Performance annotations: add attributes @_noLocks and @_noAllocation

eeckstein · eeckstein · commit 8229b374b165 · 2021-10-28T18:43:14.000+02:00
diff --git a/docs/ReferenceGuides/UnderscoredAttributes.md b/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.
+
diff --git a/docs/SIL.rst b/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
 ~~~~~~~~~~~~
diff --git a/include/swift/AST/Attr.def b/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.
 
diff --git a/include/swift/SIL/SILFunction.h b/include/swift/SIL/SILFunction.h
@@ -60,6 +60,12 @@ enum IsExactSelfClass_t {
   IsExactSelfClass,
 };
 
+enum class PerformanceConstraints : uint8_t {
+  None = 0,
+  NoAllocation = 1,
+  NoLocks = 2,
+};
+
 class SILSpecializeAttr final {
   friend SILFunction;
 public:
@@ -232,6 +238,8 @@ class SILFunction
 
   Purpose specialPurpose = Purpose::None;
 
+  PerformanceConstraints perfConstraints = PerformanceConstraints::None;
+
   /// This is the number of uses of this SILFunction inside the SIL.
   /// It does not include references from debug scopes.
   unsigned RefCount = 0;
@@ -813,6 +821,12 @@ class SILFunction
     OptMode = unsigned(mode);
   }
 
+  PerformanceConstraints getPerfConstraints() const { return perfConstraints; }
+
+  void setPerfConstraints(PerformanceConstraints perfConstr) {
+    perfConstraints = perfConstr;
+  }
+
   /// \returns True if the function is optimizable (i.e. not marked as no-opt),
   ///          or is raw SIL (so that the mandatory passes still run).
   bool shouldOptimize() const;
diff --git a/lib/SIL/IR/SILFunction.cpp b/lib/SIL/IR/SILFunction.cpp
@@ -187,6 +187,7 @@ void SILFunction::init(SILLinkage Linkage, StringRef Name,
   this->IsStaticallyLinked = false;
   this->IsWithoutActuallyEscapingThunk = false;
   this->OptMode = unsigned(OptimizationMode::NotSet);
+  this->perfConstraints = PerformanceConstraints::None;
   this->EffectsKindAttr = unsigned(E);
   assert(!Transparent || !IsDynamicReplaceable);
   validateSubclassScope(classSubclassScope, isThunk, nullptr);
diff --git a/lib/SIL/IR/SILFunctionBuilder.cpp b/lib/SIL/IR/SILFunctionBuilder.cpp
@@ -105,6 +105,12 @@ void SILFunctionBuilder::addFunctionAttributes(
   if (Attrs.hasAttribute<SILGenNameAttr>() || Attrs.hasAttribute<CDeclAttr>())
     F->setHasCReferences(true);
 
+  if (Attrs.hasAttribute<NoLocksAttr>()) {
+    F->setPerfConstraints(PerformanceConstraints::NoLocks);
+  } else if (Attrs.hasAttribute<NoAllocationAttr>()) {
+    F->setPerfConstraints(PerformanceConstraints::NoAllocation);
+  }
+
   // Validate `@differentiable` attributes by calling `getParameterIndices`.
   // This is important for:
   // - Skipping invalid `@differentiable` attributes in non-primary files.
