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