1292915Sdim// WebAssemblyMCInstLower.cpp - Convert WebAssembly MachineInstr to an MCInst // 2292915Sdim// 3353358Sdim// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4353358Sdim// See https://llvm.org/LICENSE.txt for license information. 5353358Sdim// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6292915Sdim// 7292915Sdim//===----------------------------------------------------------------------===// 8292915Sdim/// 9292915Sdim/// \file 10341825Sdim/// This file contains code to lower WebAssembly MachineInstrs to their 11292915Sdim/// corresponding MCInst records. 12292915Sdim/// 13292915Sdim//===----------------------------------------------------------------------===// 14292915Sdim 15292915Sdim#include "WebAssemblyMCInstLower.h" 16321369Sdim#include "WebAssemblyAsmPrinter.h" 17292915Sdim#include "WebAssemblyMachineFunctionInfo.h" 18321369Sdim#include "WebAssemblyRuntimeLibcallSignatures.h" 19353358Sdim#include "MCTargetDesc/WebAssemblyMCTargetDesc.h" 20292915Sdim#include "llvm/CodeGen/AsmPrinter.h" 21292915Sdim#include "llvm/CodeGen/MachineFunction.h" 22292915Sdim#include "llvm/IR/Constants.h" 23292915Sdim#include "llvm/MC/MCAsmInfo.h" 24292915Sdim#include "llvm/MC/MCContext.h" 25292915Sdim#include "llvm/MC/MCExpr.h" 26292915Sdim#include "llvm/MC/MCInst.h" 27321369Sdim#include "llvm/MC/MCSymbolWasm.h" 28292915Sdim#include "llvm/Support/ErrorHandling.h" 29292915Sdim#include "llvm/Support/raw_ostream.h" 30292915Sdimusing namespace llvm; 31292915Sdim 32344779Sdim// Defines llvm::WebAssembly::getStackOpcode to convert register instructions to 33344779Sdim// stack instructions 34344779Sdim#define GET_INSTRMAP_INFO 1 35344779Sdim#include "WebAssemblyGenInstrInfo.inc" 36344779Sdim 37344779Sdim// This disables the removal of registers when lowering into MC, as required 38344779Sdim// by some current tests. 39353358Sdimcl::opt<bool> 40344779Sdim WasmKeepRegisters("wasm-keep-registers", cl::Hidden, 41344779Sdim cl::desc("WebAssembly: output stack registers in" 42344779Sdim " instruction output for test purposes only."), 43344779Sdim cl::init(false)); 44344779Sdim 45344779Sdimstatic void removeRegisterOperands(const MachineInstr *MI, MCInst &OutMI); 46344779Sdim 47292915SdimMCSymbol * 48292915SdimWebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const { 49321369Sdim const GlobalValue *Global = MO.getGlobal(); 50353358Sdim auto *WasmSym = cast<MCSymbolWasm>(Printer.getSymbol(Global)); 51321369Sdim 52321369Sdim if (const auto *FuncTy = dyn_cast<FunctionType>(Global->getValueType())) { 53321369Sdim const MachineFunction &MF = *MO.getParent()->getParent()->getParent(); 54321369Sdim const TargetMachine &TM = MF.getTarget(); 55327952Sdim const Function &CurrentFunc = MF.getFunction(); 56321369Sdim 57344779Sdim SmallVector<MVT, 1> ResultMVTs; 58344779Sdim SmallVector<MVT, 4> ParamMVTs; 59353358Sdim computeSignatureVTs(FuncTy, CurrentFunc, TM, ParamMVTs, ResultMVTs); 60321369Sdim 61353358Sdim auto Signature = signatureFromMVTs(ResultMVTs, ParamMVTs); 62344779Sdim WasmSym->setSignature(Signature.get()); 63344779Sdim Printer.addSignature(std::move(Signature)); 64341825Sdim WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION); 65321369Sdim } 66321369Sdim 67321369Sdim return WasmSym; 68292915Sdim} 69292915Sdim 70292915SdimMCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol( 71292915Sdim const