| 1 | //===--------------------- CodeEmitter.h ------------------------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | /// \file |
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| 9 | /// |
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| 10 | /// A utility class used to compute instruction encodings. It buffers encodings |
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| 11 | /// for later usage. It exposes a simple API to compute and get the encodings as |
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| 12 | /// StringRef. |
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| 13 | // |
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| 14 | //===----------------------------------------------------------------------===// |
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| 15 | |
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| 16 | #ifndef LLVM_MCA_CODEEMITTER_H |
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| 17 | #define LLVM_MCA_CODEEMITTER_H |
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| 18 | |
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| 19 | #include "llvm/ADT/ArrayRef.h" |
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| 20 | #include "llvm/ADT/SmallString.h" |
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| 21 | #include "llvm/ADT/StringRef.h" |
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| 22 | #include "llvm/MC/MCAsmBackend.h" |
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| 23 | #include "llvm/MC/MCCodeEmitter.h" |
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| 24 | #include "llvm/MC/MCInst.h" |
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| 25 | #include "llvm/MC/MCSubtargetInfo.h" |
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| 26 | |
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| 27 | namespace llvm { |
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| 28 | namespace mca { |
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| 29 | |
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| 30 | /// A utility class used to compute instruction encodings for a code region. |
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| 31 | /// |
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| 32 | /// It provides a simple API to compute and return instruction encodings as |
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| 33 | /// strings. Encodings are cached internally for later usage. |
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| 34 | class CodeEmitter { |
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| 35 | const MCSubtargetInfo &STI; |
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| 36 | const MCAsmBackend &MAB; |
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| 37 | const MCCodeEmitter &MCE; |
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| 38 | |
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| 39 | SmallString<256> Code; |
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| 40 | ArrayRef<MCInst> Sequence; |
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| 41 | |
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| 42 | // An EncodingInfo pair stores <base, length> information. Base (i.e. first) |
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| 43 | // is an index to the `Code`. Length (i.e. second) is the encoding size. |
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| 44 | using EncodingInfo = std::pair<unsigned, unsigned>; |
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| 45 | |
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| 46 | // A cache of encodings. |
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| 47 | SmallVector<EncodingInfo, 16> Encodings; |
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| 48 | |
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| 49 | EncodingInfo getOrCreateEncodingInfo(unsigned MCID); |
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| 50 | |
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| 51 | public: |
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| 52 | CodeEmitter(const MCSubtargetInfo &ST, const MCAsmBackend &AB, |
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| 53 | const MCCodeEmitter &CE, ArrayRef<MCInst> S) |
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| 54 | : STI(ST), MAB(AB), MCE(CE), Sequence(S), Encodings(S.size()) {} |
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| 55 | |
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| 56 | StringRef getEncoding(unsigned MCID) { |
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| 57 | EncodingInfo EI = getOrCreateEncodingInfo(MCID); |
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| 58 | return StringRef(&Code[EI.first], EI.second); |
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| 59 | } |
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| 60 | }; |
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| 61 | |
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| 62 | } // namespace mca |
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| 63 | } // namespace llvm |
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| 64 | |
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| 65 | #endif // LLVM_MCA_CODEEMITTER_H |
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| 66 | |
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