mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Pietro Fezzardi
137 lines
4.3 KiB
C++
137 lines
4.3 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 <memory>
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#include <type_traits>
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/iterator_range.h"
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#include "revng/ADT/FilteredGraphTraits.h"
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#include "revng/Support/Debug.h"
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#include "DLAHelpers.h"
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#include "DLAStep.h"
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#include "DLATypeSystem.h"
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using namespace llvm;
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static Logger<> Log("dla-compute-upper-member-access");
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namespace dla {
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bool ComputeUpperMemberAccesses::runOnTypeSystem(LayoutTypeSystem &TS) {
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if (VerifyLog.isEnabled())
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revng_assert(TS.verifyDAG() and TS.verifyInheritanceTree());
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bool Changed = false;
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using LTSN = LayoutTypeSystemNode;
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std::set<const LTSN *> Visited;
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for (LTSN *Root : llvm::nodes(&TS)) {
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revng_assert(Root != nullptr);
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// Leaves need to have ValidLayouts, otherwise they should have been trimmed
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// by PruneLayoutNodesWithoutLayout
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revng_assert(not isLeaf(Root) or hasValidLayout(Root));
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if (not isRoot(Root))
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continue;
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revng_assert(isInheritanceRoot(Root));
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for (LTSN *N : post_order_ext(Root, Visited)) {
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revng_assert(not isLeaf(N) or hasValidLayout(N));
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revng_assert(not N->L.Size);
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auto FinalSize = N->L.Size;
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// Accumulate sizes of accesses associated to N
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for (const Use *U : N->L.Accesses) {
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FinalSize = std::max(FinalSize, getLoadStoreSizeFromPtrOpUse(TS, U));
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revng_assert(FinalSize);
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}
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// Look at all the instance-of edges and inheritance edges all together.
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bool HasBaseClass = false;
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for (auto &[Child, EdgeTag] : children_edges<const LTSN *>(N)) {
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auto ChildSize = Child->L.Size;
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if (ChildSize <= 0LL)
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continue;
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switch (EdgeTag->getKind()) {
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case TypeLinkTag::LK_Inheritance: {
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// Treated as instance at offset 0, but can only have one.
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// Should only have one parent in inheritance hierarchy.
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revng_assert(not HasBaseClass);
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HasBaseClass = true;
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FinalSize = std::max(FinalSize, ChildSize);
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} break;
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case TypeLinkTag::LK_Instance: {
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const OffsetExpression &OE = EdgeTag->getOffsetExpr();
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revng_assert(OE.Strides.size() == OE.TripCounts.size());
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// Ignore stuff at negative offsets.
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if (OE.Offset < 0LL)
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continue;
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// If we have an array, we have to compute its size, taking into
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// account the strides and the trip counts.
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for (const auto &[TripCount, Stride] :
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llvm::reverse(llvm::zip(OE.TripCounts, OE.Strides))) {
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// Strides should be positive. If they are not, we don't know
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// anything about how the children is layed out, so we assume the
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// children doesn't even exist.
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if (Stride <= 0LL) {
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ChildSize = 0ULL;
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break;
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}
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auto StrideSize = static_cast<uint64_t>(Stride);
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// If we have a TripCount, we expect it to be strictly positive.
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revng_assert(not TripCount.has_value() or TripCount.value() > 0LL);
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// Arrays with unknown numbers of elements are considered as if
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// they had a single element
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auto NumElems = TripCount.has_value() ? TripCount.value() : 1;
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revng_assert(NumElems);
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// Here we are computing the larger size that is known to be
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// accessed. So if we have an array, we consider it to be one
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// element shorter than expected, and we add ChildSize only once
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// at the end.
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// This is equivalent to:
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// ChildSize = (NumElems * StrideSize) - (StrideSize - ChildSize);
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ChildSize = ((NumElems - 1) * StrideSize) + ChildSize;
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}
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if (not ChildSize)
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break;
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int64_t ChildOffset = std::max<int64_t>(OE.Offset, 0LL);
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uint64_t ChildUpperOffset = ChildOffset + ChildSize;
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FinalSize = std::max(FinalSize, ChildUpperOffset);
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} break;
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default:
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revng_unreachable("unexpected edge");
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}
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}
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N->L.Size = FinalSize;
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Changed = true;
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}
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}
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if (Log.isEnabled())
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TS.dumpDotOnFile("after-compute-upper-member-access.dot");
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return Changed;
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}
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} // end namespace dla
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