MachineOperand &MO) const { 72321369Sdim const char *Name = MO.getSymbolName(); 73353358Sdim auto *WasmSym = cast<MCSymbolWasm>(Printer.GetExternalSymbolSymbol(Name)); 74321369Sdim const WebAssemblySubtarget &Subtarget = Printer.getSubtarget(); 75321369Sdim 76353358Sdim // Except for certain known symbols, all symbols used by CodeGen are 77353358Sdim // functions. It's OK to hardcode knowledge of specific symbols here; this 78353358Sdim // method is precisely there for fetching the signatures of known 79353358Sdim // Clang-provided symbols. 80353358Sdim if (strcmp(Name, "__stack_pointer") == 0 || strcmp(Name, "__tls_base") == 0 || 81353358Sdim strcmp(Name, "__memory_base") == 0 || strcmp(Name, "__table_base") == 0 || 82360784Sdim strcmp(Name, "__tls_size") == 0 || strcmp(Name, "__tls_align") == 0) { 83353358Sdim bool Mutable = 84353358Sdim strcmp(Name, "__stack_pointer") == 0 || strcmp(Name, "__tls_base") == 0; 85341825Sdim WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL); 86341825Sdim WasmSym->setGlobalType(wasm::WasmGlobalType{ 87341825Sdim uint8_t(Subtarget.hasAddr64() ? wasm::WASM_TYPE_I64 88341825Sdim : wasm::WASM_TYPE_I32), 89353358Sdim Mutable}); 90321369Sdim return WasmSym; 91341825Sdim } 92321369Sdim 93321369Sdim SmallVector<wasm::ValType, 4> Returns; 94321369Sdim SmallVector<wasm::ValType, 4> Params; 95344779Sdim if (strcmp(Name, "__cpp_exception") == 0) { 96344779Sdim WasmSym->setType(wasm::WASM_SYMBOL_TYPE_EVENT); 97344779Sdim // We can't confirm its signature index for now because there can be 98344779Sdim // imported exceptions. Set it to be 0 for now. 99344779Sdim WasmSym->setEventType( 100344779Sdim {wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION, /* SigIndex */ 0}); 101344779Sdim // We may have multiple C++ compilation units to be linked together, each of 102344779Sdim // which defines the exception symbol. To resolve them, we declare them as 103344779Sdim // weak. 104344779Sdim WasmSym->setWeak(true); 105344779Sdim WasmSym->setExternal(true); 106321369Sdim 107344779Sdim // All C++ exceptions are assumed to have a single i32 (for wasm32) or i64 108344779Sdim // (for wasm64) param type and void return type. The reaon is, all C++ 109344779Sdim // exception values are pointers, and to share the type section with 110344779Sdim // functions, exceptions are assumed to have void return type. 111344779Sdim Params.push_back(Subtarget.hasAddr64() ? wasm::ValType::I64 112344779Sdim : wasm::ValType::I32); 113344779Sdim } else { // Function symbols 114344779Sdim WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION); 115353358Sdim getLibcallSignature(Subtarget, Name, Returns, Params); 116344779Sdim } 117344779Sdim auto Signature = 118360784Sdim std::make_unique<wasm::WasmSignature>(std::move(Returns), std::move(Params)); 119344779Sdim WasmSym->setSignature(Signature.get()); 120344779Sdim Printer.addSignature(std::move(Signature)); 121321369Sdim 122321369Sdim return WasmSym; 123292915Sdim} 124292915Sdim 125353358SdimMCOperand WebAssemblyMCInstLower::lowerSymbolOperand(const MachineOperand &MO, 126353358Sdim MCSymbol *Sym) const { 127353358Sdim MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None; 128353358Sdim unsigned TargetFlags = MO.getTargetFlags(); 129321369Sdim 130353358Sdim switch (TargetFlags) { 131353358Sdim case WebAssemblyII::MO_NO_FLAG: 132353358Sdim break; 133353358Sdim