1//===- MCSubtargetInfo.cpp - Subtarget Information ------------------------===//
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 "llvm/MC/MCSubtargetInfo.h"
10#include "llvm/ADT/ArrayRef.h"
11#include "llvm/ADT/StringRef.h"
12#include "llvm/MC/MCInstrItineraries.h"
13#include "llvm/MC/MCSchedule.h"
14#include "llvm/Support/Format.h"
15#include "llvm/Support/raw_ostream.h"
16#include "llvm/TargetParser/SubtargetFeature.h"
17#include <algorithm>
18#include <cassert>
19#include <cstring>
20#include <optional>
21
22using namespace llvm;
23
24/// Find KV in array using binary search.
25template <typename T>
26static const T *Find(StringRef S, ArrayRef<T> A) {
27 // Binary search the array
28 auto F = llvm::lower_bound(A, S);
29 // If not found then return NULL
30 if (F == A.end() || StringRef(F->Key) != S) return nullptr;
31 // Return the found array item
32 return F;
33}
34
35/// For each feature that is (transitively) implied by this feature, set it.
36static
37void SetImpliedBits(FeatureBitset &Bits, const FeatureBitset &Implies,
38 ArrayRef<SubtargetFeatureKV> FeatureTable) {
39 // OR the Implies bits in outside the loop. This allows the Implies for CPUs
40 // which might imply features not in FeatureTable to use this.
41 Bits |= Implies;
42 for (const SubtargetFeatureKV &FE : FeatureTable)
43 if (Implies.test(I: FE.Value))
44 SetImpliedBits(Bits, Implies: FE.Implies.getAsBitset(), FeatureTable);
45}
46
47/// For each feature that (transitively) implies this feature, clear it.
48static
49void ClearImpliedBits(FeatureBitset &Bits, unsigned Value,
50 ArrayRef<SubtargetFeatureKV> FeatureTable) {
51 for (const SubtargetFeatureKV &FE : FeatureTable) {
52 if (FE.Implies.getAsBitset().test(I: Value)) {
53 Bits.reset(I: FE.Value);
54 ClearImpliedBits(Bits, Value: FE.Value, FeatureTable);
55 }
56 }
57}
58
59static void ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
60 ArrayRef<SubtargetFeatureKV> FeatureTable) {
61 assert(SubtargetFeatures::hasFlag(Feature) &&
62 "Feature flags should start with '+' or '-'");
63
64 // Find feature in table.
65 const SubtargetFeatureKV *FeatureEntry =
66 Find(S: SubtargetFeatures::StripFlag(Feature), A: FeatureTable);
67 // If there is a match
68 if (FeatureEntry) {
69 // Enable/disable feature in bits
70 if (SubtargetFeatures::isEnabled(Feature)) {
71 Bits.set(FeatureEntry->Value);
72
73 // For each feature that this implies, set it.
74 SetImpliedBits(Bits, Implies: FeatureEntry->Implies.getAsBitset(), FeatureTable);
75 } else {
76 Bits.reset(I: FeatureEntry->Value);
77
78 // For each feature that implies this, clear it.
79 ClearImpliedBits(Bits, Value: FeatureEntry->Value, FeatureTable);
80 }
81 } else {
82 errs() << "'" << Feature << "' is not a recognized feature for this target"
83 << " (ignoring feature)\n";
84 }
85}
86
87/// Return the length of the longest entry in the table.
88template <typename T>
89static size_t getLongestEntryLength(ArrayRef<T> Table) {
90 size_t MaxLen = 0;
91 for (auto &I : Table)
92 MaxLen = std::max(MaxLen, std::strlen(s: I.Key));
93 return MaxLen;
94}
95
96/// Display help for feature and mcpu choices.
