github.com/mattn/go@v0.0.0-20171011075504-07f7db3ea99f/src/cmd/compile/internal/ssa/gen/ARMOps.go (about)

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build ignore
     6  
     7  package main
     8  
     9  import "strings"
    10  
    11  // Notes:
    12  //  - Integer types live in the low portion of registers. Upper portions are junk.
    13  //  - Boolean types use the low-order byte of a register. 0=false, 1=true.
    14  //    Upper bytes are junk.
    15  //  - *const instructions may use a constant larger than the instruction can encode.
    16  //    In this case the assembler expands to multiple instructions and uses tmp
    17  //    register (R11).
    18  
    19  // Suffixes encode the bit width of various instructions.
    20  // W (word)      = 32 bit
    21  // H (half word) = 16 bit
    22  // HU            = 16 bit unsigned
    23  // B (byte)      = 8 bit
    24  // BU            = 8 bit unsigned
    25  // F (float)     = 32 bit float
    26  // D (double)    = 64 bit float
    27  
    28  var regNamesARM = []string{
    29  	"R0",
    30  	"R1",
    31  	"R2",
    32  	"R3",
    33  	"R4",
    34  	"R5",
    35  	"R6",
    36  	"R7",
    37  	"R8",
    38  	"R9",
    39  	"g",   // aka R10
    40  	"R11", // tmp
    41  	"R12",
    42  	"SP",  // aka R13
    43  	"R14", // link
    44  	"R15", // pc
    45  
    46  	"F0",
    47  	"F1",
    48  	"F2",
    49  	"F3",
    50  	"F4",
    51  	"F5",
    52  	"F6",
    53  	"F7",
    54  	"F8",
    55  	"F9",
    56  	"F10",
    57  	"F11",
    58  	"F12",
    59  	"F13",
    60  	"F14",
    61  	"F15", // tmp
    62  
    63  	// pseudo-registers
    64  	"SB",
    65  }
    66  
    67  func init() {
    68  	// Make map from reg names to reg integers.
    69  	if len(regNamesARM) > 64 {
    70  		panic("too many registers")
    71  	}
    72  	num := map[string]int{}
    73  	for i, name := range regNamesARM {
    74  		num[name] = i
    75  	}
    76  	buildReg := func(s string) regMask {
    77  		m := regMask(0)
    78  		for _, r := range strings.Split(s, " ") {
    79  			if n, ok := num[r]; ok {
    80  				m |= regMask(1) << uint(n)
    81  				continue
    82  			}
    83  			panic("register " + r + " not found")
    84  		}
    85  		return m
    86  	}
    87  
    88  	// Common individual register masks
    89  	var (
    90  		gp         = buildReg("R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R12 R14")
    91  		gpg        = gp | buildReg("g")
    92  		gpsp       = gp | buildReg("SP")
    93  		gpspg      = gpg | buildReg("SP")
    94  		gpspsbg    = gpspg | buildReg("SB")
    95  		fp         = buildReg("F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15")
    96  		callerSave = gp | fp | buildReg("g") // runtime.setg (and anything calling it) may clobber g
    97  	)
    98  	// Common regInfo
    99  	var (
   100  		gp01      = regInfo{inputs: nil, outputs: []regMask{gp}}
   101  		gp11      = regInfo{inputs: []regMask{gpg}, outputs: []regMask{gp}}
   102  		gp11carry = regInfo{inputs: []regMask{gpg}, outputs: []regMask{gp, 0}}
   103  		gp11sp    = regInfo{inputs: []regMask{gpspg}, outputs: []regMask{gp}}
   104  		gp1flags  = regInfo{inputs: []regMask{gpg}}
   105  		gp1flags1 = regInfo{inputs: []regMask{gp}, outputs: []regMask{gp}}
   106  		gp21      = regInfo{inputs: []regMask{gpg, gpg}, outputs: []regMask{gp}}
   107  		gp21carry = regInfo{inputs: []regMask{gpg, gpg}, outputs: []regMask{gp, 0}}
   108  		gp2flags  = regInfo{inputs: []regMask{gpg, gpg}}
   109  		gp2flags1 = regInfo{inputs: []regMask{gp, gp}, outputs: []regMask{gp}}
   110  		gp22      = regInfo{inputs: []regMask{gpg, gpg}, outputs: []regMask{gp, gp}}
   111  		gp31      = regInfo{inputs: []regMask{gp, gp, gp}, outputs: []regMask{gp}}
   112  		gp31carry = regInfo{inputs: []regMask{gp, gp, gp}, outputs: []regMask{gp, 0}}
   113  		gp3flags  = regInfo{inputs: []regMask{gp, gp, gp}}
   114  		gp3flags1 = regInfo{inputs: []regMask{gp, gp, gp}, outputs: []regMask{gp}}
   115  		gpload    = regInfo{inputs: []regMask{gpspsbg}, outputs: []regMask{gp}}
   116  		gpstore   = regInfo{inputs: []regMask{gpspsbg, gpg}}
   117  		gp2load   = regInfo{inputs: []regMask{gpspsbg, gpg}, outputs: []regMask{gp}}
   118  		gp2store  = regInfo{inputs: []regMask{gpspsbg, gpg, gpg}}
   119  		fp01      = regInfo{inputs: nil, outputs: []regMask{fp}}
   120  		fp11      = regInfo{inputs: []regMask{fp}, outputs: []regMask{fp}}
   121  		fp1flags  = regInfo{inputs: []regMask{fp}}
   122  		fpgp      = regInfo{inputs: []regMask{fp}, outputs: []regMask{gp}, clobbers: buildReg("F15")} // int-float conversion uses F15 as tmp