case WebAssemblyII::MO_GOT: 134353358Sdim Kind = MCSymbolRefExpr::VK_GOT; 135353358Sdim break; 136353358Sdim case WebAssemblyII::MO_MEMORY_BASE_REL: 137353358Sdim Kind = MCSymbolRefExpr::VK_WASM_MBREL; 138353358Sdim break; 139353358Sdim case WebAssemblyII::MO_TABLE_BASE_REL: 140353358Sdim Kind = MCSymbolRefExpr::VK_WASM_TBREL; 141353358Sdim break; 142353358Sdim default: 143353358Sdim llvm_unreachable("Unknown target flag on GV operand"); 144353358Sdim } 145292915Sdim 146353358Sdim const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Kind, Ctx); 147353358Sdim 148353358Sdim if (MO.getOffset() != 0) { 149353358Sdim const auto *WasmSym = cast<MCSymbolWasm>(Sym); 150353358Sdim if (TargetFlags == WebAssemblyII::MO_GOT) 151353358Sdim report_fatal_error("GOT symbol references do not support offsets"); 152353358Sdim if (WasmSym->isFunction()) 153294024Sdim report_fatal_error("Function addresses with offsets not supported"); 154353358Sdim if (WasmSym->isGlobal()) 155344779Sdim report_fatal_error("Global indexes with offsets not supported"); 156353358Sdim if (WasmSym->isEvent()) 157344779Sdim report_fatal_error("Event indexes with offsets not supported"); 158353358Sdim 159353358Sdim Expr = MCBinaryExpr::createAdd( 160353358Sdim Expr, MCConstantExpr::create(MO.getOffset(), Ctx), Ctx); 161292915Sdim } 162292915Sdim 163292915Sdim return MCOperand::createExpr(Expr); 164292915Sdim} 165292915Sdim 166360784SdimMCOperand WebAssemblyMCInstLower::lowerTypeIndexOperand( 167360784Sdim SmallVector<wasm::ValType, 1> &&Returns, 168360784Sdim SmallVector<wasm::ValType, 4> &&Params) const { 169360784Sdim auto Signature = std::make_unique<wasm::WasmSignature>(std::move(Returns), 170360784Sdim std::move(Params)); 171360784Sdim MCSymbol *Sym = Printer.createTempSymbol("typeindex"); 172360784Sdim auto *WasmSym = cast<MCSymbolWasm>(Sym); 173360784Sdim WasmSym->setSignature(Signature.get()); 174360784Sdim Printer.addSignature(std::move(Signature)); 175360784Sdim WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION); 176360784Sdim const MCExpr *Expr = 177360784Sdim MCSymbolRefExpr::create(WasmSym, MCSymbolRefExpr::VK_WASM_TYPEINDEX, Ctx); 178360784Sdim return MCOperand::createExpr(Expr); 179360784Sdim} 180360784Sdim 181321369Sdim// Return the WebAssembly type associated with the given register class. 182321369Sdimstatic wasm::ValType getType(const TargetRegisterClass *RC) { 183321369Sdim if (RC == &WebAssembly::I32RegClass) 184321369Sdim return wasm::ValType::I32; 185321369Sdim if (RC == &WebAssembly::I64RegClass) 186321369Sdim return wasm::ValType::I64; 187321369Sdim if (RC == &WebAssembly::F32RegClass) 188321369Sdim return wasm::ValType::F32; 189321369Sdim if (RC == &WebAssembly::F64RegClass) 190321369Sdim return wasm::ValType::F64; 191344779Sdim if (RC == &WebAssembly::V128RegClass) 192344779Sdim return wasm::ValType::V128; 193321369Sdim llvm_unreachable("Unexpected register class"); 194321369Sdim} 195321369Sdim 196360784Sdimstatic void getFunctionReturns(const MachineInstr *MI, 197360784Sdim SmallVectorImpl<wasm::ValType> &Returns) { 198360784Sdim const Function &F = MI->getMF()->getFunction(); 199360784Sdim const TargetMachine &TM = MI->getMF()->getTarget(); 200360784Sdim Type *RetTy = F.getReturnType(); 201360784Sdim SmallVector<MVT, 4> CallerRetTys; 202360784Sdim computeLegalValueVTs(F, TM, RetTy, CallerRetTys); 203360784Sdim