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;
46 void LegalizerInfo::computeTables() {
47 for (unsigned Opcode = 0; Opcode <= LastOp - FirstOp; ++Opcode) {
48 for (unsigned Idx = 0; Idx != Actions[Opcode].size(); ++Idx) {
49 for (auto &Action : Actions[Opcode][Idx]) {
50 LLT Ty = Action.first;
54 auto &Entry = MaxLegalVectorElts[std::make_pair(Opcode + FirstOp,
55 Ty.getElementType())];
56 Entry = std::max(Entry, Ty.getNumElements());
61 TablesInitialized = true;
64 // FIXME: inefficient implementation for now. Without ComputeValueVTs we're
65 // probably going to need specialized lookup structures for various types before
66 // we have any hope of doing well with something like <13 x i3>. Even the common
67 // cases should do better than what we have now.
68 std::pair<LegalizerInfo::LegalizeAction, LLT>
69 LegalizerInfo::getAction(const InstrAspect &Aspect) const {
70 assert(TablesInitialized && "backend forgot to call computeTables");
71 // These *have* to be implemented for now, they're the fundamental basis of
72 // how everything else is transformed.
74 // Nothing is going to go well with types that aren't a power of 2 yet, so
75 // don't even try because we might make things worse.
76 if (!isPowerOf2_64(Aspect.Type.getSizeInBits()))
77 return std::make_pair(Unsupported, LLT());
79 // FIXME: the long-term plan calls for expansion in terms of load/store (if
80 // they're not legal).
81 if (Aspect.Opcode == TargetOpcode::G_SEQUENCE ||
82 Aspect.Opcode == TargetOpcode::G_EXTRACT)
83 return std::make_pair(Legal, Aspect.Type);
85 LegalizeAction Action = findInActions(Aspect);
86 if (Action != NotFound)
87 return findLegalAction(Aspect, Action);
89 unsigned Opcode = Aspect.Opcode;
92 auto DefaultAction = DefaultActions.find(Aspect.Opcode);
93 if (DefaultAction != DefaultActions.end() && DefaultAction->second == Legal)
94 return std::make_pair(Legal, Ty);
96 if (DefaultAction == DefaultActions.end() ||
97 DefaultAction->second != NarrowScalar)
98 return std::make_pair(Unsupported, LLT());
99 return findLegalAction(Aspect, NarrowScalar);
102 LLT EltTy = Ty.getElementType();
103 int NumElts = Ty.getNumElements();
105 auto ScalarAction = ScalarInVectorActions.find(std::make_pair(Opcode, EltTy));
106 if (ScalarAction != ScalarInVectorActions.end() &&
107 ScalarAction->second != Legal)
108 return findLegalAction(Aspect, ScalarAction->second);
110 // The element type is legal in principle, but the number of elements is
112 auto MaxLegalElts = MaxLegalVectorElts.lookup(std::make_pair(Opcode, EltTy));
113 if (MaxLegalElts > NumElts)
114 return findLegalAction(Aspect, MoreElements);
116 if (MaxLegalElts == 0) {
117 // Scalarize if there's no legal vector type, which is just a special case
119 return std::make_pair(FewerElements, EltTy);
122 return findLegalAction(Aspect, FewerElements);
125 std::tuple<LegalizerInfo::LegalizeAction, unsigned, LLT>
126 LegalizerInfo::getAction(const MachineInstr &MI,
127 const MachineRegisterInfo &MRI) const {
128 SmallBitVector SeenTypes(8);
129 const MCOperandInfo *OpInfo = MI.getDesc().OpInfo;
130 for (unsigned i = 0; i < MI.getDesc().getNumOperands(); ++i) {
131 if (!OpInfo[i].isGenericType())
134 // We don't want to repeatedly check the same operand index, that
135 // could get expensive.
136 unsigned TypeIdx = OpInfo[i].getGenericTypeIndex();
137 if (SeenTypes[TypeIdx])
140 SeenTypes.set(TypeIdx);
142 LLT Ty = MRI.getType(MI.getOperand(i).getReg());
143 auto Action = getAction({MI.getOpcode(), TypeIdx, Ty});
144 if (Action.first != Legal)
145 return std::make_tuple(Action.first, TypeIdx, Action.second);
147 return std::make_tuple(Legal, 0, LLT{});
150 bool LegalizerInfo::isLegal(const MachineInstr &MI,
151 const MachineRegisterInfo &MRI) const {
152 return std::get<0>(getAction(MI, MRI)) == Legal;
155 LLT LegalizerInfo::findLegalType(const InstrAspect &Aspect,
156 LegalizeAction Action) const {
159 llvm_unreachable("Cannot find legal type");
165 return findLegalType(Aspect,
166 [&](LLT Ty) -> LLT { return Ty.halfScalarSize(); });
169 return findLegalType(Aspect, [&](LLT Ty) -> LLT {
170 return Ty.getSizeInBits() < 8 ? LLT::scalar(8) : Ty.doubleScalarSize();
173 case FewerElements: {
174 return findLegalType(Aspect,
175 [&](LLT Ty) -> LLT { return Ty.halfElements(); });
178 return findLegalType(Aspect,
179 [&](LLT Ty) -> LLT { return Ty.doubleElements(); });