| //===--- Devirtualizer.cpp - Devirtualize indirect calls -----------------===// |
| // |
| // This source file is part of the Swift.org open source project |
| // |
| // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors |
| // Licensed under Apache License v2.0 with Runtime Library Exception |
| // |
| // See https://swift.org/LICENSE.txt for license information |
| // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Devirtualize indirect calls to functions, turning them into direct function |
| // references. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #define DEBUG_TYPE "sil-devirtualizer" |
| |
| #include "swift/SIL/OptimizationRemark.h" |
| #include "swift/SIL/SILFunction.h" |
| #include "swift/SIL/SILInstruction.h" |
| #include "swift/SILOptimizer/Analysis/ClassHierarchyAnalysis.h" |
| #include "swift/SILOptimizer/Utils/Devirtualize.h" |
| #include "swift/SILOptimizer/PassManager/Transforms.h" |
| #include "llvm/ADT/SmallVector.h" |
| |
| using namespace swift; |
| |
| namespace { |
| |
| class Devirtualizer : public SILFunctionTransform { |
| bool Changed = false; |
| bool ChangedCFG = false; |
| |
| void devirtualizeAppliesInFunction(SILFunction &F, |
| ClassHierarchyAnalysis *CHA); |
| |
| /// The entry point to the transformation. |
| void run() override { |
| SILFunction &F = *getFunction(); |
| ClassHierarchyAnalysis *CHA = PM->getAnalysis<ClassHierarchyAnalysis>(); |
| LLVM_DEBUG(llvm::dbgs() << "***** Devirtualizer on function:" << F.getName() |
| << " *****\n"); |
| |
| Changed = false; |
| ChangedCFG = false; |
| devirtualizeAppliesInFunction(F, CHA); |
| if (ChangedCFG) |
| invalidateAnalysis(SILAnalysis::InvalidationKind::Everything); |
| else if (Changed) |
| invalidateAnalysis(SILAnalysis::InvalidationKind::CallsAndInstructions); |
| } |
| |
| }; |
| |
| } // end anonymous namespace |
| |
| // Return true if any calls changed, and true if the CFG also changed. |
| void Devirtualizer::devirtualizeAppliesInFunction(SILFunction &F, |
| ClassHierarchyAnalysis *CHA) { |
| llvm::SmallVector<ApplySite, 8> NewApplies; |
| OptRemark::Emitter ORE(DEBUG_TYPE, F); |
| |
| SmallVector<ApplySite, 16> Applies; |
| for (auto &BB : F) { |
| for (auto It = BB.begin(), End = BB.end(); It != End;) { |
| auto &I = *It++; |
| |
| // Skip non-apply instructions. |
| |
| auto Apply = ApplySite::isa(&I); |
| if (!Apply) |
| continue; |
| Applies.push_back(Apply); |
| } |
| } |
| for (auto Apply : Applies) { |
| ApplySite NewInst; |
| bool modifiedCFG; |
| std::tie(NewInst, modifiedCFG) = tryDevirtualizeApply(Apply, CHA, &ORE); |
| if (!NewInst) |
| continue; |
| |
| Changed = true; |
| ChangedCFG |= modifiedCFG; |
| |
| deleteDevirtualizedApply(Apply); |
| NewApplies.push_back(NewInst); |
| } |
| |
| // For each new apply, attempt to link in function bodies if we do |
| // not already have them, then notify the pass manager of the new |
| // functions. |
| // |
| // We do this after deleting the old applies because otherwise we |
| // hit verification errors in the linking code due to having |
| // non-cond_br critical edges. |
| while (!NewApplies.empty()) { |
| auto Apply = NewApplies.pop_back_val(); |
| |
| auto *CalleeFn = Apply.getInitiallyReferencedFunction(); |
| assert(CalleeFn && "Expected devirtualized callee!"); |
| |
| // We need to ensure that we link after devirtualizing in order to pull in |
| // everything we reference from another module, which may expose optimization |
| // opportunities and is also needed for correctness if we reference functions |
| // with non-public linkage. See lib/SIL/Linker.cpp for details. |
| if (!CalleeFn->isDefinition()) |
| F.getModule().linkFunction(CalleeFn, SILModule::LinkingMode::LinkAll); |
| |
| // We may not have optimized these functions yet, and it could |
| // be beneficial to rerun some earlier passes on the current |
| // function now that we've made these direct references visible. |
| if (CalleeFn->isDefinition() && CalleeFn->shouldOptimize()) |
| addFunctionToPassManagerWorklist(CalleeFn, nullptr); |
| } |
| } |
| |
| SILTransform *swift::createDevirtualizer() { return new Devirtualizer(); } |