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/MC/MCSectionXCOFF.h"
17 #include "llvm/MC/MCStreamer.h"
18 #include "llvm/Target/TargetLoweringObjectFile.h"
19 #include "llvm/Target/TargetMachine.h"
20
21 namespace llvm {
22
AIXException(AsmPrinter * A)23 AIXException::AIXException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
24
emitExceptionInfoTable(const MCSymbol * LSDA,const MCSymbol * PerSym)25 void AIXException::emitExceptionInfoTable(const MCSymbol *LSDA,
26 const MCSymbol *PerSym) {
27 // Generate EH Info Table.
28 // The EH Info Table, aka, 'compat unwind section' on AIX, have the following
29 // format: struct eh_info_t {
30 // unsigned version; /* EH info verion 0 */
31 // #if defined(__64BIT__)
32 // char _pad[4]; /* padding */
33 // #endif
34 // unsigned long lsda; /* Pointer to LSDA */
35 // unsigned long personality; /* Pointer to the personality routine */
36 // }
37
38 Asm->OutStreamer->SwitchSection(
39 Asm->getObjFileLowering().getCompactUnwindSection());
40 MCSymbol *EHInfoLabel = MMI->getContext().getOrCreateSymbol(
41 "__ehinfo." + Twine(Asm->getFunctionNumber()));
42 Asm->OutStreamer->emitLabel(EHInfoLabel);
43
44 // Version number.
45 Asm->emitInt32(0);
46
47 const DataLayout &DL = MMI->getModule()->getDataLayout();
48 const unsigned PointerSize = DL.getPointerSize();
49
50 // Add necessary paddings in 64 bit mode.
51 Asm->OutStreamer->emitValueToAlignment(PointerSize);
52
53 // LSDA location.
54 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(LSDA, Asm->OutContext),
55 PointerSize);
56
57 // Personality routine.
58 Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(PerSym, Asm->OutContext),
59 PointerSize);
60 }
61
endFunction(const MachineFunction * MF)62 void AIXException::endFunction(const MachineFunction *MF) {
63 const Function &F = MF->getFunction();
64 bool HasLandingPads = !MF->getLandingPads().empty();
65 const Function *Per = nullptr;
66 if (F.hasPersonalityFn())
67 Per = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
68 bool EmitEHBlock =
69 HasLandingPads || (F.hasPersonalityFn() &&
70 !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
71 F.needsUnwindTableEntry());
72
73 if (!EmitEHBlock)
74 return;
75
76 const MCSymbol *LSDALabel = emitExceptionTable();
77 const MCSymbol *PerSym = Asm->TM.getSymbol(Per);
78
79 emitExceptionInfoTable(LSDALabel, PerSym);
80 }
81
82 } // End of namespace llvm
83