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When serializing modules with `-experimental-skip-all-function-bodies`, this analysis was eagerly populating a cache that would go unused since there is no optimization to do. With `-experimental-lazy-typecheck`, this work would also trigger unnecessary typechecking requests. NFC.
117 lines
3.7 KiB
C++
117 lines
3.7 KiB
C++
//===--- ClassHierarchyAnalysis.cpp - Class hierarchy analysis ------------===//
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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/ClassHierarchyAnalysis.h"
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#include "swift/AST/ASTContext.h"
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#include "swift/AST/Module.h"
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#include "swift/SIL/SILInstruction.h"
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#include "swift/SIL/SILValue.h"
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#include "swift/SIL/SILModule.h"
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using namespace swift;
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// FIXME: This could be implemented as a request.
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void ClassHierarchyAnalysis::populateDirectSubclassesCacheIfNecessary() {
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if (DirectSubclassesCache.has_value())
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return;
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DirectSubclassesCache.emplace();
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auto module = M->getSwiftModule();
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// For each class declaration in our V-table list:
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for (auto &VT : M->getVTables()) {
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ClassDecl *C = VT->getClass();
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while (true) {
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// Ignore classes that are at the top of the class hierarchy:
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if (!C->hasSuperclass())
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break;
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ClassDecl *super = C->getSuperclassDecl();
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auto superModule = super->getModuleContext();
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// Don't bother collecting subclasses for classes from a different module.
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// TODO: cross-module WMO
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if (superModule != module)
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break;
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// Find the superclass's list of direct subclasses. If it's non-empty,
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// we've previously walked up to the class, so there's no reason to keep
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// walking from this point.
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auto &list = (*DirectSubclassesCache)[super];
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bool shouldVisitSuper = list.empty();
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// Check whether C is already in the list, which can happen
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// if we had a v-table that was a subclass of C.
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// We expect a linear scan to be cheap enough for this.
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if (std::find(list.begin(), list.end(), C) != list.end())
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break;
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list.push_back(C);
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// Keep walking if this is the first time we reached this superclass.
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// We have to do this because the SILModule might not have v-tables for
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// every class in the module.
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if (!shouldVisitSuper)
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break;
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C = super;
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}
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}
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}
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/// Get all subclasses of a given class.
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///
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/// \p Current class, whose direct and indirect subclasses are
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/// to be collected.
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/// \p IndirectSubs placeholder for collected results
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void ClassHierarchyAnalysis::getIndirectSubClasses(ClassDecl *Cur,
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ClassList &IndirectSubs) {
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unsigned Idx = IndirectSubs.size();
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if (!hasKnownDirectSubclasses(Cur))
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return;
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// Produce a set of all indirect subclasses in a
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// breadth-first order;
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// First add subclasses of direct subclasses.
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for (auto C : getDirectSubClasses(Cur)) {
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// Get direct subclasses
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if (!hasKnownDirectSubclasses(C))
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continue;
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auto &DirectSubclasses = getDirectSubClasses(C);
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// Remember all direct subclasses of the current one.
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for (auto S : DirectSubclasses) {
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IndirectSubs.push_back(S);
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}
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}
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// Then recursively add direct subclasses of already
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// added subclasses.
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while (Idx != IndirectSubs.size()) {
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auto C = IndirectSubs[Idx++];
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// Get direct subclasses
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if (!hasKnownDirectSubclasses(C))
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continue;
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auto &DirectSubclasses = getDirectSubClasses(C);
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// Remember all direct subclasses of the current one.
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for (auto S : DirectSubclasses) {
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IndirectSubs.push_back(S);
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}
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}
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}
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ClassHierarchyAnalysis::~ClassHierarchyAnalysis() {}
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