   123  		gpfp      = regInfo{inputs: []regMask{gp}, outputs: []regMask{fp}, clobbers: buildReg("F15")}
   124  		fp21      = regInfo{inputs: []regMask{fp, fp}, outputs: []regMask{fp}}
   125  		fp31      = regInfo{inputs: []regMask{fp, fp, fp}, outputs: []regMask{fp}}
   126  		fp2flags  = regInfo{inputs: []regMask{fp, fp}}
   127  		fpload    = regInfo{inputs: []regMask{gpspsbg}, outputs: []regMask{fp}}
   128  		fpstore   = regInfo{inputs: []regMask{gpspsbg, fp}}
   129  		readflags = regInfo{inputs: nil, outputs: []regMask{gp}}
   130  	)
   131  	ops := []opData{
   132  		// binary ops
   133  		{name: "ADD", argLength: 2, reg: gp21, asm: "ADD", commutative: true},     // arg0 + arg1
   134  		{name: "ADDconst", argLength: 1, reg: gp11sp, asm: "ADD", aux: "Int32"},   // arg0 + auxInt
   135  		{name: "SUB", argLength: 2, reg: gp21, asm: "SUB"},                        // arg0 - arg1
   136  		{name: "SUBconst", argLength: 1, reg: gp11, asm: "SUB", aux: "Int32"},     // arg0 - auxInt
   137  		{name: "RSB", argLength: 2, reg: gp21, asm: "RSB"},                        // arg1 - arg0
   138  		{name: "RSBconst", argLength: 1, reg: gp11, asm: "RSB", aux: "Int32"},     // auxInt - arg0
   139  		{name: "MUL", argLength: 2, reg: gp21, asm: "MUL", commutative: true},     // arg0 * arg1
   140  		{name: "HMUL", argLength: 2, reg: gp21, asm: "MULL", commutative: true},   // (arg0 * arg1) >> 32, signed
   141  		{name: "HMULU", argLength: 2, reg: gp21, asm: "MULLU", commutative: true}, // (arg0 * arg1) >> 32, unsigned
   142  
   143  		// udiv runtime call for soft division
   144  		// output0 = arg0/arg1, output1 = arg0%arg1
   145  		// see ../../../../../runtime/vlop_arm.s
   146  		{
   147  			name:      "CALLudiv",
   148  			argLength: 2,
   149  			reg: regInfo{
   150  				inputs:   []regMask{buildReg("R1"), buildReg("R0")},
   151  				outputs:  []regMask{buildReg("R0"), buildReg("R1")},
   152  				clobbers: buildReg("R2 R3 R14"), // also clobbers R12 on NaCl (modified in ../config.go)
   153  			},
   154  			clobberFlags: true,
   155  			typ:          "(UInt32,UInt32)",
   156  			call:         false, // TODO(mdempsky): Should this be true?
   157  		},
   158  
   159  		{name: "ADDS", argLength: 2, reg: gp21carry, asm: "ADD", commutative: true}, // arg0 + arg1, set carry flag
   160  		{name: "ADDSconst", argLength: 1, reg: gp11carry, asm: "ADD", aux: "Int32"}, // arg0 + auxInt, set carry flag
   161  		{name: "ADC", argLength: 3, reg: gp2flags1, asm: "ADC", commutative: true},  // arg0 + arg1 + carry, arg2=flags
   162  		{name: "ADCconst", argLength: 2, reg: gp1flags1, asm: "ADC", aux: "Int32"},  // arg0 + auxInt + carry, arg1=flags
   163  		{name: "SUBS", argLength: 2, reg: gp21carry, asm: "SUB"},                    // arg0 - arg1, set carry flag
   164  		{name: "SUBSconst", argLength: 1, reg: gp11carry, asm: "SUB", aux: "Int32"}, // arg0 - auxInt, set carry flag
   165  		{name: "RSBSconst", argLength: 1, reg: gp11carry, asm: "RSB", aux: "Int32"}, // auxInt - arg0, set carry flag
   166  		{name: "SBC", argLength: 3, reg: gp2flags1, asm: "SBC"},                     // arg0 - arg1 - carry, arg2=flags
   167  		{name: "SBCconst", argLength: 2, reg: gp1flags1, asm: "SBC", aux: "Int32"},  // arg0 - auxInt - carry, arg1=flags
   168  		{name: "RSCconst", argLength: 2, reg: gp1flags1, asm: "RSC", aux: "Int32"},  // auxInt - arg0 - carry, arg1=flags
   169  
   170  		{name: "MULLU", argLength: 2, reg: gp22, asm: "MULLU", commutative: true}, // arg0 * arg1, high 32 bits in out0, low 32 bits in out1
   171  		{name: "MULA", argLength: 3, reg: gp31, asm: "MULA"},                      // arg0 * arg1 + arg2
   172  		{name: "MULS", argLength: 3, reg: gp31, asm: "MULS"},                      // arg2 - arg0 * arg1
   173  
   174  		{name: "ADDF", argLength: 2, reg: fp21, asm: "ADDF", commutative: true},   // arg0 + arg1
   175  		{name: "ADDD", argLength: 2, reg: fp21, asm: "ADDD", commutative: true},   // arg0 + arg1
   176  		{name: "SUBF", argLength: 2, reg: fp21, asm: "SUBF"},                      // arg0 - arg1
   177  		{name: "SUBD", argLength: 2, reg: fp21, asm: "SUBD"},                      // arg0 - arg1
   178  		{name: "MULF", argLength: 2, reg: fp21, asm: "MULF", commutative: true},   // arg0 * arg1
   179  		{name: "MULD", argLength: 2, reg: fp21, asm: "MULD", commutative: true},   // arg0 * arg1
   180  		{name: "NMULF", argLength: 2, reg: fp21, asm: "NMULF", commutative: true}, // -(arg0 * arg1)
   181  		{name: "NMULD", argLength: 2, reg: fp21, asm: "NMULD", commutative: true}, // -(arg0 * arg1)
   182  		{name: "DIVF", argLength: 2, reg: fp21, asm: "DIVF"},                      // arg0 / arg1
