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// This file implements the SubtargetFeature interface.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/MC/SubtargetFeature.h"
15#include "llvm/Support/Debug.h"
16#include "llvm/Support/Format.h"
17#include "llvm/Support/raw_ostream.h"
18#include <algorithm>
19#include <cassert>
20#include <cctype>
21#include <cstdlib>
22using namespace llvm;
23
24//===----------------------------------------------------------------------===//
25//                          Static Helper Functions
26//===----------------------------------------------------------------------===//
27
28/// hasFlag - Determine if a feature has a flag; '+' or '-'
29///
30static inline bool hasFlag(const StringRef Feature) {
31  assert(!Feature.empty() && "Empty string");
32  // Get first character
33  char Ch = Feature[0];
34  // Check if first character is '+' or '-' flag
35  return Ch == '+' || Ch =='-';
36}
37
38/// StripFlag - Return string stripped of flag.
39///
40static inline std::string StripFlag(const StringRef Feature) {
41  return hasFlag(Feature) ? Feature.substr(1) : Feature;
42}
43
44/// isEnabled - Return true if enable flag; '+'.
45///
46static inline bool isEnabled(const StringRef Feature) {
47  assert(!Feature.empty() && "Empty string");
48  // Get first character
49  char Ch = Feature[0];
50  // Check if first character is '+' for enabled
51  return Ch == '+';
52}
53
54/// PrependFlag - Return a string with a prepended flag; '+' or '-'.
55///
56static inline std::string PrependFlag(const StringRef Feature,
57                                    bool IsEnabled) {
58  assert(!Feature.empty() && "Empty string");
59  if (hasFlag(Feature))
60    return Feature;
61  std::string Prefix = IsEnabled ? "+" : "-";
62  Prefix += Feature;
63  return Prefix;
64}
65
66/// Split - Splits a string of comma separated items in to a vector of strings.
67///
68static void Split(std::vector<std::string> &V, const StringRef S) {
69  if (S.empty())
70    return;
71
72  // Start at beginning of string.
73  size_t Pos = 0;
74  while (true) {
75    // Find the next comma
76    size_t Comma = S.find(',', Pos);
77    // If no comma found then the rest of the string is used
78    if (Comma == std::string::npos) {
79      // Add string to vector
80      V.push_back(S.substr(Pos));
81      break;
82    }
83    // Otherwise add substring to vector
84    V.push_back(S.substr(Pos, Comma - Pos));
85    // Advance to next item
86    Pos = Comma + 1;
87  }
88}
89
90/// Join a vector of strings to a string with a comma separating each element.
91///
92static std::string Join(const std::vector<std::string> &V) {
93  // Start with empty string.
94  std::string Result;
95  // If the vector is not empty
96  if (!V.empty()) {
97    // Start with the first feature
98    Result = V[0];
99    // For each successive feature
100    for (size_t i = 1; i < V.size(); i++) {
101      // Add a comma
102      Result += ",";
103      // Add the feature
104      Result += V[i];
105    }
106  }
107  // Return the features string
108  return Result;
109}
110
111/// Adding features.
112void SubtargetFeatures::AddFeature(const StringRef String,
113                                   bool IsEnabled) {
114  // Don't add empty features
115  if (!String.empty()) {
116    // Convert to lowercase, prepend flag and add to vector
117    Features.push_back(PrependFlag(String.lower(), IsEnabled));
118  }
119}
120
121/// Find KV in array using binary search.
122template<typename T> const T *Find(const StringRef S, const T *A, size_t L) {
123  // Make the lower bound element we're looking for
124  T KV;
125  KV.Key = S.data();
126  // Determine the end of the array
127  const T *Hi = A + L;
128  // Binary search the array
129  const T *F = std::lower_bound(A, Hi, KV);
130  // If not found then return NULL
131  if (F == Hi || StringRef(F->Key) != S) return NULL;
132  // Return the found array item
133  return F;
134}
135
136/// getLongestEntryLength - Return the length of the longest entry in the table.
137///
138static size_t getLongestEntryLength(const SubtargetFeatureKV *Table,
139                                    size_t Size) {
140  size_t MaxLen = 0;
141  for (size_t i = 0; i < Size; i++)
142    MaxLen = std::max(MaxLen, std::strlen(Table[i].Key));
143  return MaxLen;
144}
145
146/// Display help for feature choices.
