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1339b5403b
Correct format: //===--- Name of file - Description ----------------------------*- Lang -*-===//
81 lines
2.5 KiB
C++
81 lines
2.5 KiB
C++
//===--- FunctionOrder.cpp - Utility for function ordering ----------------===//
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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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#include "swift/SILOptimizer/Analysis/FunctionOrder.h"
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#include "swift/SIL/SILBasicBlock.h"
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#include "swift/SIL/SILFunction.h"
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#include "swift/SIL/SILInstruction.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/TinyPtrVector.h"
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#include <algorithm>
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using namespace swift;
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/// Use Tarjan's strongly connected components (SCC) algorithm to find
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/// the SCCs in the call graph.
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void BottomUpFunctionOrder::DFS(SILFunction *Start) {
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// Set the DFSNum for this node if we haven't already, and if we
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// have, which indicates it's already been visited, return.
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if (!DFSNum.insert(std::make_pair(Start, NextDFSNum)).second)
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return;
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assert(MinDFSNum.find(Start) == MinDFSNum.end() &&
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"Function should not already have a minimum DFS number!");
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MinDFSNum[Start] = NextDFSNum;
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++NextDFSNum;
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DFSStack.insert(Start);
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// Visit all the instructions, looking for apply sites.
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for (auto &B : *Start) {
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for (auto &I : B) {
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auto FAS = FullApplySite::isa(&I);
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if (!FAS)
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continue;
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auto Callees = BCA->getCalleeList(FAS);
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for (auto *CalleeFn : Callees) {
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// If not yet visited, visit the callee.
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if (DFSNum.find(CalleeFn) == DFSNum.end()) {
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DFS(CalleeFn);
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MinDFSNum[Start] = std::min(MinDFSNum[Start], MinDFSNum[CalleeFn]);
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} else if (DFSStack.count(CalleeFn)) {
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// If the callee is on the stack, it update our minimum DFS
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// number based on it's DFS number.
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MinDFSNum[Start] = std::min(MinDFSNum[Start], DFSNum[CalleeFn]);
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}
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}
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}
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}
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// If our DFS number is the minimum found, we've found a
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// (potentially singleton) SCC, so pop the nodes off the stack and
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// push the new SCC on our stack of SCCs.
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if (DFSNum[Start] == MinDFSNum[Start]) {
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SCC CurrentSCC;
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SILFunction *Popped;
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do {
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Popped = DFSStack.pop_back_val();
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CurrentSCC.push_back(Popped);
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} while (Popped != Start);
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TheSCCs.push_back(CurrentSCC);
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}
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}
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void BottomUpFunctionOrder::FindSCCs(SILModule &M) {
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for (auto &F : M)
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DFS(&F);
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}
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