llvm/lib/CodeGen/AsmPrinter/AIXException.cpp

   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::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   Asm->OutStreamer->SwitchSection(
  40       Asm->getObjFileLowering().getCompactUnwindSection());
  41   MCSymbol *EHInfoLabel =
  42       TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(Asm->MF);
  43   Asm->OutStreamer->emitLabel(EHInfoLabel);
  44
  45   // Version number.
  46   Asm->emitInt32(0);
  47
  48   const DataLayout &DL = MMI->getModule()->getDataLayout();
  49   const unsigned PointerSize = DL.getPointerSize();
  50
  51   // Add necessary paddings in 64 bit mode.
  52   Asm->OutStreamer->emitValueToAlignment(PointerSize);
  53
  54   // LSDA location.
  55   Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(LSDA, Asm->OutContext),
  56                               PointerSize);
  57
  58   // Personality routine.
  59   Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(PerSym, Asm->OutContext),
  60                               PointerSize);
  61 }
  62
  63 void AIXException::endFunction(const MachineFunction *MF) {
  64   // There is no easy way to access register information in `AIXException`
  65   // class. when ShouldEmitEHBlock is false and VRs are saved, A dumy eh info
  66   // table are emitted in PPCAIXAsmPrinter::emitFunctionBodyEnd.
  67   if (!TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(MF))
  68     return;
  69
  70   const MCSymbol *LSDALabel = emitExceptionTable();
  71
  72   const Function &F = MF->getFunction();
  73   assert(F.hasPersonalityFn() &&
  74          "Landingpads are presented, but no personality routine is found.");
  75   const GlobalValue *Per =
  76       dyn_cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
  77   const MCSymbol *PerSym = Asm->TM.getSymbol(Per);
  78
  79   emitExceptionInfoTable(LSDALabel, PerSym);
  80 }
  81
  82 } // End of namespace llvm