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 #include "llvm/Support/raw_ostream.h" 27 28 namespace llvm { 29 namespace mca { 30 31 /// A utility class used to compute instruction encodings for a code region. 32 /// 33 /// It provides a simple API to compute and return instruction encodings as 34 /// strings. Encodings are cached internally for later usage. 35 class CodeEmitter { 36 const MCSubtargetInfo &STI; 37 const MCAsmBackend &MAB; 38 const MCCodeEmitter &MCE; 39 40 SmallString<256> Code; 41 raw_svector_ostream VecOS; 42 ArrayRef<MCInst> Sequence; 43 44 // An EncodingInfo pair stores <base, length> information. Base (i.e. first) 45 // is an index to the `Code`. Length (i.e. second) is the encoding size. 46 using EncodingInfo = std::pair<unsigned, unsigned>; 47 48 // A cache of encodings. 49 SmallVector<EncodingInfo, 16> Encodings; 50 51 EncodingInfo getOrCreateEncodingInfo(unsigned MCID); 52 53 public: 54 CodeEmitter(const MCSubtargetInfo &ST, const MCAsmBackend &AB, 55 const MCCodeEmitter &CE, ArrayRef<MCInst> S) 56 : STI(ST), MAB(AB), MCE(CE), VecOS(Code), Sequence(S), 57 Encodings(S.size()) {} 58 59 StringRef getEncoding(unsigned MCID) { 60 EncodingInfo EI = getOrCreateEncodingInfo(MCID); 61 return StringRef(&Code[EI.first], EI.second); 62 } 63 }; 64 65 } // namespace mca 66 } // namespace llvm 67 68 #endif // LLVM_MCA_CODEEMITTER_H 69