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
AIXException(AsmPrinter * A)24 AIXException::AIXException(AsmPrinter *A) : EHStreamer(A) {}
25
emitExceptionInfoTable(const MCSymbol * LSDA,const MCSymbol * PerSym)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
endFunction(const MachineFunction * MF)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