6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
90 lines
2.4 KiB
C++
90 lines
2.4 KiB
C++
//===-- Analysis/EHUtils.h - Exception handling related utils --*-//C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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#ifndef LLVM_ANALYSIS_EHUTILS_H
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#define LLVM_ANALYSIS_EHUTILS_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/DenseSet.h"
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namespace llvm {
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/// Compute a list of blocks that are only reachable via EH paths.
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template <typename FunctionT, typename BlockT>
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static void computeEHOnlyBlocks(FunctionT &F, DenseSet<BlockT *> &EHBlocks) {
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// A block can be unknown if its not reachable from anywhere
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// EH if its only reachable from start blocks via some path through EH pads
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// NonEH if it's reachable from Non EH blocks as well.
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enum Status { Unknown = 0, EH = 1, NonEH = 2 };
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DenseSet<BlockT *> WorkList;
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DenseMap<BlockT *, Status> Statuses;
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auto GetStatus = [&](BlockT *BB) {
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if (Statuses.contains(BB))
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return Statuses[BB];
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else
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return Unknown;
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};
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auto CheckPredecessors = [&](BlockT *BB, Status Stat) {
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for (auto *PredBB : predecessors(BB)) {
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Status PredStatus = GetStatus(PredBB);
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// If status of predecessor block has gone above current block
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// we update current blocks status.
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if (PredStatus > Stat)
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Stat = PredStatus;
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}
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return Stat;
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};
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auto AddSuccesors = [&](BlockT *BB) {
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for (auto *SuccBB : successors(BB)) {
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if (!SuccBB->isEHPad())
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WorkList.insert(SuccBB);
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}
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};
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// Insert the successors of start block and landing pads successor.
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BlockT *StartBlock = &F.front();
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Statuses[StartBlock] = NonEH;
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AddSuccesors(StartBlock);
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for (auto &BB : F) {
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if (BB.isEHPad()) {
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AddSuccesors(&BB);
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Statuses[&BB] = EH;
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}
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}
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// Worklist iterative algorithm.
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while (!WorkList.empty()) {
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auto *BB = *WorkList.begin();
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WorkList.erase(BB);
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Status OldStatus = GetStatus(BB);
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// Check on predecessors and check for
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// Status update.
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Status NewStatus = CheckPredecessors(BB, OldStatus);
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// Did the block status change?
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bool Changed = OldStatus != NewStatus;
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if (Changed) {
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AddSuccesors(BB);
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Statuses[BB] = NewStatus;
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}
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}
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for (auto Entry : Statuses) {
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if (Entry.second == EH)
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EHBlocks.insert(Entry.first);
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}
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}
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} // namespace llvm
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#endif
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