   183  		{name: "DIVD", argLength: 2, reg: fp21, asm: "DIVD"},                      // arg0 / arg1
   184  
   185  		{name: "MULAF", argLength: 3, reg: fp31, asm: "MULAF", resultInArg0: true}, // arg0 + (arg1 * arg2)
   186  		{name: "MULAD", argLength: 3, reg: fp31, asm: "MULAD", resultInArg0: true}, // arg0 + (arg1 * arg2)
   187  		{name: "MULSF", argLength: 3, reg: fp31, asm: "MULSF", resultInArg0: true}, // arg0 - (arg1 * arg2)
   188  		{name: "MULSD", argLength: 3, reg: fp31, asm: "MULSD", resultInArg0: true}, // arg0 - (arg1 * arg2)
   189  
   190  		{name: "AND", argLength: 2, reg: gp21, asm: "AND", commutative: true}, // arg0 & arg1
   191  		{name: "ANDconst", argLength: 1, reg: gp11, asm: "AND", aux: "Int32"}, // arg0 & auxInt
   192  		{name: "OR", argLength: 2, reg: gp21, asm: "ORR", commutative: true},  // arg0 | arg1
   193  		{name: "ORconst", argLength: 1, reg: gp11, asm: "ORR", aux: "Int32"},  // arg0 | auxInt
   194  		{name: "XOR", argLength: 2, reg: gp21, asm: "EOR", commutative: true}, // arg0 ^ arg1
   195  		{name: "XORconst", argLength: 1, reg: gp11, asm: "EOR", aux: "Int32"}, // arg0 ^ auxInt
   196  		{name: "BIC", argLength: 2, reg: gp21, asm: "BIC"},                    // arg0 &^ arg1
   197  		{name: "BICconst", argLength: 1, reg: gp11, asm: "BIC", aux: "Int32"}, // arg0 &^ auxInt
   198  
   199  		// bit extraction, AuxInt = Width<<8 | LSB
   200  		{name: "BFX", argLength: 1, reg: gp11, asm: "BFX", aux: "Int32"},   // extract W bits from bit L in arg0, then signed extend
   201  		{name: "BFXU", argLength: 1, reg: gp11, asm: "BFXU", aux: "Int32"}, // extract W bits from bit L in arg0, then unsigned extend
   202  
   203  		// unary ops
   204  		{name: "MVN", argLength: 1, reg: gp11, asm: "MVN"}, // ^arg0
   205  
   206  		{name: "NEGF", argLength: 1, reg: fp11, asm: "NEGF"},   // -arg0, float32
   207  		{name: "NEGD", argLength: 1, reg: fp11, asm: "NEGD"},   // -arg0, float64
   208  		{name: "SQRTD", argLength: 1, reg: fp11, asm: "SQRTD"}, // sqrt(arg0), float64
   209  
   210  		{name: "CLZ", argLength: 1, reg: gp11, asm: "CLZ"},   // count leading zero
   211  		{name: "REV", argLength: 1, reg: gp11, asm: "REV"},   // reverse byte order
   212  		{name: "RBIT", argLength: 1, reg: gp11, asm: "RBIT"}, // reverse bit order
   213  
   214  		// shifts
   215  		{name: "SLL", argLength: 2, reg: gp21, asm: "SLL"},                    // arg0 << arg1, shift amount is mod 256
   216  		{name: "SLLconst", argLength: 1, reg: gp11, asm: "SLL", aux: "Int32"}, // arg0 << auxInt
   217  		{name: "SRL", argLength: 2, reg: gp21, asm: "SRL"},                    // arg0 >> arg1, unsigned, shift amount is mod 256
   218  		{name: "SRLconst", argLength: 1, reg: gp11, asm: "SRL", aux: "Int32"}, // arg0 >> auxInt, unsigned
   219  		{name: "SRA", argLength: 2, reg: gp21, asm: "SRA"},                    // arg0 >> arg1, signed, shift amount is mod 256
   220  		{name: "SRAconst", argLength: 1, reg: gp11, asm: "SRA", aux: "Int32"}, // arg0 >> auxInt, signed
   221  		{name: "SRRconst", argLength: 1, reg: gp11, aux: "Int32"},             // arg0 right rotate by auxInt bits
   222  
   223  		{name: "ADDshiftLL", argLength: 2, reg: gp21, asm: "ADD", aux: "Int32"}, // arg0 + arg1<<auxInt
   224  		{name: "ADDshiftRL", argLength: 2, reg: gp21, asm: "ADD", aux: "Int32"}, // arg0 + arg1>>auxInt, unsigned shift
   225  		{name: "ADDshiftRA", argLength: 2, reg: gp21, asm: "ADD", aux: "Int32"}, // arg0 + arg1>>auxInt, signed shift
   226  		{name: "SUBshiftLL", argLength: 2, reg: gp21, asm: "SUB", aux: "Int32"}, // arg0 - arg1<<auxInt
   227  		{name: "SUBshiftRL", argLength: 2, reg: gp21, asm: "SUB", aux: "Int32"}, // arg0 - arg1>>auxInt, unsigned shift
   228  		{name: "SUBshiftRA", argLength: 2, reg: gp21, asm: "SUB", aux: "Int32"}, // arg0 - arg1>>auxInt, signed shift
   229  		{name: "RSBshiftLL", argLength: 2, reg: gp21, asm: "RSB", aux: "Int32"}, // arg1<<auxInt - arg0
   230  		{name: "RSBshiftRL", argLength: 2, reg: gp21, asm: "RSB", aux: "Int32"}, // arg1>>auxInt - arg0, unsigned shift
   231  		{name: "RSBshiftRA", argLength: 2, reg: gp21, asm: "RSB", aux: "Int32"}, // arg1>>auxInt - arg0, signed shift
   232  		{name: "ANDshiftLL", argLength: 2, reg: gp21, asm: "AND", aux: "Int32"}, // arg0 & (arg1<<auxInt)
   233  		{name: "ANDshiftRL", argLength: 2, reg: gp21, asm: "AND", aux: "Int32"}, // arg0 & (arg1>>auxInt), unsigned shift
   234  		{name: "ANDshiftRA", argLength: 2, reg: gp21, asm: "AND", aux: "Int32"}, // arg0 & (arg1>>auxInt), signed shift
   235  		{name: "ORshiftLL", argLength: 2, reg: gp21, asm: "ORR", aux: "Int32"},  // arg0 | arg1<<auxInt
   236  		{name: "ORshiftRL", argLength: 2, reg: gp21, asm: "ORR", aux: "Int32"},  // arg0 | arg1>>auxInt, unsigned shift