147///
148static void Help(const SubtargetFeatureKV *CPUTable, size_t CPUTableSize,
149                 const SubtargetFeatureKV *FeatTable, size_t FeatTableSize) {
150  // Determine the length of the longest CPU and Feature entries.
151  unsigned MaxCPULen  = getLongestEntryLength(CPUTable, CPUTableSize);
152  unsigned MaxFeatLen = getLongestEntryLength(FeatTable, FeatTableSize);
153
154  // Print the CPU table.
155  errs() << "Available CPUs for this target:\n\n";
156  for (size_t i = 0; i != CPUTableSize; i++)
157    errs() << format("  %-*s - %s.\n",
158                     MaxCPULen, CPUTable[i].Key, CPUTable[i].Desc);
159  errs() << '\n';
160
161  // Print the Feature table.
162  errs() << "Available features for this target:\n\n";
163  for (size_t i = 0; i != FeatTableSize; i++)
164    errs() << format("  %-*s - %s.\n",
165                     MaxFeatLen, FeatTable[i].Key, FeatTable[i].Desc);
166  errs() << '\n';
167
168  errs() << "Use +feature to enable a feature, or -feature to disable it.\n"
169            "For example, llc -mcpu=mycpu -mattr=+feature1,-feature2\n";
170  std::exit(1);
171}
172
173//===----------------------------------------------------------------------===//
174//                    SubtargetFeatures Implementation
175//===----------------------------------------------------------------------===//
176
177SubtargetFeatures::SubtargetFeatures(const StringRef Initial) {
178  // Break up string into separate features
179  Split(Features, Initial);
180}
181
182
183std::string SubtargetFeatures::getString() const {
184  return Join(Features);
185}
186
187/// SetImpliedBits - For each feature that is (transitively) implied by this
188/// feature, set it.
189///
190static
191void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
192                    const SubtargetFeatureKV *FeatureTable,
193                    size_t FeatureTableSize) {
194  for (size_t i = 0; i < FeatureTableSize; ++i) {
195    const SubtargetFeatureKV &FE = FeatureTable[i];
196
197    if (FeatureEntry->Value == FE.Value) continue;
198
199    if (FeatureEntry->Implies & FE.Value) {
200      Bits |= FE.Value;
201      SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
202    }
203  }
204}
205
206/// ClearImpliedBits - For each feature that (transitively) implies this
207/// feature, clear it.
208///
209static
210void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
211                      const SubtargetFeatureKV *FeatureTable,
212                      size_t FeatureTableSize) {
213  for (size_t i = 0; i < FeatureTableSize; ++i) {
214    const SubtargetFeatureKV &FE = FeatureTable[i];
215
216    if (FeatureEntry->Value == FE.Value) continue;
217
218    if (FE.Implies & FeatureEntry->Value) {
219      Bits &= ~FE.Value;
220      ClearImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
221    }
222  }
223}
224
225/// ToggleFeature - Toggle a feature and returns the newly updated feature
226/// bits.
227uint64_t
228SubtargetFeatures::ToggleFeature(uint64_t Bits, const StringRef Feature,
229                                 const SubtargetFeatureKV *FeatureTable,
230                                 size_t FeatureTableSize) {
231  // Find feature in table.
232  const SubtargetFeatureKV *FeatureEntry =
233    Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
234  // If there is a match
235  if (FeatureEntry) {
236    if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
237      Bits &= ~FeatureEntry->Value;
238
239      // For each feature that implies this, clear it.
240      ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
241    } else {
242      Bits |=  FeatureEntry->Value;
243
244      // For each feature that this implies, set it.
245      SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
246    }
247  } else {
248    errs() << "'" << Feature
249           << "' is not a recognized feature for this target"
250           << " (ignoring feature)\n";
251  }
252
253  return Bits;
254}
255
256
257/// getFeatureBits - Get feature bits a CPU.
258///
259uint64_t SubtargetFeatures::getFeatureBits(const StringRef CPU,
260                                         const SubtargetFeatureKV *CPUTable,
261                                         size_t CPUTableSize,
262                                         const SubtargetFeatureKV *FeatureTable,
263                                         size_t FeatureTableSize) {
264  if (!FeatureTableSize || !CPUTableSize)
265    return 0;
266
267#ifndef NDEBUG
268  for (size_t i = 1; i < CPUTableSize; i++) {
269    assert(strcmp(CPUTable[i - 1].Key, CPUTable[i].Key) < 0 &&
270           "CPU table is not sorted");
271  }
272  for (size_t i = 1; i < FeatureTableSize; i++) {
273    assert(strcmp(FeatureTable[i - 1].Key, FeatureTable[i].Key) < 0 &&
274          "CPU features table is not sorted");
275  }
276#endif
277  uint64_t Bits = 0;                    // Resulting bits
278
279  // Check if help is needed
280  if (CPU == "help")
281    Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
282
283  // Find CPU entry if CPU name is specified.
