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1 //===--- Quality.cpp ---------------------------------------------*- C++-*-===//
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 
9 #include "Quality.h"
10 #include "AST.h"
11 #include "CompletionModel.h"
12 #include "FileDistance.h"
13 #include "SourceCode.h"
14 #include "URI.h"
15 #include "index/Symbol.h"
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/Decl.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/DeclTemplate.h"
20 #include "clang/AST/DeclVisitor.h"
21 #include "clang/Basic/CharInfo.h"
22 #include "clang/Basic/SourceManager.h"
23 #include "clang/Sema/CodeCompleteConsumer.h"
24 #include "llvm/ADT/ArrayRef.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/StringRef.h"
29 #include "llvm/Support/Casting.h"
30 #include "llvm/Support/FormatVariadic.h"
31 #include "llvm/Support/MathExtras.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include <algorithm>
34 #include <cmath>
35 
36 namespace clang {
37 namespace clangd {
isReserved(llvm::StringRef Name)38 static bool isReserved(llvm::StringRef Name) {
39   // FIXME: Should we exclude _Bool and others recognized by the standard?
40   return Name.size() >= 2 && Name[0] == '_' &&
41          (isUppercase(Name[1]) || Name[1] == '_');
42 }
43 
hasDeclInMainFile(const Decl & D)44 static bool hasDeclInMainFile(const Decl &D) {
45   auto &SourceMgr = D.getASTContext().getSourceManager();
46   for (auto *Redecl : D.redecls()) {
47     if (isInsideMainFile(Redecl->getLocation(), SourceMgr))
48       return true;
49   }
50   return false;
51 }
52 
hasUsingDeclInMainFile(const CodeCompletionResult & R)53 static bool hasUsingDeclInMainFile(const CodeCompletionResult &R) {
54   const auto &Context = R.Declaration->getASTContext();
55   const auto &SourceMgr = Context.getSourceManager();
56   if (R.ShadowDecl) {
57     if (isInsideMainFile(R.ShadowDecl->getLocation(), SourceMgr))
58       return true;
59   }
60   return false;
61 }
62 
categorize(const NamedDecl & ND)63 static SymbolQualitySignals::SymbolCategory categorize(const NamedDecl &ND) {
64   if (const auto *FD = dyn_cast<FunctionDecl>(&ND)) {
65     if (FD->isOverloadedOperator())
66       return SymbolQualitySignals::Operator;
67   }
68   class Switch
69       : public ConstDeclVisitor<Switch, SymbolQualitySignals::SymbolCategory> {
70   public:
71 #define MAP(DeclType, Category)                                                \
72   SymbolQualitySignals::SymbolCategory Visit##DeclType(const DeclType *) {     \
73     return SymbolQualitySignals::Category;                                     \
74   }
75     MAP(NamespaceDecl, Namespace);
76     MAP(NamespaceAliasDecl, Namespace);
77     MAP(TypeDecl, Type);
78     MAP(TypeAliasTemplateDecl, Type);
79     MAP(ClassTemplateDecl, Type);
80     MAP(CXXConstructorDecl, Constructor);
81     MAP(CXXDestructorDecl, Destructor);
82     MAP(ValueDecl, Variable);
83     MAP(VarTemplateDecl, Variable);
84     MAP(FunctionDecl, Function);
85     MAP(FunctionTemplateDecl, Function);
86     MAP(Decl, Unknown);
87 #undef MAP
88   };
89   return Switch().Visit(&ND);
90 }
91 
92 static SymbolQualitySignals::SymbolCategory
categorize(const CodeCompletionResult & R)93 categorize(const CodeCompletionResult &R) {
94   if (R.Declaration)
95     return categorize(*R.Declaration);
96   if (R.Kind == CodeCompletionResult::RK_Macro)
97     return SymbolQualitySignals::Macro;
98   // Everything else is a keyword or a pattern. Patterns are mostly keywords
99   // too, except a few which we recognize by cursor kind.
