1 //===---- lib/CodeGen/GlobalISel/LegalizerInfo.cpp - Legalizer -------==//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Implement an interface to specify and query how an illegal operation on a
11 // given type should be expanded.
13 // Issues to be resolved:
15 // + Support weird types like i3, <7 x i3>, ...
16 // + Operations with more than one type (ICMP, CMPXCHG, intrinsics, ...)
18 //===----------------------------------------------------------------------===//
20 #include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
22 #include "llvm/ADT/SmallBitVector.h"
23 #include "llvm/CodeGen/MachineInstr.h"
24 #include "llvm/CodeGen/MachineRegisterInfo.h"
25 #include "llvm/CodeGen/ValueTypes.h"
26 #include "llvm/IR/Type.h"
27 #include "llvm/Target/TargetOpcodes.h"
30 LegalizerInfo::LegalizerInfo() : TablesInitialized(false) {
31 // FIXME: these two can be legalized to the fundamental load/store Jakob
32 // proposed. Once loads & stores are supported.
33 DefaultActions[TargetOpcode::G_ANYEXT] = Legal;
34 DefaultActions[TargetOpcode::G_TRUNC] = Legal;
36 DefaultActions[TargetOpcode::G_INTRINSIC] = Legal;
37 DefaultActions[TargetOpcode::G_INTRINSIC_W_SIDE_EFFECTS] = Legal;
39 DefaultActions[TargetOpcode::G_ADD] = NarrowScalar;
40 DefaultActions[TargetOpcode::G_LOAD] = NarrowScalar;
41 DefaultActions[TargetOpcode::G_STORE] = NarrowScalar;
43 DefaultActions[TargetOpcode::G_BRCOND] = WidenScalar;
44 DefaultActions[TargetOpcode::G_INSERT] = NarrowScalar;
45 DefaultActions[TargetOpcode::G_FNEG] = Lower;
48 void LegalizerInfo::computeTables() {
49 for (unsigned Opcode = 0; Opcode <= LastOp - FirstOp; ++Opcode) {
50 for (unsigned Idx = 0; Idx != Actions[Opcode].size(); ++Idx) {
51 for (auto &Action : Actions[Opcode][Idx]) {
52 LLT Ty = Action.first;
56 auto &Entry = MaxLegalVectorElts[std::make_pair(Opcode + FirstOp,
57 Ty.getElementType())];
58 Entry = std::max(Entry, Ty.getNumElements());
63 TablesInitialized = true;
66 // FIXME: inefficient implementation for now. Without ComputeValueVTs we're
67 // probably going to need specialized lookup structures for various types before
68 // we have any hope of doing well with something like <13 x i3>. Even the common
69 // cases should do better than what we have now.
70 std::pair<LegalizerInfo::LegalizeAction, LLT>
71 LegalizerInfo::getAction(const InstrAspect &Aspect) const {
72 assert(TablesInitialized && "backend forgot to call computeTables");
73 // These *have* to be implemented for now, they're the fundamental basis of
74 // how everything else is transformed.
76 // FIXME: the long-term plan calls for expansion in terms of load/store (if
77 // they're not legal).
78 if (Aspect.Opcode == TargetOpcode::G_SEQUENCE ||
79 Aspect.Opcode == TargetOpcode::G_EXTRACT ||
80 Aspect.Opcode == TargetOpcode::G_MERGE_VALUES ||
81 Aspect.Opcode == TargetOpcode::G_UNMERGE_VALUES)
82 return std::make_pair(Legal, Aspect.Type);
85 LegalizeAction Action = findInActions(Aspect);
86 // LegalizerHelper is not able to handle non-power-of-2 types right now, so do
87 // not try to legalize them unless they are marked as Legal or Custom.
88 // FIXME: This is a temporary hack until the general non-power-of-2
89 // legalization works.
90 if (!isPowerOf2_64(Ty.getSizeInBits()) &&
91 !(Action == Legal || Action == Custom))
92 return std::make_pair(Unsupported, LLT());
94 if (Action != NotFound)
95 return findLegalAction(Aspect, Action);
97 unsigned Opcode = Aspect.Opcode;
99 auto DefaultAction = DefaultActions.find(Aspect.Opcode);
100 if (DefaultAction != DefaultActions.end() && DefaultAction->second == Legal)
101 return std::make_pair(Legal, Ty);
103 if (DefaultAction != DefaultActions.end() && DefaultAction->second == Lower)
104 return std::make_pair(Lower, Ty);
106 if (DefaultAction == DefaultActions.end() ||
107 DefaultAction->second != NarrowScalar)
108 return std::make_pair(Unsupported, LLT());
109 return findLegalAction(Aspect, NarrowScalar);
112 LLT EltTy = Ty.getElementType();
113 int NumElts = Ty.getNumElements();
115 auto ScalarAction = ScalarInVectorActions.find(std::make_pair(Opcode, EltTy));
116 if (ScalarAction != ScalarInVectorActions.end() &&
117 ScalarAction->second != Legal)
118 return findLegalAction(Aspect, ScalarAction->second);
120 // The element type is legal in principle, but the number of elements is
122 auto MaxLegalElts = MaxLegalVectorElts.lookup(std::make_pair(Opcode, EltTy));
123 if (MaxLegalElts > NumElts)
124 return findLegalAction(Aspect, MoreElements);
126 if (MaxLegalElts == 0) {
127 // Scalarize if there's no legal vector type, which is just a special case
129 return std::make_pair(FewerElements, EltTy);
132 return findLegalAction(Aspect, FewerElements);
135 std::tuple<LegalizerInfo::LegalizeAction, unsigned, LLT>
136 LegalizerInfo::getAction(const MachineInstr &MI,
137 const MachineRegisterInfo &MRI) const {
138 SmallBitVector SeenTypes(8);
139 const MCOperandInfo *OpInfo = MI.getDesc().OpInfo;
140 for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) {
141 if (!OpInfo[i].isGenericType())
144 // We don't want to repeatedly check the same operand index, that
145 // could get expensive.
146 unsigned TypeIdx = OpInfo[i].getGenericTypeIndex();
147 if (SeenTypes[TypeIdx])
150 SeenTypes.set(TypeIdx);
152 LLT Ty = MRI.getType(MI.getOperand(i).getReg());
153 auto Action = getAction({MI.getOpcode(), TypeIdx, Ty});
154 if (Action.first != Legal)
155 return std::make_tuple(Action.first, TypeIdx, Action.second);
157 return std::make_tuple(Legal, 0, LLT{});
160 bool LegalizerInfo::isLegal(const MachineInstr &MI,
161 const MachineRegisterInfo &MRI) const {
162 return std::get<0>(getAction(MI, MRI)) == Legal;
165 Optional<LLT> LegalizerInfo::findLegalType(const InstrAspect &Aspect,
166 LegalizeAction Action) const {
169 llvm_unreachable("Cannot find legal type");
176 return findLegalType(Aspect,
177 [](LLT Ty) -> LLT { return Ty.halfScalarSize(); });
180 return findLegalType(Aspect, [](LLT Ty) -> LLT {
181 return Ty.getSizeInBits() < 8 ? LLT::scalar(8) : Ty.doubleScalarSize();
184 case FewerElements: {
185 return findLegalType(Aspect,
186 [](LLT Ty) -> LLT { return Ty.halfElements(); });
189 return findLegalType(Aspect,
190 [](LLT Ty) -> LLT { return Ty.doubleElements(); });
195 bool LegalizerInfo::legalizeCustom(MachineInstr &MI,
196 MachineRegisterInfo &MRI,
197 MachineIRBuilder &MIRBuilder) const {