103 lines
4.1 KiB
C++
103 lines
4.1 KiB
C++
//===-- CodeGen/AsmPrinter/AIXException.cpp - AIX Exception Impl ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains support for writing AIX exception info into asm files.
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//
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//===----------------------------------------------------------------------===//
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#include "DwarfException.h"
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#include "llvm/CodeGen/AsmPrinter.h"
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#include "llvm/CodeGen/MachineModuleInfo.h"
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#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
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#include "llvm/MC/MCSectionXCOFF.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/Target/TargetLoweringObjectFile.h"
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#include "llvm/Target/TargetMachine.h"
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namespace llvm {
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AIXException::AIXException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
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// This overrides 'DwarfCFIExceptionBase::markFunctionEnd', to avoid the call to
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// tidyLandingPads. This is necessary, because the
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// 'PPCAIXAsmPrinter::emitFunctionBodyEnd' function already checked whether we
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// need ehinfo, and emitted a traceback table with the bits set to indicate that
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// we will be emitting it, if so. Thus, if we remove it now -- so late in the
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// process -- we'll end up having emitted a reference to __ehinfo.N symbol, but
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// not emitting a definition for said symbol.
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void AIXException::markFunctionEnd() {}
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void AIXException::emitExceptionInfoTable(const MCSymbol *LSDA,
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const MCSymbol *PerSym) {
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// Generate EH Info Table.
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// The EH Info Table, aka, 'compat unwind section' on AIX, have the following
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// format: struct eh_info_t {
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// unsigned version; /* EH info verion 0 */
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// #if defined(__64BIT__)
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// char _pad[4]; /* padding */
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// #endif
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// unsigned long lsda; /* Pointer to LSDA */
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// unsigned long personality; /* Pointer to the personality routine */
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// }
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auto *EHInfo =
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cast<MCSectionXCOFF>(Asm->getObjFileLowering().getCompactUnwindSection());
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if (Asm->TM.getFunctionSections()) {
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// If option -ffunction-sections is on, append the function name to the
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// name of EH Info Table csect so that each function has its own EH Info
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// Table csect. This helps the linker to garbage-collect EH info of unused
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// functions.
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SmallString<128> NameStr = EHInfo->getName();
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raw_svector_ostream(NameStr) << '.' << Asm->MF->getFunction().getName();
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EHInfo = Asm->OutContext.getXCOFFSection(NameStr, EHInfo->getKind(),
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EHInfo->getCsectProp());
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}
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Asm->OutStreamer->switchSection(EHInfo);
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MCSymbol *EHInfoLabel =
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TargetLoweringObjectFileXCOFF::getEHInfoTableSymbol(Asm->MF);
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Asm->OutStreamer->emitLabel(EHInfoLabel);
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// Version number.
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Asm->emitInt32(0);
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const DataLayout &DL = MMI->getModule()->getDataLayout();
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const unsigned PointerSize = DL.getPointerSize();
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// Add necessary paddings in 64 bit mode.
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Asm->OutStreamer->emitValueToAlignment(Align(PointerSize));
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// LSDA location.
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Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(LSDA, Asm->OutContext),
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PointerSize);
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// Personality routine.
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Asm->OutStreamer->emitValue(MCSymbolRefExpr::create(PerSym, Asm->OutContext),
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PointerSize);
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}
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void AIXException::endFunction(const MachineFunction *MF) {
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// There is no easy way to access register information in `AIXException`
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// class. when ShouldEmitEHBlock is false and VRs are saved, A dumy eh info
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// table are emitted in PPCAIXAsmPrinter::emitFunctionBodyEnd.
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if (!TargetLoweringObjectFileXCOFF::ShouldEmitEHBlock(MF))
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return;
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const MCSymbol *LSDALabel = emitExceptionTable();
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const Function &F = MF->getFunction();
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assert(F.hasPersonalityFn() &&
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"Landingpads are presented, but no personality routine is found.");
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const auto *Per =
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cast<GlobalValue>(F.getPersonalityFn()->stripPointerCasts());
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const MCSymbol *PerSym = Asm->TM.getSymbol(Per);
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emitExceptionInfoTable(LSDALabel, PerSym);
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}
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} // End of namespace llvm
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