100   switch (R.CursorKind) {
101   case CXCursor_CXXMethod:
102     return SymbolQualitySignals::Function;
103   case CXCursor_ModuleImportDecl:
104     return SymbolQualitySignals::Namespace;
105   case CXCursor_MacroDefinition:
106     return SymbolQualitySignals::Macro;
107   case CXCursor_TypeRef:
108     return SymbolQualitySignals::Type;
109   case CXCursor_MemberRef:
110     return SymbolQualitySignals::Variable;
111   case CXCursor_Constructor:
112     return SymbolQualitySignals::Constructor;
113   default:
114     return SymbolQualitySignals::Keyword;
115   }
116 }
117 
118 static SymbolQualitySignals::SymbolCategory
categorize(const index::SymbolInfo & D)119 categorize(const index::SymbolInfo &D) {
120   switch (D.Kind) {
121   case index::SymbolKind::Namespace:
122   case index::SymbolKind::NamespaceAlias:
123     return SymbolQualitySignals::Namespace;
124   case index::SymbolKind::Macro:
125     return SymbolQualitySignals::Macro;
126   case index::SymbolKind::Enum:
127   case index::SymbolKind::Struct:
128   case index::SymbolKind::Class:
129   case index::SymbolKind::Protocol:
130   case index::SymbolKind::Extension:
131   case index::SymbolKind::Union:
132   case index::SymbolKind::TypeAlias:
133   case index::SymbolKind::TemplateTypeParm:
134   case index::SymbolKind::TemplateTemplateParm:
135     return SymbolQualitySignals::Type;
136   case index::SymbolKind::Function:
137   case index::SymbolKind::ClassMethod:
138   case index::SymbolKind::InstanceMethod:
139   case index::SymbolKind::StaticMethod:
140   case index::SymbolKind::InstanceProperty:
141   case index::SymbolKind::ClassProperty:
142   case index::SymbolKind::StaticProperty:
143   case index::SymbolKind::ConversionFunction:
144     return SymbolQualitySignals::Function;
145   case index::SymbolKind::Destructor:
146     return SymbolQualitySignals::Destructor;
147   case index::SymbolKind::Constructor:
148     return SymbolQualitySignals::Constructor;
149   case index::SymbolKind::Variable:
150   case index::SymbolKind::Field:
151   case index::SymbolKind::EnumConstant:
152   case index::SymbolKind::Parameter:
153   case index::SymbolKind::NonTypeTemplateParm:
154     return SymbolQualitySignals::Variable;
155   case index::SymbolKind::Using:
156   case index::SymbolKind::Module:
157   case index::SymbolKind::Unknown:
158     return SymbolQualitySignals::Unknown;
159   }
160   llvm_unreachable("Unknown index::SymbolKind");
161 }
162 
isInstanceMember(const NamedDecl * ND)163 static bool isInstanceMember(const NamedDecl *ND) {
164   if (!ND)
165     return false;
166   if (const auto *TP = dyn_cast<FunctionTemplateDecl>(ND))
167     ND = TP->TemplateDecl::getTemplatedDecl();
168   if (const auto *CM = dyn_cast<CXXMethodDecl>(ND))
169     return !CM->isStatic();
170   return isa<FieldDecl>(ND); // Note that static fields are VarDecl.
171 }
172 
isInstanceMember(const index::SymbolInfo & D)173 static bool isInstanceMember(const index::SymbolInfo &D) {
174   switch (D.Kind) {
175   case index::SymbolKind::InstanceMethod:
176   case index::SymbolKind::InstanceProperty:
177   case index::SymbolKind::Field:
178     return true;
179   default:
180     return false;
181   }
182 }
183 
merge(const CodeCompletionResult & SemaCCResult)184 void SymbolQualitySignals::merge(const CodeCompletionResult &SemaCCResult) {
185   Deprecated |= (SemaCCResult.Availability == CXAvailability_Deprecated);
186   Category = categorize(SemaCCResult);
187 
188   if (SemaCCResult.Declaration) {
189     ImplementationDetail |= isImplementationDetail(SemaCCResult.Declaration);
190     if (auto *ID = SemaCCResult.Declaration->getIdentifier())
191       ReservedName = ReservedName || isReserved(ID->getName());
192   } else if (SemaCCResult.Kind == CodeCompletionResult::RK_Macro)
193     ReservedName = ReservedName || isReserved(SemaCCResult.Macro->getName());
194 }
195 
merge(const Symbol & IndexResult)196 void SymbolQualitySignals::merge(const Symbol &IndexResult) {
197   Deprecated |= (IndexResult.Flags & Symbol::Deprecated);
198   ImplementationDetail |= (IndexResult.Flags & Symbol::ImplementationDetail);
199   References = std::max(IndexResult.References, References);
200   Category = categorize(IndexResult.SymInfo);
201   ReservedName = ReservedName || isReserved(IndexResult.Name);
202 }
203 
evaluateHeuristics() const204 float SymbolQualitySignals::evaluateHeuristics() const {
205   float Score = 1;
206 
207   // This avoids a sharp gradient for tail symbols, and also neatly avoids the
208   // question of whether 0 references means a bad symbol or missing data.
