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.emitCodeAlignment(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
43 // Check if there is existing entry for the same constant. If so, reuse it.
44 auto Itr = C ? CachedEntries.find(C->getValue()) : CachedEntries.end();
45 if (Itr != CachedEntries.end())
46 return Itr->second;
47
48 MCSymbol *CPEntryLabel = Context.createTempSymbol();
49
50 Entries.push_back(ConstantPoolEntry(CPEntryLabel, Value, Size, Loc));
51 const auto SymRef = MCSymbolRefExpr::create(CPEntryLabel, Context);
52 if (C)
53 CachedEntries[C->getValue()] = SymRef;
54 return SymRef;
55 }
56
empty()57 bool ConstantPool::empty() { return Entries.empty(); }
58
clearCache()59 void ConstantPool::clearCache() {
60 CachedEntries.clear();
61 }
62
63 //
64 // AssemblerConstantPools implementation
65 //
getConstantPool(MCSection * Section)66 ConstantPool *AssemblerConstantPools::getConstantPool(MCSection *Section) {
67 ConstantPoolMapTy::iterator CP = ConstantPools.find(Section);
68 if (CP == ConstantPools.end())
69 return nullptr;
70
71 return &CP->second;
72 }
73
74 ConstantPool &
getOrCreateConstantPool(MCSection * Section)75 AssemblerConstantPools::getOrCreateConstantPool(MCSection *Section) {
76 return ConstantPools[Section];
77 }
78
emitConstantPool(MCStreamer & Streamer,MCSection * Section,ConstantPool & CP)79 static void emitConstantPool(MCStreamer &Streamer, MCSection *Section,
80 ConstantPool &CP) {
81 if (!CP.empty()) {
82 Streamer.SwitchSection(Section);
83 CP.emitEntries(Streamer);
84 }
85 }
86
emitAll(MCStreamer & Streamer)87 void AssemblerConstantPools::emitAll(MCStreamer &Streamer) {
88 // Dump contents of assembler constant pools.
89 for (auto &CPI : ConstantPools) {
90 MCSection *Section = CPI.first;
91 ConstantPool &CP = CPI.second;
92
93 emitConstantPool(Streamer, Section, CP);
94 }
95 }
96
emitForCurrentSection(MCStreamer & Streamer)97 void AssemblerConstantPools::emitForCurrentSection(MCStreamer &Streamer) {
98 MCSection *Section = Streamer.getCurrentSectionOnly();
99 if (ConstantPool *CP = getConstantPool(Section))
100 emitConstantPool(Streamer, Section, *CP);
101 }
102
clearCacheForCurrentSection(MCStreamer & Streamer)103 void AssemblerConstantPools::clearCacheForCurrentSection(MCStreamer &Streamer) {
104 MCSection *Section = Streamer.getCurrentSectionOnly();
105 if (ConstantPool *CP = getConstantPool(Section))
106 CP->clearCache();
107 }
108
addEntry(MCStreamer & Streamer,const MCExpr * Expr,unsigned Size,SMLoc Loc)109 const MCExpr *AssemblerConstantPools::addEntry(MCStreamer &Streamer,
110 const MCExpr *Expr,
111 unsigned Size, SMLoc Loc) {
112 MCSection *Section = Streamer.getCurrentSectionOnly();
113 return getOrCreateConstantPool(Section).addEntry(Expr, Streamer.getContext(),
114 Size, Loc);
115 }
116