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011358edd6
This removes the ambiguity when casting from a SingleValueInstruction to SILNode, which makes the code simpler. E.g. the "isRepresentativeSILNode" logic is not needed anymore. Also, it reduces the size of the most used instruction class - SingleValueInstruction - by one pointer. Conceptually, SILInstruction is still a SILNode. But implementation-wise SILNode is not a base class of SILInstruction anymore. Only the two sub-classes of SILInstruction - SingleValueInstruction and NonSingleValueInstruction - inherit from SILNode. SingleValueInstruction's SILNode is embedded into a ValueBase and its relative offset in the class is the same as in NonSingleValueInstruction (see SILNodeOffsetChecker). This makes it possible to cast from a SILInstruction to a SILNode without knowing which SILInstruction sub-class it is. Casting to SILNode cannot be done implicitly, but only with an LLVM `cast` or with SILInstruction::asSILNode(). But this is a rare case anyway.
107 lines
3.0 KiB
C++
107 lines
3.0 KiB
C++
//===--- IVAnalysis.cpp - SIL IV 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/IVAnalysis.h"
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#include "swift/SIL/PatternMatch.h"
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#include "swift/SIL/SILInstruction.h"
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#include "swift/SIL/SILValue.h"
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using namespace swift;
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using namespace swift::PatternMatch;
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#if !defined(NDEBUG)
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static bool inSCC(ValueBase *value, IVInfo::SCCType &SCC) {
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for (SILNode *node : SCC) {
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if (node == value)
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return true;
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}
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return false;
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}
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#endif
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// For now, we'll consider only the simplest induction variables:
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// - Exactly one element in the cycle must be a SILArgument.
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// - Only a single increment by a literal.
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//
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// In other words many valid things that could be considered induction
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// variables are disallowed at this point.
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SILArgument *IVInfo::isInductionSequence(SCCType &SCC) {
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// Ignore SCCs of size 1 for now. Some of these are derived IVs
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// like i+1 or i*4, which we will eventually want to handle.
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if (SCC.size() == 1)
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return nullptr;
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BuiltinInst *FoundBuiltin = nullptr;
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SILArgument *FoundArgument = nullptr;
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IntegerLiteralInst *IncValue = nullptr;
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for (unsigned long i = 0, e = SCC.size(); i != e; ++i) {
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if (auto IV = dyn_cast<SILArgument>(SCC[i])) {
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if (FoundArgument)
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return nullptr;
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FoundArgument = IV;
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continue;
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}
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// TODO: MultiValueInstruction
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auto *I = cast<SILInstruction>(SCC[i]);
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switch (I->getKind()) {
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case SILInstructionKind::BuiltinInst: {
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if (FoundBuiltin)
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return nullptr;
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FoundBuiltin = cast<BuiltinInst>(I);
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SILValue L, R;
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if (!match(FoundBuiltin, m_ApplyInst(BuiltinValueKind::SAddOver,
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m_SILValue(L), m_SILValue(R))))
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return nullptr;
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if (match(L, m_IntegerLiteralInst(IncValue)))
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std::swap(L, R);
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if (!match(R, m_IntegerLiteralInst(IncValue)))
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return nullptr;
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break;
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}
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case SILInstructionKind::TupleExtractInst: {
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assert(inSCC(cast<TupleExtractInst>(I)->getOperand(), SCC) &&
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"TupleExtract operand not an induction var");
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break;
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}
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default:
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return nullptr;
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}
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}
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if (!FoundBuiltin || !FoundArgument || !IncValue)
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return nullptr;
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InductionInfoMap[FoundArgument] = IVDesc(FoundBuiltin, IncValue);
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return FoundArgument;
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}
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void IVInfo::visit(SCCType &SCC) {
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assert(SCC.size() && "SCCs should have an element!!");
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SILArgument *IV;
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if (!(IV = isInductionSequence(SCC)))
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return;
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for (auto node : SCC) {
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if (auto value = dyn_cast<ValueBase>(node))
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InductionVariableMap[value] = IV;
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}
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}
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