284  if (!CPU.empty()) {
285    const SubtargetFeatureKV *CPUEntry = Find(CPU, CPUTable, CPUTableSize);
286    // If there is a match
287    if (CPUEntry) {
288      // Set base feature bits
289      Bits = CPUEntry->Value;
290
291      // Set the feature implied by this CPU feature, if any.
292      for (size_t i = 0; i < FeatureTableSize; ++i) {
293        const SubtargetFeatureKV &FE = FeatureTable[i];
294        if (CPUEntry->Value & FE.Value)
295          SetImpliedBits(Bits, &FE, FeatureTable, FeatureTableSize);
296      }
297    } else {
298      errs() << "'" << CPU
299             << "' is not a recognized processor for this target"
300             << " (ignoring processor)\n";
301    }
302  }
303
304  // Iterate through each feature
305  for (size_t i = 0, E = Features.size(); i < E; i++) {
306    const StringRef Feature = Features[i];
307
308    // Check for help
309    if (Feature == "+help")
310      Help(CPUTable, CPUTableSize, FeatureTable, FeatureTableSize);
311
312    // Find feature in table.
313    const SubtargetFeatureKV *FeatureEntry =
314                       Find(StripFlag(Feature), FeatureTable, FeatureTableSize);
315    // If there is a match
316    if (FeatureEntry) {
317      // Enable/disable feature in bits
318      if (isEnabled(Feature)) {
319        Bits |=  FeatureEntry->Value;
320
321        // For each feature that this implies, set it.
322        SetImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
323      } else {
324        Bits &= ~FeatureEntry->Value;
325
326        // For each feature that implies this, clear it.
327        ClearImpliedBits(Bits, FeatureEntry, FeatureTable, FeatureTableSize);
328      }
329    } else {
330      errs() << "'" << Feature
331             << "' is not a recognized feature for this target"
332             << " (ignoring feature)\n";
333    }
334  }
335
336  return Bits;
337}
338
339/// Get scheduling itinerary of a CPU.
340const void *SubtargetFeatures::getItinerary(const StringRef CPU,
341                                            const SubtargetInfoKV *Table,
342                                            size_t TableSize) {
343  assert(Table && "missing table");
344#ifndef NDEBUG
345  for (size_t i = 1; i < TableSize; i++) {
346    assert(strcmp(Table[i - 1].Key, Table[i].Key) < 0 && "Table is not sorted");
347  }
348#endif
349
350  // Find entry
351  const SubtargetInfoKV *Entry = Find(CPU, Table, TableSize);
352
353  if (Entry) {
354    return Entry->Value;
355  } else {
356    errs() << "'" << CPU
357           << "' is not a recognized processor for this target"
358           << " (ignoring processor)\n";
359    return NULL;
360  }
361}
362
363/// print - Print feature string.
364///
365void SubtargetFeatures::print(raw_ostream &OS) const {
366  for (size_t i = 0, e = Features.size(); i != e; ++i)
367    OS << Features[i] << "  ";
368  OS << "\n";
369}
370
371#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
372/// dump - Dump feature info.
373///
374void SubtargetFeatures::dump() const {
375  print(dbgs());
376}
377#endif
378
379/// getDefaultSubtargetFeatures - Return a string listing the features
380/// associated with the target triple.
381///
382/// FIXME: This is an inelegant way of specifying the features of a
383/// subtarget. It would be better if we could encode this information
384/// into the IR. See <rdar://5972456>.
385///
386void SubtargetFeatures::getDefaultSubtargetFeatures(const Triple& Triple) {
387  if (Triple.getVendor() == Triple::Apple) {
388    if (Triple.getArch() == Triple::ppc) {
389      // powerpc-apple-*
390      AddFeature("altivec");
391    } else if (Triple.getArch() == Triple::ppc64) {
392      // powerpc64-apple-*
393      AddFeature("64bit");
394      AddFeature("altivec");
395    }
396  }
397}
398