1 //===- OMPContext.cpp ------ Collection of helpers for OpenMP contexts ----===//
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 /// \file
9 ///
10 /// This file implements helper functions and classes to deal with OpenMP
11 /// contexts as used by `[begin/end] declare variant` and `metadirective`.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #include "llvm/Frontend/OpenMP/OMPContext.h"
16 #include "llvm/ADT/StringRef.h"
17 #include "llvm/ADT/StringSwitch.h"
18 #include "llvm/ADT/Triple.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/raw_ostream.h"
21 
22 #define DEBUG_TYPE "openmp-ir-builder"
23 
24 using namespace llvm;
25 using namespace omp;
26 
27 OMPContext::OMPContext(bool IsDeviceCompilation, Triple TargetTriple) {
28   // Add the appropriate device kind trait based on the triple and the
29   // IsDeviceCompilation flag.
30   ActiveTraits.set(unsigned(IsDeviceCompilation
31                                 ? TraitProperty::device_kind_nohost
32                                 : TraitProperty::device_kind_host));
33   switch (TargetTriple.getArch()) {
34   case Triple::arm:
35   case Triple::armeb:
36   case Triple::aarch64:
37   case Triple::aarch64_be:
38   case Triple::aarch64_32:
39   case Triple::mips:
40   case Triple::mipsel:
41   case Triple::mips64:
42   case Triple::mips64el:
43   case Triple::ppc:
44   case Triple::ppcle:
45   case Triple::ppc64:
46   case Triple::ppc64le:
47   case Triple::x86:
48   case Triple::x86_64:
49     ActiveTraits.set(unsigned(TraitProperty::device_kind_cpu));
50     break;
51   case Triple::amdgcn:
52   case Triple::nvptx:
53   case Triple::nvptx64:
54     ActiveTraits.set(unsigned(TraitProperty::device_kind_gpu));
55     break;
56   default:
57     break;
58   }
59 
60   // Add the appropriate device architecture trait based on the triple.
61 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
62   if (TraitSelector::TraitSelectorEnum == TraitSelector::device_arch) {        \
63     if (TargetTriple.getArch() == TargetTriple.getArchTypeForLLVMName(Str))    \
64       ActiveTraits.set(unsigned(TraitProperty::Enum));                         \
65     if (StringRef(Str) == StringRef("x86_64") &&                               \
66         TargetTriple.getArch() == Triple::x86_64)                              \
67       ActiveTraits.set(unsigned(TraitProperty::Enum));                         \
68   }
69 #include "llvm/Frontend/OpenMP/OMPKinds.def"
70 
71   // TODO: What exactly do we want to see as device ISA trait?
72   //       The discussion on the list did not seem to have come to an agreed
73   //       upon solution.
74 
75   // LLVM is the "OpenMP vendor" but we could also interpret vendor as the
76   // target vendor.
77   ActiveTraits.set(unsigned(TraitProperty::implementation_vendor_llvm));
78 
79   // The user condition true is accepted but not false.
80   ActiveTraits.set(unsigned(TraitProperty::user_condition_true));
81 
82   // This is for sure some device.
83   ActiveTraits.set(unsigned(TraitProperty::device_kind_any));
84 
85   LLVM_DEBUG({
86     dbgs() << "[" << DEBUG_TYPE
87            << "] New OpenMP context with the following properties:\n";
88     for (unsigned Bit : ActiveTraits.set_bits()) {
89       TraitProperty Property = TraitProperty(Bit);
90       dbgs() << "\t " << getOpenMPContextTraitPropertyFullName(Property)
91              << "\n";
92     }
93   });
94 }
95 
96 /// Return true if \p C0 is a subset of \p C1. Note that both arrays are
97 /// expected to be sorted.