209   if (References >= 10) {
210     // Use a sigmoid style boosting function, which flats out nicely for large
211     // numbers (e.g. 2.58 for 1M references).
212     // The following boosting function is equivalent to:
213     //   m = 0.06
214     //   f = 12.0
215     //   boost = f * sigmoid(m * std::log(References)) - 0.5 * f + 0.59
216     // Sample data points: (10, 1.00), (100, 1.41), (1000, 1.82),
217     //                     (10K, 2.21), (100K, 2.58), (1M, 2.94)
218     float S = std::pow(References, -0.06);
219     Score *= 6.0 * (1 - S) / (1 + S) + 0.59;
220   }
221 
222   if (Deprecated)
223     Score *= 0.1f;
224   if (ReservedName)
225     Score *= 0.1f;
226   if (ImplementationDetail)
227     Score *= 0.2f;
228 
229   switch (Category) {
230   case Keyword: // Often relevant, but misses most signals.
231     Score *= 4; // FIXME: important keywords should have specific boosts.
232     break;
233   case Type:
234   case Function:
235   case Variable:
236     Score *= 1.1f;
237     break;
238   case Namespace:
239     Score *= 0.8f;
240     break;
241   case Macro:
242   case Destructor:
243   case Operator:
244     Score *= 0.5f;
245     break;
246   case Constructor: // No boost constructors so they are after class types.
247   case Unknown:
248     break;
249   }
250 
251   return Score;
252 }
253 
operator <<(llvm::raw_ostream & OS,const SymbolQualitySignals & S)254 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
255                               const SymbolQualitySignals &S) {
256   OS << llvm::formatv("=== Symbol quality: {0}\n", S.evaluateHeuristics());
257   OS << llvm::formatv("\tReferences: {0}\n", S.References);
258   OS << llvm::formatv("\tDeprecated: {0}\n", S.Deprecated);
259   OS << llvm::formatv("\tReserved name: {0}\n", S.ReservedName);
260   OS << llvm::formatv("\tImplementation detail: {0}\n", S.ImplementationDetail);
261   OS << llvm::formatv("\tCategory: {0}\n", static_cast<int>(S.Category));
262   return OS;
263 }
264 
265 static SymbolRelevanceSignals::AccessibleScope
computeScope(const NamedDecl * D)266 computeScope(const NamedDecl *D) {
267   // Injected "Foo" within the class "Foo" has file scope, not class scope.
268   const DeclContext *DC = D->getDeclContext();
269   if (auto *R = dyn_cast_or_null<RecordDecl>(D))
270     if (R->isInjectedClassName())
271       DC = DC->getParent();
272   // Class constructor should have the same scope as the class.
273   if (isa<CXXConstructorDecl>(D))
274     DC = DC->getParent();
275   bool InClass = false;
276   for (; !DC->isFileContext(); DC = DC->getParent()) {
277     if (DC->isFunctionOrMethod())
278       return SymbolRelevanceSignals::FunctionScope;
279     InClass = InClass || DC->isRecord();
280   }
281   if (InClass)
282     return SymbolRelevanceSignals::ClassScope;
283   // ExternalLinkage threshold could be tweaked, e.g. module-visible as global.
284   // Avoid caching linkage if it may change after enclosing code completion.
285   if (hasUnstableLinkage(D) || D->getLinkageInternal() < ExternalLinkage)
286     return SymbolRelevanceSignals::FileScope;
287   return SymbolRelevanceSignals::GlobalScope;
288 }
289 
merge(const Symbol & IndexResult)290 void SymbolRelevanceSignals::merge(const Symbol &IndexResult) {
291   SymbolURI = IndexResult.CanonicalDeclaration.FileURI;
292   SymbolScope = IndexResult.Scope;
293   IsInstanceMember |= isInstanceMember(IndexResult.SymInfo);
294   if (!(IndexResult.Flags & Symbol::VisibleOutsideFile)) {
295     Scope = AccessibleScope::FileScope;
296   }
297 }
298 
merge(const CodeCompletionResult & SemaCCResult)299 void SymbolRelevanceSignals::merge(const CodeCompletionResult &SemaCCResult) {
300   if (SemaCCResult.Availability == CXAvailability_NotAvailable ||
301       SemaCCResult.Availability == CXAvailability_NotAccessible)
302     Forbidden = true;
303 
304   if (SemaCCResult.Declaration) {
305     SemaSaysInScope = true;
306     // We boost things that have decls in the main file. We give a fixed score
307     // for all other declarations in sema as they are already included in the
308     // translation unit.
