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fd98ce10c7
The PassManager should transform all functions in bottom up order. This is necessary because when optimizations like inlining looks at the callee function bodies to compute profitability, the callee functions should have already undergone optimizations to get better profitability estimates. The PassManager builds its function worklist based on bottom up order on initialization. However, newly created SILFunctions due to specialization etc, are simply appended to the function worklist. This can cause us to make bad inlining decisions due to inaccurate profitability estimates. This change now updates the function worklist such that, all the callees of the newly added SILFunction are proccessed before it by the PassManager. Fixes rdar://52202680
77 lines
2.6 KiB
C++
77 lines
2.6 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 - 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/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 && !isa<StrongReleaseInst>(&I) && !isa<ReleaseValueInst>(&I))
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continue;
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auto Callees = FAS ? BCA->getCalleeList(FAS) : BCA->getCalleeList(&I);
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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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