1 //===-- CodeGen/AsmPrinter/AIXException.cpp - AIX Exception Impl ----------===// 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 // This file contains support for writing AIX exception info into asm files. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "DwarfException.h" 14 #include "llvm/CodeGen/AsmPrinter.h" 15 #include "llvm/CodeGen/MachineModuleInfo.h" 16 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h" 17 #include "llvm/IR/Module.h" 18 #include "llvm/MC/MCSectionXCOFF.h" 19 #include "llvm/MC/MCStreamer.h" 20 #include "llvm/Target/TargetLoweringObjectFile.h" 21 #include "llvm/Target/TargetMachine.h" 22 23 namespace llvm { 24 25 AIXException::AIXException(AsmPrinter *A) : EHStreamer(A) {} 26 27 void AIXException::emitExceptionInfoTable(const MCSymbol *LSDA, 28 const MCSymbol *PerSym) { 29 // Generate EH Info Table. 30 // The EH Info Table, aka, 'compat unwind section' on AIX, have the following 31 // format: struct eh_info_t { 32 // unsigned version; /* EH info verion 0 */ 33 // #if defined(__64BIT__) 34 // char _pad[4]; /* padding */ 35 // #endif 36 // unsigned long lsda; /* Pointer to LSDA */ 37 // unsigned long personality; /* Pointer to the personality routine */ 38 // } 39 40 auto *EHInfo = 41 cast<MCSectionXCOFF>(Asm->getObjFileLowering().getCompactUnwindSection()); 42 if (Asm->TM.getFunctionSections()) { 43 // If option -ffunction-sections is on, append the function name to the 44 // name of EH Info Table csect so that each function has its own EH Info 45 // Table csect. This helps the linker to garbage-collect EH info of unused 46 // functions. 47 SmallString<128> NameStr = EHInfo->getName(); 48 raw_svector_ostream(NameStr) << '.' << Asm->MF->getFunction().getName(); 49 EHInfo = Asm->OutContext.getXCOFFSection(NameStr, EHInfo->getKind(), 50 EHInfo->getCsectProp()); 51 } 52 Asm->OutStreamer->switchSection(EHInfo); 53 MCSymbol *EHInfoLabel = 54 TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(Asm->MF); 55 Asm->OutStreamer->emitLabel(EHInfoLabel); 56 57 // Version number. 58 Asm->emitInt32(0); 59 60 const DataLayout &DL = MMI->getModule()->getDataLayout(); 61 const unsigned PointerSize = DL.getPointerSize(); 62 63 // Add necessary paddings in 64 bit mode. 64 Asm->OutStreamer->emitValueToAlignment(Align(PointerSize)); 65 66 // LSDA location. 67 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(LSDA, Asm->OutContext), 68 PointerSize); 69 70 // Personality routine. 71 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(PerSym, Asm->OutContext), 72 PointerSize); 73 } 74 75 void AIXException::endFunction(const MachineFunction *MF) { 76 // There is no easy way to access register information in `AIXException` 77 // class. when ShouldEmitEHBlock is false and VRs are saved, A dumy eh info 78 // table are emitted in PPCAIXAsmPrinter::emitFunctionBodyEnd. 79 if (!TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(MF)) 80 return; 81 82 const MCSymbol *LSDALabel = emitExceptionTable(); 83 84 const Function &F = MF->getFunction(); 85 assert(F.hasPersonalityFn() && 86 "Landingpads are presented, but no personality routine is found."); 87 const auto *Per = 88 cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts()); 89 const MCSymbol *PerSym = Asm->TM.getSymbol(Per); 90 91 emitExceptionInfoTable(LSDALabel, PerSym); 92 } 93 94 } // End of namespace llvm 95