Add SIL and IRGen support for a ConstantStringLiteral instruction

This supports a utf8 or utf16 encoding.

rdar://30545013

Author: aschwaighofer

include/swift/SIL/SILBuilder.h

@@ -461,6 +461,21 @@ class SILBuilder {
         getSILDebugLocation(Loc), text.toStringRef(Out), encoding, F));
   }
 
+  ConstStringLiteralInst *
+  createConstStringLiteral(SILLocation Loc, StringRef text,
+                           ConstStringLiteralInst::Encoding encoding) {
+    return insert(ConstStringLiteralInst::create(getSILDebugLocation(Loc), text,
+                                                 encoding, F));
+  }
+
+  ConstStringLiteralInst *
+  createConstStringLiteral(SILLocation Loc, const Twine &text,
+                           ConstStringLiteralInst::Encoding encoding) {
+    SmallVector<char, 256> Out;
+    return insert(ConstStringLiteralInst::create(
+        getSILDebugLocation(Loc), text.toStringRef(Out), encoding, F));
+  }
+
   LoadInst *createLoad(SILLocation Loc, SILValue LV,
                        LoadOwnershipQualifier Qualifier) {
     assert((Qualifier != LoadOwnershipQualifier::Unqualified) ||

include/swift/SIL/SILCloner.h

@@ -665,9 +665,18 @@ SILCloner<ImplClass>::visitStringLiteralInst(StringLiteralInst *Inst) {
                                                  Inst->getEncoding()));
 }
 
-template<typename ImplClass>
-void
-SILCloner<ImplClass>::visitLoadInst(LoadInst *Inst) {
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitConstStringLiteralInst(
+    ConstStringLiteralInst *Inst) {
+  getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
+  doPostProcess(Inst,
+                getBuilder().createConstStringLiteral(
+                    getOpLocation(Inst->getLoc()), Inst->getValue(),
+                    Inst->getEncoding()));
+}
+
+template <typename ImplClass>
+void SILCloner<ImplClass>::visitLoadInst(LoadInst *Inst) {
   getBuilder().setCurrentDebugScope(getOpScope(Inst->getDebugScope()));
   doPostProcess(Inst, getBuilder().createLoad(getOpLocation(Inst->getLoc()),
                                               getOpValue(Inst->getOperand()),

include/swift/SIL/SILInstruction.h

@@ -1655,6 +1655,51 @@ class StringLiteralInst final : public LiteralInst,
   }
 };
 
+/// ConstStringLiteralInst - Encapsulates a string constant, as defined
+/// originally by
+/// a StringLiteralExpr.  This produces the address of the string data as a
+/// Builtin.RawPointer.
+class ConstStringLiteralInst final
+    : public LiteralInst,
+      private llvm::TrailingObjects<ConstStringLiteralInst, char> {
+  friend TrailingObjects;
+  friend SILBuilder;
+
+public:
+  enum class Encoding {
+    UTF8,
+    UTF16,
+  };
+
+private:
+  unsigned Length;
+  Encoding TheEncoding;
+
+  ConstStringLiteralInst(SILDebugLocation DebugLoc, StringRef text,
+                         Encoding encoding, SILType ty);
+
+  static ConstStringLiteralInst *create(SILDebugLocation DebugLoc,
+                                        StringRef Text, Encoding encoding,
+                                        SILFunction &F);
+
+public:
+  /// getValue - Return the string data for the literal, in UTF-8.
+  StringRef getValue() const { return {getTrailingObjects<char>(), Length}; }
+
+  /// getEncoding - Return the desired encoding of the text.
+  Encoding getEncoding() const { return TheEncoding; }
+
+  /// getCodeUnitCount - Return encoding-based length of the string
+  /// literal in code units.
+  uint64_t getCodeUnitCount();
+
+  ArrayRef<Operand> getAllOperands() const { return {}; }
+  MutableArrayRef<Operand> getAllOperands() { return {}; }
+
+  static bool classof(const ValueBase *V) {
+    return V->getKind() == ValueKind::ConstStringLiteralInst;
+  }
+};
 //===----------------------------------------------------------------------===//
 // Memory instructions.
 //===----------------------------------------------------------------------===//

include/swift/SIL/SILNodes.def

@@ -185,7 +185,8 @@ ABSTRACT_VALUE(SILInstruction, ValueBase)
     INST(IntegerLiteralInst, LiteralInst, integer_literal, None, DoesNotRelease)
     INST(FloatLiteralInst, LiteralInst, float_literal, None, DoesNotRelease)
     INST(StringLiteralInst, LiteralInst, string_literal, None, DoesNotRelease)
-    VALUE_RANGE(LiteralInst, FunctionRefInst, StringLiteralInst)
+    INST(ConstStringLiteralInst, LiteralInst, const_string_literal, None, DoesNotRelease)
+    VALUE_RANGE(LiteralInst, FunctionRefInst, ConstStringLiteralInst)
 
