1 //===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 /// \file Implements the SubtargetFeature interface.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/MC/SubtargetFeature.h"
15 #include "llvm/ADT/ArrayRef.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/ADT/StringExtras.h"
18 #include "llvm/ADT/StringRef.h"
19 #include "llvm/ADT/Triple.h"
20 #include "llvm/Config/llvm-config.h"
21 #include "llvm/Support/Compiler.h"
22 #include "llvm/Support/Debug.h"
23 #include "llvm/Support/Format.h"
24 #include "llvm/Support/raw_ostream.h"
25 #include <algorithm>
26 #include <cassert>
27 #include <cstddef>
28 #include <cstring>
29 #include <iterator>
30 #include <string>
31 #include <vector>
32
33 using namespace llvm;
34
35 /// Determine if a feature has a flag; '+' or '-'
hasFlag(StringRef Feature)36 static inline bool hasFlag(StringRef Feature) {
37 assert(!Feature.empty() && "Empty string");
38 // Get first character
39 char Ch = Feature[0];
40 // Check if first character is '+' or '-' flag
41 return Ch == '+' || Ch =='-';
42 }
43
44 /// Return string stripped of flag.
StripFlag(StringRef Feature)45 static inline std::string StripFlag(StringRef Feature) {
46 return hasFlag(Feature) ? Feature.substr(1) : Feature;
47 }
48
49 /// Return true if enable flag; '+'.
isEnabled(StringRef Feature)50 static inline bool isEnabled(StringRef Feature) {
51 assert(!Feature.empty() && "Empty string");
52 // Get first character
53 char Ch = Feature[0];
54 // Check if first character is '+' for enabled
55 return Ch == '+';
56 }
57
58 /// Splits a string of comma separated items in to a vector of strings.
Split(std::vector<std::string> & V,StringRef S)59 static void Split(std::vector<std::string> &V, StringRef S) {
60 SmallVector<StringRef, 3> Tmp;
61 S.split(Tmp, ',', -1, false /* KeepEmpty */);
62 V.assign(Tmp.begin(), Tmp.end());
63 }
64
AddFeature(StringRef String,bool Enable)65 void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
66 // Don't add empty features.
67 if (!String.empty())
68 // Convert to lowercase, prepend flag if we don't already have a flag.
69 Features.push_back(hasFlag(String) ? String.lower()
70 : (Enable ? "+" : "-") + String.lower());
71 }
72
73 /// Find KV in array using binary search.
Find(StringRef S,ArrayRef<SubtargetFeatureKV> A)74 static const SubtargetFeatureKV *Find(StringRef S,
75 ArrayRef<SubtargetFeatureKV> A) {
76 // Binary search the array
77 auto F = std::lower_bound(A.begin(), A.end(), S);
78 // If not found then return NULL
79 if (F == A.end() || StringRef(F->Key) != S) return nullptr;
80 // Return the found array item
81 return F;
82 }
83
84 /// Return the length of the longest entry in the table.
getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table)85 static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) {
86 size_t MaxLen = 0;
87 for (auto &I : Table)
88 MaxLen = std::max(MaxLen, std::strlen(I.Key));
89 return MaxLen;
90 }
91
92 /// Display help for feature choices.
Help(ArrayRef<SubtargetFeatureKV> CPUTable,ArrayRef<SubtargetFeatureKV> FeatTable)93 static void Help(ArrayRef<SubtargetFeatureKV> CPUTable,
94 ArrayRef<SubtargetFeatureKV> FeatTable) {
95 // Determine the length of the longest CPU and Feature entries.
96 unsigned MaxCPULen = getLongestEntryLength(CPUTable);
97 unsigned MaxFeatLen = getLongestEntryLength(FeatTable);
98
99 // Print the CPU table.
100 errs() << "Available CPUs for this target:\n\n";
101 for (auto &CPU : CPUTable)
102 errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc);
103 errs() << '\n';
104
105 // Print the Feature table.
106 errs() << "Available features for this target:\n\n";
107 for (auto &Feature : FeatTable)
108 errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc);
109 errs() << '\n';
110
111 errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
112 "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
113 }
114
SubtargetFeatures(StringRef Initial)115 SubtargetFeatures::SubtargetFeatures(StringRef Initial) {
116 // Break up string into separate features
117 Split(Features, Initial);
118 }
119
getString() const120 std::string SubtargetFeatures::getString() const {
121 return join(Features.begin(), Features.end(), ",");
122 }
123
124 /// For each feature that is (transitively) implied by this feature, set it.
125 static
SetImpliedBits(FeatureBitset & Bits,const SubtargetFeatureKV & FeatureEntry,ArrayRef<SubtargetFeatureKV> FeatureTable)126 void SetImpliedBits(FeatureBitset &Bits, const SubtargetFeatureKV &FeatureEntry,
127 ArrayRef<SubtargetFeatureKV> FeatureTable) {
128 for (const SubtargetFeatureKV &FE : FeatureTable) {
129 if (FeatureEntry.Value == FE.Value) continue;
130
131 if ((FeatureEntry.Implies & FE.Value).any()) {
132 Bits |= FE.Value;
133 SetImpliedBits(Bits, FE, FeatureTable);
134 }
135 }
136 }
137
138 /// For each feature that (transitively) implies this feature, clear it.
