SIL: add a lazy_property_getter flag to SILFunction

eeckstein · eeckstein · commit ae93e60072c3 · 2020-03-13T09:49:55.000+01:00
It is set on getter-functions for lazy properties.
diff --git a/docs/SIL.rst b/docs/SIL.rst
@@ -936,6 +936,19 @@ This is currently true if the function is an addressor that was lazily
 generated from a global variable access. Note that the initialization
 function itself does not need this attribute. It is private and only
 called within the addressor.
+::
+
+  sil-function-purpose ::= 'lazy_getter'
+
+The function is a getter of a lazy property for which the backing storage is
+an ``Optional`` of the property's type. The getter contains a top-level
+``switch_enum`` (or ``switch_enum_addr``), which tests if the lazy property
+is already computed. In the ``None``-case, the property is computed and stored
+to the backing storage of the property.
+
+After the first call of a lazy property getter, it is guaranteed that the
+property is computed and consecutive calls always execute the ``Some``-case of
+the top-level ``switch_enum``.
 ::
 
   sil-function-attribute ::= '[weak_imported]'
diff --git a/include/swift/SIL/SILFunction.h b/include/swift/SIL/SILFunction.h
@@ -118,6 +118,13 @@ class SILFunction
 public:
   using BlockListType = llvm::iplist<SILBasicBlock>;
 
+  // For more information see docs/SIL.rst
+  enum class Purpose : uint8_t {
+    None,
+    GlobalInit,
+    LazyPropertyGetter
+  };
+
 private:
   friend class SILBasicBlock;
   friend class SILModule;
@@ -183,6 +190,8 @@ class SILFunction
   /// should use weak linking.
   AvailabilityContext Availability;
 
+  Purpose specialPurpose = Purpose::None;
+
   /// This is the number of uses of this SILFunction inside the SIL.
   /// It does not include references from debug scopes.
   unsigned RefCount = 0;
@@ -806,6 +815,8 @@ class SILFunction
   void setEffectsKind(EffectsKind E) {
     EffectsKindAttr = unsigned(E);
   }
+  
+  Purpose getSpecialPurpose() const { return specialPurpose; }
 
   /// Get this function's global_init attribute.
   ///
@@ -819,8 +830,13 @@ class SILFunction
   /// generated from a global variable access. Note that the initialization
   /// function itself does not need this attribute. It is private and only
   /// called within the addressor.
-  bool isGlobalInit() const { return GlobalInitFlag; }
-  void setGlobalInit(bool isGI) { GlobalInitFlag = isGI; }
+  bool isGlobalInit() const { return specialPurpose == Purpose::GlobalInit; }
+
+  bool isLazyPropertyGetter() const {
+    return specialPurpose == Purpose::LazyPropertyGetter;
+  }
+
+  void setSpecialPurpose(Purpose purpose) { specialPurpose = purpose; }
 