diff --git a/lib/SIL/IR/SILPrinter.cpp b/lib/SIL/IR/SILPrinter.cpp
@@ -2871,6 +2871,13 @@ void SILFunction::print(SILPrintContext &PrintCtx) const {
     default: break;
   }
 
+  PerformanceConstraints perf = getPerfConstraints();
+  switch (perf) {
+    case PerformanceConstraints::None:         break;
+    case PerformanceConstraints::NoLocks:      OS << "[no_locks] "; break;
+    case PerformanceConstraints::NoAllocation: OS << "[no_allocation] "; break;
+  }
+
   if (getEffectsKind() == EffectsKind::ReadOnly)
     OS << "[readonly] ";
   else if (getEffectsKind() == EffectsKind::ReadNone)
diff --git a/lib/SIL/Parser/ParseSIL.cpp b/lib/SIL/Parser/ParseSIL.cpp
@@ -943,6 +943,7 @@ static bool parseDeclSILOptional(bool *isTransparent,
                                  SILFunction::Purpose *specialPurpose,
                                  Inline_t *inlineStrategy,
                                  OptimizationMode *optimizationMode,
+                                 PerformanceConstraints *perfConstraints,
                                  bool *isLet,
                                  bool *isWeakImported,
                                  AvailabilityContext *availability,
@@ -1019,6 +1020,10 @@ static bool parseDeclSILOptional(bool *isTransparent,
       *optimizationMode = OptimizationMode::ForSpeed;
     else if (optimizationMode && SP.P.Tok.getText() == "Osize")
       *optimizationMode = OptimizationMode::ForSize;
+    else if (perfConstraints && SP.P.Tok.getText() == "no_locks")
+      *perfConstraints = PerformanceConstraints::NoLocks;
+    else if (perfConstraints && SP.P.Tok.getText() == "no_allocation")
+      *perfConstraints = PerformanceConstraints::NoAllocation;
     else if (inlineStrategy && SP.P.Tok.getText() == "always_inline")
       *inlineStrategy = AlwaysInline;
     else if (MRK && SP.P.Tok.getText() == "readnone")
@@ -6187,6 +6192,7 @@ bool SILParserState::parseDeclSIL(Parser &P) {
   bool isWithoutActuallyEscapingThunk = false;
   Inline_t inlineStrategy = InlineDefault;
   OptimizationMode optimizationMode = OptimizationMode::NotSet;
+  PerformanceConstraints perfConstr = PerformanceConstraints::None;
   SmallVector<std::string, 1> Semantics;
   SmallVector<ParsedSpecAttr, 4> SpecAttrs;
   ValueDecl *ClangDecl = nullptr;
@@ -6198,7 +6204,7 @@ bool SILParserState::parseDeclSIL(Parser &P) {
           &isTransparent, &isSerialized, &isCanonical, &hasOwnershipSSA,
           &isThunk, &isDynamic, &isExactSelfClass, &DynamicallyReplacedFunction,
           &objCReplacementFor, &specialPurpose, &inlineStrategy,
-          &optimizationMode, nullptr, &isWeakImported, &availability,
+          &optimizationMode, &perfConstr, nullptr, &isWeakImported, &availability,
           &isWithoutActuallyEscapingThunk, &Semantics,
           &SpecAttrs, &ClangDecl, &MRK, FunctionState, M) ||
       P.parseToken(tok::at_sign, diag::expected_sil_function_name) ||
@@ -6242,6 +6248,7 @@ bool SILParserState::parseDeclSIL(Parser &P) {
       isWithoutActuallyEscapingThunk);
     FunctionState.F->setInlineStrategy(inlineStrategy);
     FunctionState.F->setOptimizationMode(optimizationMode);
+    FunctionState.F->setPerfConstraints(perfConstr);
     FunctionState.F->setEffectsKind(MRK);
     if (ClangDecl)
       FunctionState.F->setClangNodeOwner(ClangDecl);
@@ -6410,7 +6417,7 @@ bool SILParserState::parseSILGlobal(Parser &P) {
   if (parseSILLinkage(GlobalLinkage, P) ||
       parseDeclSILOptional(nullptr, &isSerialized, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr,
-                           nullptr, nullptr,
+                           nullptr, nullptr, nullptr,
                            &isLet, nullptr, nullptr, nullptr, nullptr, nullptr,
                            nullptr, nullptr, State, M) ||
       P.parseToken(tok::at_sign, diag::expected_sil_value_name) ||
@@ -6462,7 +6469,7 @@ bool SILParserState::parseSILProperty(Parser &P) {
   if (parseDeclSILOptional(nullptr, &Serialized, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
-                           nullptr, nullptr, nullptr, SP, M))
+                           nullptr, nullptr, nullptr, nullptr, SP, M))
     return true;
   
   ValueDecl *VD;
@@ -6531,7 +6538,7 @@ bool SILParserState::parseSILVTable(Parser &P) {
   if (parseDeclSILOptional(nullptr, &Serialized, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
-                           nullptr, nullptr, nullptr,
+                           nullptr, nullptr, nullptr, nullptr,
                            VTableState, M))
     return true;
 
