " }\n return true;";
297 } else
298 o << " return false;";
299
300 o << "\n}\n\n";
301}
302
303void PseudoLoweringEmitter::run(raw_ostream &o) {
304 StringRef Classes[] = {"PseudoInstExpansion", "Instruction"};
305 std::vector<Record *> Insts = Records.getAllDerivedDefinitions(ClassNames: Classes);
306
307 // Process the pseudo expansion definitions, validating them as we do so.
308 Records.startTimer(Name: "Process definitions");
309 for (unsigned i = 0, e = Insts.size(); i != e; ++i)
310 evaluateExpansion(Rec: Insts[i]);
311
312 // Generate expansion code to lower the pseudo to an MCInst of the real
313 // instruction.
314 Records.startTimer(Name: "Emit expansion code");
315 emitLoweringEmitter(o);
316}
317
318static TableGen::Emitter::OptClass<PseudoLoweringEmitter>
319 X("gen-pseudo-lowering", "Generate pseudo instruction lowering");
320