Rename @effects to @_effects

@effects is too low a level, and not meant for general usage outside
the standard library. Therefore it deserves to be underscored like
other such attributes.

Author: nuclearace

Diff for: docs/HighLevelSILOptimizations.rst

@@ -313,19 +313,19 @@ Dictionary
 ~~~~~~~~~~
 TBD.
 
-@effects attribute
+@_effects attribute
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-The @effects attribute describes how a function affects "the state of the world".
+The @_effects attribute describes how a function affects "the state of the world".
 More practically how the optimizer can modify the program based on information
 that is provided by the attribute.
 
 Usage:
 
-  @effects(readonly) func foo() { .. }
+  @_effects(readonly) func foo() { .. }
 
 
-The @effects attribute supports the following tags:
+The @_effects attribute supports the following tags:
 
 readnone
 
@@ -363,13 +363,13 @@ releasenone
       }
     }
 
-    @effects(releasenone)
+    @_effects(releasenone)
     func validReleaseNoneFunction(x: Int) -> Int {
       global.x = 5
       return x + 2
     }
 
-    @effects(releasenone)
+    @_effects(releasenone)
     func validReleaseNoneFunction(x: Int) -> Int {
       var notExternallyVisibleObject = SomeObject()
       return x +  notExternallyVisibleObject.x

Diff for: docs/proposals/OptimizerEffects.rst

@@ -96,7 +96,7 @@ don't have a more general term for "release", which refers to any
 release_value operation.
 
 When referring to unspecified state, I will use the syntax
-``@effects(no<effectname>)``. When referring to state reachable via an
+``@_effects(no<effectname>)``. When referring to state reachable via an
 argument, ``@no<effectname> arg``.
 
 Naturally, we also need a syntax for associating effects with
@@ -110,7 +110,7 @@ effects at a call site. For now, we assume the predicate only applies
 to unspecified state and that the bridged object is always self. That
 way we can denote predicated effects as @nonbridged_effects.
 
-In examples, @effects(argonly) means that there are no effects on
+In examples, @_effects(argonly) means that there are no effects on
 unspecified state.
 
 CoW Optimization Requirements
@@ -167,7 +167,7 @@ state.
 
   Note: In terms of low-level SIL attributes such a method will be marked:::
 
-    @effects(argonly)
+    @_effects(argonly)
     @selfeffects(make_unique)
     func makeUnique() {}
 
@@ -230,7 +230,7 @@ state.
 
   Note: In terms of low-level SIL attributes such a method will be marked:::
 
-    @effects(argonly)
+    @_effects(argonly)
     @selfeffects(preserve_unique, nowrite, nocapture, norelease,
                  projects_subobject)
     func getElement(_ index: Int) -> T {}
@@ -297,7 +297,7 @@ state.
 
   Note: In terms of low-level SIL attributes such a method will be marked:::
 
-    @effects(argonly)
+    @_effects(argonly)
     @selfeffects(preserve_unique, nowrite, nocapture, norelease,
                  projects_subobject_addr)
     func getElementAddr(_ index: Int) -> T {}
@@ -320,7 +320,7 @@ state.
 
   Note: In terms of low-level SIL attributes such a method will be marked:::
 
-    @effects(argonly)
+    @_effects(argonly)
     @selfeffects(preserve_unique, nocapture, norelease)
     func appendElementAssumingUnique(@norelease @nowrite elt: T) {}
 
@@ -356,7 +356,7 @@ state.
 
   Note: In terms of low-level SIL attributes such a method will be marked:::
 
-    @effects(argonly, T.release)
+    @_effects(argonly, T.release)
     @selfeffects(preserve_unique, nocapture)
     func setElement(@nowrite e: T, index: Int) {
     }
@@ -536,15 +536,15 @@ Mostly TBD.
 
 The optimizer can only take advantage of user-specified effects before
 they have been inlined. Consequently, the optimizer initially preserves
-calls to annotated @effects() functions. After optimizing for effects
+calls to annotated @_effects() functions. After optimizing for effects
 these functions can be inlined, dropping the effects information.