139 static
ClearImpliedBits(FeatureBitset & Bits,const SubtargetFeatureKV & FeatureEntry,ArrayRef<SubtargetFeatureKV> FeatureTable)140 void ClearImpliedBits(FeatureBitset &Bits,
141 const SubtargetFeatureKV &FeatureEntry,
142 ArrayRef<SubtargetFeatureKV> FeatureTable) {
143 for (const SubtargetFeatureKV &FE : FeatureTable) {
144 if (FeatureEntry.Value == FE.Value) continue;
145
146 if ((FE.Implies & FeatureEntry.Value).any()) {
147 Bits &= ~FE.Value;
148 ClearImpliedBits(Bits, FE, FeatureTable);
149 }
150 }
151 }
152
153 void
ToggleFeature(FeatureBitset & Bits,StringRef Feature,ArrayRef<SubtargetFeatureKV> FeatureTable)154 SubtargetFeatures::ToggleFeature(FeatureBitset &Bits, StringRef Feature,
155 ArrayRef<SubtargetFeatureKV> FeatureTable) {
156 // Find feature in table.
157 const SubtargetFeatureKV *FeatureEntry =
158 Find(StripFlag(Feature), FeatureTable);
159 // If there is a match
160 if (FeatureEntry) {
161 if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
162 Bits &= ~FeatureEntry->Value;
163 // For each feature that implies this, clear it.
164 ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
165 } else {
166 Bits |= FeatureEntry->Value;
167
168 // For each feature that this implies, set it.
169 SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
170 }
171 } else {
172 errs() << "'" << Feature << "' is not a recognized feature for this target"
173 << " (ignoring feature)\n";
174 }
175 }
176
ApplyFeatureFlag(FeatureBitset & Bits,StringRef Feature,ArrayRef<SubtargetFeatureKV> FeatureTable)177 void SubtargetFeatures::ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
178 ArrayRef<SubtargetFeatureKV> FeatureTable) {
179 assert(hasFlag(Feature));
180
181 // Find feature in table.
182 const SubtargetFeatureKV *FeatureEntry =
183 Find(StripFlag(Feature), FeatureTable);
184 // If there is a match
185 if (FeatureEntry) {
186 // Enable/disable feature in bits
187 if (isEnabled(Feature)) {
188 Bits |= FeatureEntry->Value;
189
190 // For each feature that this implies, set it.
191 SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
192 } else {
193 Bits &= ~FeatureEntry->Value;
194
195 // For each feature that implies this, clear it.
196 ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
197 }
198 } else {
199 errs() << "'" << Feature << "' is not a recognized feature for this target"
200 << " (ignoring feature)\n";
201 }
202 }
203
204 FeatureBitset
getFeatureBits(StringRef CPU,ArrayRef<SubtargetFeatureKV> CPUTable,ArrayRef<SubtargetFeatureKV> FeatureTable)205 SubtargetFeatures::getFeatureBits(StringRef CPU,
206 ArrayRef<SubtargetFeatureKV> CPUTable,
207 ArrayRef<SubtargetFeatureKV> FeatureTable) {
208 if (CPUTable.empty() || FeatureTable.empty())
209 return FeatureBitset();
210
211 assert(std::is_sorted(std::begin(CPUTable), std::end(CPUTable)) &&
212 "CPU table is not sorted");
213 assert(std::is_sorted(std::begin(FeatureTable), std::end(FeatureTable)) &&
214 "CPU features table is not sorted");
215 // Resulting bits
216 FeatureBitset Bits;
217
218 // Check if help is needed
219 if (CPU == "help")
220 Help(CPUTable, FeatureTable);
221
222 // Find CPU entry if CPU name is specified.
223 else if (!CPU.empty()) {
224 const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable);
225
226 // If there is a match
227 if (CPUEntry) {
228 // Set base feature bits
229 Bits = CPUEntry->Value;
230
231 // Set the feature implied by this CPU feature, if any.
232 for (auto &FE : FeatureTable) {
233 if ((CPUEntry->Value & FE.Value).any())
234 SetImpliedBits(Bits, FE, FeatureTable);
235 }
236 } else {
237 errs() << "'" << CPU << "' is not a recognized processor for this target"
238 << " (ignoring processor)\n";
239 }
240 }
241
242 // Iterate through each feature
243 for (const std::string &Feature : Features) {
244 // Check for help
245 if (Feature == "+help")
246 Help(CPUTable, FeatureTable);
247
248 ApplyFeatureFlag(Bits, Feature, FeatureTable);
249 }
250
251 return Bits;
252 }
253
print(raw_ostream & OS) const254 void SubtargetFeatures::print(raw_ostream &OS) const {
255 for (auto &F : Features)
256 OS << F << " ";
257 OS << "\n";
258 }
259
260 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump() const261 LLVM_DUMP_METHOD void SubtargetFeatures::dump() const {
262 print(dbgs());
263 }
264 #endif
265
getDefaultSubtargetFeatures(const Triple & Triple)266 void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) {
267 // FIXME: This is an inelegant way of specifying the features of a
268 // subtarget. It would be better if we could encode this information
269 // into the IR. See <rdar://5972456>.
270 if (Triple.getVendor() == Triple::Apple) {
271 if (Triple.getArch() == Triple::ppc) {
272 // powerpc-apple-*
273 AddFeature("altivec");
274 } else if (Triple.getArch() == Triple::ppc64) {
275 // powerpc64-apple-*
276 AddFeature("64bit");
277 AddFeature("altivec");
278 }
279 }
280 }
281