1 //===-- WebAssemblyInstrInfo.cpp - WebAssembly Instruction Information ----===// 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 /// \file 10 /// This file contains the WebAssembly implementation of the 11 /// TargetInstrInfo class. 12 /// 13 //===----------------------------------------------------------------------===// 14 15 #include "WebAssemblyInstrInfo.h" 16 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" 17 #include "Utils/WebAssemblyUtilities.h" 18 #include "WebAssembly.h" 19 #include "WebAssemblyMachineFunctionInfo.h" 20 #include "WebAssemblySubtarget.h" 21 #include "llvm/CodeGen/MachineFrameInfo.h" 22 #include "llvm/CodeGen/MachineInstrBuilder.h" 23 #include "llvm/CodeGen/MachineMemOperand.h" 24 #include "llvm/CodeGen/MachineRegisterInfo.h" 25 using namespace llvm; 26 27 #define DEBUG_TYPE "wasm-instr-info" 28 29 #define GET_INSTRINFO_CTOR_DTOR 30 #include "WebAssemblyGenInstrInfo.inc" 31 32 // defines WebAssembly::getNamedOperandIdx 33 #define GET_INSTRINFO_NAMED_OPS 34 #include "WebAssemblyGenInstrInfo.inc" 35 36 WebAssemblyInstrInfo::WebAssemblyInstrInfo(const WebAssemblySubtarget &STI) 37 : WebAssemblyGenInstrInfo(WebAssembly::ADJCALLSTACKDOWN, 38 WebAssembly::ADJCALLSTACKUP, 39 WebAssembly::CATCHRET), 40 RI(STI.getTargetTriple()) {} 41 42 bool WebAssemblyInstrInfo::isReallyTriviallyReMaterializable( 43 const MachineInstr &MI) const { 44 switch (MI.getOpcode()) { 45 case WebAssembly::CONST_I32: 46 case WebAssembly::CONST_I64: 47 case WebAssembly::CONST_F32: 48 case WebAssembly::CONST_F64: 49 // isReallyTriviallyReMaterializableGeneric misses these because of the 50 // ARGUMENTS implicit def, so we manualy override it here. 51 return true; 52 default: 53 return false; 54 } 55 } 56 57 void WebAssemblyInstrInfo::copyPhysReg(MachineBasicBlock &MBB, 58 MachineBasicBlock::iterator I, 59 const DebugLoc &DL, MCRegister DestReg, 60 MCRegister SrcReg, bool KillSrc) const { 61 // This method is called by post-RA expansion, which expects only pregs to 62 // exist. However we need to handle both here. 63 auto &MRI = MBB.getParent()->getRegInfo(); 64 const TargetRegisterClass *RC = 65 Register::isVirtualRegister(DestReg) 66 ? MRI.getRegClass(DestReg) 67 : MRI.getTargetRegisterInfo()->getMinimalPhysRegClass(DestReg); 68 69 unsigned CopyOpcode = WebAssembly::getCopyOpcodeForRegClass(RC); 70 71 BuildMI(MBB, I, DL, get(CopyOpcode), DestReg) 72 .addReg(SrcReg, KillSrc ? RegState::Kill : 0); 73 } 74 75 MachineInstr *WebAssemblyInstrInfo::commuteInstructionImpl( 76 MachineInstr &MI, bool NewMI, unsigned OpIdx1, unsigned OpIdx2) const { 77 // If the operands are stackified, we can't reorder them. 78 WebAssemblyFunctionInfo &MFI = 79 *MI.getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>(); 80 if (MFI.isVRegStackified(MI.getOperand(OpIdx1).getReg()) || 81 MFI.isVRegStackified(MI.getOperand(OpIdx2).getReg())) 82 return nullptr; 83 84 // Otherwise use the default implementation. 85 return TargetInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2); 86 } 87 88 // Branch analysis. 89 bool WebAssemblyInstrInfo::analyzeBranch(MachineBasicBlock &MBB, 90 MachineBasicBlock *&TBB, 91 MachineBasicBlock *&FBB, 92 SmallVectorImpl<MachineOperand> &Cond, 93 bool /*AllowModify*/) const { 94 const auto &MFI = *MBB.getParent()->getInfo<WebAssemblyFunctionInfo>(); 95 // WebAssembly has control flow that doesn't have explicit branches or direct 96 // fallthrough (e.g. try/catch), which can't be modeled by analyzeBranch. It 97 // is created after CFGStackify. 