e63455d5e0
On some architectures such as Arm and X86 the encoding for a nop may change depending on the subtarget in operation at the time of encoding. This change replaces the per module MCSubtargetInfo retained by the targets AsmBackend in favour of passing through the local MCSubtargetInfo in operation at the time. On Arm using the architectural NOP instruction can have a performance benefit on some implementations. For Arm I've deleted the copy of the AsmBackend's MCSubtargetInfo to limit the chances of this causing problems in the future. I've not done this for other targets such as X86 as there is more frequent use of the MCSubtargetInfo and it looks to be for stable properties that we would not expect to vary per function. This change required threading STI through MCNopsFragment and MCBoundaryAlignFragment. I've attempted to take into account the in tree experimental backends. Differential Revision: https://reviews.llvm.org/D45962
71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
//===-- AVRAsmBackend.h - AVR Asm Backend --------------------------------===//
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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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// \file The AVR assembly backend implementation.
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//
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//===----------------------------------------------------------------------===//
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//
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#ifndef LLVM_AVR_ASM_BACKEND_H
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#define LLVM_AVR_ASM_BACKEND_H
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#include "MCTargetDesc/AVRFixupKinds.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/MC/MCAsmBackend.h"
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namespace llvm {
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class MCAssembler;
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class MCContext;
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struct MCFixupKindInfo;
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/// Utilities for manipulating generated AVR machine code.
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class AVRAsmBackend : public MCAsmBackend {
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public:
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AVRAsmBackend(Triple::OSType OSType)
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: MCAsmBackend(support::little), OSType(OSType) {}
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void adjustFixupValue(const MCFixup &Fixup, const MCValue &Target,
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uint64_t &Value, MCContext *Ctx = nullptr) const;
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std::unique_ptr<MCObjectTargetWriter>
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createObjectTargetWriter() const override;
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void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target, MutableArrayRef<char> Data,
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uint64_t Value, bool IsResolved,
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const MCSubtargetInfo *STI) const override;
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const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
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unsigned getNumFixupKinds() const override {
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return AVR::NumTargetFixupKinds;
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}
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bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
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const MCRelaxableFragment *DF,
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const MCAsmLayout &Layout) const override {
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llvm_unreachable("RelaxInstruction() unimplemented");
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return false;
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}
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bool writeNopData(raw_ostream &OS, uint64_t Count,
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const MCSubtargetInfo *STI) const override;
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bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
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const MCValue &Target) override;
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private:
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Triple::OSType OSType;
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};
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} // end namespace llvm
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#endif // LLVM_AVR_ASM_BACKEND_H
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