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/TGTimer.h"
19#include "llvm/TableGen/TableGenBackend.h"
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 const 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 const 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 const CodeGenTarget Target;
51
52 SmallVector<PseudoExpansion, 64> Expansions;
53
54 void addOperandMapping(unsigned MIOpNo, unsigned NumOps, const Record *Rec,
55 const DagInit *Dag, unsigned DagIdx,
56 const Record *OpRec, IndexedMap<OpData> &OperandMap,
57 const StringMap<unsigned> &SourceOperands,
58 const CodeGenInstruction &SourceInsn);
59 void evaluateExpansion(const Record *Pseudo);
60 void emitLoweringEmitter(raw_ostream &o);
61
62public:
63 PseudoLoweringEmitter(const RecordKeeper &R) : Records(R), Target(R) {}
64
65 /// run - Output the pseudo-lowerings.
66 void run(raw_ostream &o);
67};
68} // End anonymous namespace
69
70void PseudoLoweringEmitter::addOperandMapping(
71 unsigned MIOpNo, unsigned NumOps, const Record *Rec, const DagInit *Dag,
72 unsigned DagIdx, const Record *OpRec, IndexedMap<OpData> &OperandMap,
73 const StringMap<unsigned> &SourceOperands,
74 const CodeGenInstruction &SourceInsn) {
75 const Init *DagArg = Dag->getArg(Num: DagIdx);
76 if (const DefInit *DI = dyn_cast<DefInit>(Val: DagArg)) {
77 // Physical register reference. Explicit check for the special case
78 // "zero_reg" definition.
79 if (DI->getDef()->isSubClassOf(Name: "Register") ||
80 DI->getDef()->getName() == "zero_reg") {
81 auto &Entry = OperandMap[MIOpNo];
82 Entry.Kind = OpData::Reg;
83 Entry.Data.Reg = DI->getDef();
84 return;
85 }
86
87 if (DI->getDef() != OpRec)
88 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
89 "', operand type '" + DI->getDef()->getName() +
90 "' does not match expansion operand type '" +
91 OpRec->getName() + "'");
92
93 StringMap<unsigned>::const_iterator SourceOp =
94 SourceOperands.find(Key: Dag->getArgNameStr(Num: DagIdx));
95 if (SourceOp == SourceOperands.end())
96 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
97 "', output operand '" +
98 Dag->getArgNameStr(Num: DagIdx) +
99 "' has no matching source operand");
100 const auto &SrcOpnd = SourceInsn.Operands[SourceOp->getValue()];
101 if (NumOps != SrcOpnd.MINumOperands)
102 PrintFatalError(
103 Rec,
104 Msg: "In pseudo instruction '" + Rec->getName() + "', output operand '" +
105 OpRec->getName() +
106 "' has a different number of sub operands than source operand '" +
107 SrcOpnd.Rec->getName() + "'");
108
109 // Source operand maps to destination operand. Do it for each corresponding
110 // MachineInstr operand, not just the first.
111 for (unsigned I = 0, E = NumOps; I != E; ++I) {
112 auto &Entry = OperandMap[MIOpNo + I];
113 Entry.Kind = OpData::Operand;
114 Entry.Data.Operand = SrcOpnd.MIOperandNo + I;
115 }
116
117 LLVM_DEBUG(dbgs() << " " << SourceOp->getValue() << " ==> " << DagIdx
118 << "\n");
119 } else if (const auto *II = dyn_cast<IntInit>(Val: DagArg)) {
120 assert(NumOps == 1);
121 auto &Entry = OperandMap[MIOpNo];
122 Entry.Kind = OpData::Imm;
123 Entry.Data.Imm = II->getValue();
124 } else if (const auto *BI = dyn_cast<BitsInit>(Val: DagArg)) {
125 assert(NumOps == 1);
126 auto &Entry = OperandMap[MIOpNo];
127 Entry.Kind = OpData::Imm;
128 Entry.Data.Imm = *BI->convertInitializerToInt();
129 } else {
130 llvm_unreachable("Unhandled pseudo-expansion argument type!");
131 }
132}
133
134void PseudoLoweringEmitter::evaluateExpansion(const Record *Rec) {
135 LLVM_DEBUG(dbgs() << "Pseudo definition: " << Rec->getName() << "\n");
136
137 // Validate that the result pattern has the corrent number and types
138 // of arguments for the instruction it references.