309     float DeclProximity = (hasDeclInMainFile(*SemaCCResult.Declaration) ||
310                            hasUsingDeclInMainFile(SemaCCResult))
311                               ? 1.0
312                               : 0.6;
313     SemaFileProximityScore = std::max(DeclProximity, SemaFileProximityScore);
314     IsInstanceMember |= isInstanceMember(SemaCCResult.Declaration);
315     InBaseClass |= SemaCCResult.InBaseClass;
316   }
317 
318   // Declarations are scoped, others (like macros) are assumed global.
319   if (SemaCCResult.Declaration)
320     Scope = std::min(Scope, computeScope(SemaCCResult.Declaration));
321 
322   NeedsFixIts = !SemaCCResult.FixIts.empty();
323 }
324 
fileProximityScore(unsigned FileDistance)325 static float fileProximityScore(unsigned FileDistance) {
326   // Range: [0, 1]
327   // FileDistance = [0, 1, 2, 3, 4, .., FileDistance::Unreachable]
328   // Score = [1, 0.82, 0.67, 0.55, 0.45, .., 0]
329   if (FileDistance == FileDistance::Unreachable)
330     return 0;
331   // Assume approximately default options are used for sensible scoring.
332   return std::exp(FileDistance * -0.4f / FileDistanceOptions().UpCost);
333 }
334 
scopeProximityScore(unsigned ScopeDistance)335 static float scopeProximityScore(unsigned ScopeDistance) {
336   // Range: [0.6, 2].
337   // ScopeDistance = [0, 1, 2, 3, 4, 5, 6, 7, .., FileDistance::Unreachable]
338   // Score = [2.0, 1.55, 1.2, 0.93, 0.72, 0.65, 0.65, 0.65, .., 0.6]
339   if (ScopeDistance == FileDistance::Unreachable)
340     return 0.6f;
341   return std::max(0.65, 2.0 * std::pow(0.6, ScopeDistance / 2.0));
342 }
343 
344 static llvm::Optional<llvm::StringRef>
wordMatching(llvm::StringRef Name,const llvm::StringSet<> * ContextWords)345 wordMatching(llvm::StringRef Name, const llvm::StringSet<> *ContextWords) {
346   if (ContextWords)
347     for (const auto &Word : ContextWords->keys())
348       if (Name.contains_lower(Word))
349         return Word;
350   return llvm::None;
351 }
352 
353 SymbolRelevanceSignals::DerivedSignals
calculateDerivedSignals() const354 SymbolRelevanceSignals::calculateDerivedSignals() const {
355   DerivedSignals Derived;
356   Derived.NameMatchesContext = wordMatching(Name, ContextWords).hasValue();
357   Derived.FileProximityDistance = !FileProximityMatch || SymbolURI.empty()
358                                       ? FileDistance::Unreachable
359                                       : FileProximityMatch->distance(SymbolURI);
360   if (ScopeProximityMatch) {
361     // For global symbol, the distance is 0.
362     Derived.ScopeProximityDistance =
363         SymbolScope ? ScopeProximityMatch->distance(*SymbolScope) : 0;
364   }
365   return Derived;
366 }
367 
evaluateHeuristics() const368 float SymbolRelevanceSignals::evaluateHeuristics() const {
369   DerivedSignals Derived = calculateDerivedSignals();
370   float Score = 1;
371 
372   if (Forbidden)
373     return 0;
374 
375   Score *= NameMatch;
376 
377   // File proximity scores are [0,1] and we translate them into a multiplier in
378   // the range from 1 to 3.
379   Score *= 1 + 2 * std::max(fileProximityScore(Derived.FileProximityDistance),
380                             SemaFileProximityScore);
381 
382   if (ScopeProximityMatch)
383     // Use a constant scope boost for sema results, as scopes of sema results
384     // can be tricky (e.g. class/function scope). Set to the max boost as we
385     // don't load top-level symbols from the preamble and sema results are
386     // always in the accessible scope.
