1 //===- ConstantPools.cpp - ConstantPool class -----------------------------===//
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 implements the ConstantPool and AssemblerConstantPools classes.
10 //
11 //===----------------------------------------------------------------------===//
12
13 #include "llvm/MC/ConstantPools.h"
14 #include "llvm/MC/MCContext.h"
15 #include "llvm/MC/MCDirectives.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCStreamer.h"
18 #include "llvm/Support/Casting.h"
19
20 using namespace llvm;
21
22 //
23 // ConstantPool implementation
24 //
25 // Emit the contents of the constant pool using the provided streamer.
emitEntries(MCStreamer & Streamer)26 void ConstantPool::emitEntries(MCStreamer &Streamer) {
27 if (Entries.empty())
28 return;
29 Streamer.emitDataRegion(MCDR_DataRegion);
30 for (const ConstantPoolEntry &Entry : Entries) {
31 Streamer.emitValueToAlignment(Align(Entry.Size)); // align naturally
32 Streamer.emitLabel(Entry.Label);
33 Streamer.emitValue(Entry.Value, Entry.Size, Entry.Loc);
34 }
35 Streamer.emitDataRegion(MCDR_DataRegionEnd);
36 Entries.clear();
37 }
38
addEntry(const MCExpr * Value,MCContext & Context,unsigned Size,SMLoc Loc)39 const MCExpr *ConstantPool::addEntry(const MCExpr *Value, MCContext &Context,
40 unsigned Size, SMLoc Loc) {
41 const MCConstantExpr *C = dyn_cast<MCConstantExpr>(Value);
42 const MCSymbolRefExpr *S = dyn_cast<MCSymbolRefExpr>(Value);
43
44 // Check if there is existing entry for the same constant. If so, reuse it.
45 if (C) {
46 auto CItr = CachedConstantEntries.find(C->getValue());
47 if (CItr != CachedConstantEntries.end())
48 return CItr->second;
49 }
50
51 // Check if there is existing entry for the same symbol. If so, reuse it.
52 if (S) {
53 auto SItr = CachedSymbolEntries.find(&(S->getSymbol()));
54 if (SItr != CachedSymbolEntries.end())
55 return SItr->second;
56 }
57
58 MCSymbol *CPEntryLabel = Context.createTempSymbol();
59
60 Entries.push_back(ConstantPoolEntry(CPEntryLabel, Value, Size, Loc));
61 const auto SymRef = MCSymbolRefExpr::create(CPEntryLabel, Context);
62 if (C)
63 CachedConstantEntries[C->getValue()] = SymRef;
64 if (S)
65 CachedSymbolEntries[&(S->getSymbol())] = SymRef;
66 return SymRef;
67 }
68
empty()69 bool ConstantPool::empty() { return Entries.empty(); }
70
clearCache()71 void ConstantPool::clearCache() {
72 CachedConstantEntries.clear();
73 CachedSymbolEntries.clear();
74 }
75
76 //
77 // AssemblerConstantPools implementation
78 //
getConstantPool(MCSection * Section)79 ConstantPool *AssemblerConstantPools::getConstantPool(MCSection *Section) {
80 ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
81 if (CP == ConstantPools.end())
82 return nullptr;
83
84 return &CP->second;
85 }
86
87 ConstantPool &
getOrCreateConstantPool(MCSection * Section)88 AssemblerConstantPools::getOrCreateConstantPool(MCSection *Section) {
89 return ConstantPools[Section];
90 }
91
emitConstantPool(MCStreamer & Streamer,MCSection * Section,ConstantPool & CP)92 static void emitConstantPool(MCStreamer &Streamer, MCSection *Section,
93 ConstantPool &CP) {
94 if (!CP.empty()) {
95 Streamer.switchSection(Section);
96 CP.emitEntries(Streamer);
97 }
98 }
99
emitAll(MCStreamer & Streamer)100 void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
101 // Dump contents of assembler constant pools.
102 for (auto &CPI : ConstantPools) {
103 MCSection *Section = CPI.first;
104 ConstantPool &CP = CPI.second;
105
106 emitConstantPool(Streamer, Section, CP);
107 }
108 }
109
emitForCurrentSection(MCStreamer & Streamer)110 void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
111 MCSection *Section = Streamer.getCurrentSectionOnly();
112 if (ConstantPool *CP = getConstantPool(Section))
113 emitConstantPool(Streamer, Section, *CP);
114 }
115
clearCacheForCurrentSection(MCStreamer & Streamer)116 void AssemblerConstantPools::clearCacheForCurrentSection(MCStreamer &Streamer) {
117 MCSection *Section = Streamer.getCurrentSectionOnly();
118 if (ConstantPool *CP = getConstantPool(Section))
119 CP->clearCache();
120 }
121
addEntry(MCStreamer & Streamer,const MCExpr * Expr,unsigned Size,SMLoc Loc)122 const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
123 const MCExpr *Expr,
124 unsigned Size, SMLoc Loc) {
125 MCSection *Section = Streamer.getCurrentSectionOnly();
126 return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
127 Size, Loc);
128 }
129