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