70 lines
2.1 KiB
C
70 lines
2.1 KiB
C
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//===--------------------- CodeEmitter.h ------------------------*- C++ -*-===//
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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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/// \file
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///
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/// A utility class used to compute instruction encodings. It buffers encodings
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/// for later usage. It exposes a simple API to compute and get the encodings as
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/// StringRef.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MCA_CODEEMITTER_H
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#define LLVM_MCA_CODEEMITTER_H
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/StringRef.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/MCInst.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/Support/raw_ostream.h"
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#include <string>
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namespace llvm {
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namespace mca {
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/// A utility class used to compute instruction encodings for a code region.
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///
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/// It provides a simple API to compute and return instruction encodings as
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/// strings. Encodings are cached internally for later usage.
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class CodeEmitter {
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const MCSubtargetInfo &STI;
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const MCAsmBackend &MAB;
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const MCCodeEmitter &MCE;
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SmallString<256> Code;
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raw_svector_ostream VecOS;
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ArrayRef<MCInst> Sequence;
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// An EncodingInfo pair stores <base, length> information. Base (i.e. first)
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// is an index to the `Code`. Length (i.e. second) is the encoding size.
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using EncodingInfo = std::pair<unsigned, unsigned>;
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// A cache of encodings.
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SmallVector<EncodingInfo, 16> Encodings;
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EncodingInfo getOrCreateEncodingInfo(unsigned MCID);
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public:
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CodeEmitter(const MCSubtargetInfo &ST, const MCAsmBackend &AB,
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const MCCodeEmitter &CE, ArrayRef<MCInst> S)
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: STI(ST), MAB(AB), MCE(CE), VecOS(Code), Sequence(S),
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Encodings(S.size()) {}
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StringRef getEncoding(unsigned MCID) {
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EncodingInfo EI = getOrCreateEncodingInfo(MCID);
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return StringRef(&Code[EI.first], EI.second);
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}
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};
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} // namespace mca
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} // namespace llvm
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#endif // LLVM_MCA_CODEEMITTER_H
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