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Previously SILDefaultWitnessTables only included "resilient" default implementations, which are currently defined as those that appear at the end of a protocol, after any requirements without defaults. However, this was too inflexible. Instead, include all entries in the SILDefaultWitnessTable, with invalid entries standing in for requirements without defaults. Previously, the minimum witness table size was a separate parameter, also appearing in SIL syntax; now it can be calculated by looking at the entries themselves. The getResilientDefaultEntries() method of SILDefaultWitnessTable returns the same result as getEntries() did previously.
128 lines
4.3 KiB
C++
128 lines
4.3 KiB
C++
//===--- SILDefaultWitnessTable.cpp ---------------------------------------===//
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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 - 2016 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 http://swift.org/LICENSE.txt for license information
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// See http://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the SILDefaultWitnessTable class, which is used to provide
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// default implementations of protocol requirements for resilient protocols,
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// allowing IRGen to generate the appropriate metadata so that the runtime can
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// insert those requirements to witness tables that were emitted prior to the
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// requirement being added.
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//
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//===----------------------------------------------------------------------===//
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#include "swift/SIL/SILDefaultWitnessTable.h"
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#include "swift/SIL/SILModule.h"
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#include "llvm/ADT/SmallString.h"
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using namespace swift;
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void SILDefaultWitnessTable::addDefaultWitnessTable() {
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// Make sure we have not seen this witness table yet.
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assert(Mod.DefaultWitnessTableMap.find(Protocol) ==
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Mod.DefaultWitnessTableMap.end() && "Attempting to create duplicate "
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"default witness table.");
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Mod.DefaultWitnessTableMap[Protocol] = this;
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Mod.defaultWitnessTables.push_back(this);
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}
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SILDefaultWitnessTable *
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SILDefaultWitnessTable::create(SILModule &M, const ProtocolDecl *Protocol,
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ArrayRef<SILDefaultWitnessTable::Entry> entries){
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// Allocate the witness table and initialize it.
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void *buf = M.allocate(sizeof(SILDefaultWitnessTable),
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alignof(SILDefaultWitnessTable));
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SILDefaultWitnessTable *wt =
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::new (buf) SILDefaultWitnessTable(M, Protocol, entries);
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wt->addDefaultWitnessTable();
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// Return the resulting default witness table.
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return wt;
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}
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SILDefaultWitnessTable *
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SILDefaultWitnessTable::create(SILModule &M, const ProtocolDecl *Protocol) {
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// Allocate the witness table and initialize it.
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void *buf = M.allocate(sizeof(SILDefaultWitnessTable),
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alignof(SILDefaultWitnessTable));
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SILDefaultWitnessTable *wt =
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::new (buf) SILDefaultWitnessTable(M, Protocol);
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wt->addDefaultWitnessTable();
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// Return the resulting default witness table.
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return wt;
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}
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SILDefaultWitnessTable::
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SILDefaultWitnessTable(SILModule &M,
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const ProtocolDecl *Protocol,
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ArrayRef<Entry> entries)
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: Mod(M), Protocol(Protocol), Entries(), IsDeclaration(true) {
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convertToDefinition(entries);
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}
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SILDefaultWitnessTable::SILDefaultWitnessTable(SILModule &M,
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const ProtocolDecl *Protocol)
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: Mod(M), Protocol(Protocol), Entries(), IsDeclaration(true) {}
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void SILDefaultWitnessTable::
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convertToDefinition(ArrayRef<Entry> entries) {
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assert(IsDeclaration);
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IsDeclaration = false;
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void *buf = Mod.allocate(sizeof(Entry)*entries.size(), alignof(Entry));
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memcpy(buf, entries.begin(), sizeof(Entry)*entries.size());
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Entries = MutableArrayRef<Entry>(static_cast<Entry*>(buf), entries.size());
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// Bump the reference count of witness functions referenced by this table.
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for (auto entry : getEntries()) {
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if (entry.isValid()) {
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entry.getWitness()->incrementRefCount();
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}
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}
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}
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unsigned SILDefaultWitnessTable::getMinimumWitnessTableSize() const {
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unsigned defaultEntries = 0;
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unsigned minimumEntries = 0;
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// Count the number of entries up to and including the last null entry.
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// This is the number of witnesses that all conforming types must
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// provide.
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//
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// Any witnesses after the last null entry all have defaults, and can
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// be omitted from conformances; these are the resilient defaults.
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//
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// FIXME: Really this should look at availability instead.
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for (auto entry : Entries) {
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if (entry.isValid()) {
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defaultEntries++;
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} else {
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minimumEntries++;
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minimumEntries += defaultEntries;
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defaultEntries = 0;
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}
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}
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return minimumEntries;
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}
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SILDefaultWitnessTable::~SILDefaultWitnessTable() {
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// Drop the reference count of witness functions referenced by this table.
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for (auto entry : getEntries()) {
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if (entry.isValid()) {
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entry.getWitness()->decrementRefCount();
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}
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}
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}
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