1 //===- ConstantPools.cpp - ConstantPool class -----------------------------===//
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 implements the ConstantPool and AssemblerConstantPools classes.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "llvm/MC/ConstantPools.h"
15 #include "llvm/MC/MCContext.h"
16 #include "llvm/MC/MCDirectives.h"
17 #include "llvm/MC/MCExpr.h"
18 #include "llvm/MC/MCStreamer.h"
19 #include "llvm/Support/Casting.h"
20
21 using namespace llvm;
22
23 //
24 // ConstantPool implementation
25 //
26 // Emit the contents of the constant pool using the provided streamer.
emitEntries(MCStreamer & Streamer)27 void ConstantPool::emitEntries(MCStreamer &Streamer) {
28 if (Entries.empty())
29 return;
30 Streamer.EmitDataRegion(MCDR_DataRegion);
31 for (const ConstantPoolEntry &Entry : Entries) {
32 Streamer.EmitCodeAlignment(Entry.Size); // align naturally
33 Streamer.EmitLabel(Entry.Label);
34 Streamer.EmitValue(Entry.Value, Entry.Size, Entry.Loc);
35 }
36 Streamer.EmitDataRegion(MCDR_DataRegionEnd);
37 Entries.clear();
38 }
39
addEntry(const MCExpr * Value,MCContext & Context,unsigned Size,SMLoc Loc)40 const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context,
41 unsigned Size, SMLoc Loc) {
42 const MCConstantExpr *C = dyn_cast<MCConstantExpr>(Value);
43
44 // Check if there is existing entry for the same constant. If so, reuse it.
45 auto Itr = C ? CachedEntries.find(C->getValue()) : CachedEntries.end();
46 if (Itr != CachedEntries.end())
47 return Itr->second;
48
49 MCSymbol *CPEntryLabel = Context.createTempSymbol();
50
51 Entries.push_back(ConstantPoolEntry(CPEntryLabel, Value, Size, Loc));
52 const auto SymRef = MCSymbolRefExpr::create(CPEntryLabel, Context);
53 if (C)
54 CachedEntries[C->getValue()] = SymRef;
55 return SymRef;
56 }
57
empty()58 bool ConstantPool::empty() { return Entries.empty(); }
59
clearCache()60 void ConstantPool::clearCache() {
61 CachedEntries.clear();
62 }
63
64 //
65 // AssemblerConstantPools implementation
66 //
getConstantPool(MCSection * Section)67 ConstantPool *AssemblerConstantPools::getConstantPool(MCSection *Section) {
68 ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
69 if (CP == ConstantPools.end())
70 return nullptr;
71
72 return &CP->second;
73 }
74
75 ConstantPool &
getOrCreateConstantPool(MCSection * Section)76 AssemblerConstantPools::getOrCreateConstantPool(MCSection *Section) {
77 return ConstantPools[Section];
78 }
79
emitConstantPool(MCStreamer & Streamer,MCSection * Section,ConstantPool & CP)80 static void emitConstantPool(MCStreamer &Streamer, MCSection *Section,
81 ConstantPool &CP) {
82 if (!CP.empty()) {
83 Streamer.SwitchSection(Section);
84 CP.emitEntries(Streamer);
85 }
86 }
87
emitAll(MCStreamer & Streamer)88 void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
89 // Dump contents of assembler constant pools.
90 for (auto &CPI : ConstantPools) {
91 MCSection *Section = CPI.first;
92 ConstantPool &CP = CPI.second;
93
94 emitConstantPool(Streamer, Section, CP);
95 }
96 }
97
emitForCurrentSection(MCStreamer & Streamer)98 void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
99 MCSection *Section = Streamer.getCurrentSectionOnly();
100 if (ConstantPool *CP = getConstantPool(Section)) {
101 emitConstantPool(Streamer, Section, *CP);
102 }
103 }
104
clearCacheForCurrentSection(MCStreamer & Streamer)105 void AssemblerConstantPools::clearCacheForCurrentSection(MCStreamer &Streamer) {
106 MCSection *Section = Streamer.getCurrentSectionOnly();
107 if (ConstantPool *CP = getConstantPool(Section)) {
108 CP->clearCache();
109 }
110 }
111
addEntry(MCStreamer & Streamer,const MCExpr * Expr,unsigned Size,SMLoc Loc)112 const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
113 const MCExpr *Expr,
114 unsigned Size, SMLoc Loc) {
115 MCSection *Section = Streamer.getCurrentSectionOnly();
116 return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
117 Size, Loc);
118 }
119