89b57061f7
This moves the registry higher in the LLVM library dependency stack. Every client of the target registry needs to link against MC anyway to actually use the target, so we might as well move this out of Support. This allows us to ensure that Support doesn't have includes from MC/*. Differential Revision: https://reviews.llvm.org/D111454
78 lines
3.3 KiB
C++
78 lines
3.3 KiB
C++
//===-------- PPCXCOFFStreamer.cpp - XCOFF Object Output ------------------===//
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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 is a custom MCXCOFFStreamer for PowerPC.
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//
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// The purpose of the custom XCOFF streamer is to allow us to intercept
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// instructions as they are being emitted and align all 8 byte instructions
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// to a 64 byte boundary if required (by adding a 4 byte nop). This is important
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// because 8 byte instructions are not allowed to cross 64 byte boundaries
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// and by aligning anything that is within 4 bytes of the boundary we can
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// guarantee that the 8 byte instructions do not cross that boundary.
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//
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//===----------------------------------------------------------------------===//
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#include "PPCXCOFFStreamer.h"
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#include "PPCMCCodeEmitter.h"
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#include "llvm/BinaryFormat/XCOFF.h"
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#include "llvm/MC/MCAsmBackend.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCDirectives.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSectionXCOFF.h"
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#include "llvm/MC/MCSymbolXCOFF.h"
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#include "llvm/MC/TargetRegistry.h"
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using namespace llvm;
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PPCXCOFFStreamer::PPCXCOFFStreamer(MCContext &Context,
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std::unique_ptr<MCAsmBackend> MAB,
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std::unique_ptr<MCObjectWriter> OW,
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std::unique_ptr<MCCodeEmitter> Emitter)
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: MCXCOFFStreamer(Context, std::move(MAB), std::move(OW),
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std::move(Emitter)) {}
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void PPCXCOFFStreamer::emitPrefixedInstruction(const MCInst &Inst,
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const MCSubtargetInfo &STI) {
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// Prefixed instructions must not cross a 64-byte boundary (i.e. prefix is
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// before the boundary and the remaining 4-bytes are after the boundary). In
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// order to achieve this, a nop is added prior to any such boundary-crossing
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// prefixed instruction. Align to 64 bytes if possible but add a maximum of 4
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// bytes when trying to do that. If alignment requires adding more than 4
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// bytes then the instruction won't be aligned.
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emitCodeAlignment(64, &STI, 4);
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// Emit the instruction.
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// Since the previous emit created a new fragment then adding this instruction
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// also forces the addition of a new fragment. Inst is now the first
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// instruction in that new fragment.
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MCXCOFFStreamer::emitInstruction(Inst, STI);
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}
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void PPCXCOFFStreamer::emitInstruction(const MCInst &Inst,
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const MCSubtargetInfo &STI) {
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PPCMCCodeEmitter *Emitter =
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static_cast<PPCMCCodeEmitter *>(getAssembler().getEmitterPtr());
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// Special handling is only for prefixed instructions.
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if (!Emitter->isPrefixedInstruction(Inst)) {
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MCXCOFFStreamer::emitInstruction(Inst, STI);
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return;
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}
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emitPrefixedInstruction(Inst, STI);
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}
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MCXCOFFStreamer *
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llvm::createPPCXCOFFStreamer(MCContext &Context,
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std::unique_ptr<MCAsmBackend> MAB,
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std::unique_ptr<MCObjectWriter> OW,
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std::unique_ptr<MCCodeEmitter> Emitter) {
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return new PPCXCOFFStreamer(Context, std::move(MAB), std::move(OW),
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std::move(Emitter));
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}
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