   237  		{name: "ORshiftRA", argLength: 2, reg: gp21, asm: "ORR", aux: "Int32"},  // arg0 | arg1>>auxInt, signed shift
   238  		{name: "XORshiftLL", argLength: 2, reg: gp21, asm: "EOR", aux: "Int32"}, // arg0 ^ arg1<<auxInt
   239  		{name: "XORshiftRL", argLength: 2, reg: gp21, asm: "EOR", aux: "Int32"}, // arg0 ^ arg1>>auxInt, unsigned shift
   240  		{name: "XORshiftRA", argLength: 2, reg: gp21, asm: "EOR", aux: "Int32"}, // arg0 ^ arg1>>auxInt, signed shift
   241  		{name: "XORshiftRR", argLength: 2, reg: gp21, asm: "EOR", aux: "Int32"}, // arg0 ^ (arg1 right rotate by auxInt)
   242  		{name: "BICshiftLL", argLength: 2, reg: gp21, asm: "BIC", aux: "Int32"}, // arg0 &^ (arg1<<auxInt)
   243  		{name: "BICshiftRL", argLength: 2, reg: gp21, asm: "BIC", aux: "Int32"}, // arg0 &^ (arg1>>auxInt), unsigned shift
   244  		{name: "BICshiftRA", argLength: 2, reg: gp21, asm: "BIC", aux: "Int32"}, // arg0 &^ (arg1>>auxInt), signed shift
   245  		{name: "MVNshiftLL", argLength: 1, reg: gp11, asm: "MVN", aux: "Int32"}, // ^(arg0<<auxInt)
   246  		{name: "MVNshiftRL", argLength: 1, reg: gp11, asm: "MVN", aux: "Int32"}, // ^(arg0>>auxInt), unsigned shift
   247  		{name: "MVNshiftRA", argLength: 1, reg: gp11, asm: "MVN", aux: "Int32"}, // ^(arg0>>auxInt), signed shift
   248  
   249  		{name: "ADCshiftLL", argLength: 3, reg: gp2flags1, asm: "ADC", aux: "Int32"}, // arg0 + arg1<<auxInt + carry, arg2=flags
   250  		{name: "ADCshiftRL", argLength: 3, reg: gp2flags1, asm: "ADC", aux: "Int32"}, // arg0 + arg1>>auxInt + carry, unsigned shift, arg2=flags
   251  		{name: "ADCshiftRA", argLength: 3, reg: gp2flags1, asm: "ADC", aux: "Int32"}, // arg0 + arg1>>auxInt + carry, signed shift, arg2=flags
   252  		{name: "SBCshiftLL", argLength: 3, reg: gp2flags1, asm: "SBC", aux: "Int32"}, // arg0 - arg1<<auxInt - carry, arg2=flags
   253  		{name: "SBCshiftRL", argLength: 3, reg: gp2flags1, asm: "SBC", aux: "Int32"}, // arg0 - arg1>>auxInt - carry, unsigned shift, arg2=flags
   254  		{name: "SBCshiftRA", argLength: 3, reg: gp2flags1, asm: "SBC", aux: "Int32"}, // arg0 - arg1>>auxInt - carry, signed shift, arg2=flags
   255  		{name: "RSCshiftLL", argLength: 3, reg: gp2flags1, asm: "RSC", aux: "Int32"}, // arg1<<auxInt - arg0 - carry, arg2=flags
   256  		{name: "RSCshiftRL", argLength: 3, reg: gp2flags1, asm: "RSC", aux: "Int32"}, // arg1>>auxInt - arg0 - carry, unsigned shift, arg2=flags
   257  		{name: "RSCshiftRA", argLength: 3, reg: gp2flags1, asm: "RSC", aux: "Int32"}, // arg1>>auxInt - arg0 - carry, signed shift, arg2=flags
   258  
   259  		{name: "ADDSshiftLL", argLength: 2, reg: gp21carry, asm: "ADD", aux: "Int32"}, // arg0 + arg1<<auxInt, set carry flag
   260  		{name: "ADDSshiftRL", argLength: 2, reg: gp21carry, asm: "ADD", aux: "Int32"}, // arg0 + arg1>>auxInt, unsigned shift, set carry flag
   261  		{name: "ADDSshiftRA", argLength: 2, reg: gp21carry, asm: "ADD", aux: "Int32"}, // arg0 + arg1>>auxInt, signed shift, set carry flag
   262  		{name: "SUBSshiftLL", argLength: 2, reg: gp21carry, asm: "SUB", aux: "Int32"}, // arg0 - arg1<<auxInt, set carry flag
   263  		{name: "SUBSshiftRL", argLength: 2, reg: gp21carry, asm: "SUB", aux: "Int32"}, // arg0 - arg1>>auxInt, unsigned shift, set carry flag
   264  		{name: "SUBSshiftRA", argLength: 2, reg: gp21carry, asm: "SUB", aux: "Int32"}, // arg0 - arg1>>auxInt, signed shift, set carry flag
   265  		{name: "RSBSshiftLL", argLength: 2, reg: gp21carry, asm: "RSB", aux: "Int32"}, // arg1<<auxInt - arg0, set carry flag
   266  		{name: "RSBSshiftRL", argLength: 2, reg: gp21carry, asm: "RSB", aux: "Int32"}, // arg1>>auxInt - arg0, unsigned shift, set carry flag
   267  		{name: "RSBSshiftRA", argLength: 2, reg: gp21carry, asm: "RSB", aux: "Int32"}, // arg1>>auxInt - arg0, signed shift, set carry flag
   268  
   269  		{name: "ADDshiftLLreg", argLength: 3, reg: gp31, asm: "ADD"}, // arg0 + arg1<<arg2
   270  		{name: "ADDshiftRLreg", argLength: 3, reg: gp31, asm: "ADD"}, // arg0 + arg1>>arg2, unsigned shift
   271  		{name: "ADDshiftRAreg", argLength: 3, reg: gp31, asm: "ADD"}, // arg0 + arg1>>arg2, signed shift
   272  		{name: "SUBshiftLLreg", argLength: 3, reg: gp31, asm: "SUB"}, // arg0 - arg1<<arg2
   273  		{name: "SUBshiftRLreg", argLength: 3, reg: gp31, asm: "SUB"}, // arg0 - arg1>>arg2, unsigned shift
   274  		{name: "SUBshiftRAreg", argLength: 3, reg: gp31, asm: "SUB"}, // arg0 - arg1>>arg2, signed shift
   275  		{name: "RSBshiftLLreg", argLength: 3, reg: gp31, asm: "RSB"}, // arg1<<arg2 - arg0
   276  		{name: "RSBshiftRLreg", argLength: 3, reg: gp31, asm: "RSB"}, // arg1>>arg2 - arg0, unsigned shift
