1 //===-- WebAssemblyInstrInfo.cpp - WebAssembly Instruction Information ----===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// This file contains the WebAssembly implementation of the
12 /// TargetInstrInfo class.
13 ///
14 //===----------------------------------------------------------------------===//
15
16 #include "WebAssemblyInstrInfo.h"
17 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
18 #include "WebAssemblyMachineFunctionInfo.h"
19 #include "WebAssemblySubtarget.h"
20 #include "llvm/CodeGen/MachineFrameInfo.h"
21 #include "llvm/CodeGen/MachineInstrBuilder.h"
22 #include "llvm/CodeGen/MachineMemOperand.h"
23 #include "llvm/CodeGen/MachineRegisterInfo.h"
24 using namespace llvm;
25
26 #define DEBUG_TYPE "wasm-instr-info"
27
28 #define GET_INSTRINFO_CTOR_DTOR
29 #include "WebAssemblyGenInstrInfo.inc"
30
WebAssemblyInstrInfo(const WebAssemblySubtarget & STI)31 WebAssemblyInstrInfo::WebAssemblyInstrInfo(const WebAssemblySubtarget &STI)
32 : WebAssemblyGenInstrInfo(WebAssembly::ADJCALLSTACKDOWN,
33 WebAssembly::ADJCALLSTACKUP,
34 WebAssembly::CATCHRET),
35 RI(STI.getTargetTriple()) {}
36
isReallyTriviallyReMaterializable(const MachineInstr & MI,AliasAnalysis * AA) const37 bool WebAssemblyInstrInfo::isReallyTriviallyReMaterializable(
38 const MachineInstr &MI, AliasAnalysis *AA) const {
39 switch (MI.getOpcode()) {
40 case WebAssembly::CONST_I32:
41 case WebAssembly::CONST_I64:
42 case WebAssembly::CONST_F32:
43 case WebAssembly::CONST_F64:
44 // isReallyTriviallyReMaterializableGeneric misses these because of the
45 // ARGUMENTS implicit def, so we manualy override it here.
46 return true;
47 default:
48 return false;
49 }
50 }
51
copyPhysReg(MachineBasicBlock & MBB,MachineBasicBlock::iterator I,const DebugLoc & DL,unsigned DestReg,unsigned SrcReg,bool KillSrc) const52 void WebAssemblyInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
53 MachineBasicBlock::iterator I,
54 const DebugLoc &DL, unsigned DestReg,
55 unsigned SrcReg, bool KillSrc) const {
56 // This method is called by post-RA expansion, which expects only pregs to
57 // exist. However we need to handle both here.
58 auto &MRI = MBB.getParent()->getRegInfo();
59 const TargetRegisterClass *RC =
60 TargetRegisterInfo::isVirtualRegister(DestReg)
61 ? MRI.getRegClass(DestReg)
62 : MRI.getTargetRegisterInfo()->getMinimalPhysRegClass(DestReg);
63
64 unsigned CopyOpcode;
65 if (RC == &WebAssembly::I32RegClass)
66 CopyOpcode = WebAssembly::COPY_I32;
67 else if (RC == &WebAssembly::I64RegClass)
68 CopyOpcode = WebAssembly::COPY_I64;
69 else if (RC == &WebAssembly::F32RegClass)
70 CopyOpcode = WebAssembly::COPY_F32;
71 else if (RC == &WebAssembly::F64RegClass)
72 CopyOpcode = WebAssembly::COPY_F64;
73 else
74 llvm_unreachable("Unexpected register class");
75
76 BuildMI(MBB, I, DL, get(CopyOpcode), DestReg)
77 .addReg(SrcReg, KillSrc ? RegState::Kill : 0);
78 }
79
80 MachineInstr *
commuteInstructionImpl(MachineInstr & MI,bool NewMI,unsigned OpIdx1,unsigned OpIdx2) const81 WebAssemblyInstrInfo::commuteInstructionImpl(MachineInstr &MI, bool NewMI,
82 unsigned OpIdx1,
83 unsigned OpIdx2) const {
84 // If the operands are stackified, we can't reorder them.
85 WebAssemblyFunctionInfo &MFI =
86 *MI.getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
87 if (MFI.isVRegStackified(MI.getOperand(OpIdx1).getReg()) ||
88 MFI.isVRegStackified(MI.getOperand(OpIdx2).getReg()))
89 return nullptr;
90
91 // Otherwise use the default implementation.
