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632b72a6a3
This adds a new utility as well as a test pass for computing the bottom-up SCC ordering of the functions in the module. Currently all functions are included, but we could consider in the future including only those functions that are potentially reachable from outside the current scope of compilation (module or file depending on compile mode). This would allow us to skip optimizing functions that we'll eventually eliminate.
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 - 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/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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