98 template <typename T> static bool isSubset(ArrayRef<T> C0, ArrayRef<T> C1) {
99 #ifdef EXPENSIVE_CHECKS
100   assert(llvm::is_sorted(C0) && llvm::is_sorted(C1) &&
101          "Expected sorted arrays!");
102 #endif
103   if (C0.size() > C1.size())
104     return false;
105   auto It0 = C0.begin(), End0 = C0.end();
106   auto It1 = C1.begin(), End1 = C1.end();
107   while (It0 != End0) {
108     if (It1 == End1)
109       return false;
110     if (*It0 == *It1) {
111       ++It0;
112       ++It1;
113       continue;
114     }
115     ++It0;
116   }
117   return true;
118 }
119 
120 /// Return true if \p C0 is a strict subset of \p C1. Note that both arrays are
121 /// expected to be sorted.
122 template <typename T>
123 static bool isStrictSubset(ArrayRef<T> C0, ArrayRef<T> C1) {
124   if (C0.size() >= C1.size())
125     return false;
126   return isSubset<T>(C0, C1);
127 }
128 
129 static bool isStrictSubset(const VariantMatchInfo &VMI0,
130                            const VariantMatchInfo &VMI1) {
131   // If all required traits are a strict subset and the ordered vectors storing
132   // the construct traits, we say it is a strict subset. Note that the latter
133   // relation is not required to be strict.
134   if (VMI0.RequiredTraits.count() >= VMI1.RequiredTraits.count())
135     return false;
136   for (unsigned Bit : VMI0.RequiredTraits.set_bits())
137     if (!VMI1.RequiredTraits.test(Bit))
138       return false;
139   if (!isSubset<TraitProperty>(VMI0.ConstructTraits, VMI1.ConstructTraits))
140     return false;
141   return true;
142 }
143 
144 static int isVariantApplicableInContextHelper(
145     const VariantMatchInfo &VMI, const OMPContext &Ctx,
146     SmallVectorImpl<unsigned> *ConstructMatches, bool DeviceSetOnly) {
147 
148   // The match kind determines if we need to match all traits, any of the
149   // traits, or none of the traits for it to be an applicable context.
150   enum MatchKind { MK_ALL, MK_ANY, MK_NONE };
151 
152   MatchKind MK = MK_ALL;
153   // Determine the match kind the user wants, "all" is the default and provided
154   // to the user only for completeness.
155   if (VMI.RequiredTraits.test(
156           unsigned(TraitProperty::implementation_extension_match_any)))
157     MK = MK_ANY;
158   if (VMI.RequiredTraits.test(
159           unsigned(TraitProperty::implementation_extension_match_none)))
160     MK = MK_NONE;
161 
162   // Helper to deal with a single property that was (not) found in the OpenMP
163   // context based on the match kind selected by the user via
164   // `implementation={extensions(match_[all,any,none])}'
165   auto HandleTrait = [MK](TraitProperty Property,
166                           bool WasFound) -> Optional<bool> /* Result */ {
167     // For kind "any" a single match is enough but we ignore non-matched
168     // properties.
169     if (MK == MK_ANY) {
170       if (WasFound)
171         return true;
172       return None;
173     }
174 
175     // In "all" or "none" mode we accept a matching or non-matching property
176     // respectively and move on. We are not done yet!
177     if ((WasFound && MK == MK_ALL) || (!WasFound && MK == MK_NONE))
178       return None;
179 
180     // We missed a property, provide some debug output and indicate failure.
181     LLVM_DEBUG({
182       if (MK == MK_ALL)
183         dbgs() << "[" << DEBUG_TYPE << "] Property "
184                << getOpenMPContextTraitPropertyName(Property, "")
185                << " was not in the OpenMP context but match kind is all.\n";
186       if (MK == MK_NONE)
187         dbgs() << "[" << DEBUG_TYPE << "] Property "
188                << getOpenMPContextTraitPropertyName(Property, "")
189                << " was in the OpenMP context but match kind is none.\n";
190     });
191     return false;
192   };
193 
194   for (unsigned Bit : VMI.RequiredTraits.set_bits()) {
195     TraitProperty Property = TraitProperty(Bit);
196     if (DeviceSetOnly &&
197         getOpenMPContextTraitSetForProperty(Property) != TraitSet::device)
198       continue;
199 
200     // So far all extensions are handled elsewhere, we skip them here as they
201     // are not part of the OpenMP context.
