mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
Giacomo Vercesi
ab125b35b0
Change company name to "rev.ng Labs Srl" in all license headers to reflect changed company name and legal status Add missing license headers to files that didn't have one
98 lines
2.9 KiB
C++
98 lines
2.9 KiB
C++
//
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// Copyright (c) rev.ng Labs Srl. See LICENSE.md for details.
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//
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#include "llvm/ADT/PostOrderIterator.h"
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#include "llvm/ADT/STLExtras.h"
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#include "revng/Support/Assert.h"
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#include "revng/Support/Debug.h"
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#include "revng-c/DataLayoutAnalysis/DLATypeSystem.h"
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#include "DLAStep.h"
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using LTSN = dla::LayoutTypeSystemNode;
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using VecToCollapseT = std::vector<LTSN *>;
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using NonPointerFilterT = EdgeFilteredGraph<LTSN *, dla::isNotPointerEdge>;
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using Link = dla::LayoutTypeSystemNode::Link;
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using namespace llvm;
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static Logger<> Log("dla-collapse-single-child");
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namespace dla {
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bool CollapseSingleChild::collapseSingle(LayoutTypeSystem &TS,
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LayoutTypeSystemNode *Node) {
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bool Changed = false;
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auto HasSingleChild = [](const LTSN *Node) {
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return (Node->Successors.size() == 1);
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};
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auto HasAtMostOneParent = [](const LTSN *Node) {
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return (Node->Predecessors.size() <= 1);
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};
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if (VerifyLog.isEnabled() and not HasSingleChild(Node)) {
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revng_assert(llvm::none_of(Node->Successors,
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[](const Link &L) { return isPointerEdge(L); }));
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}
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// Get nodes that have a single instance or inheritance child
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if (HasSingleChild(Node) and isInstanceEdge(*Node->Successors.begin())) {
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auto &ChildEdge = *(Node->Successors.begin());
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const unsigned ChildOffset = ChildEdge.second->getOffsetExpr().Offset;
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auto &ToMerge = ChildEdge.first;
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// Don't collapse if the child has more than one parent
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if (not HasAtMostOneParent(ToMerge))
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return false;
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// Collapse only if the child is at offset 0
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if (ChildOffset == 0) {
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revng_log(Log, "Collapsing " << ToMerge->ID << " into " << Node->ID);
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const unsigned ChildSize = ToMerge->Size;
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revng_assert(Node->Size == 0 or Node->Size >= ChildSize);
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// Merge single child into parent.
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// mergeNodes resets InterferingInfo of Node, but we're collapsing
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// ToMerge that is the only child of Node, so we have to attach ToMerge's
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// InterferingInfo to the parent Node that we're preserving.
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// This is always correct because the InterferingInfo of a node only
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// depend on its children.
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auto ChildInterferingInfo = ToMerge->InterferingInfo;
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TS.mergeNodes({ /*Into=*/Node, /*From=*/ToMerge });
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Node->Size = ChildSize;
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Node->InterferingInfo = ChildInterferingInfo;
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Changed = true;
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}
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}
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return Changed;
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}
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bool CollapseSingleChild::runOnTypeSystem(LayoutTypeSystem &TS) {
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bool Changed = false;
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if (VerifyLog.isEnabled())
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revng_assert(TS.verifyDAG());
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for (LTSN *Root : llvm::nodes(&TS)) {
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revng_assert(Root != nullptr);
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if (not isRoot(Root))
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continue;
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for (LTSN *Node : post_order(Root))
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Changed |= collapseSingle(TS, Node);
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}
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if (VerifyLog.isEnabled())
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revng_assert(TS.verifyDAG());
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return Changed;
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}
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} // end namespace dla
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