@@ -7037,7 +7044,7 @@ bool SILParserState::parseSILWitnessTable(Parser &P) {
   if (parseDeclSILOptional(nullptr, &isSerialized, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
                            nullptr, nullptr, nullptr, nullptr, nullptr, nullptr,
-                           nullptr, nullptr, nullptr,
+                           nullptr, nullptr, nullptr, nullptr,
                            WitnessState, M))
     return true;
 
diff --git a/lib/Sema/TypeCheckAttr.cpp b/lib/Sema/TypeCheckAttr.cpp
@@ -92,6 +92,8 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
   IGNORED_ATTR(RequiresStoredPropertyInits)
   IGNORED_ATTR(RestatedObjCConformance)
   IGNORED_ATTR(Semantics)
+  IGNORED_ATTR(NoLocks)
+  IGNORED_ATTR(NoAllocation)
   IGNORED_ATTR(EmitAssemblyVisionRemarks)
   IGNORED_ATTR(ShowInInterface)
   IGNORED_ATTR(SILGenName)
diff --git a/lib/Sema/TypeCheckDeclOverride.cpp b/lib/Sema/TypeCheckDeclOverride.cpp
@@ -1466,6 +1466,8 @@ namespace  {
     UNINTERESTING_ATTR(InheritsConvenienceInitializers)
     UNINTERESTING_ATTR(Inline)
     UNINTERESTING_ATTR(Optimize)
+    UNINTERESTING_ATTR(NoLocks)
+    UNINTERESTING_ATTR(NoAllocation)
     UNINTERESTING_ATTR(Inlinable)
     UNINTERESTING_ATTR(Effects)
     UNINTERESTING_ATTR(Final)
diff --git a/lib/Serialization/DeserializeSIL.cpp b/lib/Serialization/DeserializeSIL.cpp
@@ -526,14 +526,16 @@ SILDeserializer::readSILFunctionChecked(DeclID FID, SILFunction *existingFn,
   GenericSignatureID genericSigID;
   unsigned rawLinkage, isTransparent, isSerialized, isThunk,
       isWithoutactuallyEscapingThunk, specialPurpose, inlineStrategy,
-      optimizationMode, subclassScope, hasCReferences, effect, numSpecAttrs,
+      optimizationMode, perfConstr,
+      subclassScope, hasCReferences, effect, numSpecAttrs,
       hasQualifiedOwnership, isWeakImported, LIST_VER_TUPLE_PIECES(available),
       isDynamic, isExactSelfClass;
   ArrayRef<uint64_t> SemanticsIDs;
   SILFunctionLayout::readRecord(
       scratch, rawLinkage, isTransparent, isSerialized, isThunk,
       isWithoutactuallyEscapingThunk, specialPurpose, inlineStrategy,
-      optimizationMode, subclassScope, hasCReferences, effect, numSpecAttrs,
+      optimizationMode, perfConstr,
+      subclassScope, hasCReferences, effect, numSpecAttrs,
       hasQualifiedOwnership, isWeakImported, LIST_VER_TUPLE_PIECES(available),
       isDynamic, isExactSelfClass, funcTyID, replacedFunctionID, genericSigID,
       clangNodeOwnerID, SemanticsIDs);
@@ -656,6 +658,7 @@ SILDeserializer::readSILFunctionChecked(DeclID FID, SILFunction *existingFn,
     fn->setSpecialPurpose(SILFunction::Purpose(specialPurpose));
     fn->setEffectsKind(EffectsKind(effect));
     fn->setOptimizationMode(OptimizationMode(optimizationMode));
+    fn->setPerfConstraints((PerformanceConstraints)perfConstr);
     fn->setAlwaysWeakImported(isWeakImported);
     fn->setClassSubclassScope(SubclassScope(subclassScope));
     fn->setHasCReferences(bool(hasCReferences));
@@ -2921,14 +2924,16 @@ bool SILDeserializer::hasSILFunction(StringRef Name,
   GenericSignatureID genericSigID;
   unsigned rawLinkage, isTransparent, isSerialized, isThunk,
       isWithoutactuallyEscapingThunk, isGlobal, inlineStrategy,
-      optimizationMode, subclassScope, hasCReferences, effect, numSpecAttrs,
+      optimizationMode, perfConstr,
+      subclassScope, hasCReferences, 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,
-      optimizationMode, subclassScope, hasCReferences, effect, numSpecAttrs,
+      optimizationMode, perfConstr,
+      subclassScope, hasCReferences, effect, numSpecAttrs,
       hasQualifiedOwnership, isWeakImported, LIST_VER_TUPLE_PIECES(available),
       isDynamic, isExactSelfClass, funcTyID, replacedFunctionID, genericSigID,
       clangOwnerID, SemanticsIDs);
diff --git a/lib/Serialization/ModuleFormat.h b/lib/Serialization/ModuleFormat.h
@@ -56,7 +56,7 @@ 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 = 637; // @_noImplicitCopy
+const uint16_t SWIFTMODULE_VERSION_MINOR = 638; // PerformanceConstraints
 
 /// 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
@@ -283,6 +283,7 @@ namespace sil_block {
                      BCFixed<3>,  // specialPurpose
                      BCFixed<2>,  // inlineStrategy
                      BCFixed<2>,  // optimizationMode
+                     BCFixed<3>,  // perfConstraints
                      BCFixed<2>,  // classSubclassScope
                      BCFixed<1>,  // hasCReferences
                      BCFixed<3>,  // side effect info.