202     if (getOpenMPContextTraitSelectorForProperty(Property) ==
203         TraitSelector::implementation_extension)
204       continue;
205 
206     bool IsActiveTrait = Ctx.ActiveTraits.test(unsigned(Property));
207 
208     // We overwrite the isa trait as it is actually up to the OMPContext hook to
209     // check the raw string(s).
210     if (Property == TraitProperty::device_isa___ANY)
211       IsActiveTrait = llvm::all_of(VMI.ISATraits, [&](StringRef RawString) {
212         return Ctx.matchesISATrait(RawString);
213       });
214 
215     Optional<bool> Result = HandleTrait(Property, IsActiveTrait);
216     if (Result)
217       return Result.getValue();
218   }
219 
220   if (!DeviceSetOnly) {
221     // We could use isSubset here but we also want to record the match
222     // locations.
223     unsigned ConstructIdx = 0, NoConstructTraits = Ctx.ConstructTraits.size();
224     for (TraitProperty Property : VMI.ConstructTraits) {
225       assert(getOpenMPContextTraitSetForProperty(Property) ==
226                  TraitSet::construct &&
227              "Variant context is ill-formed!");
228 
229       // Verify the nesting.
230       bool FoundInOrder = false;
231       while (!FoundInOrder && ConstructIdx != NoConstructTraits)
232         FoundInOrder = (Ctx.ConstructTraits[ConstructIdx++] == Property);
233       if (ConstructMatches)
234         ConstructMatches->push_back(ConstructIdx - 1);
235 
236       Optional<bool> Result = HandleTrait(Property, FoundInOrder);
237       if (Result)
238         return Result.getValue();
239 
240       if (!FoundInOrder) {
241         LLVM_DEBUG(dbgs() << "[" << DEBUG_TYPE << "] Construct property "
242                           << getOpenMPContextTraitPropertyName(Property, "")
243                           << " was not nested properly.\n");
244         return false;
245       }
246 
247       // TODO: Verify SIMD
248     }
249 
250     assert(isSubset<TraitProperty>(VMI.ConstructTraits, Ctx.ConstructTraits) &&
251            "Broken invariant!");
252   }
253 
254   if (MK == MK_ANY) {
255     LLVM_DEBUG(dbgs() << "[" << DEBUG_TYPE
256                       << "] None of the properties was in the OpenMP context "
257                          "but match kind is any.\n");
258     return false;
259   }
260 
261   return true;
262 }
263 
264 bool llvm::omp::isVariantApplicableInContext(const VariantMatchInfo &VMI,
265                                              const OMPContext &Ctx,
266                                              bool DeviceSetOnly) {
267   return isVariantApplicableInContextHelper(
268       VMI, Ctx, /* ConstructMatches */ nullptr, DeviceSetOnly);
269 }
270 
271 static APInt getVariantMatchScore(const VariantMatchInfo &VMI,
272                                   const OMPContext &Ctx,
273                                   SmallVectorImpl<unsigned> &ConstructMatches) {
274   APInt Score(64, 1);
275 
276   unsigned NoConstructTraits = VMI.ConstructTraits.size();
277   for (unsigned Bit : VMI.RequiredTraits.set_bits()) {
278     TraitProperty Property = TraitProperty(Bit);
279     // If there is a user score attached, use it.