92 return TargetInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
93 }
94
95 // Branch analysis.
analyzeBranch(MachineBasicBlock & MBB,MachineBasicBlock * & TBB,MachineBasicBlock * & FBB,SmallVectorImpl<MachineOperand> & Cond,bool) const96 bool WebAssemblyInstrInfo::analyzeBranch(MachineBasicBlock &MBB,
97 MachineBasicBlock *&TBB,
98 MachineBasicBlock *&FBB,
99 SmallVectorImpl<MachineOperand> &Cond,
100 bool /*AllowModify*/) const {
101 bool HaveCond = false;
102 for (MachineInstr &MI : MBB.terminators()) {
103 switch (MI.getOpcode()) {
104 default:
105 // Unhandled instruction; bail out.
106 return true;
107 case WebAssembly::BR_IF:
108 if (HaveCond)
109 return true;
110 // If we're running after CFGStackify, we can't optimize further.
111 if (!MI.getOperand(0).isMBB())
112 return true;
113 Cond.push_back(MachineOperand::CreateImm(true));
114 Cond.push_back(MI.getOperand(1));
115 TBB = MI.getOperand(0).getMBB();
116 HaveCond = true;
117 break;
118 case WebAssembly::BR_UNLESS:
119 if (HaveCond)
120 return true;
121 // If we're running after CFGStackify, we can't optimize further.
122 if (!MI.getOperand(0).isMBB())
123 return true;
124 Cond.push_back(MachineOperand::CreateImm(false));
125 Cond.push_back(MI.getOperand(1));
126 TBB = MI.getOperand(0).getMBB();
127 HaveCond = true;
128 break;
129 case WebAssembly::BR:
130 // If we're running after CFGStackify, we can't optimize further.
131 if (!MI.getOperand(0).isMBB())
132 return true;
133 if (!HaveCond)
134 TBB = MI.getOperand(0).getMBB();
135 else
136 FBB = MI.getOperand(0).getMBB();
137 break;
138 }
139 if (MI.isBarrier())
140 break;
141 }
142
143 return false;
144 }
145
removeBranch(MachineBasicBlock & MBB,int * BytesRemoved) const146 unsigned WebAssemblyInstrInfo::removeBranch(MachineBasicBlock &MBB,
147 int *BytesRemoved) const {
148 assert(!BytesRemoved && "code size not handled");
149
150 MachineBasicBlock::instr_iterator I = MBB.instr_end();
151 unsigned Count = 0;
152
153 while (I != MBB.instr_begin()) {
154 --I;
155 if (I->isDebugInstr())
156 continue;
157 if (!I->isTerminator())
158 break;
159 // Remove the branch.
160 I->eraseFromParent();
161 I = MBB.instr_end();
162 ++Count;
163 }
164
165 return Count;
166 }
167
insertBranch(MachineBasicBlock & MBB,MachineBasicBlock * TBB,MachineBasicBlock * FBB,ArrayRef<MachineOperand> Cond,const DebugLoc & DL,int * BytesAdded) const168 unsigned WebAssemblyInstrInfo::insertBranch(MachineBasicBlock &MBB,
169 MachineBasicBlock *TBB,
170 MachineBasicBlock *FBB,
171 ArrayRef<MachineOperand> Cond,
172 const DebugLoc &DL,
173 int *BytesAdded) const {
174 assert(!BytesAdded && "code size not handled");
175
176 if (Cond.empty()) {
177 if (!TBB)
178 return 0;
179
180 BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(TBB);
181 return 1;
182 }
183
184 assert(Cond.size() == 2 && "Expected a flag and a successor block");
185
186 if (Cond[0].getImm()) {
187 BuildMI(&MBB, DL, get(WebAssembly::BR_IF)).addMBB(TBB).add(Cond[1]);
188 } else {
189 BuildMI(&MBB, DL, get(WebAssembly::BR_UNLESS)).addMBB(TBB).add(Cond[1]);
190 }
191 if (!FBB)
192 return 1;
193
194 BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(FBB);
195 return 2;
196 }
197
reverseBranchCondition(SmallVectorImpl<MachineOperand> & Cond) const198 bool WebAssemblyInstrInfo::reverseBranchCondition(
199 SmallVectorImpl<MachineOperand> &Cond) const {
200 assert(Cond.size() == 2 && "Expected a flag and a successor block");
201 Cond.front() = MachineOperand::CreateImm(!Cond.front().getImm());
202 return false;
203 }
204