139 const DagInit *Dag = Rec->getValueAsDag(FieldName: "ResultInst");
140 assert(Dag && "Missing result instruction in pseudo expansion!");
141 LLVM_DEBUG(dbgs() << " Result: " << *Dag << "\n");
142
143 const DefInit *OpDef = dyn_cast<DefInit>(Val: Dag->getOperator());
144 if (!OpDef)
145 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
146 "', result operator is not a record");
147 const Record *Operator = OpDef->getDef();
148 if (!Operator->isSubClassOf(Name: "Instruction"))
149 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
150 "', result operator '" + Operator->getName() +
151 "' is not an instruction");
152
153 CodeGenInstruction Insn(Operator);
154
155 if (Insn.isCodeGenOnly || Insn.isPseudo)
156 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
157 "', result operator '" + Operator->getName() +
158 "' cannot be a pseudo instruction");
159
160 if (Insn.Operands.size() != Dag->getNumArgs())
161 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
162 "', result operator '" + Operator->getName() +
163 "' has the wrong number of operands");
164
165 // If there are more operands that weren't in the DAG, they have to
166 // be operands that have default values, or we have an error. Currently,
167 // Operands that are a subclass of OperandWithDefaultOp have default values.
168
169 // Validate that each result pattern argument has a matching (by name)
170 // argument in the source instruction, in either the (outs) or (ins) list.
171 // Also check that the type of the arguments match.
172 //
173 // Record the mapping of the source to result arguments for use by
174 // the lowering emitter.
175 CodeGenInstruction SourceInsn(Rec);
176 StringMap<unsigned> SourceOperands;
177 for (const auto &[Idx, SrcOp] : enumerate(First&: SourceInsn.Operands))
178 SourceOperands[SrcOp.Name] = Idx;
179
180 unsigned NumMIOperands = 0;
181 for (const auto &Op : Insn.Operands)
182 NumMIOperands += Op.MINumOperands;
183 IndexedMap<OpData> OperandMap;
184 OperandMap.grow(n: NumMIOperands);
185
186 // FIXME: This pass currently can only expand a pseudo to a single
187 // instruction. The pseudo expansion really should take a list of dags, not
188 // just a single dag, so we can do fancier things.
189 LLVM_DEBUG(dbgs() << " Operand mapping:\n");
190 for (const auto &[Idx, DstOp] : enumerate(First&: Insn.Operands)) {
191 unsigned MIOpNo = DstOp.MIOperandNo;
192
193 if (const auto *SubDag = dyn_cast<DagInit>(Val: Dag->getArg(Num: Idx))) {
194 if (!DstOp.MIOperandInfo || DstOp.MIOperandInfo->getNumArgs() == 0)
195 PrintFatalError(Rec, Msg: "In pseudo instruction '" + Rec->getName() +
196 "', operand '" + DstOp.Rec->getName() +
197 "' does not have suboperands");
198 if (DstOp.MINumOperands != SubDag->getNumArgs()) {
199 PrintFatalError(
200 Rec, Msg: "In pseudo instruction '" + Rec->getName() + "', '" +
201 SubDag->getAsString() +
202 "' has wrong number of operands for operand type '" +
203 DstOp.Rec->getName() + "'");
204 }
205 for (unsigned I = 0, E = DstOp.MINumOperands; I != E; ++I) {
206 auto *OpndRec = cast<DefInit>(Val: DstOp.MIOperandInfo->getArg(Num: I))->getDef();
207 addOperandMapping(MIOpNo: MIOpNo + I, NumOps: 1, Rec, Dag: SubDag, DagIdx: I, OpRec: OpndRec, OperandMap,
208 SourceOperands, SourceInsn);
209 }
210 } else {
211 addOperandMapping(MIOpNo, NumOps: DstOp.MINumOperands, Rec, Dag, DagIdx: Idx, OpRec: DstOp.Rec,
212 OperandMap, SourceOperands, SourceInsn);
213 }
214 }
215
216 Expansions.emplace_back(Args&: SourceInsn, Args&: Insn, Args&: OperandMap);
217}
218
219void PseudoLoweringEmitter::emitLoweringEmitter(raw_ostream &o) {
220 // Emit file header.
