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//===-- Nios2InstrFormats.td - Nios2 Instruction Formats ---*- tablegen -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//===----------------------------------------------------------------------===//
// Describe NIOS2 instructions format
//
//
//===----------------------------------------------------------------------===//
// Format specifies the encoding used by the instruction. This is part of the
// ad-hoc solution used to emit machine instruction encodings by our machine
// code emitter.
class Format<bits<3> val> {
bits<3> Value = val;
}
def Pseudo : Format<0>;
def FrmI : Format<1>;
def FrmR : Format<2>;
def FrmJ : Format<3>;
def FrmOther : Format<4>; // Instruction w/ a custom format
// Generic Nios2 Format
class Nios2Inst<dag outs, dag ins, string asmstr, list<dag> pattern, Format f>
: Instruction {
field bits<32> Inst;
Format Form = f;
let Namespace = "Nios2";
let Size = 4;
bits<6> Opcode = 0;
// Bottom 6 bits are the 'opcode' field
let Inst{5 - 0} = Opcode;
let OutOperandList = outs;
let InOperandList = ins;
let AsmString = asmstr;
let Pattern = pattern;
//
// Attributes specific to Nios2 instructions:
//
bits<3> FormBits = Form.Value;
// TSFlags layout should be kept in sync with Nios2InstrInfo.h.
let TSFlags{2 - 0} = FormBits;
let DecoderNamespace = "Nios2";
}
// Nios2 Instruction Format
class InstSE<dag outs, dag ins, string asmstr, list<dag> pattern, Format f>
: Nios2Inst<outs, ins, asmstr, pattern, f> {
}
//===----------------------------------------------------------------------===//
// Format I instruction class in Nios2 : <|A|B|immediate|opcode|>
//===----------------------------------------------------------------------===//
class FI<bits<6> op, dag outs, dag ins, string asmstr, list<dag> pattern>
: InstSE<outs, ins, asmstr, pattern, FrmI> {
bits<5> rA;
bits<5> rB;
bits<16> imm;
let Opcode = op;
let Inst{31 - 27} = rA;
let Inst{26 - 22} = rB;
let Inst{21 - 6} = imm;
}
//===----------------------------------------------------------------------===//
// Format R instruction : <|A|B|C|opx|imm|opcode|>
//===----------------------------------------------------------------------===//
class FR<bits<6> opx, dag outs, dag ins, string asmstr, list<dag> pattern>
: InstSE<outs, ins, asmstr, pattern, FrmR> {
bits<5> rA;
bits<5> rB;
bits<5> rC;
bits<5> imm = 0;
// opcode is always 0x3a for R instr.
let Opcode = 0x3a;
let Inst{31 - 27} = rA;
let Inst{26 - 22} = rB;
let Inst{21 - 17} = rC;
// opx stands for opcode extension
let Inst{16 - 11} = opx;
// optional 5-bit immediate value
let Inst{10 - 6} = imm;
}
//===----------------------------------------------------------------------===//
// Format J instruction class in Nios2 : <|address|opcode|>
//===----------------------------------------------------------------------===//
class FJ<bits<6> op, dag outs, dag ins, string asmstr, list<dag> pattern>
: InstSE<outs, ins, asmstr, pattern, FrmJ> {
bits<26> addr;
let Opcode = op;
let Inst{31 - 6} = addr;
}
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