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) : EHStreamer(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 | auto *EHInfo = |
40 | cast<MCSectionXCOFF>(Val: 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(Section: NameStr, K: EHInfo->getKind(), |
49 | CsectProp: EHInfo->getCsectProp()); |
50 | } |
51 | Asm->OutStreamer->switchSection(Section: EHInfo); |
52 | MCSymbol *EHInfoLabel = |
53 | TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(MF: Asm->MF); |
54 | Asm->OutStreamer->emitLabel(Symbol: EHInfoLabel); |
55 | |
56 | // Version number. |
57 | Asm->emitInt32(Value: 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(Alignment: Align(PointerSize)); |
64 | |
65 | // LSDA location. |
66 | Asm->OutStreamer->emitValue(Value: MCSymbolRefExpr::create(Symbol: LSDA, Ctx&: Asm->OutContext), |
67 | Size: PointerSize); |
68 | |
69 | // Personality routine. |
70 | Asm->OutStreamer->emitValue(Value: MCSymbolRefExpr::create(Symbol: PerSym, Ctx&: Asm->OutContext), |
71 | Size: PointerSize); |
72 | } |
73 | |
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>(Val: F.getPersonalityFn()->stripPointerCasts()); |
88 | const MCSymbol *PerSym = Asm->TM.getSymbol(GV: Per); |
89 | |
90 | emitExceptionInfoTable(LSDA: LSDALabel, PerSym); |
91 | } |
92 | |
93 | } // End of namespace llvm |
94 | |