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There was a (commented out) assert that the entry node to each SCC we find would be a SILArgument. This is not always the case, so I removed the assert and added a test case that demonstrates this. I tightened up the IV recognition code a little bit as well. Swift SVN r19885
107 lines
2.9 KiB
C++
107 lines
2.9 KiB
C++
//===----------------- IVAnalysis.cpp - SIL IV Analysis -------*- 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 - 2015 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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#include "swift/SILAnalysis/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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static bool inSCC(ValueBase *Value, IVInfo::SCCType &SCC) {
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return std::find(SCC.begin(), SCC.end(), Value) != SCC.end();
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}
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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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bool IVInfo::isInductionSequence(SCCType &SCC,
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unsigned &ArgIndex) {
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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 false;
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bool FoundApply = false;
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bool FoundArgument = false;
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for (unsigned long i = 0, e = SCC.size(); i != e; ++i) {
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if (isa<SILArgument>(SCC[i])) {
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if (FoundArgument)
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return false;
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FoundArgument = true;
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ArgIndex = i;
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continue;
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}
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auto *I = cast<SILInstruction>(SCC[i]);
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switch (I->getKind()) {
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case ValueKind::ApplyInst: {
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if (FoundApply)
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return false;
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FoundApply = true;
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auto *AI = cast<ApplyInst>(I);
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SILValue L, R;
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if (!match(AI, m_ApplyInst(BuiltinValueKind::SAddOver, m_SILValue(L),
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m_SILValue(R))))
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return false;
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if (match(L, m_IntegerLiteralInst()))
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std::swap(L, R);
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if (!match(R, m_IntegerLiteralInst()))
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return false;
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break;
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}
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case ValueKind::TupleExtractInst: {
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auto *TEI = cast<TupleExtractInst>(I);
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if (!inSCC(TEI->getOperand().getDef(), SCC))
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return false;
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break;
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}
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default:
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return false;
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}
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}
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return FoundApply && 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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unsigned ArgIndex;
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if (!isInductionSequence(SCC, ArgIndex))
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return;
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auto Header = cast<SILArgument>(SCC[ArgIndex]);
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assert(isa<SILArgument>(Header) &&
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"Expected head of IV sequence to be an argument!");
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for (auto V : SCC)
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InductionVariableMap[V] = Header;
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}
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IVAnalysis::~IVAnalysis() {
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for (auto I = IVInfos.begin(), E = IVInfos.end(); I != E; ++I)
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delete I->second;
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}
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