LLVM: lib/Target/AArch64/AArch64CompressJumpTables.cpp Source File (original) (raw)
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24using namespace llvm;
25
26#define DEBUG_TYPE "aarch64-jump-tables"
27
28STATISTIC(NumJT8, "Number of jump-tables with 1-byte entries");
29STATISTIC(NumJT16, "Number of jump-tables with 2-byte entries");
30STATISTIC(NumJT32, "Number of jump-tables with 4-byte entries");
31
32namespace {
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43
44 bool scanFunction();
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47
48public:
49 static char ID;
51
52 bool runOnMachineFunction(MachineFunction &MF) override;
53
54 MachineFunctionProperties getRequiredProperties() const override {
55 return MachineFunctionProperties().setNoVRegs();
56 }
57 StringRef getPassName() const override {
58 return "AArch64 Compress Jump Tables";
59 }
60};
61char AArch64CompressJumpTables::ID = 0;
62}
63
65 "AArch64 compress jump tables pass", false, false)
66
67std::optional<int>
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72
73
74 if (MI.getOpcode() == AArch64::INLINEASM ||
75 MI.getOpcode() == AArch64::INLINEASM_BR)
76 return std::nullopt;
77 Size += TII->getInstSizeInBytes(MI);
78 }
80}
81
82bool AArch64CompressJumpTables::scanFunction() {
83 BlockInfo.clear();
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86
87
89 for (MachineBasicBlock &MBB : *MF) {
91 unsigned OffsetAfterAlignment = Offset;
92
93 if (Alignment > Align(4))
94 OffsetAfterAlignment += Alignment.value() - 4;
95 BlockInfo[MBB.getNumber()] = OffsetAfterAlignment;
98 return false;
100 }
101 return true;
102}
103
104bool AArch64CompressJumpTables::compressJumpTable(MachineInstr &MI,
106 if (MI.getOpcode() != AArch64::JumpTableDest32)
107 return false;
108
109 int JTIdx = MI.getOperand(4).getIndex();
110 auto &JTInfo = *MF->getJumpTableInfo();
111 const MachineJumpTableEntry &JT = JTInfo.getJumpTables()[JTIdx];
112
113
114 if (JT.MBBs.empty())
115 return false;
116
117 int MaxOffset = std::numeric_limits::min(),
118 MinOffset = std::numeric_limits::max();
119 MachineBasicBlock *MinBlock = nullptr;
120 for (auto *Block : JT.MBBs) {
121 int BlockOffset = BlockInfo[Block->getNumber()];
122 assert(BlockOffset % 4 == 0 && "misaligned basic block");
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124 MaxOffset = std::max(MaxOffset, BlockOffset);
125 if (BlockOffset <= MinOffset) {
126 MinOffset = BlockOffset;
127 MinBlock = Block;
128 }
129 }
130 assert(MinBlock && "Failed to find minimum offset block");
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135 ++NumJT32;
136 return false;
137 }
138
139 int Span = MaxOffset - MinOffset;
140 auto *AFI = MF->getInfo();
142 AFI->setJumpTableEntryInfo(JTIdx, 1, MinBlock->getSymbol());
143 MI.setDesc(TII->get(AArch64::JumpTableDest8));
144 ++NumJT8;
145 return true;
146 }
148 AFI->setJumpTableEntryInfo(JTIdx, 2, MinBlock->getSymbol());
149 MI.setDesc(TII->get(AArch64::JumpTableDest16));
150 ++NumJT16;
151 return true;
152 }
153
154 ++NumJT32;
155 return false;
156}
157
158bool AArch64CompressJumpTables::runOnMachineFunction(MachineFunction &MFIn) {
160 MF = &MFIn;
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162 const auto &ST = MF->getSubtarget();
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165 if (ST.force32BitJumpTables() && !MF->getFunction().hasMinSize())
166 return false;
167
168 if (!scanFunction())
169 return false;
170
171 for (MachineBasicBlock &MBB : *MF) {
173 for (MachineInstr &MI : MBB) {
176 }
177 }
178
180}
181
183 return new AArch64CompressJumpTables();
184}
assert(UImm &&(UImm !=~static_cast< T >(0)) &&"Invalid immediate!")
const HexagonInstrInfo * TII
#define INITIALIZE_PASS(passName, arg, name, cfg, analysis)
This file defines the 'Statistic' class, which is designed to be an easy way to expose various metric...
#define STATISTIC(VARNAME, DESC)
static const int BlockSize
FunctionPass class - This class is used to implement most global optimizations.
LLVM_ABI MCSymbol * getSymbol() const
Return the MCSymbol for this basic block.
int getNumber() const
MachineBasicBlocks are uniquely numbered at the function level, unless they're not in a MachineFuncti...
Align getAlignment() const
Return alignment of the basic block.
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
unsigned getNumBlockIDs() const
getNumBlockIDs - Return the number of MBB ID's allocated.
Representation of each machine instruction.
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small.
TargetInstrInfo - Interface to description of machine instruction set.
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
unsigned ID
LLVM IR allows to use arbitrary numbers as calling convention identifiers.
This is an optimization pass for GlobalISel generic memory operations.
constexpr bool isInt(int64_t x)
Checks if an integer fits into the given bit width.
FunctionPass * createAArch64CompressJumpTablesPass()
Definition AArch64CompressJumpTables.cpp:182
constexpr bool isUInt(uint64_t x)
Checks if an unsigned integer fits into the given bit width.
Implement std::hash so that hash_code can be used in STL containers.
constexpr uint64_t value() const
This is a hole in the type system and should not be abused.