280     if (VMI.ScoreMap.count(Property)) {
281       const APInt &UserScore = VMI.ScoreMap.lookup(Property);
282       assert(UserScore.uge(0) && "Expect non-negative user scores!");
283       Score += UserScore.getZExtValue();
284       continue;
285     }
286 
287     switch (getOpenMPContextTraitSetForProperty(Property)) {
288     case TraitSet::construct:
289       // We handle the construct traits later via the VMI.ConstructTraits
290       // container.
291       continue;
292     case TraitSet::implementation:
293       // No effect on the score (implementation defined).
294       continue;
295     case TraitSet::user:
296       // No effect on the score.
297       continue;
298     case TraitSet::device:
299       // Handled separately below.
300       break;
301     case TraitSet::invalid:
302       llvm_unreachable("Unknown trait set is not to be used!");
303     }
304 
305     // device={kind(any)} is "as if" no kind selector was specified.
306     if (Property == TraitProperty::device_kind_any)
307       continue;
308 
309     switch (getOpenMPContextTraitSelectorForProperty(Property)) {
310     case TraitSelector::device_kind:
311       Score += (1ULL << (NoConstructTraits + 0));
312       continue;
313     case TraitSelector::device_arch:
314       Score += (1ULL << (NoConstructTraits + 1));
315       continue;
316     case TraitSelector::device_isa:
317       Score += (1ULL << (NoConstructTraits + 2));
318       continue;
319     default:
320       continue;
321     }
322   }
323 
324   unsigned ConstructIdx = 0;
325   assert(NoConstructTraits == ConstructMatches.size() &&
326          "Mismatch in the construct traits!");
327   for (TraitProperty Property : VMI.ConstructTraits) {
328     assert(getOpenMPContextTraitSetForProperty(Property) ==
329                TraitSet::construct &&
330            "Ill-formed variant match info!");
331     (void)Property;
332     // ConstructMatches is the position p - 1 and we need 2^(p-1).
333     Score += (1ULL << ConstructMatches[ConstructIdx++]);
334   }
335 
336   LLVM_DEBUG(dbgs() << "[" << DEBUG_TYPE << "] Variant has a score of " << Score
337                     << "\n");
338   return Score;
339 }
340 
341 int llvm::omp::getBestVariantMatchForContext(
342     const SmallVectorImpl<VariantMatchInfo> &VMIs, const OMPContext &Ctx) {
343 
344   APInt BestScore(64, 0);
345   int BestVMIIdx = -1;
346   const VariantMatchInfo *BestVMI = nullptr;
347 
348   for (unsigned u = 0, e = VMIs.size(); u < e; ++u) {
349     const VariantMatchInfo &VMI = VMIs[u];
350 
351     SmallVector<unsigned, 8> ConstructMatches;
352     // If the variant is not applicable its not the best.
353     if (!isVariantApplicableInContextHelper(VMI, Ctx, &ConstructMatches,
354                                             /* DeviceSetOnly */ false))
355       continue;
356     // Check if its clearly not the best.
357     APInt Score = getVariantMatchScore(VMI, Ctx, ConstructMatches);
358     if (Score.ult(BestScore))
359       continue;
360     // Equal score need subset checks.
361     if (Score.eq(BestScore)) {
362       // Strict subset are never best.
363       if (isStrictSubset(VMI, *BestVMI))
364         continue;
365       // Same score and the current best is no strict subset so we keep it.
366       if (!isStrictSubset(*BestVMI, VMI))
367         continue;
368     }
369     // New best found.
