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c180d1363e
Add `deletableInstructions()` and `reverseDeletableInstructions()` in SILBasicBlock. It allows deleting instructions while iterating over all instructions of the block. This is a replacement for `InstructionDeleter::updatingRange()`. It's a simpler implementation than the existing `UpdatingListIterator` and `UpdatingInstructionIteratorRegistry`, because it just needs to keep the prev/next pointers for "deleted" instructions instead of the iterator-registration machinery. It's also safer, because it doesn't require to delete instructions via a specific instance of an InstructionDeleter (which can be missed easily).
142 lines
4.5 KiB
C++
142 lines
4.5 KiB
C++
//===--- OSSALifetimeAnalysis.cpp - OSSA lifetime analysis ----------------===//
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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 - 2022 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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/// This currently runs SSAPrunedLiveness on SSA values, MultiDefPrunedLiveness
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/// on phi webs, and MultiDefPrunedLiveness on 'copy_addr [init]' and 'store
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/// [init]'.
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///
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/// Soon, it will also run OSSALiveness on OSSA values.
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "ossa-lifetime-analysis"
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#include "swift/SIL/PrunedLiveness.h"
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#include "swift/SIL/SILArgument.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/SIL/SILValue.h"
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#include "swift/SIL/ScopedAddressUtils.h"
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#include "swift/SILOptimizer/PassManager/Passes.h"
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#include "swift/SILOptimizer/PassManager/Transforms.h"
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#include "swift/SILOptimizer/Utils/InstructionDeleter.h"
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#include "llvm/Support/Debug.h"
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using namespace swift;
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namespace {
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struct OSSALifetimeAnalyzer {
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SILFunction *function;
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OSSALifetimeAnalyzer(SILFunction *function): function(function) {}
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void analyzeSSAValue(SILValue value);
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void analyzeScopedAddress(ScopedAddressValue scopedAddress);
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void analyzeValues(ArrayRef<SILValue> values);
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};
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void OSSALifetimeAnalyzer::analyzeSSAValue(SILValue value) {
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llvm::outs() << "\nSSA lifetime analysis: " << value;
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SmallVector<SILBasicBlock *, 8> discoveredBlocks;
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SSAPrunedLiveness liveness(&discoveredBlocks);
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liveness.initializeDef(value);
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liveness.computeSimple();
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liveness.print(llvm::outs());
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PrunedLivenessBoundary boundary;
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liveness.computeBoundary(boundary);
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boundary.print(llvm::outs());
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}
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void OSSALifetimeAnalyzer::analyzeScopedAddress(
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ScopedAddressValue scopedAddress) {
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llvm::outs() << "\nScoped address analysis: " << scopedAddress.value;
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SmallVector<SILBasicBlock *, 8> discoveredBlocks;
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SSAPrunedLiveness liveness(&discoveredBlocks);
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scopedAddress.computeTransitiveLiveness(liveness);
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liveness.print(llvm::outs());
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PrunedLivenessBoundary boundary;
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liveness.computeBoundary(boundary);
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boundary.print(llvm::outs());
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}
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void OSSALifetimeAnalyzer::analyzeValues(ArrayRef<SILValue> values) {
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llvm::outs() << "\nMultiDef lifetime analysis:\n";
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SmallVector<SILBasicBlock *, 8> discoveredBlocks;
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MultiDefPrunedLiveness liveness(function, &discoveredBlocks);
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for (SILValue value : values) {
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llvm::outs() << " def: " << value;
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liveness.initializeDef(value);
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}
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liveness.computeSimple();
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liveness.print(llvm::outs());
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PrunedLivenessBoundary boundary;
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liveness.computeBoundary(boundary);
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boundary.print(llvm::outs());
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}
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class OSSALifetimeAnalysis : public SILModuleTransform {
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void run() override;
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};
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// Find and record all debug_value [trace] instructions. Strip them before
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// querying liveness so we can test dead values. Alternatively, we could
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// override SSAPrunedLiveness::compute above and simply ignore trace
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// instructions.
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//
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// Consider each traced value first as an indivual live range, then consider
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// them all together as a single live range.
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void OSSALifetimeAnalysis::run() {
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for (auto &function : *getModule()) {
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llvm::outs() << "\n@" << function.getName() << "\n";
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if (function.empty()) {
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llvm::outs() << "<unknown>\n";
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continue;
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}
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SmallVector<SILValue, 8> traceValues;
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InstructionDeleter deleter;
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for (auto &block : function) {
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for (SILInstruction &inst : block.deletableInstructions()) {
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if (auto *debugValue = dyn_cast<DebugValueInst>(&inst)) {
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if (!debugValue->hasTrace())
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continue;
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traceValues.push_back(debugValue->getOperand());
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deleter.forceDelete(debugValue);
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}
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}
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}
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OSSALifetimeAnalyzer analyzer(&function);
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for (auto value : traceValues) {
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if (value->getType().isAddress()) {
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ScopedAddressValue scopedAddress(value);
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if (scopedAddress) {
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analyzer.analyzeScopedAddress(scopedAddress);
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continue;
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}
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}
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analyzer.analyzeSSAValue(value);
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}
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if (traceValues.size() > 1) {
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analyzer.analyzeValues(traceValues);
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}
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}
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}
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} // end anonymous namespace
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SILTransform *swift::createOSSALifetimeAnalysis() {
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return new OSSALifetimeAnalysis();
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}
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