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) : DwarfCFIExceptionBase(A) {} 25 26 void AIXException::markFunctionEnd() { endFragment(); } 27 28 void AIXException::emitExceptionInfoTable(const MCSymbol *LSDA, 29 const MCSymbol *PerSym) { 30 // Generate EH Info Table. 31 // The EH Info Table, aka, 'compat unwind section' on AIX, have the following 32 // format: struct eh_info_t { 33 // unsigned version; /* EH info verion 0 */ 34 // #if defined(__64BIT__) 35 // char _pad[4]; /* padding */ 36 // #endif 37 // unsigned long lsda; /* Pointer to LSDA */ 38 // unsigned long personality; /* Pointer to the personality routine */ 39 // } 40 41 auto *EHInfo = 42 cast<MCSectionXCOFF>(Asm->getObjFileLowering().getCompactUnwindSection()); 43 if (Asm->TM.getFunctionSections()) { 44 // If option -ffunction-sections is on, append the function name to the 45 // name of EH Info Table csect so that each function has its own EH Info 46 // Table csect. This helps the linker to garbage-collect EH info of unused 47 // functions. 48 SmallString<128> NameStr = EHInfo->getName(); 49 raw_svector_ostream(NameStr) << '.' << Asm->MF->getFunction().getName(); 50 EHInfo = Asm->OutContext.getXCOFFSection(NameStr, EHInfo->getKind(), 51 EHInfo->getCsectProp()); 52 } 53 Asm->OutStreamer->switchSection(EHInfo); 54 MCSymbol *EHInfoLabel = 55 TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(Asm->MF); 56 Asm->OutStreamer->emitLabel(EHInfoLabel); 57 58 // Version number. 59 Asm->emitInt32(0); 60 61 const DataLayout &DL = MMI->getModule()->getDataLayout(); 62 const unsigned PointerSize = DL.getPointerSize(); 63 64 // Add necessary paddings in 64 bit mode. 65 Asm->OutStreamer->emitValueToAlignment(PointerSize); 66 67 // LSDA location. 68 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(LSDA, Asm->OutContext), 69 PointerSize); 70 71 // Personality routine. 72 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(PerSym, Asm->OutContext), 73 PointerSize); 74 } 75 76 void AIXException::endFunction(const MachineFunction *MF) { 77 // There is no easy way to access register information in `AIXException` 78 // class. when ShouldEmitEHBlock is false and VRs are saved, A dumy eh info 79 // table are emitted in PPCAIXAsmPrinter::emitFunctionBodyEnd. 80 if (!TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(MF)) 81 return; 82 83 const MCSymbol *LSDALabel = emitExceptionTable(); 84 85 const Function &F = MF->getFunction(); 86 assert(F.hasPersonalityFn() && 87 "Landingpads are presented, but no personality routine is found."); 88 const auto *Per = 89 cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts()); 90 const MCSymbol *PerSym = Asm->TM.getSymbol(Per); 91 92 emitExceptionInfoTable(LSDALabel, PerSym); 93 } 94 95 } // End of namespace llvm 96