   277  		{name: "RSBshiftRAreg", argLength: 3, reg: gp31, asm: "RSB"}, // arg1>>arg2 - arg0, signed shift
   278  		{name: "ANDshiftLLreg", argLength: 3, reg: gp31, asm: "AND"}, // arg0 & (arg1<<arg2)
   279  		{name: "ANDshiftRLreg", argLength: 3, reg: gp31, asm: "AND"}, // arg0 & (arg1>>arg2), unsigned shift
   280  		{name: "ANDshiftRAreg", argLength: 3, reg: gp31, asm: "AND"}, // arg0 & (arg1>>arg2), signed shift
   281  		{name: "ORshiftLLreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1<<arg2
   282  		{name: "ORshiftRLreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1>>arg2, unsigned shift
   283  		{name: "ORshiftRAreg", argLength: 3, reg: gp31, asm: "ORR"},  // arg0 | arg1>>arg2, signed shift
   284  		{name: "XORshiftLLreg", argLength: 3, reg: gp31, asm: "EOR"}, // arg0 ^ arg1<<arg2
   285  		{name: "XORshiftRLreg", argLength: 3, reg: gp31, asm: "EOR"}, // arg0 ^ arg1>>arg2, unsigned shift
   286  		{name: "XORshiftRAreg", argLength: 3, reg: gp31, asm: "EOR"}, // arg0 ^ arg1>>arg2, signed shift
   287  		{name: "BICshiftLLreg", argLength: 3, reg: gp31, asm: "BIC"}, // arg0 &^ (arg1<<arg2)
   288  		{name: "BICshiftRLreg", argLength: 3, reg: gp31, asm: "BIC"}, // arg0 &^ (arg1>>arg2), unsigned shift
   289  		{name: "BICshiftRAreg", argLength: 3, reg: gp31, asm: "BIC"}, // arg0 &^ (arg1>>arg2), signed shift
   290  		{name: "MVNshiftLLreg", argLength: 2, reg: gp21, asm: "MVN"}, // ^(arg0<<arg1)
   291  		{name: "MVNshiftRLreg", argLength: 2, reg: gp21, asm: "MVN"}, // ^(arg0>>arg1), unsigned shift
   292  		{name: "MVNshiftRAreg", argLength: 2, reg: gp21, asm: "MVN"}, // ^(arg0>>arg1), signed shift
   293  
   294  		{name: "ADCshiftLLreg", argLength: 4, reg: gp3flags1, asm: "ADC"}, // arg0 + arg1<<arg2 + carry, arg3=flags
   295  		{name: "ADCshiftRLreg", argLength: 4, reg: gp3flags1, asm: "ADC"}, // arg0 + arg1>>arg2 + carry, unsigned shift, arg3=flags
   296  		{name: "ADCshiftRAreg", argLength: 4, reg: gp3flags1, asm: "ADC"}, // arg0 + arg1>>arg2 + carry, signed shift, arg3=flags
   297  		{name: "SBCshiftLLreg", argLength: 4, reg: gp3flags1, asm: "SBC"}, // arg0 - arg1<<arg2 - carry, arg3=flags
   298  		{name: "SBCshiftRLreg", argLength: 4, reg: gp3flags1, asm: "SBC"}, // arg0 - arg1>>arg2 - carry, unsigned shift, arg3=flags
   299  		{name: "SBCshiftRAreg", argLength: 4, reg: gp3flags1, asm: "SBC"}, // arg0 - arg1>>arg2 - carry, signed shift, arg3=flags
   300  		{name: "RSCshiftLLreg", argLength: 4, reg: gp3flags1, asm: "RSC"}, // arg1<<arg2 - arg0 - carry, arg3=flags
   301  		{name: "RSCshiftRLreg", argLength: 4, reg: gp3flags1, asm: "RSC"}, // arg1>>arg2 - arg0 - carry, unsigned shift, arg3=flags
   302  		{name: "RSCshiftRAreg", argLength: 4, reg: gp3flags1, asm: "RSC"}, // arg1>>arg2 - arg0 - carry, signed shift, arg3=flags
   303  
   304  		{name: "ADDSshiftLLreg", argLength: 3, reg: gp31carry, asm: "ADD"}, // arg0 + arg1<<arg2, set carry flag
   305  		{name: "ADDSshiftRLreg", argLength: 3, reg: gp31carry, asm: "ADD"}, // arg0 + arg1>>arg2, unsigned shift, set carry flag
   306  		{name: "ADDSshiftRAreg", argLength: 3, reg: gp31carry, asm: "ADD"}, // arg0 + arg1>>arg2, signed shift, set carry flag
   307  		{name: "SUBSshiftLLreg", argLength: 3, reg: gp31carry, asm: "SUB"}, // arg0 - arg1<<arg2, set carry flag
   308  		{name: "SUBSshiftRLreg", argLength: 3, reg: gp31carry, asm: "SUB"}, // arg0 - arg1>>arg2, unsigned shift, set carry flag
   309  		{name: "SUBSshiftRAreg", argLength: 3, reg: gp31carry, asm: "SUB"}, // arg0 - arg1>>arg2, signed shift, set carry flag
   310  		{name: "RSBSshiftLLreg", argLength: 3, reg: gp31carry, asm: "RSB"}, // arg1<<arg2 - arg0, set carry flag
   311  		{name: "RSBSshiftRLreg", argLength: 3, reg: gp31carry, asm: "RSB"}, // arg1>>arg2 - arg0, unsigned shift, set carry flag
   312  		{name: "RSBSshiftRAreg", argLength: 3, reg: gp31carry, asm: "RSB"}, // arg1>>arg2 - arg0, signed shift, set carry flag
   313  
   314  		// comparisons
   315  		{name: "CMP", argLength: 2, reg: gp2flags, asm: "CMP", typ: "Flags"},                    // arg0 compare to arg1
   316  		{name: "CMPconst", argLength: 1, reg: gp1flags, asm: "CMP", aux: "Int32", typ: "Flags"}, // arg0 compare to auxInt
   317  		{name: "CMN", argLength: 2, reg: gp2flags, asm: "CMN", typ: "Flags"},                    // arg0 compare to -arg1
   318  		{name: "CMNconst", argLength: 1, reg: gp1flags, asm: "CMN", aux: "Int32", typ: "Flags"}, // arg0 compare to -auxInt
   319  		{name: "TST", argLength: 2, reg: gp2flags, asm: "TST", typ: "Flags", commutative: true}, // arg0 & arg1 compare to 0
   320  		{name: "TSTconst", argLength: 1, reg: gp1flags, asm: "TST", aux: "Int32", typ: "Flags"}, // arg0 & auxInt compare to 0
