Merge pull request swiftlang#33128 from eeckstein/string-optimization

SIL optimizer: Add a new string optimization

Author: eeckstein

include/swift/AST/ASTContext.h

@@ -553,6 +553,9 @@ class ASTContext final {
   /// Array.reserveCapacityForAppend(newElementsCount: Int)
   FuncDecl *getArrayReserveCapacityDecl() const;
 
+  /// Retrieve the declaration of String.init(_builtinStringLiteral ...)
+  ConstructorDecl *getMakeUTF8StringDecl() const;
+
   // Retrieve the declaration of Swift._stdlib_isOSVersionAtLeast.
   FuncDecl *getIsOSVersionAtLeastDecl() const;
 

include/swift/AST/ASTMangler.h

@@ -213,6 +213,9 @@ class ASTMangler : public Mangler {
 
   std::string mangleTypeForDebugger(Type decl, const DeclContext *DC);
 
+  /// Create a mangled name to be used for _typeName constant propagation.
+  std::string mangleTypeForTypeName(Type type);
+
   std::string mangleOpaqueTypeDescriptor(const OpaqueTypeDecl *decl);
 
   std::string mangleDeclType(const ValueDecl *decl);

include/swift/AST/SemanticAttrs.def

@@ -30,6 +30,7 @@ SEMANTICS_ATTR(STRING_ESCAPE_PERCENT_GET, "string.escapePercent.get")
 SEMANTICS_ATTR(STRING_CONCAT, "string.concat")
 SEMANTICS_ATTR(STRING_APPEND, "string.append")
 SEMANTICS_ATTR(STRING_INIT_EMPTY, "string.init_empty")
+SEMANTICS_ATTR(STRING_INIT_EMPTY_WITH_CAPACITY, "string.init_empty_with_capacity")
 SEMANTICS_ATTR(STRING_PLUS_EQUALS, "string.plusequals")
 SEMANTICS_ATTR(FIND_STRING_SWITCH_CASE, "findStringSwitchCase")
 SEMANTICS_ATTR(FIND_STRING_SWITCH_CASE_WITH_CACHE, "findStringSwitchCaseWithCache")
@@ -63,6 +64,7 @@ SEMANTICS_ATTR(ARRAY_UNINITIALIZED_INTRINSIC, "array.uninitialized_intrinsic")
 SEMANTICS_ATTR(ARRAY_FINALIZE_INTRINSIC, "array.finalize_intrinsic")
 
 SEMANTICS_ATTR(SEQUENCE_FOR_EACH, "sequence.forEach")
+SEMANTICS_ATTR(TYPENAME, "typeName")
 
 SEMANTICS_ATTR(OPTIMIZE_SIL_SPECIALIZE_GENERIC_NEVER, "optimize.sil.specialize.generic.never")
 SEMANTICS_ATTR(OPTIMIZE_SIL_SPECIALIZE_GENERIC_PARTIAL_NEVER,

include/swift/Demangling/Demangle.h

@@ -62,6 +62,8 @@ struct DemangleOptions {
   bool DisplayDebuggerGeneratedModule = true;
   bool DisplayStdlibModule = true;
   bool DisplayObjCModule = true;
+  bool PrintForTypeName = false;
+
   /// If this is nonempty, entities in this module name will not be qualified.
   llvm::StringRef HidingCurrentModule;
   /// A function to render generic parameter names.

include/swift/SILOptimizer/PassManager/Passes.def

@@ -317,6 +317,8 @@ PASS(StackPromotion, "stack-promotion",
      "Stack Promotion of Class Objects")
 PASS(StripDebugInfo, "strip-debug-info",
      "Strip Debug Information")
+PASS(StringOptimization, "string-optimization",
+     "Optimization for String operations")
 PASS(SwiftArrayPropertyOpt, "array-property-opt",
      "Loop Specialization for Array Properties")
 PASS(UnsafeGuaranteedPeephole, "unsafe-guaranteed-peephole",

lib/AST/ASTContext.cpp

@@ -40,6 +40,7 @@
 #include "swift/AST/PropertyWrappers.h"
 #include "swift/AST/ProtocolConformance.h"
 #include "swift/AST/RawComment.h"
+#include "swift/AST/SemanticAttrs.h"
 #include "swift/AST/SourceFile.h"
 #include "swift/AST/SubstitutionMap.h"
 #include "swift/AST/SILLayout.h"
@@ -240,6 +241,9 @@ struct ASTContext::Implementation {
   /// func append(Element) -> void
   FuncDecl *ArrayAppendElementDecl = nullptr;
 