97static void Help(ArrayRef<SubtargetSubTypeKV> CPUTable,
98 ArrayRef<SubtargetFeatureKV> FeatTable) {
99 // the static variable ensures that the help information only gets
100 // printed once even though a target machine creates multiple subtargets
101 static bool PrintOnce = false;
102 if (PrintOnce) {
103 return;
104 }
105
106 // Determine the length of the longest CPU and Feature entries.
107 unsigned MaxCPULen = getLongestEntryLength(Table: CPUTable);
108 unsigned MaxFeatLen = getLongestEntryLength(Table: FeatTable);
109
110 // Print the CPU table.
111 errs() << "Available CPUs for this target:\n\n";
112 for (auto &CPU : CPUTable)
113 errs() << format(Fmt: " %-*s - Select the %s processor.\n", Vals: MaxCPULen, Vals: CPU.Key,
114 Vals: CPU.Key);
115 errs() << '\n';
116
117 // Print the Feature table.
118 errs() << "Available features for this target:\n\n";
119 for (auto &Feature : FeatTable)
120 errs() << format(Fmt: " %-*s - %s.\n", Vals: MaxFeatLen, Vals: Feature.Key, Vals: Feature.Desc);
121 errs() << '\n';
122
123 errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
124 "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
125
126 PrintOnce = true;
127}
128
129/// Display help for mcpu choices only
130static void cpuHelp(ArrayRef<SubtargetSubTypeKV> CPUTable) {
131 // the static variable ensures that the help information only gets
132 // printed once even though a target machine creates multiple subtargets
133 static bool PrintOnce = false;
134 if (PrintOnce) {
135 return;
136 }
137
138 // Print the CPU table.
139 errs() << "Available CPUs for this target:\n\n";
140 for (auto &CPU : CPUTable)
141 errs() << "\t" << CPU.Key << "\n";
142 errs() << '\n';
143
144 errs() << "Use -mcpu or -mtune to specify the target's processor.\n"
145 "For example, clang --target=aarch64-unknown-linux-gnu "
146 "-mcpu=cortex-a35\n";
147
148 PrintOnce = true;
149}
150
151static FeatureBitset getFeatures(StringRef CPU, StringRef TuneCPU, StringRef FS,
152 ArrayRef<SubtargetSubTypeKV> ProcDesc,
153 ArrayRef<SubtargetFeatureKV> ProcFeatures) {
154 SubtargetFeatures Features(FS);
155
156 if (ProcDesc.empty() || ProcFeatures.empty())
157 return FeatureBitset();
158
159 assert(llvm::is_sorted(ProcDesc) && "CPU table is not sorted");
160 assert(llvm::is_sorted(ProcFeatures) && "CPU features table is not sorted");
161 // Resulting bits
162 FeatureBitset Bits;
163
164 // Check if help is needed
165 if (CPU == "help")
166 Help(CPUTable: ProcDesc, FeatTable: ProcFeatures);
167
168 // Find CPU entry if CPU name is specified.
169 else if (!CPU.empty()) {
170 const SubtargetSubTypeKV *CPUEntry = Find(S: CPU, A: ProcDesc);
171
172 // If there is a match
173 if (CPUEntry) {
174 // Set the features implied by this CPU feature, if any.
175 SetImpliedBits(Bits, Implies: CPUEntry->Implies.getAsBitset(), FeatureTable: ProcFeatures);
176 } else {
177 errs() << "'" << CPU << "' is not a recognized processor for this target"
178 << " (ignoring processor)\n";
179 }
180 }
181
182 if (!TuneCPU.empty()) {
183 const SubtargetSubTypeKV *CPUEntry = Find(S: TuneCPU, A: ProcDesc);
184
185 // If there is a match
186 if (CPUEntry) {
187 // Set the features implied by this CPU feature, if any.
