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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 '-'
36 0 : static inline bool hasFlag(StringRef Feature) {
37 : assert(!Feature.empty() && "Empty string");
38 : // Get first character
39 0 : char Ch = Feature[0];
40 : // Check if first character is '+' or '-' flag
41 373377 : return Ch == '+' || Ch =='-';
42 : }
43 :
44 : /// Return string stripped of flag.
45 361488 : static inline std::string StripFlag(StringRef Feature) {
46 1084145 : return hasFlag(Feature) ? Feature.substr(1) : Feature;
47 : }
48 :
49 : /// Return true if enable flag; '+'.
50 0 : static inline bool isEnabled(StringRef Feature) {
51 : assert(!Feature.empty() && "Empty string");
52 : // Get first character
53 0 : char Ch = Feature[0];
54 : // Check if first character is '+' for enabled
55 0 : return Ch == '+';
56 : }
57 :
58 : /// Splits a string of comma separated items in to a vector of strings.
59 174176 : static void Split(std::vector<std::string> &V, StringRef S) {
60 : SmallVector<StringRef, 3> Tmp;
61 174176 : S.split(Tmp, ',', -1, false /* KeepEmpty */);
62 : V.assign(Tmp.begin(), Tmp.end());
63 174176 : }
64 :
65 11890 : void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
66 : // Don't add empty features.
67 11890 : if (!String.empty())
68 : // Convert to lowercase, prepend flag if we don't already have a flag.
69 25178 : Features.push_back(hasFlag(String) ? String.lower()
70 14671 : : (Enable ? "+" : "-") + String.lower());
71 11890 : }
72 :
73 : /// Find KV in array using binary search.
74 469312 : 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 469667 : 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.
85 0 : static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) {
86 0 : size_t MaxLen = 0;
87 0 : for (auto &I : Table)
88 0 : MaxLen = std::max(MaxLen, std::strlen(I.Key));
89 0 : return MaxLen;
90 : }
91 :
92 : /// Display help for feature choices.
93 0 : static void Help(ArrayRef<SubtargetFeatureKV> CPUTable,
94 : ArrayRef<SubtargetFeatureKV> FeatTable) {
95 : // Determine the length of the longest CPU and Feature entries.
96 0 : unsigned MaxCPULen = getLongestEntryLength(CPUTable);
97 0 : unsigned MaxFeatLen = getLongestEntryLength(FeatTable);
98 :
99 : // Print the CPU table.
100 0 : errs() << "Available CPUs for this target:\n\n";
101 0 : for (auto &CPU : CPUTable)
102 0 : errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc);
103 0 : errs() << '\n';
104 :
105 : // Print the Feature table.
106 0 : errs() << "Available features for this target:\n\n";
107 0 : for (auto &Feature : FeatTable)
108 0 : errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc);
109 0 : errs() << '\n';
110 :
111 0 : errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
112 0 : "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
113 0 : }
114 :
115 174176 : SubtargetFeatures::SubtargetFeatures(StringRef Initial) {
116 : // Break up string into separate features
117 174176 : Split(Features, Initial);
118 174176 : }
119 :
120 29667 : std::string SubtargetFeatures::getString() const {
121 29667 : return join(Features.begin(), Features.end(), ",");
122 : }
123 :
124 : /// For each feature that is (transitively) implied by this feature, set it.
125 : static
126 2210838 : void SetImpliedBits(FeatureBitset &Bits, const SubtargetFeatureKV &FeatureEntry,
127 : ArrayRef<SubtargetFeatureKV> FeatureTable) {
128 231549367 : for (const SubtargetFeatureKV &FE : FeatureTable) {
129 229338529 : if (FeatureEntry.Value == FE.Value) continue;
130 :
131 227127716 : if ((FeatureEntry.Implies & FE.Value).any()) {
132 : Bits |= FE.Value;
133 1320966 : SetImpliedBits(Bits, FE, FeatureTable);
134 : }
135 : }
136 2210838 : }
137 :
138 : /// For each feature that (transitively) implies this feature, clear it.
