1 //===- SubtargetFeature.cpp - CPU characteristics Implementation ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 /// \file Implements the SubtargetFeature interface.
12 //===----------------------------------------------------------------------===//
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/Support/Compiler.h"
21 #include "llvm/Support/Debug.h"
22 #include "llvm/Support/Format.h"
23 #include "llvm/Support/raw_ostream.h"
34 /// Determine if a feature has a flag; '+' or '-'
35 static inline bool hasFlag(StringRef Feature) {
36 assert(!Feature.empty() && "Empty string");
37 // Get first character
39 // Check if first character is '+' or '-' flag
40 return Ch == '+' || Ch =='-';
43 /// Return string stripped of flag.
44 static inline std::string StripFlag(StringRef Feature) {
45 return hasFlag(Feature) ? Feature.substr(1) : Feature;
48 /// Return true if enable flag; '+'.
49 static inline bool isEnabled(StringRef Feature) {
50 assert(!Feature.empty() && "Empty string");
51 // Get first character
53 // Check if first character is '+' for enabled
57 /// Splits a string of comma separated items in to a vector of strings.
58 static void Split(std::vector<std::string> &V, StringRef S) {
59 SmallVector<StringRef, 3> Tmp;
60 S.split(Tmp, ',', -1, false /* KeepEmpty */);
61 V.assign(Tmp.begin(), Tmp.end());
64 void SubtargetFeatures::AddFeature(StringRef String, bool Enable) {
65 // Don't add empty features.
67 // Convert to lowercase, prepend flag if we don't already have a flag.
68 Features.push_back(hasFlag(String) ? String.lower()
69 : (Enable ? "+" : "-") + String.lower());
72 /// Find KV in array using binary search.
73 static const SubtargetFeatureKV *Find(StringRef S,
74 ArrayRef<SubtargetFeatureKV> A) {
75 // Binary search the array
76 auto F = std::lower_bound(A.begin(), A.end(), S);
77 // If not found then return NULL
78 if (F == A.end() || StringRef(F->Key) != S) return nullptr;
79 // Return the found array item
83 /// Return the length of the longest entry in the table.
84 static size_t getLongestEntryLength(ArrayRef<SubtargetFeatureKV> Table) {
87 MaxLen = std::max(MaxLen, std::strlen(I.Key));
91 /// Display help for feature choices.
92 static void Help(ArrayRef<SubtargetFeatureKV> CPUTable,
93 ArrayRef<SubtargetFeatureKV> FeatTable) {
94 // Determine the length of the longest CPU and Feature entries.
95 unsigned MaxCPULen = getLongestEntryLength(CPUTable);
96 unsigned MaxFeatLen = getLongestEntryLength(FeatTable);
98 // Print the CPU table.
99 errs() << "Available CPUs for this target:\n\n";
100 for (auto &CPU : CPUTable)
101 errs() << format(" %-*s - %s.\n", MaxCPULen, CPU.Key, CPU.Desc);
104 // Print the Feature table.
105 errs() << "Available features for this target:\n\n";
106 for (auto &Feature : FeatTable)
107 errs() << format(" %-*s - %s.\n", MaxFeatLen, Feature.Key, Feature.Desc);
110 errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
111 "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
114 SubtargetFeatures::SubtargetFeatures(StringRef Initial) {
115 // Break up string into separate features
116 Split(Features, Initial);
119 std::string SubtargetFeatures::getString() const {
120 return join(Features.begin(), Features.end(), ",");
123 /// For each feature that is (transitively) implied by this feature, set it.
125 void SetImpliedBits(FeatureBitset &Bits, const SubtargetFeatureKV &FeatureEntry,
126 ArrayRef<SubtargetFeatureKV> FeatureTable) {
127 for (const SubtargetFeatureKV &FE : FeatureTable) {
128 if (FeatureEntry.Value == FE.Value) continue;
130 if ((FeatureEntry.Implies & FE.Value).any()) {
132 SetImpliedBits(Bits, FE, FeatureTable);
137 /// For each feature that (transitively) implies this feature, clear it.
