LLVM  4.0.0
ConstantPools.h
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1 //===- ConstantPool.h - Keep track of assembler-generated ------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file declares the ConstantPool and AssemblerConstantPools classes.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 
15 #ifndef LLVM_MC_CONSTANTPOOLS_H
16 #define LLVM_MC_CONSTANTPOOLS_H
17 
18 #include "llvm/ADT/MapVector.h"
19 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/Support/SMLoc.h"
21 
22 namespace llvm {
23 class MCContext;
24 class MCExpr;
25 class MCSection;
26 class MCStreamer;
27 class MCSymbol;
28 class MCSymbolRefExpr;
29 
31  ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)
32  : Label(L), Value(Val), Size(Sz), Loc(Loc_) {}
34  const MCExpr *Value;
35  unsigned Size;
37 };
38 
39 // A class to keep track of assembler-generated constant pools that are use to
40 // implement the ldr-pseudo.
41 class ConstantPool {
43  EntryVecTy Entries;
45 
46 public:
47  // Initialize a new empty constant pool
49 
50  // Add a new entry to the constant pool in the next slot.
51  // \param Value is the new entry to put in the constant pool.
52  // \param Size is the size in bytes of the entry
53  //
54  // \returns a MCExpr that references the newly inserted value
55  const MCExpr *addEntry(const MCExpr *Value, MCContext &Context,
56  unsigned Size, SMLoc Loc);
57 
58  // Emit the contents of the constant pool using the provided streamer.
59  void emitEntries(MCStreamer &Streamer);
60 
61  // Return true if the constant pool is empty
62  bool empty();
63 };
64 
66  // Map type used to keep track of per-Section constant pools used by the
67  // ldr-pseudo opcode. The map associates a section to its constant pool. The
68  // constant pool is a vector of (label, value) pairs. When the ldr
69  // pseudo is parsed we insert a new (label, value) pair into the constant pool
70  // for the current section and add MCSymbolRefExpr to the new label as
71  // an opcode to the ldr. After we have parsed all the user input we
72  // output the (label, value) pairs in each constant pool at the end of the
73  // section.
74  //
75  // We use the MapVector for the map type to ensure stable iteration of
76  // the sections at the end of the parse. We need to iterate over the
77  // sections in a stable order to ensure that we have print the
78  // constant pools in a deterministic order when printing an assembly
79  // file.
81  ConstantPoolMapTy ConstantPools;
82 
83 public:
84  void emitAll(MCStreamer &Streamer);
85  void emitForCurrentSection(MCStreamer &Streamer);
86  const MCExpr *addEntry(MCStreamer &Streamer, const MCExpr *Expr,
87  unsigned Size, SMLoc Loc);
88 
89 private:
90  ConstantPool *getConstantPool(MCSection *Section);
91  ConstantPool &getOrCreateConstantPool(MCSection *Section);
92 };
93 } // end namespace llvm
94 
95 #endif
MachineLoop * L
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:40
const MCExpr * Value
Definition: ConstantPools.h:34
LLVMContext & Context
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:39
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:34
ConstantPoolEntry(MCSymbol *L, const MCExpr *Val, unsigned Sz, SMLoc Loc_)
Definition: ConstantPools.h:31
Context object for machine code objects.
Definition: MCContext.h:51
const MCExpr * addEntry(const MCExpr *Value, MCContext &Context, unsigned Size, SMLoc Loc)
Streaming machine code generation interface.
Definition: MCStreamer.h:161
void emitForCurrentSection(MCStreamer &Streamer)
const MCExpr * addEntry(MCStreamer &Streamer, const MCExpr *Expr, unsigned Size, SMLoc Loc)
void emitAll(MCStreamer &Streamer)
void emitEntries(MCStreamer &Streamer)
LLVM Value Representation.
Definition: Value.h:71
Represents a location in source code.
Definition: SMLoc.h:24