1 // WebAssemblyMCInstLower.cpp - Convert WebAssembly MachineInstr to an MCInst // 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 /// \brief This file contains code to lower WebAssembly MachineInstrs to their 12 /// corresponding MCInst records. 13 /// 14 //===----------------------------------------------------------------------===// 15 16 #include "WebAssemblyMCInstLower.h" 17 #include "WebAssemblyMachineFunctionInfo.h" 18 #include "llvm/CodeGen/AsmPrinter.h" 19 #include "llvm/CodeGen/MachineFunction.h" 20 #include "llvm/IR/Constants.h" 21 #include "llvm/MC/MCAsmInfo.h" 22 #include "llvm/MC/MCContext.h" 23 #include "llvm/MC/MCExpr.h" 24 #include "llvm/MC/MCInst.h" 25 #include "llvm/Support/ErrorHandling.h" 26 #include "llvm/Support/raw_ostream.h" 27 using namespace llvm; 28 29 MCSymbol * 30 WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const { 31 return Printer.getSymbol(MO.getGlobal()); 32 } 33 34 MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol( 35 const MachineOperand &MO) const { 36 return Printer.GetExternalSymbolSymbol(MO.getSymbolName()); 37 } 38 39 MCOperand WebAssemblyMCInstLower::LowerSymbolOperand(MCSymbol *Sym, 40 int64_t Offset, 41 bool IsFunc) const { 42 MCSymbolRefExpr::VariantKind VK = 43 IsFunc ? MCSymbolRefExpr::VK_WebAssembly_FUNCTION 44 : MCSymbolRefExpr::VK_None; 45 const MCExpr *Expr = MCSymbolRefExpr::create(Sym, VK, Ctx); 46 47 if (Offset != 0) { 48 if (IsFunc) 49 report_fatal_error("Function addresses with offsets not supported"); 50 Expr = 51 MCBinaryExpr::createAdd(Expr, MCConstantExpr::create(Offset, Ctx), Ctx); 52 } 53 54 return MCOperand::createExpr(Expr); 55 } 56 57 void WebAssemblyMCInstLower::Lower(const MachineInstr *MI, 58 MCInst &OutMI) const { 59 OutMI.setOpcode(MI->getOpcode()); 60 61 for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { 62 const MachineOperand &MO = MI->getOperand(i); 63 64 MCOperand MCOp; 65 switch (MO.getType()) { 66 default: 67 MI->dump(); 68 llvm_unreachable("unknown operand type"); 69 case MachineOperand::MO_MachineBasicBlock: 70 MI->dump(); 71 llvm_unreachable("MachineBasicBlock operand should have been rewritten"); 72 case MachineOperand::MO_Register: { 73 // Ignore all implicit register operands. 74 if (MO.isImplicit()) 75 continue; 76 const WebAssemblyFunctionInfo &MFI = 77 *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>(); 78 unsigned WAReg = MFI.getWAReg(MO.getReg()); 79 MCOp = MCOperand::createReg(WAReg); 80 break; 81 } 82 case MachineOperand::MO_Immediate: 83 MCOp = MCOperand::createImm(MO.getImm()); 84 break; 85 case MachineOperand::MO_FPImmediate: { 86 // TODO: MC converts all floating point immediate operands to double. 87 // This is fine for numeric values, but may cause NaNs to change bits. 88 const ConstantFP *Imm = MO.getFPImm(); 89 if (Imm->getType()->isFloatTy()) 90 MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat()); 91 else if (Imm->getType()->isDoubleTy()) 92 MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble()); 93 else 94 llvm_unreachable("unknown floating point immediate type"); 95 break; 96 } 97 case MachineOperand::MO_GlobalAddress: 98 assert(MO.getTargetFlags() == 0 && 99 "WebAssembly does not use target flags on GlobalAddresses"); 100 MCOp = LowerSymbolOperand(GetGlobalAddressSymbol(MO), MO.getOffset(), 101 MO.getGlobal()->getValueType()->isFunctionTy()); 102 break; 103 case MachineOperand::MO_ExternalSymbol: 104 // The target flag indicates whether this is a symbol for a 105 // variable or a function. 106 assert((MO.getTargetFlags() & -2) == 0 && 107 "WebAssembly uses only one target flag bit on ExternalSymbols"); 108 MCOp = LowerSymbolOperand(GetExternalSymbolSymbol(MO), /*Offset=*/0, 109 MO.getTargetFlags() & 1); 110 break; 111 } 112 113 OutMI.addOperand(MCOp); 114 } 115 } 116