370     BestVMI = &VMI;
371     BestVMIIdx = u;
372     BestScore = Score;
373   }
374 
375   return BestVMIIdx;
376 }
377 
378 TraitSet llvm::omp::getOpenMPContextTraitSetKind(StringRef S) {
379   return StringSwitch<TraitSet>(S)
380 #define OMP_TRAIT_SET(Enum, Str) .Case(Str, TraitSet::Enum)
381 #include "llvm/Frontend/OpenMP/OMPKinds.def"
382       .Default(TraitSet::invalid);
383 }
384 
385 TraitSet
386 llvm::omp::getOpenMPContextTraitSetForSelector(TraitSelector Selector) {
387   switch (Selector) {
388 #define OMP_TRAIT_SELECTOR(Enum, TraitSetEnum, Str, ReqProp)                   \
389   case TraitSelector::Enum:                                                    \
390     return TraitSet::TraitSetEnum;
391 #include "llvm/Frontend/OpenMP/OMPKinds.def"
392   }
393   llvm_unreachable("Unknown trait selector!");
394 }
395 TraitSet
396 llvm::omp::getOpenMPContextTraitSetForProperty(TraitProperty Property) {
397   switch (Property) {
398 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
399   case TraitProperty::Enum:                                                    \
400     return TraitSet::TraitSetEnum;
401 #include "llvm/Frontend/OpenMP/OMPKinds.def"
402   }
403   llvm_unreachable("Unknown trait set!");
404 }
405 StringRef llvm::omp::getOpenMPContextTraitSetName(TraitSet Kind) {
406   switch (Kind) {
407 #define OMP_TRAIT_SET(Enum, Str)                                               \
408   case TraitSet::Enum:                                                         \
409     return Str;
410 #include "llvm/Frontend/OpenMP/OMPKinds.def"
411   }
412   llvm_unreachable("Unknown trait set!");
413 }
414 
415 TraitSelector llvm::omp::getOpenMPContextTraitSelectorKind(StringRef S) {
416   return StringSwitch<TraitSelector>(S)
417 #define OMP_TRAIT_SELECTOR(Enum, TraitSetEnum, Str, ReqProp)                   \
418   .Case(Str, TraitSelector::Enum)
419 #include "llvm/Frontend/OpenMP/OMPKinds.def"
420       .Default(TraitSelector::invalid);
421 }
422 TraitSelector
423 llvm::omp::getOpenMPContextTraitSelectorForProperty(TraitProperty Property) {
424   switch (Property) {
425 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
426   case TraitProperty::Enum:                                                    \
427     return TraitSelector::TraitSelectorEnum;
428 #include "llvm/Frontend/OpenMP/OMPKinds.def"
429   }
430   llvm_unreachable("Unknown trait set!");
431 }
432 StringRef llvm::omp::getOpenMPContextTraitSelectorName(TraitSelector Kind) {
433   switch (Kind) {
434 #define OMP_TRAIT_SELECTOR(Enum, TraitSetEnum, Str, ReqProp)                   \
435   case TraitSelector::Enum:                                                    \
436     return Str;
437 #include "llvm/Frontend/OpenMP/OMPKinds.def"
438   }
439   llvm_unreachable("Unknown trait selector!");
440 }
441 
442 TraitProperty llvm::omp::getOpenMPContextTraitPropertyKind(
443     TraitSet Set, TraitSelector Selector, StringRef S) {
444   // Special handling for `device={isa(...)}` as we accept anything here. It is
445   // up to the target to decide if the feature is available.
