Use StringRef::starts_with (NFC) (#94886)

Author: kazutakahirata

bolt/lib/Profile/BoltAddressTranslation.cpp

@@ -304,7 +304,7 @@ std::error_code BoltAddressTranslation::parse(raw_ostream &OS, StringRef Buf) {
 
   StringRef Name = Buf.slice(Offset, Offset + NameSz);
   Offset = alignTo(Offset + NameSz, 4);
-  if (Name.substr(0, 4) != "BOLT")
+  if (!Name.starts_with("BOLT"))
     return make_error_code(llvm::errc::io_error);
 
   Error Err(Error::success());

clang-tools-extra/clang-query/QueryParser.cpp

@@ -144,13 +144,11 @@ QueryRef QueryParser::endQuery(QueryRef Q) {
   StringRef Extra = Line;
   StringRef ExtraTrimmed = Extra.ltrim(" \t\v\f\r");
 
-  if ((!ExtraTrimmed.empty() && ExtraTrimmed[0] == '\n') ||
-      (ExtraTrimmed.size() >= 2 && ExtraTrimmed[0] == '\r' &&
-       ExtraTrimmed[1] == '\n'))
+  if (ExtraTrimmed.starts_with('\n') || ExtraTrimmed.starts_with("\r\n"))
     Q->RemainingContent = Extra;
   else {
     StringRef TrailingWord = lexWord();
-    if (!TrailingWord.empty() && TrailingWord.front() == '#') {
+    if (TrailingWord.starts_with('#')) {
       Line = Line.drop_until([](char c) { return c == '\n'; });
       Line = Line.drop_while([](char c) { return c == '\n'; });
       return endQuery(Q);

mlir/lib/Query/QueryParser.cpp

@@ -91,13 +91,11 @@ QueryRef QueryParser::endQuery(QueryRef queryRef) {
   llvm::StringRef extra = line;
   llvm::StringRef extraTrimmed = extra.ltrim(" \t\v\f\r");
 
-  if ((!extraTrimmed.empty() && extraTrimmed[0] == '\n') ||
-      (extraTrimmed.size() >= 2 && extraTrimmed[0] == '\r' &&
-       extraTrimmed[1] == '\n'))
+  if (extraTrimmed.starts_with('\n') || extraTrimmed.starts_with("\r\n"))
     queryRef->remainingContent = extra;
   else {
     llvm::StringRef trailingWord = lexWord();
-    if (!trailingWord.empty() && trailingWord.front() == '#') {
+    if (trailingWord.starts_with('#')) {
       line = line.drop_until([](char c) { return c == '\n'; });
       line = line.drop_while([](char c) { return c == '\n'; });
       return endQuery(queryRef);