LLVM 19.0.0git
ConstantPools.h
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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"
18#include "llvm/Support/SMLoc.h"
19#include <cstdint>
20#include <map>
21
22namespace llvm {
23
24class MCContext;
25class MCExpr;
26class MCSection;
27class MCStreamer;
28class MCSymbol;
29class MCSymbolRefExpr;
30
32 ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)
33 : Label(L), Value(Val), Size(Sz), Loc(Loc_) {}
34
36 const MCExpr *Value;
37 unsigned Size;
39};
40
41// A class to keep track of assembler-generated constant pools that are use to
42// implement the ldr-pseudo.
45 EntryVecTy Entries;
46
47 // Caches of entries that already exist, indexed by their contents
48 // and also the size of the constant.
49 std::map<std::pair<int64_t, unsigned>, const MCSymbolRefExpr *>
50 CachedConstantEntries;
52 CachedSymbolEntries;
53
54public:
55 // Initialize a new empty constant pool
56 ConstantPool() = default;
57
58 // Add a new entry to the constant pool in the next slot.
59 // \param Value is the new entry to put in the constant pool.
60 // \param Size is the size in bytes of the entry
61 //
62 // \returns a MCExpr that references the newly inserted value
63 const MCExpr *addEntry(const MCExpr *Value, MCContext &Context,
64 unsigned Size, SMLoc Loc);
65
66 // Emit the contents of the constant pool using the provided streamer.
67 void emitEntries(MCStreamer &Streamer);
68
69 // Return true if the constant pool is empty
70 bool empty();
71
72 void clearCache();
73};
74
76 // Map type used to keep track of per-Section constant pools used by the
77 // ldr-pseudo opcode. The map associates a section to its constant pool. The
78 // constant pool is a vector of (label, value) pairs. When the ldr
79 // pseudo is parsed we insert a new (label, value) pair into the constant pool
80 // for the current section and add MCSymbolRefExpr to the new label as
81 // an opcode to the ldr. After we have parsed all the user input we
82 // output the (label, value) pairs in each constant pool at the end of the
83 // section.
84 //
85 // We use the MapVector for the map type to ensure stable iteration of
86 // the sections at the end of the parse. We need to iterate over the
87 // sections in a stable order to ensure that we have print the
88 // constant pools in a deterministic order when printing an assembly
89 // file.
91 ConstantPoolMapTy ConstantPools;
92
93public:
94 void emitAll(MCStreamer &Streamer);
95 void emitForCurrentSection(MCStreamer &Streamer);
97 const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,
98 unsigned Size, SMLoc Loc);
99
100private:
101 ConstantPool *getConstantPool(MCSection *Section);
102 ConstantPool &getOrCreateConstantPool(MCSection *Section);
103};
104
105} // end namespace llvm
106
107#endif // LLVM_MC_CONSTANTPOOLS_H
uint64_t Size
This file implements a map that provides insertion order iteration.
This file defines the SmallVector class.
void emitAll(MCStreamer &Streamer)
void clearCacheForCurrentSection(MCStreamer &Streamer)
void emitForCurrentSection(MCStreamer &Streamer)
const MCExpr * addEntry(MCStreamer &Streamer, const MCExpr *Expr, unsigned Size, SMLoc Loc)
const MCExpr * addEntry(const MCExpr *Value, MCContext &Context, unsigned Size, SMLoc Loc)
ConstantPool()=default
void emitEntries(MCStreamer &Streamer)
Context object for machine code objects.
Definition: MCContext.h:83
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
Instances of this class represent a uniqued identifier for a section in the current translation unit.
Definition: MCSection.h:35
Streaming machine code generation interface.
Definition: MCStreamer.h:212
Represent a reference to a symbol from inside an expression.
Definition: MCExpr.h:192
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
Represents a location in source code.
Definition: SMLoc.h:23
LLVM Value Representation.
Definition: Value.h:74
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)
Definition: ConstantPools.h:32
const MCExpr * Value
Definition: ConstantPools.h:36