139 void ClearImpliedBits(FeatureBitset &Bits,
140 const SubtargetFeatureKV &FeatureEntry,
141 ArrayRef<SubtargetFeatureKV> FeatureTable) {
142 for (const SubtargetFeatureKV &FE : FeatureTable) {
143 if (FeatureEntry.Value == FE.Value) continue;
145 if ((FE.Implies & FeatureEntry.Value).any()) {
147 ClearImpliedBits(Bits, FE, FeatureTable);
153 SubtargetFeatures::ToggleFeature(FeatureBitset &Bits, StringRef Feature,
154 ArrayRef<SubtargetFeatureKV> FeatureTable) {
155 // Find feature in table.
156 const SubtargetFeatureKV *FeatureEntry =
157 Find(StripFlag(Feature), FeatureTable);
158 // If there is a match
160 if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
161 Bits &= ~FeatureEntry->Value;
162 // For each feature that implies this, clear it.
163 ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
165 Bits |= FeatureEntry->Value;
167 // For each feature that this implies, set it.
168 SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
171 errs() << "'" << Feature << "' is not a recognized feature for this target"
172 << " (ignoring feature)\n";
176 void SubtargetFeatures::ApplyFeatureFlag(FeatureBitset &Bits, StringRef Feature,
177 ArrayRef<SubtargetFeatureKV> FeatureTable) {
178 assert(hasFlag(Feature));
180 // Find feature in table.
181 const SubtargetFeatureKV *FeatureEntry =
182 Find(StripFlag(Feature), FeatureTable);
183 // If there is a match
185 // Enable/disable feature in bits
186 if (isEnabled(Feature)) {
187 Bits |= FeatureEntry->Value;
189 // For each feature that this implies, set it.
190 SetImpliedBits(Bits, *FeatureEntry, FeatureTable);
192 Bits &= ~FeatureEntry->Value;
194 // For each feature that implies this, clear it.
195 ClearImpliedBits(Bits, *FeatureEntry, FeatureTable);
198 errs() << "'" << Feature << "' is not a recognized feature for this target"
199 << " (ignoring feature)\n";
204 SubtargetFeatures::getFeatureBits(StringRef CPU,
205 ArrayRef<SubtargetFeatureKV> CPUTable,
206 ArrayRef<SubtargetFeatureKV> FeatureTable) {
207 if (CPUTable.empty() || FeatureTable.empty())
208 return FeatureBitset();
210 assert(std::is_sorted(std::begin(CPUTable), std::end(CPUTable)) &&
211 "CPU table is not sorted");
212 assert(std::is_sorted(std::begin(FeatureTable), std::end(FeatureTable)) &&
213 "CPU features table is not sorted");
217 // Check if help is needed
219 Help(CPUTable, FeatureTable);
221 // Find CPU entry if CPU name is specified.
222 else if (!CPU.empty()) {
223 const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable);
225 // If there is a match
227 // Set base feature bits
228 Bits = CPUEntry->Value;
230 // Set the feature implied by this CPU feature, if any.
231 for (auto &FE : FeatureTable) {
232 if ((CPUEntry->Value & FE.Value).any())
233 SetImpliedBits(Bits, FE, FeatureTable);
236 errs() << "'" << CPU << "' is not a recognized processor for this target"
237 << " (ignoring processor)\n";
241 // Iterate through each feature
242 for (const std::string &Feature : Features) {
244 if (Feature == "+help")
245 Help(CPUTable, FeatureTable);
247 ApplyFeatureFlag(Bits, Feature, FeatureTable);
253 void SubtargetFeatures::print(raw_ostream &OS) const {
254 for (auto &F : Features)
259 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
260 LLVM_DUMP_METHOD void SubtargetFeatures::dump() const {
265 void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) {
266 // FIXME: This is an inelegant way of specifying the features of a
267 // subtarget. It would be better if we could encode this information
268 // into the IR. See <rdar://5972456>.
269 if (Triple.getVendor() == Triple::Apple) {
270 if (Triple.getArch() == Triple::ppc) {
272 AddFeature("altivec");
273 } else if (Triple.getArch() == Triple::ppc64) {
276 AddFeature("altivec");