[Support] Use StringRef::operator== instead of StringRef::equals (NFC) (#91042)

I'm planning to remove StringRef::equals in favor of
StringRef::operator==.

- StringRef::operator== outnumbers StringRef::equals by a factor of 25
  under llvm/ in terms of their usage.

- The elimination of StringRef::equals brings StringRef closer to
  std::string_view, which has operator== but not equals.

- S == "foo" is more readable than S.equals("foo"), especially for
  !Long.Expression.equals("str") vs Long.Expression != "str".

Author: kazutakahirata

llvm/include/llvm/Support/VirtualFileSystem.h

@@ -961,7 +961,7 @@ class RedirectingFileSystem
   // that, other than the root, path components should not contain slashes or
   // backslashes.
   bool pathComponentMatches(llvm::StringRef lhs, llvm::StringRef rhs) const {
-    if ((CaseSensitive ? lhs.equals(rhs) : lhs.equals_insensitive(rhs)))
+    if ((CaseSensitive ? lhs == rhs : lhs.equals_insensitive(rhs)))
       return true;
     return (lhs == "/" && rhs == "\\") || (lhs == "\\" && rhs == "/");
   }

llvm/include/llvm/Support/YAMLTraits.h

@@ -567,18 +567,18 @@ inline bool isNumeric(StringRef S) {
 
   // Make S.front() and S.drop_front().front() (if S.front() is [+-]) calls
   // safe.
-  if (S.empty() || S.equals("+") || S.equals("-"))
+  if (S.empty() || S == "+" || S == "-")
     return false;
 
-  if (S.equals(".nan") || S.equals(".NaN") || S.equals(".NAN"))
+  if (S == ".nan" || S == ".NaN" || S == ".NAN")
     return true;
 
   // Infinity and decimal numbers can be prefixed with sign.
   StringRef Tail = (S.front() == '-' || S.front() == '+') ? S.drop_front() : S;
 
   // Check for infinity first, because checking for hex and oct numbers is more
   // expensive.
-  if (Tail.equals(".inf") || Tail.equals(".Inf") || Tail.equals(".INF"))
+  if (Tail == ".inf" || Tail == ".Inf" || Tail == ".INF")
     return true;
 
   // Section 10.3.2 Tag Resolution
@@ -599,7 +599,7 @@ inline bool isNumeric(StringRef S) {
   // digit after dot (as opposed by number which has digits before the dot), but
   // doesn't have one.
   if (S.starts_with(".") &&
-      (S.equals(".") ||
+      (S == "." ||
        (S.size() > 1 && std::strchr("0123456789", S[1]) == nullptr)))
     return false;
 
@@ -656,14 +656,13 @@ inline bool isNumeric(StringRef S) {
 }
 
 inline bool isNull(StringRef S) {
-  return S.equals("null") || S.equals("Null") || S.equals("NULL") ||
-         S.equals("~");
+  return S == "null" || S == "Null" || S == "NULL" || S == "~";
 }
 
 inline bool isBool(StringRef S) {
   // FIXME: using parseBool is causing multiple tests to fail.
-  return S.equals("true") || S.equals("True") || S.equals("TRUE") ||
-         S.equals("false") || S.equals("False") || S.equals("FALSE");
+  return S == "true" || S == "True" || S == "TRUE" || S == "false" ||
+         S == "False" || S == "FALSE";
 }
 
 // 5.1. Character Set

llvm/lib/Support/APFloat.cpp

@@ -3123,7 +3123,7 @@ bool IEEEFloat::convertFromStringSpecials(StringRef str) {
   if (str.size() < MIN_NAME_SIZE)
     return false;
 
-  if (str.equals("inf") || str.equals("INFINITY") || str.equals("+Inf")) {
+  if (str == "inf" || str == "INFINITY" || str == "+Inf") {
     makeInf(false);
     return true;
   }
@@ -3134,7 +3134,7 @@ bool IEEEFloat::convertFromStringSpecials(StringRef str) {
     if (str.size() < MIN_NAME_SIZE)
       return false;
 
-    if (str.equals("inf") || str.equals("INFINITY") || str.equals("Inf")) {
+    if (str == "inf" || str == "INFINITY" || str == "Inf") {
       makeInf(true);
       return true;
     }

llvm/lib/Support/CodeGenCoverage.cpp

@@ -53,7 +53,7 @@ bool CodeGenCoverage::parse(MemoryBuffer &Buffer, StringRef BackendName) {
     if (CurPtr == Buffer.getBufferEnd())
       return false; // Data is invalid, expected rule id's to follow.
 
-    bool IsForThisBackend = BackendName.equals(LexedBackendName);
+    bool IsForThisBackend = BackendName == LexedBackendName;
     while (CurPtr != Buffer.getBufferEnd()) {
       if (std::distance(CurPtr, Buffer.getBufferEnd()) < 8)
         return false; // Data is invalid. Not enough bytes for another rule id.

llvm/lib/Support/FileCollector.cpp

@@ -44,7 +44,7 @@ static bool isCaseSensitivePath(StringRef Path) {
   // sensitive in the absence of real_path, since this is the YAMLVFSWriter
   // default.
   UpperDest = Path.upper();
-  if (!sys::fs::real_path(UpperDest, RealDest) && Path.equals(RealDest))
+  if (!sys::fs::real_path(UpperDest, RealDest) && Path == RealDest)
     return false;
   return true;
 }

llvm/lib/Support/JSON.cpp

@@ -336,7 +336,7 @@ void Path::Root::printErrorContext(const Value &R, raw_ostream &OS) const {
       JOS.object([&] {
         for (const auto *KV : sortedElements(*O)) {
           JOS.attributeBegin(KV->first);
-          if (FieldName.equals(KV->first))
+          if (FieldName == StringRef(KV->first))
             Recurse(KV->second, Path.drop_back(), Recurse);
           else
             abbreviate(KV->second, JOS);

llvm/lib/Support/VirtualFileSystem.cpp

@@ -157,7 +157,7 @@ void FileSystem::dump() const { print(dbgs(), PrintType::RecursiveContents); }
 
 #ifndef NDEBUG
 static bool isTraversalComponent(StringRef Component) {
-  return Component.equals("..") || Component.equals(".");
+  return Component == ".." || Component == ".";
 }
 
 static bool pathHasTraversal(StringRef Path) {

llvm/lib/Support/YAMLTraits.cpp

@@ -120,7 +120,7 @@ bool Input::mapTag(StringRef Tag, bool Default) {
     return Default;
   }
   // Return true iff found tag matches supplied tag.
-  return Tag.equals(foundTag);
+  return Tag == foundTag;
 }
 
 void Input::beginMapping() {
@@ -271,7 +271,7 @@ bool Input::matchEnumScalar(const char *Str, bool) {
   if (ScalarMatchFound)
     return false;
   if (ScalarHNode *SN = dyn_cast<ScalarHNode>(CurrentNode)) {
-    if (SN->value().equals(Str)) {
+    if (SN->value() == Str) {
       ScalarMatchFound = true;
       return true;
     }
@@ -310,7 +310,7 @@ bool Input::bitSetMatch(const char *Str, bool) {
     unsigned Index = 0;
     for (auto &N : SQ->Entries) {
       if (ScalarHNode *SN = dyn_cast<ScalarHNode>(N)) {
-        if (SN->value().equals(Str)) {
+        if (SN->value() == Str) {
           BitValuesUsed[Index] = true;
           return true;
         }