   321  		{name: "TEQ", argLength: 2, reg: gp2flags, asm: "TEQ", typ: "Flags", commutative: true}, // arg0 ^ arg1 compare to 0
   322  		{name: "TEQconst", argLength: 1, reg: gp1flags, asm: "TEQ", aux: "Int32", typ: "Flags"}, // arg0 ^ auxInt compare to 0
   323  		{name: "CMPF", argLength: 2, reg: fp2flags, asm: "CMPF", typ: "Flags"},                  // arg0 compare to arg1, float32
   324  		{name: "CMPD", argLength: 2, reg: fp2flags, asm: "CMPD", typ: "Flags"},                  // arg0 compare to arg1, float64
   325  
   326  		{name: "CMPshiftLL", argLength: 2, reg: gp2flags, asm: "CMP", aux: "Int32", typ: "Flags"}, // arg0 compare to arg1<<auxInt
   327  		{name: "CMPshiftRL", argLength: 2, reg: gp2flags, asm: "CMP", aux: "Int32", typ: "Flags"}, // arg0 compare to arg1>>auxInt, unsigned shift
   328  		{name: "CMPshiftRA", argLength: 2, reg: gp2flags, asm: "CMP", aux: "Int32", typ: "Flags"}, // arg0 compare to arg1>>auxInt, signed shift
   329  
   330  		{name: "CMPshiftLLreg", argLength: 3, reg: gp3flags, asm: "CMP", typ: "Flags"}, // arg0 compare to arg1<<arg2
   331  		{name: "CMPshiftRLreg", argLength: 3, reg: gp3flags, asm: "CMP", typ: "Flags"}, // arg0 compare to arg1>>arg2, unsigned shift
   332  		{name: "CMPshiftRAreg", argLength: 3, reg: gp3flags, asm: "CMP", typ: "Flags"}, // arg0 compare to arg1>>arg2, signed shift
   333  
   334  		{name: "CMPF0", argLength: 1, reg: fp1flags, asm: "CMPF", typ: "Flags"}, // arg0 compare to 0, float32
   335  		{name: "CMPD0", argLength: 1, reg: fp1flags, asm: "CMPD", typ: "Flags"}, // arg0 compare to 0, float64
   336  
   337  		// moves
   338  		{name: "MOVWconst", argLength: 0, reg: gp01, aux: "Int32", asm: "MOVW", typ: "UInt32", rematerializeable: true},    // 32 low bits of auxint
   339  		{name: "MOVFconst", argLength: 0, reg: fp01, aux: "Float64", asm: "MOVF", typ: "Float32", rematerializeable: true}, // auxint as 64-bit float, convert to 32-bit float
   340  		{name: "MOVDconst", argLength: 0, reg: fp01, aux: "Float64", asm: "MOVD", typ: "Float64", rematerializeable: true}, // auxint as 64-bit float
   341  
   342  		{name: "MOVWaddr", argLength: 1, reg: regInfo{inputs: []regMask{buildReg("SP") | buildReg("SB")}, outputs: []regMask{gp}}, aux: "SymOff", asm: "MOVW", rematerializeable: true, symEffect: "Addr"}, // arg0 + auxInt + aux.(*gc.Sym), arg0=SP/SB
   343  
   344  		{name: "MOVBload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVB", typ: "Int8", faultOnNilArg0: true, symEffect: "Read"},     // load from arg0 + auxInt + aux.  arg1=mem.
   345  		{name: "MOVBUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVBU", typ: "UInt8", faultOnNilArg0: true, symEffect: "Read"},  // load from arg0 + auxInt + aux.  arg1=mem.
   346  		{name: "MOVHload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVH", typ: "Int16", faultOnNilArg0: true, symEffect: "Read"},    // load from arg0 + auxInt + aux.  arg1=mem.
   347  		{name: "MOVHUload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVHU", typ: "UInt16", faultOnNilArg0: true, symEffect: "Read"}, // load from arg0 + auxInt + aux.  arg1=mem.
   348  		{name: "MOVWload", argLength: 2, reg: gpload, aux: "SymOff", asm: "MOVW", typ: "UInt32", faultOnNilArg0: true, symEffect: "Read"},   // load from arg0 + auxInt + aux.  arg1=mem.
   349  		{name: "MOVFload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVF", typ: "Float32", faultOnNilArg0: true, symEffect: "Read"},  // load from arg0 + auxInt + aux.  arg1=mem.
   350  		{name: "MOVDload", argLength: 2, reg: fpload, aux: "SymOff", asm: "MOVD", typ: "Float64", faultOnNilArg0: true, symEffect: "Read"},  // load from arg0 + auxInt + aux.  arg1=mem.
   351  
   352  		{name: "MOVBstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVB", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // store 1 byte of arg1 to arg0 + auxInt + aux.  arg2=mem.
   353  		{name: "MOVHstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVH", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // store 2 bytes of arg1 to arg0 + auxInt + aux.  arg2=mem.
   354  		{name: "MOVWstore", argLength: 3, reg: gpstore, aux: "SymOff", asm: "MOVW", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // store 4 bytes of arg1 to arg0 + auxInt + aux.  arg2=mem.
   355  		{name: "MOVFstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVF", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // store 4 bytes of arg1 to arg0 + auxInt + aux.  arg2=mem.
   356  		{name: "MOVDstore", argLength: 3, reg: fpstore, aux: "SymOff", asm: "MOVD", typ: "Mem", faultOnNilArg0: true, symEffect: "Write"}, // store 8 bytes of arg1 to arg0 + auxInt + aux.  arg2=mem.
