AST: Introduce @_inlineable attribute

This attribute causes a function's body to be serialized, but unlike
@_transparent and @inline(__always), does not force it to be inlined.

Author: slavapestov

include/swift/AST/Attr.def

@@ -164,9 +164,13 @@ SIMPLE_DECL_ATTR(nonobjc, NonObjC,
 SIMPLE_DECL_ATTR(_fixed_layout, FixedLayout,
                  OnVar | OnClass | OnStruct | OnEnum | UserInaccessible, 31)
 
+SIMPLE_DECL_ATTR(_inlineable, Inlineable,
+                 OnVar | OnSubscript | OnFunc | OnConstructor | OnDestructor |
+                 UserInaccessible, 32)
+
 DECL_ATTR(_specialize, Specialize,
           OnConstructor | OnFunc | AllowMultipleAttributes | LongAttribute
-          | UserInaccessible, 32)
+          | UserInaccessible, 33)
 
 // Non-serialized attributes.
 

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 = 281; // Last change: complete witnesses
+const uint16_t VERSION_MINOR = 282; // Last change: @_inlineable
 
 using DeclID = PointerEmbeddedInt<unsigned, 31>;
 using DeclIDField = BCFixed<31>;

lib/AST/DeclContext.cpp

@@ -503,21 +503,31 @@ bool DeclContext::isValidGenericContext() const {
 /// are used.
 ResilienceExpansion DeclContext::getResilienceExpansion() const {
   for (const auto *dc = this; dc->isLocalContext(); dc = dc->getParent()) {
-    if (auto *func = dyn_cast<AbstractFunctionDecl>(dc)) {
+    if (auto *AFD = dyn_cast<AbstractFunctionDecl>(dc)) {
       // If the function is not externally visible, we will not be serializing
       // its body.
-      if (!func->getDeclContext()->isLocalContext() &&
-          func->getEffectiveAccess() < Accessibility::Public)
+      if (!AFD->getDeclContext()->isLocalContext() &&
+          AFD->getEffectiveAccess() < Accessibility::Public)
         break;
 
       // Bodies of public transparent and always-inline functions are
       // serialized, so use conservative access patterns.
-      if (func->isTransparent())
+      if (AFD->isTransparent())
         return ResilienceExpansion::Minimal;
 
-      if (auto attr = func->getAttrs().getAttribute<InlineAttr>())
+      if (AFD->getAttrs().hasAttribute<InlineableAttr>())
+        return ResilienceExpansion::Minimal;
+
+      if (auto attr = AFD->getAttrs().getAttribute<InlineAttr>())
         if (attr->getKind() == InlineKind::Always)
           return ResilienceExpansion::Minimal;
+
+      // If a property or subscript is @_fragile, the accessors are
+      // @_fragile also.
+      if (auto FD = dyn_cast<FuncDecl>(AFD))
+        if (auto *ASD = FD->getAccessorStorageDecl())
+          if (ASD->getAttrs().getAttribute<InlineableAttr>())
+            return ResilienceExpansion::Minimal;
     }
   }
 

lib/Sema/TypeCheckAttr.cpp

@@ -57,6 +57,7 @@ class AttributeEarlyChecker : public AttributeVisitor<AttributeEarlyChecker> {
   IGNORED_ATTR(FixedLayout)
   IGNORED_ATTR(Infix)
   IGNORED_ATTR(Inline)
+  IGNORED_ATTR(Inlineable)
   IGNORED_ATTR(NSApplicationMain)
   IGNORED_ATTR(NSCopying)
   IGNORED_ATTR(NonObjC)
@@ -688,18 +689,18 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
 