   /// Return whether this function has a foreign implementation which can
   /// be emitted on demand.
diff --git a/lib/ParseSIL/ParseSIL.cpp b/lib/ParseSIL/ParseSIL.cpp
@@ -910,7 +910,7 @@ static bool parseDeclSILOptional(bool *isTransparent,
                                  IsExactSelfClass_t *isExactSelfClass,
                                  SILFunction **dynamicallyReplacedFunction,
                                  Identifier *objCReplacementFor,
-                                 bool *isGlobalInit,
+                                 SILFunction::Purpose *specialPurpose,
                                  Inline_t *inlineStrategy,
                                  OptimizationMode *optimizationMode,
                                  bool *isLet,
@@ -955,8 +955,10 @@ static bool parseDeclSILOptional(bool *isTransparent,
     else if (isWithoutActuallyEscapingThunk
              && SP.P.Tok.getText() == "without_actually_escaping")
       *isWithoutActuallyEscapingThunk = true;
-    else if (isGlobalInit && SP.P.Tok.getText() == "global_init")
-      *isGlobalInit = true;
+    else if (specialPurpose && SP.P.Tok.getText() == "global_init")
+      *specialPurpose = SILFunction::Purpose::GlobalInit;
+    else if (specialPurpose && SP.P.Tok.getText() == "lazy_getter")
+      *specialPurpose = SILFunction::Purpose::LazyPropertyGetter;
     else if (isWeakImported && SP.P.Tok.getText() == "weak_imported") {
       if (M.getASTContext().LangOpts.Target.isOSBinFormatCOFF())
         SP.P.diagnose(SP.P.Tok, diag::attr_unsupported_on_target,
@@ -5462,7 +5464,8 @@ bool SILParserTUState::parseDeclSIL(Parser &P) {
   IsExactSelfClass_t isExactSelfClass = IsNotExactSelfClass;
   bool hasOwnershipSSA = false;
   IsThunk_t isThunk = IsNotThunk;
-  bool isGlobalInit = false, isWeakImported = false;
+  SILFunction::Purpose specialPurpose = SILFunction::Purpose::None;
+  bool isWeakImported = false;
   AvailabilityContext availability = AvailabilityContext::alwaysAvailable();
   bool isWithoutActuallyEscapingThunk = false;
   Inline_t inlineStrategy = InlineDefault;
@@ -5477,8 +5480,9 @@ bool SILParserTUState::parseDeclSIL(Parser &P) {
       parseDeclSILOptional(
           &isTransparent, &isSerialized, &isCanonical, &hasOwnershipSSA,
           &isThunk, &isDynamic, &isExactSelfClass, &DynamicallyReplacedFunction,
-          &objCReplacementFor, &isGlobalInit, &inlineStrategy, &optimizationMode, nullptr,
-          &isWeakImported, &availability, &isWithoutActuallyEscapingThunk, &Semantics,
+          &objCReplacementFor, &specialPurpose, &inlineStrategy,
+          &optimizationMode, nullptr, &isWeakImported, &availability,
+          &isWithoutActuallyEscapingThunk, &Semantics,
           &SpecAttrs, &ClangDecl, &MRK, FunctionState, M) ||
       P.parseToken(tok::at_sign, diag::expected_sil_function_name) ||
       P.parseIdentifier(FnName, FnNameLoc, diag::expected_sil_function_name) ||
@@ -5512,7 +5516,7 @@ bool SILParserTUState::parseDeclSIL(Parser &P) {
         DynamicallyReplacedFunction);
     if (!objCReplacementFor.empty())
       FunctionState.F->setObjCReplacement(objCReplacementFor);
-    FunctionState.F->setGlobalInit(isGlobalInit);
+    FunctionState.F->setSpecialPurpose(specialPurpose);
     FunctionState.F->setAlwaysWeakImported(isWeakImported);
     FunctionState.F->setAvailabilityForLinkage(availability);
     FunctionState.F->setWithoutActuallyEscapingThunk(
diff --git a/lib/SIL/SILFunctionBuilder.cpp b/lib/SIL/SILFunctionBuilder.cpp
@@ -157,7 +157,9 @@ SILFunction *SILFunctionBuilder::getOrCreateFunction(
                                 inlineStrategy, EK);
   F->setDebugScope(new (mod) SILDebugScope(loc, F));
 
-  F->setGlobalInit(constant.isGlobal());
+  if (constant.isGlobal())
+    F->setSpecialPurpose(SILFunction::Purpose::GlobalInit);
+
   if (constant.hasDecl()) {
     auto decl = constant.getDecl();
 
@@ -172,6 +174,12 @@ SILFunction *SILFunctionBuilder::getOrCreateFunction(
       // Add attributes for e.g. computed properties.
       addFunctionAttributes(F, storage->getAttrs(), mod,
                             getOrCreateDeclaration);
+                            
+      auto *varDecl = dyn_cast<VarDecl>(storage);
+      if (varDecl && varDecl->getAttrs().hasAttribute<LazyAttr>() &&
+          accessor->getAccessorKind() == AccessorKind::Get) {
+        F->setSpecialPurpose(SILFunction::Purpose::LazyPropertyGetter);
+      }
     }
     addFunctionAttributes(F, decl->getAttrs(), mod, getOrCreateDeclaration,
                           constant);
diff --git a/lib/SIL/SILPrinter.cpp b/lib/SIL/SILPrinter.cpp
@@ -2444,8 +2444,16 @@ void SILFunction::print(SILPrintContext &PrintCtx) const {
   if (isWithoutActuallyEscapingThunk())
     OS << "[without_actually_escaping] ";
 