98 if (MFI.isCFGStackified()) 99 return true; 100 101 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 Cond.push_back(MachineOperand::CreateImm(true)); 111 Cond.push_back(MI.getOperand(1)); 112 TBB = MI.getOperand(0).getMBB(); 113 HaveCond = true; 114 break; 115 case WebAssembly::BR_UNLESS: 116 if (HaveCond) 117 return true; 118 Cond.push_back(MachineOperand::CreateImm(false)); 119 Cond.push_back(MI.getOperand(1)); 120 TBB = MI.getOperand(0).getMBB(); 121 HaveCond = true; 122 break; 123 case WebAssembly::BR: 124 if (!HaveCond) 125 TBB = MI.getOperand(0).getMBB(); 126 else 127 FBB = MI.getOperand(0).getMBB(); 128 break; 129 } 130 if (MI.isBarrier()) 131 break; 132 } 133 134 return false; 135 } 136 137 unsigned WebAssemblyInstrInfo::removeBranch(MachineBasicBlock &MBB, 138 int *BytesRemoved) const { 139 assert(!BytesRemoved && "code size not handled"); 140 141 MachineBasicBlock::instr_iterator I = MBB.instr_end(); 142 unsigned Count = 0; 143 144 while (I != MBB.instr_begin()) { 145 --I; 146 if (I->isDebugInstr()) 147 continue; 148 if (!I->isTerminator()) 149 break; 150 // Remove the branch. 151 I->eraseFromParent(); 152 I = MBB.instr_end(); 153 ++Count; 154 } 155 156 return Count; 157 } 158 159 unsigned WebAssemblyInstrInfo::insertBranch( 160 MachineBasicBlock &MBB, MachineBasicBlock *TBB, MachineBasicBlock *FBB, 161 ArrayRef<MachineOperand> Cond, const DebugLoc &DL, int *BytesAdded) const { 162 assert(!BytesAdded && "code size not handled"); 163 164 if (Cond.empty()) { 165 if (!TBB) 166 return 0; 167 168 BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(TBB); 169 return 1; 170 } 171 172 assert(Cond.size() == 2 && "Expected a flag and a successor block"); 173 174 if (Cond[0].getImm()) 175 BuildMI(&MBB, DL, get(WebAssembly::BR_IF)).addMBB(TBB).add(Cond[1]); 176 else 177 BuildMI(&MBB, DL, get(WebAssembly::BR_UNLESS)).addMBB(TBB).add(Cond[1]); 178 if (!FBB) 179 return 1; 180 181 BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(FBB); 182 return 2; 183 } 184 185 bool WebAssemblyInstrInfo::reverseBranchCondition( 186 SmallVectorImpl<MachineOperand> &Cond) const { 187 assert(Cond.size() == 2 && "Expected a flag and a condition expression"); 188 Cond.front() = MachineOperand::CreateImm(!Cond.front().getImm()); 189 return false; 190 } 191 192 ArrayRef<std::pair<int, const char *>> 193 WebAssemblyInstrInfo::getSerializableTargetIndices() const { 194 static const std::pair<int, const char *> TargetIndices[] = { 195 {WebAssembly::TI_LOCAL, "wasm-local"}, 196 {WebAssembly::TI_GLOBAL_FIXED, "wasm-global-fixed"}, 197 {WebAssembly::TI_OPERAND_STACK, "wasm-operand-stack"}, 198 {WebAssembly::TI_GLOBAL_RELOC, "wasm-global-reloc"}, 199 {WebAssembly::TI_LOCAL_INDIRECT, "wasm-local-indirect"}}; 200 return ArrayRef(TargetIndices); 201 } 202 203 const MachineOperand & 204 WebAssemblyInstrInfo::getCalleeOperand(const MachineInstr &MI) const { 205 return WebAssembly::getCalleeOp(MI); 206 } 207 208 // This returns true when the instruction defines a value of a TargetIndex 209 // operand that can be tracked by offsets. For Wasm, this returns true for only 210 // local.set/local.tees. This is currently used by LiveDebugValues analysis. 211 // 212 // These are not included: 213 // - In theory we need to add global.set here too, but we don't have global 214 // indices at this point because they are relocatable and we address them by 215 // names until linking, so we don't have 'offsets' (which are used to store 216 // local/global indices) to deal with in LiveDebugValues. And we don't 217 // associate debug info in values in globals anyway. 218 // - All other value-producing instructions, i.e. instructions with defs, can 219 // define values in the Wasm stack, which is represented by TI_OPERAND_STACK 220 // TargetIndex. But they don't have offset info within the instruction itself, 221 // and debug info analysis for them is handled separately in 222 // WebAssemblyDebugFixup pass, so we don't worry about them here. 223 bool WebAssemblyInstrInfo::isExplicitTargetIndexDef(const MachineInstr &MI, 224 int &Index, 225 int64_t &Offset) const { 226 unsigned Opc = MI.getOpcode(); 227 if (WebAssembly::isLocalSet(Opc) || WebAssembly::isLocalTee(Opc)) { 228 Index = WebAssembly::TI_LOCAL; 229 Offset = MI.explicit_uses().begin()->getImm(); 230 return true; 231 } 232 return false; 233 } 234