| 1 | //===------- SEHFrameSupport.h - JITLink seh-frame utils --------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | // |
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| 9 | // SEHFrame utils for JITLink. |
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| 10 | // |
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| 11 | //===----------------------------------------------------------------------===// |
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| 12 | |
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| 13 | #ifndef LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H |
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| 14 | #define LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H |
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| 15 | |
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| 16 | #include "llvm/ExecutionEngine/JITLink/JITLink.h" |
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| 17 | #include "llvm/ExecutionEngine/JITSymbol.h" |
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| 18 | #include "llvm/Support/Error.h" |
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| 19 | #include "llvm/TargetParser/Triple.h" |
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| 20 | |
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| 21 | namespace llvm { |
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| 22 | namespace jitlink { |
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| 23 | /// This pass adds keep-alive edge from SEH frame sections |
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| 24 | /// to the parent function content block. |
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| 25 | class SEHFrameKeepAlivePass { |
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| 26 | public: |
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| 27 | SEHFrameKeepAlivePass(StringRef SEHFrameSectionName) |
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| 28 | : SEHFrameSectionName(SEHFrameSectionName) {} |
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| 29 | |
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| 30 | Error operator()(LinkGraph &G) { |
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| 31 | auto *S = G.findSectionByName(Name: SEHFrameSectionName); |
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| 32 | if (!S) |
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| 33 | return Error::success(); |
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| 34 | |
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| 35 | // Simply consider every block pointed by seh frame block as parants. |
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| 36 | // This adds some unnecessary keep-alive edges to unwind info blocks, |
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| 37 | // (xdata) but these blocks are usually dead by default, so they wouldn't |
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| 38 | // count for the fate of seh frame block. |
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| 39 | for (auto *B : S->blocks()) { |
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| 40 | auto &DummySymbol = G.addAnonymousSymbol(Content&: *B, Offset: 0, Size: 0, IsCallable: false, IsLive: false); |
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| 41 | DenseSet<Block *> Children; |
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| 42 | for (auto &E : B->edges()) { |
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| 43 | auto &Sym = E.getTarget(); |
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| 44 | if (!Sym.isDefined()) |
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| 45 | continue; |
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| 46 | Children.insert(V: &Sym.getBlock()); |
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| 47 | } |
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| 48 | for (auto *Child : Children) |
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| 49 | Child->addEdge(E: Edge(Edge::KeepAlive, 0, DummySymbol, 0)); |
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| 50 | } |
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| 51 | return Error::success(); |
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| 52 | } |
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| 53 | |
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| 54 | private: |
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| 55 | StringRef SEHFrameSectionName; |
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| 56 | }; |
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| 57 | |
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| 58 | } // end namespace jitlink |
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| 59 | } // end namespace llvm |
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| 60 | |
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| 61 | #endif // LLVM_EXECUTIONENGINE_JITLINK_SEHFRAMESUPPORT_H |
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| 62 | |
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