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//===------- SEHFrameSupport.h - JITLink seh-frame utils --------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// SEHFrame utils for JITLink.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H
#define LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#include "llvm/ExecutionEngine/JITSymbol.h"
#include "llvm/Support/Error.h"
#include "llvm/TargetParser/Triple.h"
namespace llvm {
namespace jitlink {
/// This pass adds keep-alive edge from SEH frame sections
/// to the parent function content block.
class SEHFrameKeepAlivePass {
public:
SEHFrameKeepAlivePass(StringRef SEHFrameSectionName)
: SEHFrameSectionName(SEHFrameSectionName) {}
Error operator()(LinkGraph &G) {
auto *S = G.findSectionByName(SEHFrameSectionName);
if (!S)
return Error::success();
// Simply consider every block pointed by seh frame block as parants.
// This adds some unnecessary keep-alive edges to unwind info blocks,
// (xdata) but these blocks are usually dead by default, so they wouldn't
// count for the fate of seh frame block.
for (auto *B : S->blocks()) {
auto &DummySymbol = G.addAnonymousSymbol(*B, 0, 0, false, false);
DenseSet<Block *> Children;
for (auto &E : B->edges()) {
auto &Sym = E.getTarget();
if (!Sym.isDefined())
continue;
Children.insert(&Sym.getBlock());
}
for (auto *Child : Children)
Child->addEdge(Edge(Edge::KeepAlive, 0, DummySymbol, 0));
}
return Error::success();
}
private:
StringRef SEHFrameSectionName;
};
} // end namespace jitlink
} // end namespace llvm
#endif // LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H
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