 
 Without special syntax, specifying a pure function would require::
 
-  @effects(argonly)
+  @_effects(argonly)
   func foo(@noread @nowrite arg)
 
-A shorthand, such as @effects(none) could easily be
+A shorthand, such as @_effects(none) could easily be
 introduced. Typically, this shouldn't be needed because the purity of
 a function can probably be deduced from its argument types given that
 it has no effect on unspecified state. i.e. If the function does not
@@ -576,7 +576,7 @@ example. But there are two situations to be concerned about:
 Solving this requires a system for polymorphic effects. Language
 support for polymorphic effects might look something like this::
 
-  @effects(T.release)
+  @_effects(T.release)
   func foo<T>(t: T) { ... }
 
 This would mean that foo's unspecified effects are bounded by the

Diff for: include/swift/AST/Attr.def

@@ -269,7 +269,7 @@ CONTEXTUAL_DECL_ATTR(weak, ReferenceOwnership,
   DeclModifier |
   NotSerialized, 49)
 CONTEXTUAL_DECL_ATTR_ALIAS(unowned, ReferenceOwnership)
-DECL_ATTR(effects, Effects,
+DECL_ATTR(_effects, Effects,
   OnAbstractFunction |
   UserInaccessible,
   50)

Diff for: include/swift/AST/AttrKind.h

@@ -72,7 +72,7 @@ enum class InlineKind : uint8_t {
 enum : unsigned { NumInlineKindBits =
   countBitsUsed(static_cast<unsigned>(InlineKind::Last_InlineKind)) };
 
-/// This enum represents the possible values of the @effects attribute.
+/// This enum represents the possible values of the @_effects attribute.
 /// These values are ordered from the strongest guarantee to the weakest,
 /// so please do not reorder existing values.
 enum class EffectsKind : uint8_t {

Diff for: include/swift/SIL/SILFunction.h

@@ -587,7 +587,7 @@ class SILFunction
   /// \return the function side effects information.
   EffectsKind getEffectsKind() const { return EffectsKindAttr; }
 
-  /// \return True if the function is annotated with the @effects attribute.
+  /// \return True if the function is annotated with the @_effects attribute.
   bool hasEffectsKind() const {
     return EffectsKindAttr != EffectsKind::Unspecified;
   }

Diff for: include/swift/SILOptimizer/Analysis/SideEffectAnalysis.h

@@ -406,8 +406,8 @@ class FunctionSideEffects {
   }
 
 protected:
-  /// Set the side-effects of a function, which has an @effects attribute.
-  /// Returns true if \a F has an @effects attribute which could be handled.
+  /// Set the side-effects of a function, which has an @_effects attribute.
+  /// Returns true if \a F has an @_effects attribute which could be handled.
   bool setDefinedEffects(SILFunction *F);
 
   /// Set the side-effects of a semantic call.

Diff for: lib/IRGen/GenDecl.cpp

@@ -2222,7 +2222,7 @@ Address IRGenModule::getAddrOfSILGlobalVariable(SILGlobalVariable *var,
 }
 
 /// Return True if the function \p f is a 'readonly' function. Checking
-/// for the SIL @effects(readonly) attribute is not enough because this
+/// for the SIL @_effects(readonly) attribute is not enough because this
 /// definition does not match the definition of the LLVM readonly function
 /// attribute. In this function we do the actual check.
 static bool isReadOnlyFunction(SILFunction *f) {
@@ -2235,11 +2235,11 @@ static bool isReadOnlyFunction(SILFunction *f) {
   auto Eff = f->getEffectsKind();
 
   // Swift's readonly does not automatically match LLVM's readonly.
-  // Swift SIL optimizer relies on @effects(readonly) to remove e.g.
+  // Swift SIL optimizer relies on @_effects(readonly) to remove e.g.
   // dead code remaining from initializers of strings or dictionaries
   // of variables that are not used. But those initializers are often
   // not really readonly in terms of LLVM IR. For example, the
-  // Dictionary.init() is marked as @effects(readonly) in Swift, but
+  // Dictionary.init() is marked as @_effects(readonly) in Swift, but
   // it does invoke reference-counting operations.
   if (Eff == EffectsKind::ReadOnly || Eff == EffectsKind::ReadNone) {
     // TODO: Analyze the body of function f and return true if it is

Diff for: lib/SILOptimizer/Analysis/SideEffectAnalysis.cpp

@@ -334,7 +334,7 @@ bool FunctionSideEffects::setDefinedEffects(SILFunction *F) {
     case EffectsKind::ReadNone:
       return true;
     case EffectsKind::ReadOnly:
-      // @effects(readonly) is worthless if we have owned parameters, because
+      // @_effects(readonly) is worthless if we have owned parameters, because
       // the release inside the callee may call a deinit, which itself can do
       // anything.
       if (!F->hasOwnedParameters()) {
@@ -356,7 +356,7 @@ bool FunctionSideEffects::summarizeFunction(SILFunction *F) {
   if (!F->empty())
     ParamEffects.resize(F->getArguments().size());
 
-  // Handle @effects attributes
+  // Handle @_effects attributes
   if (setDefinedEffects(F)) {
     DEBUG(llvm::dbgs() << "  -- has defined effects " << F->getName() << '\n');
     return true;
@@ -463,7 +463,7 @@ bool FunctionSideEffects::summarizeCall(FullApplySite fullApply) {
   }
 
   if (SILFunction *SingleCallee = fullApply.getReferencedFunction()) {
-    // Does the function have any @effects?