valTypesFromMVTs(CallerRetTys, Returns); 204360784Sdim} 205360784Sdim 206353358Sdimvoid WebAssemblyMCInstLower::lower(const MachineInstr *MI, 207292915Sdim MCInst &OutMI) const { 208292915Sdim OutMI.setOpcode(MI->getOpcode()); 209292915Sdim 210321369Sdim const MCInstrDesc &Desc = MI->getDesc(); 211353358Sdim for (unsigned I = 0, E = MI->getNumOperands(); I != E; ++I) { 212353358Sdim const MachineOperand &MO = MI->getOperand(I); 213292915Sdim 214292915Sdim MCOperand MCOp; 215292915Sdim switch (MO.getType()) { 216292915Sdim default: 217321369Sdim MI->print(errs()); 218292915Sdim llvm_unreachable("unknown operand type"); 219294024Sdim case MachineOperand::MO_MachineBasicBlock: 220321369Sdim MI->print(errs()); 221294024Sdim llvm_unreachable("MachineBasicBlock operand should have been rewritten"); 222292915Sdim case MachineOperand::MO_Register: { 223292915Sdim // Ignore all implicit register operands. 224292915Sdim if (MO.isImplicit()) 225292915Sdim continue; 226292915Sdim const WebAssemblyFunctionInfo &MFI = 227292915Sdim *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>(); 228292915Sdim unsigned WAReg = MFI.getWAReg(MO.getReg()); 229292915Sdim MCOp = MCOperand::createReg(WAReg); 230292915Sdim break; 231292915Sdim } 232292915Sdim case MachineOperand::MO_Immediate: 233353358Sdim if (I < Desc.NumOperands) { 234353358Sdim const MCOperandInfo &Info = Desc.OpInfo[I]; 235321369Sdim if (Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) { 236341825Sdim SmallVector<wasm::ValType, 4> Returns; 237341825Sdim SmallVector<wasm::ValType, 4> Params; 238321369Sdim 239341825Sdim const MachineRegisterInfo &MRI = 240341825Sdim MI->getParent()->getParent()->getRegInfo(); 241341825Sdim for (const MachineOperand &MO : MI->defs()) 242341825Sdim Returns.push_back(getType(MRI.getRegClass(MO.getReg()))); 243341825Sdim for (const MachineOperand &MO : MI->explicit_uses()) 244341825Sdim if (MO.isReg()) 245341825Sdim Params.push_back(getType(MRI.getRegClass(MO.getReg()))); 246321369Sdim 247341825Sdim // call_indirect instructions have a callee operand at the end which 248341825Sdim // doesn't count as a param. 249353358Sdim if (WebAssembly::isCallIndirect(MI->getOpcode())) 250341825Sdim Params.pop_back(); 251321369Sdim 252360784Sdim // return_call_indirect instructions have the return type of the 253360784Sdim // caller 254360784Sdim if (MI->getOpcode() == WebAssembly::RET_CALL_INDIRECT) 255360784Sdim getFunctionReturns(MI, Returns); 256341825Sdim 257360784Sdim MCOp = lowerTypeIndexOperand(std::move(Returns), std::move(Params)); 258341825Sdim break; 259360784Sdim } else if (Info.OperandType == WebAssembly::OPERAND_SIGNATURE) { 260360784Sdim auto BT = static_cast<WebAssembly::BlockType>(MO.getImm()); 261360784Sdim assert(BT != WebAssembly::BlockType::Invalid); 262360784Sdim if (BT == WebAssembly::BlockType::Multivalue) { 263360784Sdim SmallVector<wasm::ValType, 1> Returns; 264360784Sdim getFunctionReturns(MI, Returns); 265360784Sdim MCOp = lowerTypeIndexOperand(std::move(Returns), 266360784Sdim SmallVector<wasm::ValType, 4>()); 267360784Sdim break; 268360784Sdim } 269321369Sdim } 270321369Sdim } 271292915Sdim MCOp = MCOperand::createImm(MO.getImm()); 272292915Sdim break; 273292915Sdim case MachineOperand::MO_FPImmediate: { 274292915Sdim // TODO: MC converts all floating point immediate operands to double. 