   357  
   358  		{name: "MOVWloadidx", argLength: 3, reg: gp2load, asm: "MOVW"},                   // load from arg0 + arg1. arg2=mem
   359  		{name: "MOVWloadshiftLL", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1<<auxInt. arg2=mem
   360  		{name: "MOVWloadshiftRL", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1>>auxInt, unsigned shift. arg2=mem
   361  		{name: "MOVWloadshiftRA", argLength: 3, reg: gp2load, asm: "MOVW", aux: "Int32"}, // load from arg0 + arg1>>auxInt, signed shift. arg2=mem
   362  		{name: "MOVBUloadidx", argLength: 3, reg: gp2load, asm: "MOVBU"},                 // load from arg0 + arg1. arg2=mem
   363  		{name: "MOVBloadidx", argLength: 3, reg: gp2load, asm: "MOVB"},                   // load from arg0 + arg1. arg2=mem
   364  		{name: "MOVHUloadidx", argLength: 3, reg: gp2load, asm: "MOVHU"},                 // load from arg0 + arg1. arg2=mem
   365  		{name: "MOVHloadidx", argLength: 3, reg: gp2load, asm: "MOVH"},                   // load from arg0 + arg1. arg2=mem
   366  
   367  		{name: "MOVWstoreidx", argLength: 4, reg: gp2store, asm: "MOVW"},                   // store arg2 to arg0 + arg1. arg3=mem
   368  		{name: "MOVWstoreshiftLL", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1<<auxInt. arg3=mem
   369  		{name: "MOVWstoreshiftRL", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1>>auxInt, unsigned shift. arg3=mem
   370  		{name: "MOVWstoreshiftRA", argLength: 4, reg: gp2store, asm: "MOVW", aux: "Int32"}, // store arg2 to arg0 + arg1>>auxInt, signed shift. arg3=mem
   371  		{name: "MOVBstoreidx", argLength: 4, reg: gp2store, asm: "MOVB"},                   // store arg2 to arg0 + arg1. arg3=mem
   372  		{name: "MOVHstoreidx", argLength: 4, reg: gp2store, asm: "MOVH"},                   // store arg2 to arg0 + arg1. arg3=mem
   373  
   374  		{name: "MOVBreg", argLength: 1, reg: gp11, asm: "MOVBS"},  // move from arg0, sign-extended from byte
   375  		{name: "MOVBUreg", argLength: 1, reg: gp11, asm: "MOVBU"}, // move from arg0, unsign-extended from byte
   376  		{name: "MOVHreg", argLength: 1, reg: gp11, asm: "MOVHS"},  // move from arg0, sign-extended from half
   377  		{name: "MOVHUreg", argLength: 1, reg: gp11, asm: "MOVHU"}, // move from arg0, unsign-extended from half
   378  		{name: "MOVWreg", argLength: 1, reg: gp11, asm: "MOVW"},   // move from arg0
   379  
   380  		{name: "MOVWnop", argLength: 1, reg: regInfo{inputs: []regMask{gp}, outputs: []regMask{gp}}, resultInArg0: true}, // nop, return arg0 in same register
   381  
   382  		{name: "MOVWF", argLength: 1, reg: gpfp, asm: "MOVWF"},  // int32 -> float32
   383  		{name: "MOVWD", argLength: 1, reg: gpfp, asm: "MOVWD"},  // int32 -> float64
   384  		{name: "MOVWUF", argLength: 1, reg: gpfp, asm: "MOVWF"}, // uint32 -> float32, set U bit in the instruction
   385  		{name: "MOVWUD", argLength: 1, reg: gpfp, asm: "MOVWD"}, // uint32 -> float64, set U bit in the instruction
   386  		{name: "MOVFW", argLength: 1, reg: fpgp, asm: "MOVFW"},  // float32 -> int32
   387  		{name: "MOVDW", argLength: 1, reg: fpgp, asm: "MOVDW"},  // float64 -> int32
   388  		{name: "MOVFWU", argLength: 1, reg: fpgp, asm: "MOVFW"}, // float32 -> uint32, set U bit in the instruction
   389  		{name: "MOVDWU", argLength: 1, reg: fpgp, asm: "MOVDW"}, // float64 -> uint32, set U bit in the instruction
   390  		{name: "MOVFD", argLength: 1, reg: fp11, asm: "MOVFD"},  // float32 -> float64
   391  		{name: "MOVDF", argLength: 1, reg: fp11, asm: "MOVDF"},  // float64 -> float32
   392  
   393  		// conditional instructions, for lowering shifts
   394  		{name: "CMOVWHSconst", argLength: 2, reg: gp1flags1, asm: "MOVW", aux: "Int32", resultInArg0: true}, // replace arg0 w/ const if flags indicates HS, arg1=flags
   395  		{name: "CMOVWLSconst", argLength: 2, reg: gp1flags1, asm: "MOVW", aux: "Int32", resultInArg0: true}, // replace arg0 w/ const if flags indicates LS, arg1=flags
   396  		{name: "SRAcond", argLength: 3, reg: gp2flags1, asm: "SRA"},                                         // arg0 >> 31 if flags indicates HS, arg0 >> arg1 otherwise, signed shift, arg2=flags
   397  
   398  		// function calls
   399  		{name: "CALLstatic", argLength: 1, reg: regInfo{clobbers: callerSave}, aux: "SymOff", clobberFlags: true, call: true, symEffect: "None"},                          // call static function aux.(*obj.LSym).  arg0=mem, auxint=argsize, returns mem
   400  		{name: "CALLclosure", argLength: 3, reg: regInfo{inputs: []regMask{gpsp, buildReg("R7"), 0}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true}, // call function via closure.  arg0=codeptr, arg1=closure, arg2=mem, auxint=argsize, returns mem
   401  		{name: "CALLinter", argLength: 2, reg: regInfo{inputs: []regMask{gp}, clobbers: callerSave}, aux: "Int64", clobberFlags: true, call: true},                        // call fn by pointer.  arg0=codeptr, arg1=mem, auxint=argsize, returns mem
   402  
   403  		// pseudo-ops
   404  		{name: "LoweredNilCheck", argLength: 2, reg: regInfo{inputs: []regMask{gpg}}, nilCheck: true, faultOnNilArg0: true}, // panic if arg0 is nil.  arg1=mem.
   405  
   406  		{name: "Equal", argLength: 1, reg: readflags},         // bool, true flags encode x==y false otherwise.
   407  		{name: "NotEqual", argLength: 1, reg: readflags},      // bool, true flags encode x!=y false otherwise.
   408  		{name: "LessThan", argLength: 1, reg: readflags},      // bool, true flags encode signed x<y false otherwise.
   409  		{name: "LessEqual", argLength: 1, reg: readflags},     // bool, true flags encode signed x<=y false otherwise.
   410  		{name: "GreaterThan", argLength: 1, reg: readflags},   // bool, true flags encode signed x>y false otherwise.
   411  		{name: "GreaterEqual", argLength: 1, reg: readflags},  // bool, true flags encode signed x>=y false otherwise.
   412  		{name: "LessThanU", argLength: 1, reg: readflags},     // bool, true flags encode unsigned x<y false otherwise.
   413  		{name: "LessEqualU", argLength: 1, reg: readflags},    // bool, true flags encode unsigned x<=y false otherwise.