+  /// init(Builtin.RawPointer, Builtin.Word, Builtin.Int1)
+  ConstructorDecl *MakeUTF8StringDecl = nullptr;
+
   /// func reserveCapacityForAppend(newElementsCount: Int)
   FuncDecl *ArrayReserveCapacityDecl = nullptr;
 
@@ -1247,6 +1251,33 @@ FuncDecl *ASTContext::getArrayReserveCapacityDecl() const {
   return nullptr;
 }
 
+ConstructorDecl *ASTContext::getMakeUTF8StringDecl() const {
+  if (getImpl().MakeUTF8StringDecl)
+    return getImpl().MakeUTF8StringDecl;
+
+  auto initializers =
+    getStringDecl()->lookupDirect(DeclBaseName::createConstructor());
+
+  for (Decl *initializer : initializers) {
+    auto *constructor = cast<ConstructorDecl>(initializer);
+    auto Attrs = constructor->getAttrs();
+    for (auto *A : Attrs.getAttributes<SemanticsAttr, false>()) {
+      if (A->Value != semantics::STRING_MAKE_UTF8)
+        continue;
+      auto ParamList = constructor->getParameters();
+      if (ParamList->size() != 3)
+        continue;
+      ParamDecl *param = constructor->getParameters()->get(0);
+      if (param->getArgumentName().str() != "_builtinStringLiteral")
+        continue;
+
+      getImpl().MakeUTF8StringDecl = constructor;
+      return constructor;
+    }
+  }
+  return nullptr;
+}
+
 FuncDecl *ASTContext::getIsOSVersionAtLeastDecl() const {
   if (getImpl().IsOSVersionAtLeastDecl)
     return getImpl().IsOSVersionAtLeastDecl;

lib/AST/ASTMangler.cpp

@@ -533,6 +533,12 @@ std::string ASTMangler::mangleTypeForDebugger(Type Ty, const DeclContext *DC) {
   return finalize();
 }
 
+std::string ASTMangler::mangleTypeForTypeName(Type type) {
+  beginMangling();
+  appendType(type);
+  return finalize();
+}
+
 std::string ASTMangler::mangleDeclType(const ValueDecl *decl) {
   DWARFMangling = true;
   beginMangling();

lib/Demangling/NodePrinter.cpp

@@ -1131,8 +1131,12 @@ NodePointer NodePrinter::print(NodePointer Node, bool asPrefixContext) {
       Printer << "):";
     }
     print(Node->getChild(1));
-    if (Node->getNumChildren() == 3)
-      print(Node->getChild(2));
+    if (Node->getNumChildren() == 3) {
+      // Currently the runtime does not mangle the generic signature.
+      // This is an open to-do in swift::_buildDemanglingForContext().
+      if (!Options.PrintForTypeName)
+        print(Node->getChild(2));
+    }
     return nullptr;
   case Node::Kind::Variable:
     return printEntity(Node, asPrefixContext, TypePrinting::WithColon,

lib/SILOptimizer/PassManager/PassPipeline.cpp

@@ -524,6 +524,9 @@ static void addSerializePipeline(SILPassPipelinePlan &P) {
 
 static void addMidLevelFunctionPipeline(SILPassPipelinePlan &P) {
   P.startPipeline("MidLevel,Function", true /*isFunctionPassPipeline*/);
+
+  P.addStringOptimization();
+
   addFunctionPasses(P, OptimizationLevelKind::MidLevel);
 
   // Specialize partially applied functions with dead arguments as a preparation

lib/SILOptimizer/Transforms/CMakeLists.txt

@@ -39,6 +39,7 @@ target_sources(swiftSILOptimizer PRIVATE
   Sink.cpp
   SpeculativeDevirtualizer.cpp
   StackPromotion.cpp
+  StringOptimization.cpp
   TempLValueOpt.cpp
   TempRValueElimination.cpp
   UnsafeGuaranteedPeephole.cpp)