188 SetImpliedBits(Bits, Implies: CPUEntry->TuneImplies.getAsBitset(), FeatureTable: ProcFeatures);
189 } else if (TuneCPU != CPU) {
190 errs() << "'" << TuneCPU << "' is not a recognized processor for this "
191 << "target (ignoring processor)\n";
192 }
193 }
194
195 // Iterate through each feature
196 for (const std::string &Feature : Features.getFeatures()) {
197 // Check for help
198 if (Feature == "+help")
199 Help(CPUTable: ProcDesc, FeatTable: ProcFeatures);
200 else if (Feature == "+cpuhelp")
201 cpuHelp(CPUTable: ProcDesc);
202 else
203 ApplyFeatureFlag(Bits, Feature, FeatureTable: ProcFeatures);
204 }
205
206 return Bits;
207}
208
209void MCSubtargetInfo::InitMCProcessorInfo(StringRef CPU, StringRef TuneCPU,
210 StringRef FS) {
211 FeatureBits = getFeatures(CPU, TuneCPU, FS, ProcDesc, ProcFeatures);
212 FeatureString = std::string(FS);
213
214 if (!TuneCPU.empty())
215 CPUSchedModel = &getSchedModelForCPU(CPU: TuneCPU);
216 else
217 CPUSchedModel = &MCSchedModel::Default;
218}
219
220void MCSubtargetInfo::setDefaultFeatures(StringRef CPU, StringRef TuneCPU,
221 StringRef FS) {
222 FeatureBits = getFeatures(CPU, TuneCPU, FS, ProcDesc, ProcFeatures);
223 FeatureString = std::string(FS);
224}
225
226MCSubtargetInfo::MCSubtargetInfo(const Triple &TT, StringRef C, StringRef TC,
227 StringRef FS, ArrayRef<SubtargetFeatureKV> PF,
228 ArrayRef<SubtargetSubTypeKV> PD,
229 const MCWriteProcResEntry *WPR,
230 const MCWriteLatencyEntry *WL,
231 const MCReadAdvanceEntry *RA,
232 const InstrStage *IS, const unsigned *OC,
233 const unsigned *FP)
234 : TargetTriple(TT), CPU(std::string(C)), TuneCPU(std::string(TC)),
235 ProcFeatures(PF), ProcDesc(PD), WriteProcResTable(WPR),
236 WriteLatencyTable(WL), ReadAdvanceTable(RA), Stages(IS),
237 OperandCycles(OC), ForwardingPaths(FP) {
238 InitMCProcessorInfo(CPU, TuneCPU, FS);
239}
240
241FeatureBitset MCSubtargetInfo::ToggleFeature(uint64_t FB) {
242 FeatureBits.flip(I: FB);
243 return FeatureBits;
244}
245
246FeatureBitset MCSubtargetInfo::ToggleFeature(const FeatureBitset &FB) {
247 FeatureBits ^= FB;
248 return FeatureBits;
249}
250
251FeatureBitset MCSubtargetInfo::SetFeatureBitsTransitively(
252 const FeatureBitset &FB) {
253 SetImpliedBits(Bits&: FeatureBits, Implies: FB, FeatureTable: ProcFeatures);
254 return FeatureBits;
255}
256
257FeatureBitset MCSubtargetInfo::ClearFeatureBitsTransitively(
258 const FeatureBitset &FB) {
259 for (unsigned I = 0, E = FB.size(); I < E; I++) {
260 if (FB[I]) {
261 FeatureBits.reset(I);
262 ClearImpliedBits(Bits&: FeatureBits, Value: I, FeatureTable: ProcFeatures);
263 }
264 }
265 return FeatureBits;
266}
267
268FeatureBitset MCSubtargetInfo::ToggleFeature(StringRef Feature) {
269 // Find feature in table.
270 const SubtargetFeatureKV *FeatureEntry =
271 Find(S: SubtargetFeatures::StripFlag(Feature), A: ProcFeatures);
272 // If there is a match
273 if (FeatureEntry) {
274 if (FeatureBits.test(I: FeatureEntry->Value)) {
275 FeatureBits.reset(I: FeatureEntry->Value);
276 // For each feature that implies this, clear it.
