Merge pull request swiftlang#39902 from eeckstein/performance-annotations

First prototype of Performance Annotations

Author: eeckstein

docs/ReferenceGuides/UnderscoredAttributes.md

@@ -625,3 +625,12 @@ for more details.
 
 Marks a var decl as a variable that must be copied explicitly using the builtin
 function Builtin.copy.
+
+## `@_noAllocation`, `@_noLocks`
+
+These attributes are performance annotations. If a function is annotated with
+such an attribute, the compiler issues a diagnostic message if the function
+calls a runtime function which allocates memory or locks, respectively.
+The `@_noLocks` attribute implies `@_noAllocation` because a memory allocation
+also locks.
+

docs/SIL.rst

@@ -1107,6 +1107,15 @@ Specifies for which types specialized code should be generated.
   sil-function-attribute ::= '[clang "' identifier '"]'
 
 The clang node owner.
+::
+
+  sil-function-attribute ::= '[' performance-constraint ']'
+  performance-constraint :: 'no_locks'
+  performance-constraint :: 'no_allocation'
+
+Specifies the performance constraints for the function, which defines which type
+of runtime functions are allowed to be called from the function.
+
 
 Basic Blocks
 ~~~~~~~~~~~~

include/swift/AST/Attr.def

@@ -679,6 +679,16 @@ SIMPLE_DECL_ATTR(_noImplicitCopy, NoImplicitCopy,
   OnVar,
   122)
 
+SIMPLE_DECL_ATTR(_noLocks, NoLocks,
+  OnAbstractFunction | OnSubscript | UserInaccessible |
+  ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
+  123)
+
+SIMPLE_DECL_ATTR(_noAllocation, NoAllocation,
+  OnAbstractFunction | OnSubscript | UserInaccessible |
+  ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
+  124)
+
 // If you're adding a new underscored attribute here, please document it in
 // docs/ReferenceGuides/UnderscoredAttributes.md.
 

include/swift/AST/DiagnosticsSIL.def

@@ -311,6 +311,34 @@ WARNING(warn_dead_weak_store,none,
         "weak reference will always be nil because the referenced object is "
         "deallocated here", ())
 
+// performance diagnostics
+ERROR(performance_annotations_not_enabled,none,
+      "use -experimental-performance-annotations to enable performance annotations", ())
+ERROR(performance_dynamic_casting,none,
+      "dynamic casting can lock or allocate", ())
+ERROR(performance_metadata,none,
+      "%0 can cause metadata allocation or locks", (StringRef))
+ERROR(performance_metadata_type,none,
+      "Using type %0 can cause metadata allocation or locks", (Type))
+ERROR(performance_allocating,none,
+      "%0 can cause an allocation", (StringRef))
+ERROR(performance_deallocating,none,
+      "%0 can cause an deallocation", (StringRef))
+ERROR(performance_deallocating_type,none,
+      "%0 a value of type %1 can cause a deallocation", (StringRef, Type))
+ERROR(performance_locking,none,
+      "%0 can cause locking", (StringRef))
+ERROR(performance_arc,none,
+      "this code performs reference counting operations which can cause locking", ())
+ERROR(performance_objectivec,none,
+      "calls of Objective-C methods can have unpredictable performance", ())
+ERROR(performance_unknown_callees,none,
+      "called function is not known at compile time and can have unpredictable performance", ())
+ERROR(performance_callee_unavailable,none,
+      "called function is not availbale in this module and can have unpredictable performance", ())
+NOTE(performance_called_from,none,
+      "called from here", ())
+
 // 'transparent' diagnostics
 ERROR(circular_transparent,none,
       "inlining 'transparent' functions forms circular loop", ())

include/swift/AST/SILOptions.h

@@ -78,7 +78,10 @@ class SILOptions {
 
   /// Controls whether cross module optimization is enabled.
   bool CrossModuleOptimization = false;
-  
+
+  /// Enables experimental performance annotations.
+  bool EnablePerformanceAnnotations = false;
+
   /// Controls whether or not paranoid verification checks are run.
   bool VerifyAll = false;
 

include/swift/AST/SemanticAttrs.def

@@ -115,5 +115,7 @@ SEMANTICS_ATTR(OBJC_FORBID_ASSOCIATED_OBJECTS, "objc.forbidAssociatedObjects")
 
 SEMANTICS_ATTR(LIFETIMEMANAGEMENT_MOVE, "lifetimemanagement.move")
 
+SEMANTICS_ATTR(NO_PERFORMANCE_ANALYSIS, "no_performance_analysis")
+
 #undef SEMANTICS_ATTR
 

include/swift/Option/Options.td

@@ -798,6 +798,10 @@ def CrossModuleOptimization : Flag<["-"], "cross-module-optimization">,
   Flags<[HelpHidden, FrontendOption]>,
   HelpText<"Perform cross-module optimization">;
 
+def ExperimentalPerformanceAnnotations : Flag<["-"], "experimental-performance-annotations">,
+  Flags<[HelpHidden, FrontendOption]>,
+  HelpText<"Perform cross-module optimization">;
+
 def RemoveRuntimeAsserts : Flag<["-"], "remove-runtime-asserts">,
   Flags<[FrontendOption]>,
   HelpText<"Remove runtime safety checks.">;

include/swift/Runtime/RuntimeFnWrappersGen.h

@@ -16,6 +16,7 @@
 #ifndef SWIFT_RUNTIME_RUNTIMEFNWRAPPERSGEN_H
 #define SWIFT_RUNTIME_RUNTIMEFNWRAPPERSGEN_H
 
+#include "swift/SIL/RuntimeEffect.h"
 #include "llvm/IR/Module.h"
 #include "llvm/ADT/ArrayRef.h"