diff --git a/lib/Serialization/SerializeSIL.cpp b/lib/Serialization/SerializeSIL.cpp
@@ -484,7 +484,8 @@ void SILSerializer::writeSILFunction(const SILFunction &F, bool DeclOnly) {
       (unsigned)F.isTransparent(), (unsigned)F.isSerialized(),
       (unsigned)F.isThunk(), (unsigned)F.isWithoutActuallyEscapingThunk(),
       (unsigned)F.getSpecialPurpose(), (unsigned)F.getInlineStrategy(),
-      (unsigned)F.getOptimizationMode(), (unsigned)F.getClassSubclassScope(),
+      (unsigned)F.getOptimizationMode(), (unsigned)F.getPerfConstraints(),
+      (unsigned)F.getClassSubclassScope(),
       (unsigned)F.hasCReferences(), (unsigned)F.getEffectsKind(),
       (unsigned)numSpecAttrs, (unsigned)F.hasOwnership(),
       F.isAlwaysWeakImported(), LIST_VER_TUPLE_PIECES(available),
diff --git a/test/SIL/Parser/attributes.sil b/test/SIL/Parser/attributes.sil
@@ -6,6 +6,20 @@ bb0:
   return undef : $()
 }
 
+// CHECK-LABEL: sil [no_allocation] [ossa] @test_no_allocation : $@convention(thin) () -> () {
+sil [no_allocation] [ossa] @test_no_allocation : $@convention(thin) () -> () {
+bb0:
+  %1 = tuple ()
+  return %1 : $()
+}
+
+// CHECK-LABEL: sil [no_locks] [ossa] @test_no_locks : $@convention(thin) () -> () {
+sil [no_locks] [ossa] @test_no_locks : $@convention(thin) () -> () {
+bb0:
+  %1 = tuple ()
+  return %1 : $()
+}
+
 // Make sure we don't try to parse the Swift decl as '@owned() func baz()'.
 sil @bar : $@convention(thin) () -> @owned ()
 func baz()
diff --git a/test/SIL/Serialization/basic.sil b/test/SIL/Serialization/basic.sil
@@ -90,6 +90,20 @@ bb0(%0 : $Builtin.NativeObject):
   return %1 : $Builtin.NativeObject
 }
 
+// CHECK-LABEL: sil [no_allocation] [ossa] @test_no_allocation : $@convention(thin) () -> () {
+sil [no_allocation] [ossa] @test_no_allocation : $@convention(thin) () -> () {
+bb0:
+  %1 = tuple ()
+  return %1 : $()
+}
+
+// CHECK-LABEL: sil [no_locks] [ossa] @test_no_locks : $@convention(thin) () -> () {
+sil [no_locks] [ossa] @test_no_locks : $@convention(thin) () -> () {
+bb0:
+  %1 = tuple ()
+  return %1 : $()
+}
+
 // CHECK-LABEL: sil [ossa] @test_pointer_to_address : $@convention(thin) (Builtin.RawPointer, Builtin.Int64) -> () {
 // CHECK:   pointer_to_address %0 : $Builtin.RawPointer to [strict] $*Builtin.Int64
 // CHECK:   pointer_to_address %0 : $Builtin.RawPointer to [invariant] $*Builtin.Int64