277 ClearImpliedBits(Bits&: FeatureBits, Value: FeatureEntry->Value, FeatureTable: ProcFeatures);
278 } else {
279 FeatureBits.set(FeatureEntry->Value);
280
281 // For each feature that this implies, set it.
282 SetImpliedBits(Bits&: FeatureBits, Implies: FeatureEntry->Implies.getAsBitset(),
283 FeatureTable: ProcFeatures);
284 }
285 } else {
286 errs() << "'" << Feature << "' is not a recognized feature for this target"
287 << " (ignoring feature)\n";
288 }
289
290 return FeatureBits;
291}
292
293FeatureBitset MCSubtargetInfo::ApplyFeatureFlag(StringRef FS) {
294 ::ApplyFeatureFlag(Bits&: FeatureBits, Feature: FS, FeatureTable: ProcFeatures);
295 return FeatureBits;
296}
297
298bool MCSubtargetInfo::checkFeatures(StringRef FS) const {
299 SubtargetFeatures T(FS);
300 FeatureBitset Set, All;
301 for (std::string F : T.getFeatures()) {
302 ::ApplyFeatureFlag(Bits&: Set, Feature: F, FeatureTable: ProcFeatures);
303 if (F[0] == '-')
304 F[0] = '+';
305 ::ApplyFeatureFlag(Bits&: All, Feature: F, FeatureTable: ProcFeatures);
306 }
307 return (FeatureBits & All) == Set;
308}
309
310const MCSchedModel &MCSubtargetInfo::getSchedModelForCPU(StringRef CPU) const {
311 assert(llvm::is_sorted(ProcDesc) &&
312 "Processor machine model table is not sorted");
313
314 // Find entry
315 const SubtargetSubTypeKV *CPUEntry = Find(S: CPU, A: ProcDesc);
316
317 if (!CPUEntry) {
318 if (CPU != "help") // Don't error if the user asked for help.
319 errs() << "'" << CPU
320 << "' is not a recognized processor for this target"
321 << " (ignoring processor)\n";
322 return MCSchedModel::Default;
323 }
324 assert(CPUEntry->SchedModel && "Missing processor SchedModel value");
325 return *CPUEntry->SchedModel;
326}
327
328InstrItineraryData
329MCSubtargetInfo::getInstrItineraryForCPU(StringRef CPU) const {
330 const MCSchedModel &SchedModel = getSchedModelForCPU(CPU);
331 return InstrItineraryData(SchedModel, Stages, OperandCycles, ForwardingPaths);
332}
333
334void MCSubtargetInfo::initInstrItins(InstrItineraryData &InstrItins) const {
335 InstrItins = InstrItineraryData(getSchedModel(), Stages, OperandCycles,
336 ForwardingPaths);
337}
338
339std::optional<unsigned> MCSubtargetInfo::getCacheSize(unsigned Level) const {
340 return std::nullopt;
341}
342
343std::optional<unsigned>
344MCSubtargetInfo::getCacheAssociativity(unsigned Level) const {
345 return std::nullopt;
346}
347
348std::optional<unsigned>
349MCSubtargetInfo::getCacheLineSize(unsigned Level) const {
350 return std::nullopt;
351}
352
353unsigned MCSubtargetInfo::getPrefetchDistance() const {
354 return 0;
355}
356
357unsigned MCSubtargetInfo::getMaxPrefetchIterationsAhead() const {
358 return UINT_MAX;
359}
360
361bool MCSubtargetInfo::enableWritePrefetching() const {
362 return false;
363}
364
365unsigned MCSubtargetInfo::getMinPrefetchStride(unsigned NumMemAccesses,
366 unsigned NumStridedMemAccesses,
367 unsigned NumPrefetches,
368 bool HasCall) const {
369 return 1;
370}
371
372bool MCSubtargetInfo::shouldPrefetchAddressSpace(unsigned AS) const {
373 return !AS;
374}
375

source code of llvm/lib/MC/MCSubtargetInfo.cpp