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