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/ADT/SmallString.h"
19 #include "llvm/CodeGen/AsmPrinter.h"
20 #include "llvm/CodeGen/MachineBasicBlock.h"
21 #include "llvm/CodeGen/MachineFunction.h"
22 #include "llvm/CodeGen/MachineInstr.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/MC/MCAsmInfo.h"
25 #include "llvm/MC/MCContext.h"
26 #include "llvm/MC/MCExpr.h"
27 #include "llvm/MC/MCInst.h"
28 #include "llvm/Support/ErrorHandling.h"
29 #include "llvm/Support/raw_ostream.h"
30 using namespace llvm;
31 
32 MCSymbol *
33 WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
34   return Printer.getSymbol(MO.getGlobal());
35 }
36 
37 MCOperand WebAssemblyMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
38                                                      MCSymbol *Sym) const {
39 
40   const MCExpr *Expr = MCSymbolRefExpr::create(Sym, Ctx);
41 
42   if (!MO.isJTI() && MO.getOffset())
43     llvm_unreachable("unknown symbol op");
44 
45   return MCOperand::createExpr(Expr);
46 }
47 
48 void WebAssemblyMCInstLower::Lower(const MachineInstr *MI,
49                                    MCInst &OutMI) const {
50   OutMI.setOpcode(MI->getOpcode());
51 
52   for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
53     const MachineOperand &MO = MI->getOperand(i);
54 
55     MCOperand MCOp;
56     switch (MO.getType()) {
57     default:
58       MI->dump();
59       llvm_unreachable("unknown operand type");
60     case MachineOperand::MO_Register: {
61       // Ignore all implicit register operands.
62       if (MO.isImplicit())
63         continue;
64       // TODO: Handle physical registers.
65       const WebAssemblyFunctionInfo &MFI =
66           *MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
67       unsigned WAReg = MFI.getWAReg(MO.getReg());
68       MCOp = MCOperand::createReg(WAReg);
69       break;
70     }
71     case MachineOperand::MO_Immediate:
72       MCOp = MCOperand::createImm(MO.getImm());
73       break;
74     case MachineOperand::MO_FPImmediate: {
75       // TODO: MC converts all floating point immediate operands to double.
76       // This is fine for numeric values, but may cause NaNs to change bits.
77       const ConstantFP *Imm = MO.getFPImm();
78       if (Imm->getType()->isFloatTy())
79         MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat());
80       else if (Imm->getType()->isDoubleTy())
81         MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble());
82       else
83         llvm_unreachable("unknown floating point immediate type");
84       break;
85     }
86     case MachineOperand::MO_MachineBasicBlock:
87       MCOp = MCOperand::createExpr(
88           MCSymbolRefExpr::create(MO.getMBB()->getSymbol(), Ctx));
89       break;
90     case MachineOperand::MO_GlobalAddress:
91       MCOp = LowerSymbolOperand(MO, GetGlobalAddressSymbol(MO));
92       break;
93     }
94 
95     OutMI.addOperand(MCOp);
96   }
97 }
98