1 //===- VarLenCodeEmitterGen.h - CEG for variable-length insts ---*- 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 //
9 // This file declare the CodeEmitterGen component for variable-length
10 // instructions. See the .cpp file for more details.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_UTILS_TABLEGEN_VARLENCODEEMITTERGEN_H
15 #define LLVM_UTILS_TABLEGEN_VARLENCODEEMITTERGEN_H
16 
17 #include "llvm/TableGen/Record.h"
18 
19 namespace llvm {
20 
21 struct EncodingSegment {
22   unsigned BitWidth;
23   const Init *Value;
24   StringRef CustomEncoder = "";
25 };
26 
27 class VarLenInst {
28   const RecordVal *TheDef;
29   size_t NumBits;
30 
31   // Set if any of the segment is not fixed value.
32   bool HasDynamicSegment;
33 
34   SmallVector<EncodingSegment, 4> Segments;
35 
36   void buildRec(const DagInit *DI);
37 
38   StringRef getCustomEncoderName(const Init *EI) const {
39     if (const auto *DI = dyn_cast<DagInit>(EI)) {
40       if (DI->getNumArgs() && isa<StringInit>(DI->getArg(0)))
41         return cast<StringInit>(DI->getArg(0))->getValue();
42     }
43     return "";
44   }
45 
46 public:
47   VarLenInst() : TheDef(nullptr), NumBits(0U), HasDynamicSegment(false) {}
48 
49   explicit VarLenInst(const DagInit *DI, const RecordVal *TheDef);
50 
51   /// Number of bits
52   size_t size() const { return NumBits; }
53 
54   using const_iterator = decltype(Segments)::const_iterator;
55 
56   const_iterator begin() const { return Segments.begin(); }
57   const_iterator end() const { return Segments.end(); }
58   size_t getNumSegments() const { return Segments.size(); }
59 
60   bool isFixedValueOnly() const { return !HasDynamicSegment; }
61 };
62 
63 void emitVarLenCodeEmitter(RecordKeeper &R, raw_ostream &OS);
64 
65 } // end namespace llvm
66 #endif
67