1 | //===- ConstantPools.h - Keep track of assembler-generated ------*- 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 declares the ConstantPool and AssemblerConstantPools classes. |
10 | // |
11 | //===----------------------------------------------------------------------===// |
12 | |
13 | #ifndef LLVM_MC_CONSTANTPOOLS_H |
14 | #define LLVM_MC_CONSTANTPOOLS_H |
15 | |
16 | #include "llvm/ADT/MapVector.h" |
17 | #include "llvm/ADT/SmallVector.h" |
18 | #include "llvm/Support/SMLoc.h" |
19 | #include <cstdint> |
20 | #include <map> |
21 | |
22 | namespace llvm { |
23 | |
24 | class MCContext; |
25 | class MCExpr; |
26 | class MCSection; |
27 | class MCStreamer; |
28 | class MCSymbol; |
29 | class MCSymbolRefExpr; |
30 | |
31 | struct ConstantPoolEntry { |
32 | ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_) |
33 | : Label(L), Value(Val), Size(Sz), Loc(Loc_) {} |
34 | |
35 | MCSymbol *Label; |
36 | const MCExpr *Value; |
37 | unsigned Size; |
38 | SMLoc Loc; |
39 | }; |
40 | |
41 | // A class to keep track of assembler-generated constant pools that are use to |
42 | // implement the ldr-pseudo. |
43 | class ConstantPool { |
44 | using EntryVecTy = SmallVector<ConstantPoolEntry, 4>; |
45 | EntryVecTy Entries; |
46 | std::map<int64_t, const MCSymbolRefExpr *> CachedConstantEntries; |
47 | DenseMap<const MCSymbol *, const MCSymbolRefExpr *> CachedSymbolEntries; |
48 | |
49 | public: |
50 | // Initialize a new empty constant pool |
51 | ConstantPool() = default; |
52 | |
53 | // Add a new entry to the constant pool in the next slot. |
54 | // \param Value is the new entry to put in the constant pool. |
55 | // \param Size is the size in bytes of the entry |
56 | // |
57 | // \returns a MCExpr that references the newly inserted value |
58 | const MCExpr *addEntry(const MCExpr *Value, MCContext &Context, |
59 | unsigned Size, SMLoc Loc); |
60 | |
61 | // Emit the contents of the constant pool using the provided streamer. |
62 | void emitEntries(MCStreamer &Streamer); |
63 | |
64 | // Return true if the constant pool is empty |
65 | bool empty(); |
66 | |
67 | void clearCache(); |
68 | }; |
69 | |
70 | class AssemblerConstantPools { |
71 | // Map type used to keep track of per-Section constant pools used by the |
72 | // ldr-pseudo opcode. The map associates a section to its constant pool. The |
73 | // constant pool is a vector of (label, value) pairs. When the ldr |
74 | // pseudo is parsed we insert a new (label, value) pair into the constant pool |
75 | // for the current section and add MCSymbolRefExpr to the new label as |
76 | // an opcode to the ldr. After we have parsed all the user input we |
77 | // output the (label, value) pairs in each constant pool at the end of the |
78 | // section. |
79 | // |
80 | // We use the MapVector for the map type to ensure stable iteration of |
81 | // the sections at the end of the parse. We need to iterate over the |
82 | // sections in a stable order to ensure that we have print the |
83 | // constant pools in a deterministic order when printing an assembly |
84 | // file. |
85 | using ConstantPoolMapTy = MapVector<MCSection *, ConstantPool>; |
86 | ConstantPoolMapTy ConstantPools; |
87 | |
88 | public: |
89 | void emitAll(MCStreamer &Streamer); |
90 | void emitForCurrentSection(MCStreamer &Streamer); |
91 | void clearCacheForCurrentSection(MCStreamer &Streamer); |
92 | const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr, |
93 | unsigned Size, SMLoc Loc); |
94 | |
95 | private: |
96 | ConstantPool *getConstantPool(MCSection *Section); |
97 | ConstantPool &getOrCreateConstantPool(MCSection *Section); |
98 | }; |
99 | |
100 | } // end namespace llvm |
101 | |
102 | #endif // LLVM_MC_CONSTANTPOOLS_H |
103 | |