4af73d7ebb
The existing behaviors and callbacks were overlapping and had very confusing semantics: beginBasicBlock/endBasicBlock were not always called, beginFragment/endFragment seemed like they were meant to mean the same thing, but were slightly different, etc. This resulted in confusing semantics, virtual method overloads, and control flow. Remove the above, and replace with new beginBasicBlockSection and endBasicBlockSection callbacks. And document them. These are always called before the first and after the last blocks in a function, even when basic-block-sections are disabled.
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(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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