139 : static
140 192958 : void ClearImpliedBits(FeatureBitset &Bits,
141 : const SubtargetFeatureKV &FeatureEntry,
142 : ArrayRef<SubtargetFeatureKV> FeatureTable) {
143 21569582 : for (const SubtargetFeatureKV &FE : FeatureTable) {
144 21376624 : if (FeatureEntry.Value == FE.Value) continue;
145 :
146 21183700 : if ((FE.Implies & FeatureEntry.Value).any()) {
147 109768 : Bits &= ~FE.Value;
148 109768 : ClearImpliedBits(Bits, FE, FeatureTable);
149 : }
150 : }
151 192958 : }
152 :
153 : void
154 319 : SubtargetFeatures::ToggleFeature(FeatureBitset &Bits, StringRef Feature,
155 : ArrayRef<SubtargetFeatureKV> FeatureTable) {
156 : // Find feature in table.
157 : const SubtargetFeatureKV *FeatureEntry =
158 319 : Find(StripFlag(Feature), FeatureTable);
159 : // If there is a match
160 319 : if (FeatureEntry) {
161 318 : if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
162 60 : Bits &= ~FeatureEntry->Value;
163 : // For each feature that implies this, clear it.
164 60 : ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
165 : } else {
166 : Bits |= FeatureEntry->Value;
167 :
168 : // For each feature that this implies, set it.
169 258 : SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
170 : }
171 : } else {
172 1 : errs() << "'" << Feature << "' is not a recognized feature for this target"
173 1 : << " (ignoring feature)\n";
174 : }
175 319 : }
176 :
177 361169 : 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 361169 : Find(StripFlag(Feature), FeatureTable);
184 : // If there is a match
185 361169 : if (FeatureEntry) {
186 : // Enable/disable feature in bits
187 721890 : if (isEnabled(Feature)) {
188 : Bits |= FeatureEntry->Value;
189 :
190 : // For each feature that this implies, set it.
191 277815 : SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
192 : } else {
193 83130 : Bits &= ~FeatureEntry->Value;
194 :
195 : // For each feature that implies this, clear it.
196 83130 : ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
197 : }
198 : } else {
199 224 : errs() << "'" << Feature << "' is not a recognized feature for this target"
200 224 : << " (ignoring feature)\n";
201 : }
202 361169 : }
203 :
204 : FeatureBitset
205 137282 : SubtargetFeatures::getFeatureBits(StringRef CPU,
206 : ArrayRef<SubtargetFeatureKV> CPUTable,
207 : ArrayRef<SubtargetFeatureKV> FeatureTable) {
208 137282 : if (CPUTable.empty() || FeatureTable.empty())
209 663 : 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 274122 : FeatureBitset Bits;
217 :
218 : // Check if help is needed
219 : if (CPU == "help")
220 0 : Help(CPUTable, FeatureTable);
221 :
222 : // Find CPU entry if CPU name is specified.
223 137061 : else if (!CPU.empty()) {
224 107824 : const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable);
225 :
226 : // If there is a match
227 107824 : if (CPUEntry) {
228 : // Set base feature bits
229 107691 : Bits = CPUEntry->Value;
230 :
231 : // Set the feature implied by this CPU feature, if any.
232 10871341 : for (auto &FE : FeatureTable) {
233 10763650 : if ((CPUEntry->Value & FE.Value).any())
234 611799 : SetImpliedBits(Bits, FE, FeatureTable);
235 : }
236 : } else {
237 133 : errs() << "'" << CPU << "' is not a recognized processor for this target"
238 133 : << " (ignoring processor)\n";
239 : }
240 : }
241 :
242 : // Iterate through each feature
243 483752 : for (const std::string &Feature : Features) {
244 : // Check for help
245 346691 : if (Feature == "+help")
246 0 : Help(CPUTable, FeatureTable);
247 :
248 346691 : ApplyFeatureFlag(Bits, Feature, FeatureTable);
249 : }
250 :
251 137061 : return Bits;
252 : }
253 :
254 0 : void SubtargetFeatures::print(raw_ostream &OS) const {
255 0 : for (auto &F : Features)
256 0 : OS << F << " ";
257 0 : OS << "\n";
258 0 : }
259 :
260 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
261 : LLVM_DUMP_METHOD void SubtargetFeatures::dump() const {
262 : print(dbgs());
263 : }
264 : #endif
265 :
266 859 : 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>.
270 859 : if (Triple.getVendor() == Triple::Apple) {
271 115 : if (Triple.getArch() == Triple::ppc) {
272 : // powerpc-apple-*
273 0 : AddFeature("altivec");
274 115 : } else if (Triple.getArch() == Triple::ppc64) {
275 : // powerpc64-apple-*
276 0 : AddFeature("64bit");
277 0 : AddFeature("altivec");
278 : }
279 : }
280 859 : }
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