275292915Sdim // This is fine for numeric values, but may cause NaNs to change bits. 276292915Sdim const ConstantFP *Imm = MO.getFPImm(); 277292915Sdim if (Imm->getType()->isFloatTy()) 278292915Sdim MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat()); 279292915Sdim else if (Imm->getType()->isDoubleTy()) 280292915Sdim MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble()); 281292915Sdim else 282292915Sdim llvm_unreachable("unknown floating point immediate type"); 283292915Sdim break; 284292915Sdim } 285292915Sdim case MachineOperand::MO_GlobalAddress: 286353358Sdim MCOp = lowerSymbolOperand(MO, GetGlobalAddressSymbol(MO)); 287292915Sdim break; 288292915Sdim case MachineOperand::MO_ExternalSymbol: 289294024Sdim // The target flag indicates whether this is a symbol for a 290294024Sdim // variable or a function. 291353358Sdim assert(MO.getTargetFlags() == 0 && 292344779Sdim "WebAssembly uses only symbol flags on ExternalSymbols"); 293353358Sdim MCOp = lowerSymbolOperand(MO, GetExternalSymbolSymbol(MO)); 294292915Sdim break; 295344779Sdim case MachineOperand::MO_MCSymbol: 296344779Sdim // This is currently used only for LSDA symbols (GCC_except_table), 297344779Sdim // because global addresses or other external symbols are handled above. 298344779Sdim assert(MO.getTargetFlags() == 0 && 299344779Sdim "WebAssembly does not use target flags on MCSymbol"); 300353358Sdim MCOp = lowerSymbolOperand(MO, MO.getMCSymbol()); 301344779Sdim break; 302292915Sdim } 303292915Sdim 304292915Sdim OutMI.addOperand(MCOp); 305292915Sdim } 306344779Sdim 307344779Sdim if (!WasmKeepRegisters) 308344779Sdim removeRegisterOperands(MI, OutMI); 309292915Sdim} 310344779Sdim 311344779Sdimstatic void removeRegisterOperands(const MachineInstr *MI, MCInst &OutMI) { 312344779Sdim // Remove all uses of stackified registers to bring the instruction format 313344779Sdim // into its final stack form used thruout MC, and transition opcodes to 314344779Sdim // their _S variant. 315344779Sdim // We do this seperate from the above code that still may need these 316344779Sdim // registers for e.g. call_indirect signatures. 317344779Sdim // See comments in lib/Target/WebAssembly/WebAssemblyInstrFormats.td for 318344779Sdim // details. 319344779Sdim // TODO: the code above creates new registers which are then removed here. 320344779Sdim // That code could be slightly simplified by not doing that, though maybe 321344779Sdim // it is simpler conceptually to keep the code above in "register mode" 322344779Sdim // until this transition point. 323344779Sdim // FIXME: we are not processing inline assembly, which contains register 324344779Sdim // operands, because it is used by later target generic code. 325344779Sdim if (MI->isDebugInstr() || MI->isLabel() || MI->isInlineAsm()) 326344779Sdim return; 327344779Sdim 328344779Sdim // Transform to _S instruction. 329344779Sdim auto RegOpcode = OutMI.getOpcode(); 330344779Sdim auto StackOpcode = WebAssembly::getStackOpcode(RegOpcode); 331344779Sdim assert(StackOpcode != -1 && "Failed to stackify instruction"); 332344779Sdim OutMI.setOpcode(StackOpcode); 333344779Sdim 334344779Sdim // Remove register operands. 335344779Sdim for (auto I = OutMI.getNumOperands(); I; --I) { 336344779Sdim auto &MO = OutMI.getOperand(I - 1); 337344779Sdim if (MO.isReg()) { 338344779Sdim OutMI.erase(&MO); 339344779Sdim } 340344779Sdim } 341344779Sdim} 342