AST, SIL: Remove UTF16 encoding from StringLiteralExpr and StringLiteralInst

The UTF16 encoding is not used (anymore). I think it became obsolete with the switch to the UTF8 String representation.

Author: eeckstein

include/swift/AST/Expr.h

@@ -861,9 +861,6 @@ class StringLiteralExpr : public LiteralExpr {
     /// A UTF-8 string.
     UTF8,
 
-    /// A UTF-16 string.
-    UTF16,
-
     /// A single UnicodeScalar, passed as an integer.
     OneUnicodeScalar
   };

include/swift/Basic/Unicode.h

@@ -68,10 +68,6 @@ bool isSingleUnicodeScalar(StringRef S);
 
 unsigned extractFirstUnicodeScalar(StringRef S);
 
-/// Get the length of the UTF8 string transcoded into UTF16.
-/// Returns the number of code units in UTF16 representation
-uint64_t getUTF16Length(StringRef Str);
-
 } // end namespace unicode
 } // end namespace swift
 

include/swift/SIL/SILInstruction.h

@@ -3307,7 +3307,6 @@ class StringLiteralInst final
   enum class Encoding {
     Bytes,
     UTF8,
-    UTF16,
     /// UTF-8 encoding of an Objective-C selector.
     ObjCSelector,
   };

lib/AST/ASTDumper.cpp

@@ -368,7 +368,6 @@ static StringRef
 getStringLiteralExprEncodingString(StringLiteralExpr::Encoding value) {
   switch (value) {
     case StringLiteralExpr::UTF8: return "utf8";
-    case StringLiteralExpr::UTF16: return "utf16";
     case StringLiteralExpr::OneUnicodeScalar: return "unicodeScalar";
   }
 

lib/Basic/Unicode.cpp

@@ -123,22 +123,3 @@ unsigned swift::unicode::extractFirstUnicodeScalar(StringRef S) {
   (void)Result;
   return Scalar;
 }
-
-uint64_t swift::unicode::getUTF16Length(StringRef Str) {
-  uint64_t Length;
-  // Transcode the string to UTF-16 to get its length.
-  SmallVector<llvm::UTF16, 128> buffer(Str.size() + 1); // +1 for ending nulls.
-  const llvm::UTF8 *fromPtr = (const llvm::UTF8 *) Str.data();
-  llvm::UTF16 *toPtr = &buffer[0];
-  llvm::ConversionResult Result =
-    ConvertUTF8toUTF16(&fromPtr, fromPtr + Str.size(),
-                       &toPtr, toPtr + Str.size(),
-                       llvm::strictConversion);
-  assert(Result == llvm::conversionOK &&
-         "UTF-8 encoded string cannot be converted into UTF-16 encoding");
-  (void)Result;
-
-  // The length of the transcoded string in UTF-16 code points.
-  Length = toPtr - &buffer[0];
-  return Length;
-}

lib/IRGen/GenConstant.cpp

@@ -102,14 +102,6 @@ llvm::Constant *irgen::emitAddrOfConstantString(IRGenModule &IGM,
   case StringLiteralInst::Encoding::UTF8:
     return IGM.getAddrOfGlobalString(SLI->getValue());
 
-  case StringLiteralInst::Encoding::UTF16: {
-    // This is always a GEP of a GlobalVariable with a nul terminator.
-    auto addr = IGM.getAddrOfGlobalUTF16String(SLI->getValue());
-
-    // Cast to Builtin.RawPointer.
-    return llvm::ConstantExpr::getBitCast(addr, IGM.Int8PtrTy);
-  }
-
   case StringLiteralInst::Encoding::ObjCSelector:
     llvm_unreachable("cannot get the address of an Objective-C selector");
   }

lib/SIL/IR/SILGlobalVariable.cpp

@@ -157,7 +157,6 @@ bool SILGlobalVariable::isValidStaticInitializerInst(const SILInstruction *I,
       switch (cast<StringLiteralInst>(I)->getEncoding()) {
         case StringLiteralInst::Encoding::Bytes:
         case StringLiteralInst::Encoding::UTF8:
-        case StringLiteralInst::Encoding::UTF16:
           return true;
         case StringLiteralInst::Encoding::ObjCSelector:
           // Objective-C selector string literals cannot be used in static

lib/SIL/IR/SILInstructions.cpp

@@ -1043,9 +1043,6 @@ CondFailInst *CondFailInst::create(SILDebugLocation DebugLoc, SILValue Operand,
 }
 
 uint64_t StringLiteralInst::getCodeUnitCount() {
-  auto E = unsigned(Encoding::UTF16);
-  if (SILInstruction::Bits.StringLiteralInst.TheEncoding == E)
-    return unicode::getUTF16Length(getValue());
   return SILInstruction::Bits.StringLiteralInst.Length;
 }
 

lib/SIL/IR/SILPrinter.cpp

@@ -1339,7 +1339,6 @@ class SILPrinter : public SILInstructionVisitor<SILPrinter> {
     switch (kind) {
     case StringLiteralInst::Encoding::Bytes: return "bytes ";
     case StringLiteralInst::Encoding::UTF8: return "utf8 ";
-    case StringLiteralInst::Encoding::UTF16: return "utf16 ";
     case StringLiteralInst::Encoding::ObjCSelector: return "objc_selector ";
     }
     llvm_unreachable("bad string literal encoding");

lib/SIL/Parser/ParseSIL.cpp

@@ -2619,8 +2619,6 @@ bool SILParser::parseSpecificSILInstruction(SILBuilder &B,
     StringLiteralInst::Encoding encoding;
     if (P.Tok.getText() == "utf8") {
       encoding = StringLiteralInst::Encoding::UTF8;
-    } else if (P.Tok.getText() == "utf16") {
-      encoding = StringLiteralInst::Encoding::UTF16;
     } else if (P.Tok.getText() == "objc_selector") {
       encoding = StringLiteralInst::Encoding::ObjCSelector;
     } else if (P.Tok.getText() == "bytes") {