+    // Does the function have any @_effects?
     if (setDefinedEffects(SingleCallee))
       return true;
   }

Diff for: lib/SILOptimizer/Transforms/PerformanceInliner.cpp

@@ -924,7 +924,7 @@ class SILPerformanceInlinerPass : public SILFunctionTransform {
 } // end anonymous namespace
 
 /// Create an inliner pass that does not inline functions that are marked with
-/// the @_semantics, @effects or global_init attributes.
+/// the @_semantics, @_effects or global_init attributes.
 SILTransform *swift::createEarlyInliner() {
   return new SILPerformanceInlinerPass(
     InlineSelection::NoSemanticsAndGlobalInit, "Early");
@@ -937,7 +937,7 @@ SILTransform *swift::createPerfInliner() {
 }
 
 /// Create an inliner pass that inlines all functions that are marked with
-/// the @_semantics, @effects or global_init attributes.
+/// the @_semantics, @_effects or global_init attributes.
 SILTransform *swift::createLateInliner() {
   return new SILPerformanceInlinerPass(InlineSelection::Everything, "Late");
 }

Diff for: lib/SILOptimizer/Utils/PerformanceInlinerUtils.cpp

@@ -669,7 +669,7 @@ SILFunction *swift::getEligibleFunction(FullApplySite AI,
   auto ModuleName = Callee->getModule().getSwiftModule()->getName().str();
   bool IsInStdlib = (ModuleName == STDLIB_NAME || ModuleName == SWIFT_ONONE_SUPPORT);
 
-  // Don't inline functions that are marked with the @_semantics or @effects
+  // Don't inline functions that are marked with the @_semantics or @_effects
   // attribute if the inliner is asked not to inline them.
   if (Callee->hasSemanticsAttrs() || Callee->hasEffectsKind()) {
     if (WhatToInline == InlineSelection::NoSemanticsAndGlobalInit) {

Diff for: stdlib/public/core/Character.swift

@@ -130,7 +130,7 @@ extension Character
   }
 
   @inlinable // FIXME(sil-serialize-all)
-  @effects(readonly)
+  @_effects(readonly)
   public init(_builtinUnicodeScalarLiteral value: Builtin.Int32) {
     self.init(Unicode.Scalar(_builtinUnicodeScalarLiteral: value))
   }
@@ -139,7 +139,7 @@ extension Character
   // integer constant in case of small character literals.
   @inlinable // FIXME(sil-serialize-all)
   @inline(__always)
-  @effects(readonly)
+  @_effects(readonly)
   public init(
     _builtinExtendedGraphemeClusterLiteral start: Builtin.RawPointer,
     utf8CodeUnitCount: Builtin.Word,
@@ -194,7 +194,7 @@ extension Character
   // integer constant in case of small character literals.
   @inlinable // FIXME(sil-serialize-all)
   @inline(__always)
-  @effects(readonly)
+  @_effects(readonly)
   public init(
     _builtinExtendedGraphemeClusterLiteral start: Builtin.RawPointer,
     utf16CodeUnitCount: Builtin.Word
@@ -483,7 +483,7 @@ extension Character: Hashable {
   ///
   /// - Parameter hasher: The hasher to use when combining the components
   ///   of this instance.
-  @effects(releasenone)
+  @_effects(releasenone)
   public func hash(into hasher: inout Hasher) {
     // FIXME(performance): constructing a temporary string is extremely
     // wasteful and inefficient.

Diff for: stdlib/public/core/Dictionary.swift

@@ -798,7 +798,7 @@ extension Dictionary: ExpressibleByDictionaryLiteral {
   /// - Parameter elements: The key-value pairs that will make up the new
   ///   dictionary. Each key in `elements` must be unique.
   @inlinable // FIXME(sil-serialize-all)
-  @effects(readonly)
+  @_effects(readonly)
   public init(dictionaryLiteral elements: (Key, Value)...) {
     self.init(_nativeBuffer: _NativeDictionaryBuffer.fromArray(elements))
   }