387     Score *= SemaSaysInScope
388                  ? 2.0
389                  : scopeProximityScore(Derived.ScopeProximityDistance);
390 
391   if (Derived.NameMatchesContext)
392     Score *= 1.5;
393 
394   // Symbols like local variables may only be referenced within their scope.
395   // Conversely if we're in that scope, it's likely we'll reference them.
396   if (Query == CodeComplete) {
397     // The narrower the scope where a symbol is visible, the more likely it is
398     // to be relevant when it is available.
399     switch (Scope) {
400     case GlobalScope:
401       break;
402     case FileScope:
403       Score *= 1.5f;
404       break;
405     case ClassScope:
406       Score *= 2;
407       break;
408     case FunctionScope:
409       Score *= 4;
410       break;
411     }
412   } else {
413     // For non-completion queries, the wider the scope where a symbol is
414     // visible, the more likely it is to be relevant.
415     switch (Scope) {
416     case GlobalScope:
417       break;
418     case FileScope:
419       Score *= 0.5f;
420       break;
421     default:
422       // TODO: Handle other scopes as we start to use them for index results.
423       break;
424     }
425   }
426 
427   if (TypeMatchesPreferred)
428     Score *= 5.0;
429 
430   // Penalize non-instance members when they are accessed via a class instance.
431   if (!IsInstanceMember &&
432       (Context == CodeCompletionContext::CCC_DotMemberAccess ||
433        Context == CodeCompletionContext::CCC_ArrowMemberAccess)) {
434     Score *= 0.2f;
435   }
436 
437   if (InBaseClass)
438     Score *= 0.5f;
439 
440   // Penalize for FixIts.
441   if (NeedsFixIts)
442     Score *= 0.5f;
443 
444   return Score;
445 }
446 
operator <<(llvm::raw_ostream & OS,const SymbolRelevanceSignals & S)447 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
448                               const SymbolRelevanceSignals &S) {
449   OS << llvm::formatv("=== Symbol relevance: {0}\n", S.evaluateHeuristics());
450   OS << llvm::formatv("\tName: {0}\n", S.Name);
451   OS << llvm::formatv("\tName match: {0}\n", S.NameMatch);
452   if (S.ContextWords)
453     OS << llvm::formatv(
454         "\tMatching context word: {0}\n",
455         wordMatching(S.Name, S.ContextWords).getValueOr("<none>"));
456   OS << llvm::formatv("\tForbidden: {0}\n", S.Forbidden);
457   OS << llvm::formatv("\tNeedsFixIts: {0}\n", S.NeedsFixIts);
458   OS << llvm::formatv("\tIsInstanceMember: {0}\n", S.IsInstanceMember);
459   OS << llvm::formatv("\tInBaseClass: {0}\n", S.InBaseClass);
460   OS << llvm::formatv("\tContext: {0}\n", getCompletionKindString(S.Context));
461   OS << llvm::formatv("\tQuery type: {0}\n", static_cast<int>(S.Query));
462   OS << llvm::formatv("\tScope: {0}\n", static_cast<int>(S.Scope));
463 
464   OS << llvm::formatv("\tSymbol URI: {0}\n", S.SymbolURI);
465   OS << llvm::formatv("\tSymbol scope: {0}\n",
466                       S.SymbolScope ? *S.SymbolScope : "<None>");
467 
468   SymbolRelevanceSignals::DerivedSignals Derived = S.calculateDerivedSignals();
469   if (S.FileProximityMatch) {
470     unsigned Score = fileProximityScore(Derived.FileProximityDistance);
471     OS << llvm::formatv("\tIndex URI proximity: {0} (distance={1})\n", Score,
472                         Derived.FileProximityDistance);
473   }
474   OS << llvm::formatv("\tSema file proximity: {0}\n", S.SemaFileProximityScore);
475 
476   OS << llvm::formatv("\tSema says in scope: {0}\n", S.SemaSaysInScope);
477   if (S.ScopeProximityMatch)
478     OS << llvm::formatv("\tIndex scope boost: {0}\n",
479                         scopeProximityScore(Derived.ScopeProximityDistance));
480 
481   OS << llvm::formatv(
482       "\tType matched preferred: {0} (Context type: {1}, Symbol type: {2}\n",
483       S.TypeMatchesPreferred, S.HadContextType, S.HadSymbolType);
484 
485   return OS;
486 }
487 
evaluateSymbolAndRelevance(float SymbolQuality,float SymbolRelevance)488 float evaluateSymbolAndRelevance(float SymbolQuality, float SymbolRelevance) {
