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
23namespace llvm {
24
25AIXException::AIXException(AsmPrinter *A) : EHStreamer(A) {}
26
27void 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>(Val: 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(Section: NameStr, K: EHInfo->getKind(),
50 CsectProp: EHInfo->getCsectProp());
51 }
52 Asm->OutStreamer->switchSection(Section: EHInfo);
53 MCSymbol *EHInfoLabel =
54 TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(MF: Asm->MF);
55 Asm->OutStreamer->emitLabel(Symbol: EHInfoLabel);
56
57 // Version number.
58 Asm->emitInt32(Value: 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(Alignment: Align(PointerSize));
65
66 // LSDA location.
67 Asm->OutStreamer->emitValue(Value: MCSymbolRefExpr::create(Symbol: LSDA, Ctx&: Asm->OutContext),
68 Size: PointerSize);
69
70 // Personality routine.
71 Asm->OutStreamer->emitValue(Value: MCSymbolRefExpr::create(Symbol: PerSym, Ctx&: Asm->OutContext),
72 Size: PointerSize);
73}
74
75void 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>(Val: F.getPersonalityFn()->stripPointerCasts());
89 const MCSymbol *PerSym = Asm->TM.getSymbol(GV: Per);
90
91 emitExceptionInfoTable(LSDA: LSDALabel, PerSym);
92}
93
94} // End of namespace llvm
95