   // Dynamic Dispatch
   ABSTRACT_VALUE(MethodInst, SILInstruction)

include/swift/Serialization/ModuleFormat.h

@@ -54,7 +54,7 @@ const uint16_t VERSION_MAJOR = 0;
 /// in source control, you should also update the comment to briefly
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
-const uint16_t VERSION_MINOR = 331; // Last change: type witness substitutions
+const uint16_t VERSION_MINOR = 332; // Last change: constant_string_literal
 
 using DeclID = PointerEmbeddedInt<unsigned, 31>;
 using DeclIDField = BCFixed<31>;

lib/IRGen/GenDecl.cpp

@@ -27,7 +27,9 @@
 #include "swift/AST/TypeMemberVisitor.h"
 #include "swift/AST/Types.h"
 #include "swift/ClangImporter/ClangModule.h"
+#include "swift/Demangling/ManglingMacros.h"
 #include "swift/IRGen/Linking.h"
+#include "swift/Runtime/HeapObject.h"
 #include "swift/SIL/FormalLinkage.h"
 #include "swift/SIL/SILDebugScope.h"
 #include "swift/SIL/SILModule.h"
@@ -3079,6 +3081,169 @@ llvm::Constant *IRGenModule::getAddrOfGlobalUTF16String(StringRef utf8) {
   return address;
 }
 