-  if (isGlobalInit())
+  switch (getSpecialPurpose()) {
+  case SILFunction::Purpose::None:
+    break;
+  case SILFunction::Purpose::GlobalInit:
     OS << "[global_init] ";
+    break;
+  case SILFunction::Purpose::LazyPropertyGetter:
+    OS << "[lazy_getter] ";
+    break;
+  }
   if (isAlwaysWeakImported())
     OS << "[weak_imported] ";
   auto availability = getAvailabilityForLinkage();
diff --git a/lib/Serialization/DeserializeSIL.cpp b/lib/Serialization/DeserializeSIL.cpp
@@ -511,14 +511,14 @@ SILDeserializer::readSILFunctionChecked(DeclID FID, SILFunction *existingFn,
   IdentifierID replacedFunctionID;
   GenericSignatureID genericSigID;
   unsigned rawLinkage, isTransparent, isSerialized, isThunk,
-      isWithoutactuallyEscapingThunk, isGlobal, inlineStrategy,
+      isWithoutactuallyEscapingThunk, specialPurpose, inlineStrategy,
       optimizationMode, effect, numSpecAttrs, hasQualifiedOwnership,
       isWeakImported, LIST_VER_TUPLE_PIECES(available),
       isDynamic, isExactSelfClass;
   ArrayRef<uint64_t> SemanticsIDs;
   SILFunctionLayout::readRecord(
       scratch, rawLinkage, isTransparent, isSerialized, isThunk,
-      isWithoutactuallyEscapingThunk, isGlobal, inlineStrategy,
+      isWithoutactuallyEscapingThunk, specialPurpose, inlineStrategy,
       optimizationMode, effect, numSpecAttrs, hasQualifiedOwnership,
       isWeakImported, LIST_VER_TUPLE_PIECES(available),
       isDynamic, isExactSelfClass,
@@ -630,7 +630,7 @@ SILDeserializer::readSILFunctionChecked(DeclID FID, SILFunction *existingFn,
     fn->setThunk(IsThunk_t(isThunk));
     fn->setWithoutActuallyEscapingThunk(bool(isWithoutactuallyEscapingThunk));
     fn->setInlineStrategy(Inline_t(inlineStrategy));
-    fn->setGlobalInit(isGlobal == 1);
+    fn->setSpecialPurpose(SILFunction::Purpose(specialPurpose));
     fn->setEffectsKind(EffectsKind(effect));
     fn->setOptimizationMode(OptimizationMode(optimizationMode));
     fn->setAlwaysWeakImported(isWeakImported);
diff --git a/lib/Serialization/ModuleFormat.h b/lib/Serialization/ModuleFormat.h
@@ -55,7 +55,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// 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.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 546; // Avoid conflict with downstream bump
+const uint16_t SWIFTMODULE_VERSION_MINOR = 547; // lazyPropertyGetter flag
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
diff --git a/lib/Serialization/SILFormat.h b/lib/Serialization/SILFormat.h
@@ -273,7 +273,7 @@ namespace sil_block {
                      BCFixed<2>,  // serialized
                      BCFixed<2>,  // thunks: signature optimized/reabstraction
                      BCFixed<1>,  // without_actually_escaping
-                     BCFixed<1>,  // global_init
+                     BCFixed<3>,  // specialPurpose
                      BCFixed<2>,  // inlineStrategy
                      BCFixed<2>,  // optimizationMode
                      BCFixed<3>,  // side effect info.
diff --git a/lib/Serialization/SerializeSIL.cpp b/lib/Serialization/SerializeSIL.cpp
@@ -434,7 +434,7 @@ void SILSerializer::writeSILFunction(const SILFunction &F, bool DeclOnly) {
       Out, ScratchRecord, abbrCode, toStableSILLinkage(Linkage),
       (unsigned)F.isTransparent(), (unsigned)F.isSerialized(),
       (unsigned)F.isThunk(), (unsigned)F.isWithoutActuallyEscapingThunk(),
-      (unsigned)F.isGlobalInit(), (unsigned)F.getInlineStrategy(),
+      (unsigned)F.getSpecialPurpose(), (unsigned)F.getInlineStrategy(),
       (unsigned)F.getOptimizationMode(), (unsigned)F.getEffectsKind(),
       (unsigned)numSpecAttrs, (unsigned)F.hasOwnership(),
       F.isAlwaysWeakImported(), LIST_VER_TUPLE_PIECES(available),
diff --git a/test/SIL/Parser/basic.sil b/test/SIL/Parser/basic.sil
@@ -1651,6 +1651,13 @@ bb0:
   return %0 : $()
 }
 
+// CHECK-LABEL: sil [lazy_getter] @test_lazy_getter
+sil [lazy_getter] @test_lazy_getter : $@convention(thin) () -> () {
+bb0:
+  %0 = tuple ()
+  return %0 : $()
+}
+
 struct EmptyStruct {}
 
 sil @test_empty_destructure : $@convention(thin) () -> () {
diff --git a/test/SIL/Serialization/basic.sil b/test/SIL/Serialization/basic.sil
@@ -58,6 +58,14 @@ entry(%0 : @guaranteed $@callee_guaranteed @substituted <C, D> (@in C, @in D) ->
   return undef : $()
 }
 
+// CHECK-LABEL: sil [lazy_getter] @test_lazy_getter
+sil [lazy_getter] @test_lazy_getter : $@convention(thin) () -> () {
+bb0:
+  %0 = tuple ()
+  return %0 : $()
+}
+
+
 struct EmptyStruct {}
 
 sil @test_empty_destructure : $@convention(thin) () -> () {
diff --git a/test/SILGen/lazy_properties.swift b/test/SILGen/lazy_properties.swift
@@ -2,7 +2,7 @@
 
 // <rdar://problem/17405715> lazy property crashes silgen of implicit memberwise initializer
 
