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7a251af60c
executing unknown code This means we have to claw back some performance by recognizing harmless releases. Such as releases on types we known don't call a deinit with unknown side-effects. rdar://143497196 rdar://143141695
136 lines
4.3 KiB
C++
136 lines
4.3 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include "swift/SILOptimizer/Analysis/DestructorAnalysis.h"
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#include "swift/SIL/SILInstruction.h"
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#include "swift/AST/ASTContext.h"
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#include "swift/AST/Decl.h"
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#include "swift/AST/Module.h"
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#include "swift/AST/LazyResolver.h"
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#include "swift/SIL/SILModule.h"
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#include "llvm/Support/Debug.h"
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#define DEBUG_TYPE "destructor-analysis"
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using namespace swift;
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/// A type T's destructor does not store to memory if the type
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/// * is a trivial builtin type like builtin float or int types
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/// * is a value type with stored properties that are safe or
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/// * is a value type that implements the _DestructorSafeContainer protocol and
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/// whose type parameters are safe types T1...Tn.
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bool DestructorAnalysis::mayStoreToMemoryOnDestruction(SILType T) {
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bool IsSafe = isSafeType(T.getASTType());
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LLVM_DEBUG(llvm::dbgs() << " DestructorAnalysis::"
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"mayStoreToMemoryOnDestruction is"
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<< (IsSafe ? " false: " : " true: "));
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LLVM_DEBUG(T.getASTType()->print(llvm::errs()));
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LLVM_DEBUG(llvm::errs() << "\n");
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return !IsSafe;
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}
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bool DestructorAnalysis::cacheResult(CanType Type, bool Result) {
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Cached[Type] = Result;
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return Result;
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}
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static bool isKnownSafeStdlibContainerType(CanType Ty) {
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return Ty->isArray() ||
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Ty->is_ArrayBuffer() ||
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Ty->is_ContiguousArrayBuffer() ||
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Ty->isDictionary();
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}
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bool DestructorAnalysis::isSafeType(CanType Ty) {
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// Don't visit types twice.
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auto CachedRes = Cached.find(Ty);
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if (CachedRes != Cached.end()) {
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return CachedRes->second;
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}
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// Before we recurse mark the type as safe i.e if we see it in a recursive
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// position it is safe in the absence of another fact that proves otherwise.
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// We will reset this value to the correct value once we return from the
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// recursion below.
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cacheResult(Ty, true);
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// Trivial value types.
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if (Ty->is<BuiltinIntegerType>())
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return cacheResult(Ty, true);
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if (Ty->is<BuiltinFloatType>())
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return cacheResult(Ty, true);
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// A struct is safe if
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// * either it implements the _DestructorSafeContainer protocol and
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// all the type parameters are safe types.
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// * or all stored properties are safe types.
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if (auto *Struct = Ty->getStructOrBoundGenericStruct()) {
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if ((implementsDestructorSafeContainerProtocol(Struct) ||
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isKnownSafeStdlibContainerType(Ty)) &&
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areTypeParametersSafe(Ty))
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return cacheResult(Ty, true);
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// Check the stored properties.
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for (auto SP : Struct->getStoredProperties()) {
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if (!isSafeType(SP->getInterfaceType()->getCanonicalType()))
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return cacheResult(Ty, false);
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}
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return cacheResult(Ty, true);
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}
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// A tuple type is safe if its elements are safe.
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if (auto Tuple = dyn_cast<TupleType>(Ty)) {
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for (auto &Elt : Tuple->getElements())
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if (!isSafeType(Elt.getType()->getCanonicalType()))
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return cacheResult(Ty, false);
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return cacheResult(Ty, true);
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}
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// TODO: enum types.
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return cacheResult(Ty, false);
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}
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bool DestructorAnalysis::implementsDestructorSafeContainerProtocol(
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NominalTypeDecl *NomDecl) {
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ProtocolDecl *DestructorSafeContainer =
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getASTContext().getProtocol(KnownProtocolKind::DestructorSafeContainer);
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for (auto Proto : NomDecl->getAllProtocols())
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if (Proto == DestructorSafeContainer)
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return true;
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return false;
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}
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bool DestructorAnalysis::areTypeParametersSafe(CanType Ty) {
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auto BGT = dyn_cast<BoundGenericType>(Ty);
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if (!BGT)
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return false;
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// Make sure all type parameters are safe.
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for (auto TP : BGT->getGenericArgs()) {
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if (!isSafeType(TP->getCanonicalType()))
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return false;
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}
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return true;
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}
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ASTContext &DestructorAnalysis::getASTContext() {
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return Mod->getASTContext();
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}
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SILAnalysis *swift::createDestructorAnalysis(SILModule *M) {
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return new DestructorAnalysis(M);
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}
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