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1d961ba22d
Although I don't plan to bring over new assertions wholesale into the current qualification branch, it's entirely possible that various minor changes in main will use the new assertions; having this basic support in the release branch will simplify that. (This is why I'm adding the includes as a separate pass from rewriting the individual assertions)
122 lines
4.2 KiB
C++
122 lines
4.2 KiB
C++
//===--- Devirtualizer.cpp - Devirtualize indirect calls -----------------===//
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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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//
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// Devirtualize indirect calls to functions, turning them into direct function
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// references.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "sil-devirtualizer"
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#include "swift/Basic/Assertions.h"
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#include "swift/SIL/OptimizationRemark.h"
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#include "swift/SIL/SILFunction.h"
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#include "swift/SIL/SILInstruction.h"
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#include "swift/SILOptimizer/Analysis/ClassHierarchyAnalysis.h"
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#include "swift/SILOptimizer/Utils/Devirtualize.h"
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#include "swift/SILOptimizer/PassManager/Transforms.h"
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#include "llvm/ADT/SmallVector.h"
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using namespace swift;
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namespace {
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class Devirtualizer : public SILFunctionTransform {
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bool Changed = false;
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bool ChangedCFG = false;
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void devirtualizeAppliesInFunction(SILFunction &F,
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ClassHierarchyAnalysis *CHA);
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/// The entry point to the transformation.
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void run() override {
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SILFunction &F = *getFunction();
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ClassHierarchyAnalysis *CHA = PM->getAnalysis<ClassHierarchyAnalysis>();
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LLVM_DEBUG(llvm::dbgs() << "***** Devirtualizer on function:" << F.getName()
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<< " *****\n");
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Changed = false;
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ChangedCFG = false;
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devirtualizeAppliesInFunction(F, CHA);
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if (ChangedCFG)
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invalidateAnalysis(SILAnalysis::InvalidationKind::FunctionBody);
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else if (Changed)
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invalidateAnalysis(SILAnalysis::InvalidationKind::CallsAndInstructions);
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}
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};
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} // end anonymous namespace
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// Return true if any calls changed, and true if the CFG also changed.
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void Devirtualizer::devirtualizeAppliesInFunction(SILFunction &F,
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ClassHierarchyAnalysis *CHA) {
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llvm::SmallVector<ApplySite, 8> NewApplies;
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OptRemark::Emitter ORE(DEBUG_TYPE, F);
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SmallVector<ApplySite, 16> Applies;
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for (auto &BB : F) {
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for (auto It = BB.begin(), End = BB.end(); It != End;) {
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auto &I = *It++;
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// Skip non-apply instructions.
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auto Apply = ApplySite::isa(&I);
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if (!Apply)
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continue;
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Applies.push_back(Apply);
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}
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}
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for (auto Apply : Applies) {
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ApplySite NewInst;
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bool modifiedCFG;
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std::tie(NewInst, modifiedCFG) = tryDevirtualizeApply(getPassManager(), Apply, CHA, &ORE);
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if (!NewInst)
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continue;
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Changed = true;
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ChangedCFG |= modifiedCFG;
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deleteDevirtualizedApply(Apply);
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NewApplies.push_back(NewInst);
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}
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// For each new apply, attempt to link in function bodies if we do
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// not already have them, then notify the pass manager of the new
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// functions.
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//
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// We do this after deleting the old applies because otherwise we
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// hit verification errors in the linking code due to having
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// non-cond_br critical edges.
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while (!NewApplies.empty()) {
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auto Apply = NewApplies.pop_back_val();
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auto *CalleeFn = Apply.getInitiallyReferencedFunction();
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assert(CalleeFn && "Expected devirtualized callee!");
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// We need to ensure that we link after devirtualizing in order to pull in
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// everything we reference from another module, which may expose optimization
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// opportunities and is also needed for correctness if we reference functions
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// with non-public linkage. See lib/SIL/Linker.cpp for details.
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if (!CalleeFn->isDefinition())
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F.getModule().linkFunction(CalleeFn, SILModule::LinkingMode::LinkAll);
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// We may not have optimized these functions yet, and it could
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// be beneficial to rerun some earlier passes on the current
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// function now that we've made these direct references visible.
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if (CalleeFn->isDefinition() && CalleeFn->shouldOptimize())
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addFunctionToPassManagerWorklist(CalleeFn, nullptr);
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}
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}
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SILTransform *swift::createDevirtualizer() { return new Devirtualizer(); }
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