489   return SymbolQuality * SymbolRelevance;
490 }
491 
492 DecisionForestScores
evaluateDecisionForest(const SymbolQualitySignals & Quality,const SymbolRelevanceSignals & Relevance,float Base)493 evaluateDecisionForest(const SymbolQualitySignals &Quality,
494                        const SymbolRelevanceSignals &Relevance, float Base) {
495   Example E;
496   E.setIsDeprecated(Quality.Deprecated);
497   E.setIsReservedName(Quality.ReservedName);
498   E.setIsImplementationDetail(Quality.ImplementationDetail);
499   E.setNumReferences(Quality.References);
500   E.setSymbolCategory(Quality.Category);
501 
502   SymbolRelevanceSignals::DerivedSignals Derived =
503       Relevance.calculateDerivedSignals();
504   E.setIsNameInContext(Derived.NameMatchesContext);
505   E.setIsForbidden(Relevance.Forbidden);
506   E.setIsInBaseClass(Relevance.InBaseClass);
507   E.setFileProximityDistance(Derived.FileProximityDistance);
508   E.setSemaFileProximityScore(Relevance.SemaFileProximityScore);
509   E.setSymbolScopeDistance(Derived.ScopeProximityDistance);
510   E.setSemaSaysInScope(Relevance.SemaSaysInScope);
511   E.setScope(Relevance.Scope);
512   E.setContextKind(Relevance.Context);
513   E.setIsInstanceMember(Relevance.IsInstanceMember);
514   E.setHadContextType(Relevance.HadContextType);
515   E.setHadSymbolType(Relevance.HadSymbolType);
516   E.setTypeMatchesPreferred(Relevance.TypeMatchesPreferred);
517   E.setFilterLength(Relevance.FilterLength);
518 
519   DecisionForestScores Scores;
520   // Exponentiating DecisionForest prediction makes the score of each tree a
521   // multiplciative boost (like NameMatch). This allows us to weigh the
522   // prediciton score and NameMatch appropriately.
523   Scores.ExcludingName = pow(Base, Evaluate(E));
524   // NeedsFixIts is not part of the DecisionForest as generating training
525   // data that needs fixits is not-feasible.
526   if (Relevance.NeedsFixIts)
527     Scores.ExcludingName *= 0.5;
528   // NameMatch should be a multiplier on total score to support rescoring.
529   Scores.Total = Relevance.NameMatch * Scores.ExcludingName;
530   return Scores;
531 }
532 
533 // Produces an integer that sorts in the same order as F.
534 // That is: a < b <==> encodeFloat(a) < encodeFloat(b).
encodeFloat(float F)535 static uint32_t encodeFloat(float F) {
536   static_assert(std::numeric_limits<float>::is_iec559, "");
537   constexpr uint32_t TopBit = ~(~uint32_t{0} >> 1);
538 
539   // Get the bits of the float. Endianness is the same as for integers.
540   uint32_t U = llvm::FloatToBits(F);
541   // IEEE 754 floats compare like sign-magnitude integers.
542   if (U & TopBit)    // Negative float.
543     return 0 - U;    // Map onto the low half of integers, order reversed.
544   return U + TopBit; // Positive floats map onto the high half of integers.
545 }
546 
sortText(float Score,llvm::StringRef Name)547 std::string sortText(float Score, llvm::StringRef Name) {
548   // We convert -Score to an integer, and hex-encode for readability.
549   // Example: [0.5, "foo"] -> "41000000foo"
550   std::string S;
551   llvm::raw_string_ostream OS(S);
552   llvm::write_hex(OS, encodeFloat(-Score), llvm::HexPrintStyle::Lower,
553                   /*Width=*/2 * sizeof(Score));
554   OS << Name;
555   OS.flush();
556   return S;
557 }
558 
operator <<(llvm::raw_ostream & OS,const SignatureQualitySignals & S)559 llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
560                               const SignatureQualitySignals &S) {
561   OS << llvm::formatv("=== Signature Quality:\n");
562   OS << llvm::formatv("\tNumber of parameters: {0}\n", S.NumberOfParameters);
563   OS << llvm::formatv("\tNumber of optional parameters: {0}\n",
564                       S.NumberOfOptionalParameters);
565   OS << llvm::formatv("\tKind: {0}\n", S.Kind);
566   return OS;
567 }
568 
569 } // namespace clangd
570 } // namespace clang
571