+static llvm::Constant *getMetatypeDeclarationFor(IRGenModule &IGM,
+                                                 StringRef name) {
+  auto *storageType = IGM.ObjCClassStructTy;
+
+  // We may have defined the variable already.
+  if (auto existing = IGM.Module.getNamedGlobal(name))
+    return getElementBitCast(existing, storageType);
+
+  auto linkage = llvm::GlobalValue::ExternalLinkage;
+  auto visibility = llvm::GlobalValue::DefaultVisibility;
+  auto storageClass = llvm::GlobalValue::DefaultStorageClass;
+
+  auto var = new llvm::GlobalVariable(IGM.Module, storageType,
+                                      /*constant*/ false, linkage,
+                                      /*initializer*/ nullptr, name);
+  var->setVisibility(visibility);
+  var->setDLLStorageClass(storageClass);
+  var->setAlignment(IGM.getPointerAlignment().getValue());
+
+  return var;
+}
+#define STRINGIFY_IMPL(x) #x
+#define REALLY_STRINGIFY( x) STRINGIFY_IMPL(x)
+
+llvm::Constant *
+IRGenModule::getAddrOfGlobalConstantString(StringRef utf8) {
+  auto &entry = GlobalConstantStrings[utf8];
+  if (entry)
+    return entry;
+
+  // If not, create it.  This implicitly adds a trailing null.
+  auto data = llvm::ConstantDataArray::getString(LLVMContext, utf8);
+  auto *dataTy = data->getType();
+
+  llvm::Type *constantStringTy[] = {
+      RefCountedStructTy,
+      Int32Ty,
+      Int32Ty,
+      Int8Ty,
+      dataTy
+  };
+  auto *ConstantStringTy =
+      llvm::StructType::get(getLLVMContext(), constantStringTy,
+                            /*packed*/ false);
+
+  auto metaclass = getMetatypeDeclarationFor(
+      *this, REALLY_STRINGIFY(CLASS_METADATA_SYM(s20_Latin1StringStorage)));
+
+  metaclass = llvm::ConstantExpr::getBitCast(metaclass, TypeMetadataPtrTy);
+
+  // Get a reference count of two.
+  auto *strongRefCountInit = llvm::ConstantInt::get(
+      Int32Ty,
+      InlineRefCountBits(0 /*unowned ref count*/, 2 /*strong ref count*/)
+          .getBitsValue());
+  auto *unownedRefCountInit = llvm::ConstantInt::get(Int32Ty, 0);
+
+  auto *count = llvm::ConstantInt::get(Int32Ty, utf8.size());
+  // Capacitity is length plus one because of the implicitly added '\0'
+  // character.
+  auto *capacity = llvm::ConstantInt::get(Int32Ty, utf8.size() + 1);
+  auto *flags = llvm::ConstantInt::get(Int8Ty, 0);
+
+  // FIXME: Big endian-ness.
+  llvm::Constant *heapObjectHeaderFields[] = {
+      metaclass, strongRefCountInit, unownedRefCountInit
+  };
+
+  auto *initRefCountStruct = llvm::ConstantStruct::get(
+      RefCountedStructTy, makeArrayRef(heapObjectHeaderFields));
+
+  llvm::Constant *fields[] = {
+      initRefCountStruct, count, capacity, flags, data};
+  auto *init =
+      llvm::ConstantStruct::get(ConstantStringTy, makeArrayRef(fields));
+
+  auto global = new llvm::GlobalVariable(Module, init->getType(), true,
+                                         llvm::GlobalValue::PrivateLinkage,
+                                         init);
+  global->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+
+  // Cache string entry.
+  entry = global;
+
+  return global;
+}
+
+llvm::Constant *
+IRGenModule::getAddrOfGlobalUTF16ConstantString(StringRef utf8) {
+  auto &entry = GlobalConstantUTF16Strings[utf8];
+  if (entry)
+    return entry;
+
+  // If not, first transcode it to UTF16.
+  SmallVector<llvm::UTF16, 128> buffer(utf8.size() + 1); // +1 for ending nulls.
+  const llvm::UTF8 *fromPtr = (const llvm::UTF8 *) utf8.data();
+  llvm::UTF16 *toPtr = &buffer[0];
+  (void) ConvertUTF8toUTF16(&fromPtr, fromPtr + utf8.size(),
+                            &toPtr, toPtr + utf8.size(),
+                            llvm::strictConversion);
+
+  // The length of the transcoded string in UTF-8 code points.
+  size_t utf16Length = toPtr - &buffer[0];
+
+  // Null-terminate the UTF-16 string.
+  *toPtr = 0;
+  ArrayRef<llvm::UTF16> utf16(&buffer[0], utf16Length + 1);
+
+  auto *data = llvm::ConstantDataArray::get(LLVMContext, utf16);
+  auto *dataTy = data->getType();
+
+  llvm::Type *constantUTFStringTy[] = {
+      RefCountedStructTy,
+      Int32Ty,
+      Int32Ty,
+      Int8Ty,
+      Int8Ty, // For 16-byte alignment.
+      dataTy
+  };
+  auto *ConstantUTFStringTy =
+      llvm::StructType::get(getLLVMContext(), constantUTFStringTy,
+                            /*packed*/ false);
+
+  auto metaclass = getMetatypeDeclarationFor(
+      *this, REALLY_STRINGIFY(CLASS_METADATA_SYM(s19_UTF16StringStorage)));
+
+  metaclass = llvm::ConstantExpr::getBitCast(metaclass, TypeMetadataPtrTy);
+
+  // Get a reference count of two.
+  auto *strongRefCountInit = llvm::ConstantInt::get(
+      Int32Ty,
+      InlineRefCountBits(0 /*unowned ref count*/, 2 /*strong ref count*/)
+          .getBitsValue());
+  auto *unownedRefCountInit = llvm::ConstantInt::get(Int32Ty, 0);
+
+  auto *count = llvm::ConstantInt::get(Int32Ty, utf16Length);
+  auto *capacity = llvm::ConstantInt::get(Int32Ty, utf16Length + 1);
+  auto *flags = llvm::ConstantInt::get(Int8Ty, 0);
+  auto *padding = llvm::ConstantInt::get(Int8Ty, 0);
+
+  llvm::Constant *heapObjectHeaderFields[] = {
+      metaclass, strongRefCountInit, unownedRefCountInit
+  };
+
+  auto *initRefCountStruct = llvm::ConstantStruct::get(
+      RefCountedStructTy, makeArrayRef(heapObjectHeaderFields));
+
+  llvm::Constant *fields[] = {
+      initRefCountStruct, count, capacity, flags, padding, data};
+  auto *init =
+      llvm::ConstantStruct::get(ConstantUTFStringTy, makeArrayRef(fields));
+
+  auto global = new llvm::GlobalVariable(Module, init->getType(), true,
+                                         llvm::GlobalValue::PrivateLinkage,
+                                         init);
+  global->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+
+  // Cache string entry.
+  entry = global;
+
+  return global;
+}
+
 /// Do we have to use resilient access patterns when working with this
 /// declaration?
 ///

lib/IRGen/IRGenModule.cpp

@@ -256,8 +256,7 @@ IRGenModule::IRGenModule(IRGenerator &irgen,
   });
   FullBoxMetadataPtrTy = FullBoxMetadataStructTy->getPointerTo(DefaultAS);
 
