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https://github.com/revng/revng
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Alvise de Faveri
4c8215fc47
* Changes to the `LayoutTypeSystem` graph
Pointers are identified in the TypeSystem graph as leaf nodes which
have a new type of edge (PointerEdge) that connects them to another
node of the graph. The destination of the edge represents the layout of
the pointed type.
* Changes to the Front-end
Pointer edges, and their destination nodes, are created by the DLA
front-end (`DLACreateIntraProceduralTypes`) whenever an access node has
a size that is compatible with the size of a pointer in the current
Architecture.
Successors might then be added to the newly generated node, if any,
by looking up the llvm::Value it is attached to.
* Changes to the Middle-end
Most of the DLA passes should ignore Pointer Edges, so they are modified
accordingly. Most notably, nodes that represent pointed layouts should
never be merged/pruned-off.
* Changes to the Back-end
The `TypeDeclCreationAction` of the decompiler and the `DLAMakeLayouts`
step of the DLA back-end are modified to take into account the new
information about pointers.
⚠️ There is a known issue with this version of the decompiler,
namely the fact that type loops are not detected and can cause the
emitter to enter an infinite loop.
81 lines
2.9 KiB
C++
81 lines
2.9 KiB
C++
//
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// Copyright (c) rev.ng Srls. See LICENSE.md for details.
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//
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#include "revng/Model/LoadModelPass.h"
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#include "revng-c/DataLayoutAnalysis/DLALayouts.h"
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#include "revng-c/DataLayoutAnalysis/DLAPass.h"
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#include "revng-c/Utils/Utils.h"
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#include "Backend/DLAMakeLayouts.h"
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#include "Frontend/DLATypeSystemBuilder.h"
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#include "Middleend/DLAStep.h"
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namespace {
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llvm::cl::opt<std::string> DLADir("dla-flatc-dir",
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llvm::cl::desc("Path to serialize flatc"),
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llvm::cl::value_desc("Path"),
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llvm::cl::cat(MainCategory),
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llvm::cl::NumOccurrencesFlag::Optional);
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} // end of unnamed namespace
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char DLAPass::ID = 0;
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static Logger<> BuilderLog("dla-builder-log");
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using Register = llvm::RegisterPass<DLAPass>;
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static Register X("dla", "Data Layout Analysis Pass", false, false);
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void DLAPass::getAnalysisUsage(llvm::AnalysisUsage &AU) const {
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AU.addRequired<LoadModelWrapperPass>();
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AU.addRequired<llvm::LoopInfoWrapperPass>();
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AU.addRequired<llvm::ScalarEvolutionWrapperPass>();
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AU.setPreservesAll();
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}
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bool DLAPass::runOnModule(llvm::Module &M) {
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auto &ModelWrapper = getAnalysis<LoadModelWrapperPass>().get();
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// Front-end: Create the LayoutTypeSystem graph from an LLVM module
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dla::LayoutTypeSystem TS;
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dla::DLATypeSystemLLVMBuilder Builder{ TS };
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Builder.buildFromLLVMModule(M, this, ModelWrapper.getReadOnlyModel());
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if (BuilderLog.isEnabled())
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Builder.dumpValuesMapping("DLA-values-initial.csv");
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// Middle-end Steps: manipulate nodes and edges of the DLATypeSystem graph
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dla::StepManager SM;
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revng_check(SM.addStep<dla::CollapseIdentityAndInheritanceCC>());
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revng_check(SM.addStep<dla::PropagateInheritanceToAccessors>());
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revng_check(SM.addStep<dla::RemoveTransitiveInheritanceEdges>());
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revng_check(SM.addStep<dla::MakeInheritanceTree>());
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revng_check(SM.addStep<dla::PruneLayoutNodesWithoutLayout>());
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revng_check(SM.addStep<dla::RemoveConflictingEdges>());
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revng_check(SM.addStep<dla::CollapseSingleChild>());
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revng_check(SM.addStep<dla::ComputeUpperMemberAccesses>());
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revng_check(SM.addStep<dla::CollapseCompatibleArrays>());
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revng_check(SM.addStep<dla::ComputeNonInterferingComponents>());
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revng_check(SM.addStep<dla::DeduplicateUnionFields>());
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revng_check(SM.addStep<dla::ComputeNonInterferingComponents>());
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SM.run(TS);
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if (BuilderLog.isEnabled())
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Builder.dumpValuesMapping("DLA-values-after-ME.csv");
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// Compress the equivalence classes obtained after graph manipulation
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dla::VectEqClasses &EqClasses = TS.getEqClasses();
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EqClasses.compress();
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// Create Layouts from the final nodes of the graph
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dla::LayoutPtrVector OrderedLayouts = makeLayouts(TS, this->Layouts);
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// Map Layouts back to their corresponding LayoutTypePtr
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dla::LayoutTypePtrVect Values = Builder.getValues();
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this->ValueLayoutsMap = makeLayoutMap(Values, OrderedLayouts, EqClasses);
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return true;
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}
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