   414  		{name: "GreaterThanU", argLength: 1, reg: readflags},  // bool, true flags encode unsigned x>y false otherwise.
   415  		{name: "GreaterEqualU", argLength: 1, reg: readflags}, // bool, true flags encode unsigned x>=y false otherwise.
   416  
   417  		// duffzero (must be 4-byte aligned)
   418  		// arg0 = address of memory to zero (in R1, changed as side effect)
   419  		// arg1 = value to store (always zero)
   420  		// arg2 = mem
   421  		// auxint = offset into duffzero code to start executing
   422  		// returns mem
   423  		{
   424  			name:      "DUFFZERO",
   425  			aux:       "Int64",
   426  			argLength: 3,
   427  			reg: regInfo{
   428  				inputs:   []regMask{buildReg("R1"), buildReg("R0")},
   429  				clobbers: buildReg("R1 R14"),
   430  			},
   431  			faultOnNilArg0: true,
   432  		},
   433  
   434  		// duffcopy (must be 4-byte aligned)
   435  		// arg0 = address of dst memory (in R2, changed as side effect)
   436  		// arg1 = address of src memory (in R1, changed as side effect)
   437  		// arg2 = mem
   438  		// auxint = offset into duffcopy code to start executing
   439  		// returns mem
   440  		{
   441  			name:      "DUFFCOPY",
   442  			aux:       "Int64",
   443  			argLength: 3,
   444  			reg: regInfo{
   445  				inputs:   []regMask{buildReg("R2"), buildReg("R1")},
   446  				clobbers: buildReg("R0 R1 R2 R14"),
   447  			},
   448  			faultOnNilArg0: true,
   449  			faultOnNilArg1: true,
   450  		},
   451  
   452  		// large or unaligned zeroing
   453  		// arg0 = address of memory to zero (in R1, changed as side effect)
   454  		// arg1 = address of the last element to zero
   455  		// arg2 = value to store (always zero)
   456  		// arg3 = mem
   457  		// returns mem
   458  		//	MOVW.P	Rarg2, 4(R1)
   459  		//	CMP	R1, Rarg1
   460  		//	BLE	-2(PC)
   461  		{
   462  			name:      "LoweredZero",
   463  			aux:       "Int64",
   464  			argLength: 4,
   465  			reg: regInfo{
   466  				inputs:   []regMask{buildReg("R1"), gp, gp},
   467  				clobbers: buildReg("R1"),
   468  			},
   469  			clobberFlags:   true,
   470  			faultOnNilArg0: true,
   471  		},
   472  
   473  		// large or unaligned move
   474  		// arg0 = address of dst memory (in R2, changed as side effect)
   475  		// arg1 = address of src memory (in R1, changed as side effect)
   476  		// arg2 = address of the last element of src
   477  		// arg3 = mem
   478  		// returns mem
   479  		//	MOVW.P	4(R1), Rtmp
   480  		//	MOVW.P	Rtmp, 4(R2)
   481  		//	CMP	R1, Rarg2
   482  		//	BLE	-3(PC)
   483  		{
   484  			name:      "LoweredMove",
   485  			aux:       "Int64",
   486  			argLength: 4,
   487  			reg: regInfo{
   488  				inputs:   []regMask{buildReg("R2"), buildReg("R1"), gp},
   489  				clobbers: buildReg("R1 R2"),
   490  			},
   491  			clobberFlags:   true,
   492  			faultOnNilArg0: true,
   493  			faultOnNilArg1: true,
   494  		},
   495  
   496  		// Scheduler ensures LoweredGetClosurePtr occurs only in entry block,
   497  		// and sorts it to the very beginning of the block to prevent other
   498  		// use of R7 (arm.REGCTXT, the closure pointer)
   499  		{name: "LoweredGetClosurePtr", reg: regInfo{outputs: []regMask{buildReg("R7")}}},
   500  
   501  		// LoweredGetCallerSP returns the SP of the caller of the current function.
   502  		{name: "LoweredGetCallerSP", reg: gp01, rematerializeable: true},
   503  
   504  		// MOVWconvert converts between pointers and integers.
   505  		// We have a special op for this so as to not confuse GC
   506  		// (particularly stack maps).  It takes a memory arg so it
   507  		// gets correctly ordered with respect to GC safepoints.
   508  		// arg0=ptr/int arg1=mem, output=int/ptr
   509  		{name: "MOVWconvert", argLength: 2, reg: gp11, asm: "MOVW"},
   510  
   511  		// Constant flag values. For any comparison, there are 5 possible
   512  		// outcomes: the three from the signed total order (<,==,>) and the
   513  		// three from the unsigned total order. The == cases overlap.
   514  		// Note: there's a sixth "unordered" outcome for floating-point
   515  		// comparisons, but we don't use such a beast yet.
   516  		// These ops are for temporary use by rewrite rules. They
   517  		// cannot appear in the generated assembly.
   518  		{name: "FlagEQ"},     // equal
   519  		{name: "FlagLT_ULT"}, // signed < and unsigned <
   520  		{name: "FlagLT_UGT"}, // signed < and unsigned >
   521  		{name: "FlagGT_UGT"}, // signed > and unsigned <
   522  		{name: "FlagGT_ULT"}, // signed > and unsigned >
   523  
   524  		// (InvertFlags (CMP a b)) == (CMP b a)
   525  		// InvertFlags is a pseudo-op which can't appear in assembly output.
   526  		{name: "InvertFlags", argLength: 1}, // reverse direction of arg0
   527  	}
   528  
   529  	blocks := []blockData{
   530  		{name: "EQ"},
   531  		{name: "NE"},
   532  		{name: "LT"},
   533  		{name: "LE"},
   534  		{name: "GT"},
   535  		{name: "GE"},
   536  		{name: "ULT"},
   537  		{name: "ULE"},
   538  		{name: "UGT"},
   539  		{name: "UGE"},
   540  	}
   541  
   542  	archs = append(archs, arch{
   543  		name:            "ARM",
   544  		pkg:             "cmd/internal/obj/arm",
   545  		genfile:         "../../arm/ssa.go",
   546  		ops:             ops,
   547  		blocks:          blocks,
   548  		regnames:        regNamesARM,
   549  		gpregmask:       gp,
   550  		fpregmask:       fp,
   551  		framepointerreg: -1, // not used
   552  		linkreg:         int8(num["R14"]),
   553  	})
   554  }