mirror of
https://github.com/revng/revng
synced 2026-06-21 14:07:57 +00:00
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.
104 lines
2.9 KiB
C++
104 lines
2.9 KiB
C++
//
|
|
// Copyright (c) rev.ng Srls. See LICENSE.md for details.
|
|
//
|
|
|
|
#include "llvm/ADT/PostOrderIterator.h"
|
|
#include "llvm/ADT/STLExtras.h"
|
|
|
|
#include "revng/Support/Assert.h"
|
|
#include "revng/Support/Debug.h"
|
|
|
|
#include "revng-c/DataLayoutAnalysis/DLATypeSystem.h"
|
|
|
|
#include "../DLAHelpers.h"
|
|
#include "DLAStep.h"
|
|
|
|
using LTSN = dla::LayoutTypeSystemNode;
|
|
using VecToCollapseT = std::vector<LTSN *>;
|
|
using NonPointerFilterT = EdgeFilteredGraph<LTSN *, dla::isNotPointerEdge>;
|
|
using Link = dla::LayoutTypeSystemNode::Link;
|
|
|
|
using namespace llvm;
|
|
|
|
static Logger<> Log("dla-collapse-single-child");
|
|
|
|
namespace dla {
|
|
bool CollapseSingleChild::collapseSingle(LayoutTypeSystem &TS,
|
|
LayoutTypeSystemNode *Node) {
|
|
bool Changed = false;
|
|
|
|
auto HasSingleChild = [](const LTSN *Node) {
|
|
return (Node->Successors.size() == 1);
|
|
};
|
|
|
|
auto ChildIsInstanceOrInheritance = [](const LTSN *Node) {
|
|
auto &Child = *Node->Successors.begin();
|
|
return (isInstanceEdge(Child) or isInheritanceEdge(Child));
|
|
};
|
|
|
|
auto HasAtMostOneParent = [](const LTSN *Node) {
|
|
return (Node->Predecessors.size() <= 1);
|
|
};
|
|
|
|
if (VerifyLog.isEnabled() and not HasSingleChild(Node)) {
|
|
revng_assert(llvm::none_of(Node->Successors,
|
|
[](const Link &L) { return isPointerEdge(L); }));
|
|
}
|
|
|
|
// Get nodes that have a single instance or inheritance child
|
|
if (HasSingleChild(Node) and ChildIsInstanceOrInheritance(Node)) {
|
|
auto &ChildEdge = *(Node->Successors.begin());
|
|
const unsigned ChildOffset = isInheritanceEdge(ChildEdge) ?
|
|
0U :
|
|
ChildEdge.second->getOffsetExpr().Offset;
|
|
auto &ToMerge = ChildEdge.first;
|
|
|
|
// Don't collapse if the child has more than one parent
|
|
if (not HasAtMostOneParent(ToMerge))
|
|
return false;
|
|
|
|
// Collapse only if the child is at offset 0
|
|
if (ChildOffset == 0) {
|
|
revng_log(Log, "Collapsing " << ToMerge->ID << " into " << Node->ID);
|
|
|
|
const unsigned ChildSize = ToMerge->Size;
|
|
revng_assert(Node->Size == 0 or Node->Size == ChildSize);
|
|
|
|
// Merge single child into parent
|
|
TS.mergeNodes({ /*Into=*/Node, /*From=*/ToMerge });
|
|
Node->Size = ChildSize;
|
|
|
|
Changed = true;
|
|
}
|
|
}
|
|
|
|
return Changed;
|
|
}
|
|
|
|
bool CollapseSingleChild::runOnTypeSystem(LayoutTypeSystem &TS) {
|
|
bool Changed = false;
|
|
if (VerifyLog.isEnabled())
|
|
revng_assert(TS.verifyDAG() and TS.verifyInheritanceTree());
|
|
|
|
if (Log.isEnabled())
|
|
TS.dumpDotOnFile("before-collapse-single-child.dot");
|
|
|
|
for (LTSN *Root : llvm::nodes(&TS)) {
|
|
revng_assert(Root != nullptr);
|
|
if (not isRoot(Root))
|
|
continue;
|
|
|
|
for (LTSN *Node : post_order(Root))
|
|
Changed |= collapseSingle(TS, Node);
|
|
}
|
|
|
|
if (Log.isEnabled())
|
|
TS.dumpDotOnFile("after-collapse-single-child.dot");
|
|
if (VerifyLog.isEnabled())
|
|
revng_assert(TS.verifyInheritanceDAG() and TS.verifyInheritanceTree());
|
|
|
|
return Changed;
|
|
}
|
|
|
|
} // end namespace dla
|