446   if (Set == TraitSet::device && Selector == TraitSelector::device_isa)
447     return TraitProperty::device_isa___ANY;
448 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
449   if (Set == TraitSet::TraitSetEnum && Str == S)                               \
450     return TraitProperty::Enum;
451 #include "llvm/Frontend/OpenMP/OMPKinds.def"
452   return TraitProperty::invalid;
453 }
454 TraitProperty
455 llvm::omp::getOpenMPContextTraitPropertyForSelector(TraitSelector Selector) {
456   return StringSwitch<TraitProperty>(
457              getOpenMPContextTraitSelectorName(Selector))
458 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
459   .Case(Str, Selector == TraitSelector::TraitSelectorEnum                      \
460                  ? TraitProperty::Enum                                         \
461                  : TraitProperty::invalid)
462 #include "llvm/Frontend/OpenMP/OMPKinds.def"
463       .Default(TraitProperty::invalid);
464 }
465 StringRef llvm::omp::getOpenMPContextTraitPropertyName(TraitProperty Kind,
466                                                        StringRef RawString) {
467   if (Kind == TraitProperty::device_isa___ANY)
468     return RawString;
469   switch (Kind) {
470 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
471   case TraitProperty::Enum:                                                    \
472     return Str;
473 #include "llvm/Frontend/OpenMP/OMPKinds.def"
474   }
475   llvm_unreachable("Unknown trait property!");
476 }
477 StringRef llvm::omp::getOpenMPContextTraitPropertyFullName(TraitProperty Kind) {
478   switch (Kind) {
479 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
480   case TraitProperty::Enum:                                                    \
481     return "(" #TraitSetEnum "," #TraitSelectorEnum "," Str ")";
482 #include "llvm/Frontend/OpenMP/OMPKinds.def"
483   }
484   llvm_unreachable("Unknown trait property!");
485 }
486 
487 bool llvm::omp::isValidTraitSelectorForTraitSet(TraitSelector Selector,
488                                                 TraitSet Set,
489                                                 bool &AllowsTraitScore,
490                                                 bool &RequiresProperty) {
491   AllowsTraitScore = Set != TraitSet::construct && Set != TraitSet::device;
492   switch (Selector) {
493 #define OMP_TRAIT_SELECTOR(Enum, TraitSetEnum, Str, ReqProp)                   \
494   case TraitSelector::Enum:                                                    \
495     RequiresProperty = ReqProp;                                                \
496     return Set == TraitSet::TraitSetEnum;
497 #include "llvm/Frontend/OpenMP/OMPKinds.def"
498   }
499   llvm_unreachable("Unknown trait selector!");
500 }
501 
502 bool llvm::omp::isValidTraitPropertyForTraitSetAndSelector(
503     TraitProperty Property, TraitSelector Selector, TraitSet Set) {
504   switch (Property) {
505 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
506   case TraitProperty::Enum:                                                    \
507     return Set == TraitSet::TraitSetEnum &&                                    \
508            Selector == TraitSelector::TraitSelectorEnum;
509 #include "llvm/Frontend/OpenMP/OMPKinds.def"
510   }
511   llvm_unreachable("Unknown trait property!");
512 }
513 
514 std::string llvm::omp::listOpenMPContextTraitSets() {
515   std::string S;
516 #define OMP_TRAIT_SET(Enum, Str)                                               \
517   if (StringRef(Str) != "invalid")                                             \
518     S.append("'").append(Str).append("'").append(" ");
519 #include "llvm/Frontend/OpenMP/OMPKinds.def"
520   S.pop_back();
521   return S;
522 }
523 
524 std::string llvm::omp::listOpenMPContextTraitSelectors(TraitSet Set) {
525   std::string S;
526 #define OMP_TRAIT_SELECTOR(Enum, TraitSetEnum, Str, ReqProp)                   \
527   if (TraitSet::TraitSetEnum == Set && StringRef(Str) != "Invalid")            \
528     S.append("'").append(Str).append("'").append(" ");
529 #include "llvm/Frontend/OpenMP/OMPKinds.def"
530   S.pop_back();
531   return S;
532 }
533 
534 std::string
535 llvm::omp::listOpenMPContextTraitProperties(TraitSet Set,
536                                             TraitSelector Selector) {
537   std::string S;
538 #define OMP_TRAIT_PROPERTY(Enum, TraitSetEnum, TraitSelectorEnum, Str)         \
539   if (TraitSet::TraitSetEnum == Set &&                                         \
540       TraitSelector::TraitSelectorEnum == Selector &&                          \
541       StringRef(Str) != "invalid")                                             \
542     S.append("'").append(Str).append("'").append(" ");
543 #include "llvm/Frontend/OpenMP/OMPKinds.def"
544   if (S.empty())
545     return "<none>";
546   S.pop_back();
547   return S;
548 }
549