     IGNORED_ATTR(AutoClosure)
     IGNORED_ATTR(Alignment)
-    IGNORED_ATTR(SILGenName)
+    IGNORED_ATTR(Convenience)
     IGNORED_ATTR(Dynamic)
+    IGNORED_ATTR(Effects)
     IGNORED_ATTR(Exported)
-    IGNORED_ATTR(Convenience)
+    IGNORED_ATTR(FixedLayout)
     IGNORED_ATTR(GKInspectable)
     IGNORED_ATTR(IBDesignable)
     IGNORED_ATTR(IBInspectable)
     IGNORED_ATTR(IBOutlet) // checked early.
     IGNORED_ATTR(Indirect)
     IGNORED_ATTR(Inline)
-    IGNORED_ATTR(Effects)
-    IGNORED_ATTR(FixedLayout)
+    IGNORED_ATTR(Inlineable)
     IGNORED_ATTR(Lazy)      // checked early.
     IGNORED_ATTR(LLDBDebuggerFunction)
     IGNORED_ATTR(Mutating)
@@ -716,6 +717,7 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
     IGNORED_ATTR(Override)
     IGNORED_ATTR(RawDocComment)
     IGNORED_ATTR(Semantics)
+    IGNORED_ATTR(SILGenName)
     IGNORED_ATTR(Transparent)
     IGNORED_ATTR(SynthesizedProtocol)
     IGNORED_ATTR(RequiresStoredPropertyInits)

lib/Sema/TypeCheckDecl.cpp

@@ -5864,6 +5864,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     UNINTERESTING_ATTR(IBOutlet)
     UNINTERESTING_ATTR(Indirect)
     UNINTERESTING_ATTR(Inline)
+    UNINTERESTING_ATTR(Inlineable)
     UNINTERESTING_ATTR(Effects)
     UNINTERESTING_ATTR(FixedLayout)
     UNINTERESTING_ATTR(Lazy)

test/SILGen/inlineable_attribute.swift

@@ -0,0 +1,26 @@
+// RUN: %target-swift-frontend -emit-silgen -emit-verbose-sil %s | %FileCheck %s
+
+// CHECK-LABEL: sil [fragile] @_TF20inlineable_attribute15fragileFunctionFT_T_ : $@convention(thin) () -> ()
+@_inlineable public func fragileFunction() {
+
+}
+
+public struct MySt {
+  // CHECK-LABEL: sil [fragile] @_TFV20inlineable_attribute4MySt6methodfT_T_ : $@convention(method) (MySt) -> ()
+  @_inlineable public func method() {}
+
+  // CHECK-LABEL: sil [fragile] @_TFV20inlineable_attribute4MyStg8propertySi : $@convention(method) (MySt) -> Int
+  @_inlineable public var property: Int {
+    return 5
+  }
+
+  // CHECK-LABEL: sil [fragile] @_TFV20inlineable_attribute4MyStg9subscriptFSiSi : $@convention(method) (Int, MySt) -> Int
+  @_inlineable public subscript(x: Int) -> Int {
+    return x
+  }
+}
+
+public class MyCls {
+  // CHECK-LABEL: sil [fragile] @_TFC20inlineable_attribute5MyClsD : $@convention(method) (@owned MyCls) -> ()
+  @_inlineable deinit {}
+}

test/SILGen/transparent_attribute.swift

@@ -8,8 +8,8 @@ func useTransparentFuncWithDefaultArgument() -> Int {
   return transparentFuncWithDefaultArgument();
 
   // CHECK-LABEL: sil hidden @_TF21transparent_attribute37useTransparentFuncWithDefaultArgumentFT_Si
-  // CHECK: apply {{.*}} line:10:44
-  // CHECK: apply {{.*}} line:10:10
+  // CHECK: apply {{.*}} line:8:44
+  // CHECK: apply {{.*}} line:8:10
   // CHECK: return
 
 }
@@ -21,9 +21,9 @@ func useTransparentFuncWithoutDefaultArgument() -> Int {
   return transparentFuncWithoutDefaultArgument();
 
   // CHECK-LABEL: sil hidden @_TF21transparent_attribute40useTransparentFuncWithoutDefaultArgumentFT_Si
-  // CHECK: apply {{.*}} line:23:47
+  // CHECK: apply {{.*}} line:21:47
   // CHECK-NOT: transparent
-  // CHECK: apply {{.*}} line:23:10
+  // CHECK: apply {{.*}} line:21:10
   // CHECK: return
 
 }
@@ -40,7 +40,7 @@ func testStructWithTranspConstructor() -> StructWithTranspConstructor {
 
   // testStructWithTranspConstructor
   // CHECK-APPLY: _T21transparent_attribute31testStructWithTranspConstructorFT_VS_27StructWithTranspConstructor
-  // CHECK: apply {{.*}} line:38:10
+  // CHECK: apply {{.*}} line:36:10
 
 }