-// CHECK-LABEL: sil hidden [ossa] @$s15lazy_properties19StructWithLazyFieldV4onceSivg : $@convention(method) (@inout StructWithLazyField) -> Int
+// CHECK-LABEL: sil hidden [lazy_getter] [ossa] @$s15lazy_properties19StructWithLazyFieldV4onceSivg : $@convention(method) (@inout StructWithLazyField) -> Int
 
 // CHECK-LABEL: sil hidden [ossa] @$s15lazy_properties19StructWithLazyFieldV4onceSivs : $@convention(method) (Int, @inout StructWithLazyField) -> ()
 
@@ -23,7 +23,7 @@ func test21057425() {
 
 // Anonymous closure parameters in lazy initializer crash SILGen
 
-// CHECK-LABEL: sil hidden [ossa] @$s15lazy_properties22HasAnonymousParametersV1xSivg : $@convention(method) (@inout HasAnonymousParameters) -> Int
+// CHECK-LABEL: sil hidden [lazy_getter] [ossa] @$s15lazy_properties22HasAnonymousParametersV1xSivg : $@convention(method) (@inout HasAnonymousParameters) -> Int
 
 // CHECK-LABEL: sil private [ossa] @$s15lazy_properties22HasAnonymousParametersV1xSivgS2iXEfU_ : $@convention(thin) (Int) -> Int
 
@@ -39,7 +39,7 @@ class LazyClass {
   lazy var x = 0
 }
 
-// CHECK-LABEL: sil hidden [ossa] @$s15lazy_properties9LazyClassC1xSivg : $@convention(method) (@guaranteed LazyClass) -> Int
+// CHECK-LABEL: sil hidden [lazy_getter] [ossa] @$s15lazy_properties9LazyClassC1xSivg : $@convention(method) (@guaranteed LazyClass) -> Int
 // CHECK: ref_element_addr %0 : $LazyClass, #LazyClass.$__lazy_storage_$_x
 // CHECK: return
 
diff --git a/test/SILGen/objc_properties.swift b/test/SILGen/objc_properties.swift
@@ -242,7 +242,7 @@ class HasLazyProperty : NSObject, HasProperty {
   lazy var window = self.instanceMethod()
 }
 
-// CHECK-LABEL: sil hidden [ossa] @$s15objc_properties15HasLazyPropertyC6windowSo8NSObjectCSgvg : $@convention(method) (@guaranteed HasLazyProperty) -> @owned Optional<NSObject> {
+// CHECK-LABEL: sil hidden [lazy_getter] [ossa] @$s15objc_properties15HasLazyPropertyC6windowSo8NSObjectCSgvg : $@convention(method) (@guaranteed HasLazyProperty) -> @owned Optional<NSObject> {
 // CHECK: class_method %0 : $HasLazyProperty, #HasLazyProperty.instanceMethod!1 : (HasLazyProperty) -> () -> NSObject?
 // CHECK: return
 
diff --git a/test/SILGen/opaque_result_type.swift b/test/SILGen/opaque_result_type.swift
@@ -157,7 +157,7 @@ class Sub2 : Base {}
 
 public class D {
    var cond = true
-   // CHECK-LABEL: sil private [ossa] @$s18opaque_result_type1DC1c33_C2C55A4BAF30C3244D4A165D48A91142LLQrvg
+   // CHECK-LABEL: sil private [lazy_getter] [ossa] @$s18opaque_result_type1DC1c33_C2C55A4BAF30C3244D4A165D48A91142LLQrvg
    // CHECK: bb3([[RET:%[0-9]+]] : @owned $Base):
    // CHECH:  return [[RET]]
    // CHECK: } // end sil function '$s18opaque_result_type1DC1c33_C2C55A4BAF30C3244D4A165D48A91142LLQrvg'
diff --git a/test/SILGen/optional_to_bool.swift b/test/SILGen/optional_to_bool.swift
@@ -5,10 +5,10 @@ extension Int: P {}
 
 public class A {}
 public class B: A {
-  // CHECK-LABEL: sil [ossa] @$s16optional_to_bool1BC1x{{[_0-9a-zA-Z]*}}vg
+  // CHECK-LABEL: sil [lazy_getter] [ossa] @$s16optional_to_bool1BC1x{{[_0-9a-zA-Z]*}}vg
   // CHECK:         switch_enum {{%.*}} : $Optional<Int>
   public lazy var x: Int = 0
-  // CHECK-LABEL: sil [ossa] @$s16optional_to_bool1BC1y{{[_0-9a-zA-Z]*}}vg
+  // CHECK-LABEL: sil [lazy_getter] [ossa] @$s16optional_to_bool1BC1y{{[_0-9a-zA-Z]*}}vg
   // CHECK:         switch_enum_addr {{%.*}} : $*Optional<P>
   public lazy var y: P = 0
 }