-
-  llvm::Type *refCountedElts[] = { TypeMetadataPtrTy, Int32Ty, Int32Ty };
+  llvm::Type *refCountedElts[] = {TypeMetadataPtrTy, Int32Ty, Int32Ty};
   RefCountedStructTy->setBody(refCountedElts);
 
   PtrSize = Size(DataLayout.getPointerSize(DefaultAS));
@@ -351,7 +350,7 @@ IRGenModule::IRGenModule(IRGenerator &irgen,
                                               openedErrorTriple,
                                               /*packed*/ false);
   OpenedErrorTriplePtrTy = OpenedErrorTripleTy->getPointerTo(DefaultAS);
-  
+
   InvariantMetadataID = LLVMContext.getMDKindID("invariant.load");
   InvariantNode = llvm::MDNode::get(LLVMContext, {});
   DereferenceableID = LLVMContext.getMDKindID("dereferenceable");

lib/IRGen/IRGenModule.h

@@ -652,6 +652,8 @@ class IRGenModule {
   llvm::Constant *getAddrOfGlobalString(StringRef utf8,
                                         bool willBeRelativelyAddressed = false);
   llvm::Constant *getAddrOfGlobalUTF16String(StringRef utf8);
+  llvm::Constant *getAddrOfGlobalConstantString(StringRef utf8);
+  llvm::Constant *getAddrOfGlobalUTF16ConstantString(StringRef utf8);
   llvm::Constant *getAddrOfObjCSelectorRef(StringRef selector);
   llvm::Constant *getAddrOfObjCMethodName(StringRef methodName);
   llvm::Constant *getAddrOfObjCProtocolRecord(ProtocolDecl *proto,
@@ -693,6 +695,10 @@ class IRGenModule {
   llvm::StringMap<llvm::Constant*> ObjCSelectorRefs;
   llvm::StringMap<llvm::Constant*> ObjCMethodNames;
 
+  /// Maps to constant swift 'String's.
+  llvm::StringMap<llvm::Constant*> GlobalConstantStrings;
+  llvm::StringMap<llvm::Constant*> GlobalConstantUTF16Strings;
+
   /// LLVMUsed - List of global values which are required to be
   /// present in the object file; bitcast to i8*. This is used for
   /// forcing visibility of symbols which may otherwise be optimized

lib/IRGen/IRGenSIL.cpp

@@ -822,6 +822,7 @@ class IRGenSILFunction :
   void visitIntegerLiteralInst(IntegerLiteralInst *i);
   void visitFloatLiteralInst(FloatLiteralInst *i);
   void visitStringLiteralInst(StringLiteralInst *i);
+  void visitConstStringLiteralInst(ConstStringLiteralInst *i);
 
   void visitLoadInst(LoadInst *i);
   void visitStoreInst(StoreInst *i);
@@ -2343,6 +2344,22 @@ void IRGenSILFunction::visitStringLiteralInst(swift::StringLiteralInst *i) {
   setLoweredExplosion(i, e);
 }
 
+void IRGenSILFunction::visitConstStringLiteralInst(
+    swift::ConstStringLiteralInst *i) {
+
+  llvm::Constant *addr;
+  if (i->getEncoding() == ConstStringLiteralInst::Encoding::UTF8)
+    addr = IGM.getAddrOfGlobalConstantString(i->getValue());
+  else
+    addr = IGM.getAddrOfGlobalUTF16ConstantString(i->getValue());
+
+  addr = llvm::ConstantExpr::getBitCast(addr, IGM.Int8PtrTy);
+
+  Explosion e;
+  e.add(addr);
+  setLoweredExplosion(i, e);
+}
+
 void IRGenSILFunction::visitUnreachableInst(swift::UnreachableInst *i) {
   Builder.CreateUnreachable();
 }