mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Andrea Gussoni
c05974478c
Add a pass which removes the `unexpectedpc` as successor of the `switch` instructions. This simplifies the subsequent analyses. This pass also removes the unreachable basic blocks dandling around (as the `unexpectedpc` and `anypc` blocks when they are not needed).
65 lines
1.8 KiB
C++
65 lines
1.8 KiB
C++
/// \file RemoveUnexpectedPCPass.cpp
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/// \brief FunctionPass that applies the comb to the RegionCFG of a function
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//
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// This file is distributed under the MIT License. See LICENSE.md for details.
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//
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// Standard includes
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#include <sstream>
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#include <stdlib.h>
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// LLVM includes
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/raw_os_ostream.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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// revng includes
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#include "revng/Support/Debug.h"
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#include "revng/Support/IRHelpers.h"
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// Local libraries includes
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#include "revng-c/RemoveUnexpectedPCPass/RemoveUnexpectedPCPass.h"
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using namespace llvm;
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char RemoveUnexpectedPC::ID = 0;
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static RegisterPass<RemoveUnexpectedPC>
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X("removeunexpectedpc", "Remove unexpectedpc from switches", false, false);
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bool RemoveUnexpectedPC::runOnFunction(Function &F) {
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if (!F.getName().startswith("bb.")) {
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return false;
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}
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ReversePostOrderTraversal<llvm::Function *> RPOT(&F);
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for (BasicBlock *BB : RPOT) {
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LLVMContext &Context = getContext(&F);
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TerminatorInst *Terminator = BB->getTerminator();
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if (auto *Switch = dyn_cast<SwitchInst>(Terminator)) {
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// Get a pointer to the last successor basic block.
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revng_assert(Switch->getNumCases() > 0);
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unsigned SuccessorNumber = Switch->getNumSuccessors();
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BasicBlock *LastSuccessor = Switch->getSuccessor(SuccessorNumber - 1);
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// Remove the last successor from the cases.
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ConstantInt *LastCase = Switch->findCaseDest(LastSuccessor);
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Switch->removeCase(Switch->findCaseValue(LastCase));
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// Make the last successor the default case.
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Switch->setDefaultDest(LastSuccessor);
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}
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}
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removeUnreachableBlocks(F);
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return true;
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}
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