221 emitSourceFileHeader(Desc: "Pseudo-instruction MC lowering Source Fragment", OS&: o);
222
223 o << "bool " << Target.getName() + "AsmPrinter::\n"
224 << "lowerPseudoInstExpansion(const MachineInstr *MI, MCInst &Inst) {\n";
225
226 if (!Expansions.empty()) {
227 o << " Inst.clear();\n"
228 << " switch (MI->getOpcode()) {\n"
229 << " default: return false;\n";
230 for (auto &Expansion : Expansions) {
231 CodeGenInstruction &Source = Expansion.Source;
232 CodeGenInstruction &Dest = Expansion.Dest;
233 o << " case " << Source.Namespace << "::" << Source.TheDef->getName()
234 << ": {\n"
235 << " MCOperand MCOp;\n"
236 << " Inst.setOpcode(" << Dest.Namespace
237 << "::" << Dest.TheDef->getName() << ");\n";
238
239 // Copy the operands from the source instruction.
240 // FIXME: Instruction operands with defaults values (predicates and cc_out
241 // in ARM, for example shouldn't need explicit values in the
242 // expansion DAG.
243 for (const auto &DestOperand : Dest.Operands) {
244 o << " // Operand: " << DestOperand.Name << "\n";
245 unsigned MIOpNo = DestOperand.MIOperandNo;
246 for (unsigned i = 0, e = DestOperand.MINumOperands; i != e; ++i) {
247 switch (Expansion.OperandMap[MIOpNo + i].Kind) {
248 case OpData::Operand:
249 o << " lowerOperand(MI->getOperand("
250 << Expansion.OperandMap[MIOpNo + i].Data.Operand << "), MCOp);\n"
251 << " Inst.addOperand(MCOp);\n";
252 break;
253 case OpData::Imm:
254 o << " Inst.addOperand(MCOperand::createImm("
255 << Expansion.OperandMap[MIOpNo + i].Data.Imm << "));\n";
256 break;
257 case OpData::Reg: {
258 const Record *Reg = Expansion.OperandMap[MIOpNo + i].Data.Reg;
259 o << " Inst.addOperand(MCOperand::createReg(";
260 // "zero_reg" is special.
261 if (Reg->getName() == "zero_reg")
262 o << "0";
263 else
264 o << Reg->getValueAsString(FieldName: "Namespace") << "::" << Reg->getName();
265 o << "));\n";
266 break;
267 }
268 }
269 }
270 }
271 if (Dest.Operands.isVariadic) {
272 unsigned LastOpNo = 0;
273 for (const auto &Op : Source.Operands)
274 LastOpNo += Op.MINumOperands;
275 o << " // variable_ops\n";
276 o << " for (unsigned i = " << LastOpNo
277 << ", e = MI->getNumOperands(); i != e; ++i)\n"
278 << " if (lowerOperand(MI->getOperand(i), MCOp))\n"
279 << " Inst.addOperand(MCOp);\n";
280 }
281 o << " break;\n"
282 << " }\n";
283 }
284 o << " }\n return true;";
285 } else {
286 o << " return false;";
287 }
288
289 o << "\n}\n\n";
290}
291
292void PseudoLoweringEmitter::run(raw_ostream &OS) {
293 StringRef Classes[] = {"PseudoInstExpansion", "Instruction"};
294
295 // Process the pseudo expansion definitions, validating them as we do so.
296 TGTimer &Timer = Records.getTimer();
297 Timer.startTimer(Name: "Process definitions");
298 for (const Record *Inst : Records.getAllDerivedDefinitions(ClassNames: Classes))
299 evaluateExpansion(Rec: Inst);
300
301 // Generate expansion code to lower the pseudo to an MCInst of the real
302 // instruction.
303 Timer.startTimer(Name: "Emit expansion code");
304 emitLoweringEmitter(o&: OS);
305}
306
307static TableGen::Emitter::OptClass<PseudoLoweringEmitter>
308 X("gen-pseudo-lowering", "Generate pseudo instruction lowering");
309