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Text file src/cmd/compile/internal/ssa/_gen/S390X.rules

Documentation: cmd/compile/internal/ssa/_gen

     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// Lowering arithmetic
     6(Add(64|Ptr) ...) => (ADD ...)
     7(Add(32|16|8) ...) => (ADDW ...)
     8(Add32F x y) => (Select0 (FADDS x y))
     9(Add64F x y) => (Select0 (FADD x y))
    10
    11(Sub(64|Ptr) ...) => (SUB ...)
    12(Sub(32|16|8) ...) => (SUBW ...)
    13(Sub32F x y) => (Select0 (FSUBS x y))
    14(Sub64F x y) => (Select0 (FSUB x y))
    15
    16(Mul64 ...) => (MULLD ...)
    17(Mul(32|16|8) ...) => (MULLW ...)
    18(Mul32F ...) => (FMULS ...)
    19(Mul64F ...) => (FMUL ...)
    20(Mul64uhilo ...) => (MLGR ...)
    21
    22(Div32F ...) => (FDIVS ...)
    23(Div64F ...) => (FDIV ...)
    24
    25(Div64 x y) => (DIVD x y)
    26(Div64u ...) => (DIVDU ...)
    27// DIVW/DIVWU has a 64-bit dividend and a 32-bit divisor,
    28// so a sign/zero extension of the dividend is required.
    29(Div32  x y) => (DIVW  (MOVWreg x) y)
    30(Div32u x y) => (DIVWU (MOVWZreg x) y)
    31(Div16  x y) => (DIVW  (MOVHreg x) (MOVHreg y))
    32(Div16u x y) => (DIVWU (MOVHZreg x) (MOVHZreg y))
    33(Div8   x y) => (DIVW  (MOVBreg x) (MOVBreg y))
    34(Div8u  x y) => (DIVWU (MOVBZreg x) (MOVBZreg y))
    35
    36(Hmul(64|64u) ...) => (MULH(D|DU) ...)
    37(Hmul32  x y) => (SRDconst [32] (MULLD (MOVWreg x) (MOVWreg y)))
    38(Hmul32u x y) => (SRDconst [32] (MULLD (MOVWZreg x) (MOVWZreg y)))
    39
    40(Mod64 x y) => (MODD x y)
    41(Mod64u ...) => (MODDU ...)
    42// MODW/MODWU has a 64-bit dividend and a 32-bit divisor,
    43// so a sign/zero extension of the dividend is required.
    44(Mod32  x y) => (MODW  (MOVWreg x) y)
    45(Mod32u x y) => (MODWU (MOVWZreg x) y)
    46(Mod16  x y) => (MODW  (MOVHreg x) (MOVHreg y))
    47(Mod16u x y) => (MODWU (MOVHZreg x) (MOVHZreg y))
    48(Mod8   x y) => (MODW  (MOVBreg x) (MOVBreg y))
    49(Mod8u  x y) => (MODWU (MOVBZreg x) (MOVBZreg y))
    50
    51// (x + y) / 2 with x>=y -> (x - y) / 2 + y
    52(Avg64u <t> x y) => (ADD (SRDconst <t> (SUB <t> x y) [1]) y)
    53
    54(And64 ...) => (AND ...)
    55(And(32|16|8) ...) => (ANDW ...)
    56
    57(Or64 ...) => (OR ...)
    58(Or(32|16|8) ...) => (ORW ...)
    59
    60(Xor64 ...) => (XOR ...)
    61(Xor(32|16|8) ...) => (XORW ...)
    62
    63(Neg64 ...) => (NEG ...)
    64(Neg(32|16|8) ...) => (NEGW ...)
    65(Neg32F ...) => (FNEGS ...)
    66(Neg64F ...) => (FNEG ...)
    67
    68(Com64 ...) => (NOT ...)
    69(Com(32|16|8) ...) => (NOTW ...)
    70(NOT x) => (XOR (MOVDconst [-1]) x)
    71(NOTW x) => (XORWconst [-1] x)
    72
    73// Lowering boolean ops
    74(AndB ...) => (ANDW ...)
    75(OrB ...) => (ORW ...)
    76(Not x) => (XORWconst [1] x)
    77
    78// Lowering pointer arithmetic
    79(OffPtr [off] ptr:(SP)) => (MOVDaddr [int32(off)] ptr)
    80(OffPtr [off] ptr) && is32Bit(off) => (ADDconst [int32(off)] ptr)
    81(OffPtr [off] ptr) => (ADD (MOVDconst [off]) ptr)
    82
    83(Ctz(64|32|16|8)NonZero ...) => (Ctz64 ...)
    84
    85// Ctz(x) = 64 - findLeftmostOne((x-1)&^x)
    86(Ctz64 <t> x) => (SUB (MOVDconst [64]) (FLOGR (AND <t> (SUBconst <t> [1] x) (NOT <t> x))))
    87(Ctz32 <t> x) => (SUB (MOVDconst [64]) (FLOGR (MOVWZreg (ANDW <t> (SUBWconst <t> [1] x) (NOTW <t> x)))))
    88(Ctz16 x) => (Ctz64 (Or64 <typ.UInt64> x (MOVDconst [1<<16])))
    89(Ctz8  x) => (Ctz64 (Or64 <typ.UInt64> x (MOVDconst [1<<8])))
    90
    91(BitLen64 x) => (SUB (MOVDconst [64]) (FLOGR x))
    92(BitLen(32|16|8) x) => (BitLen64 (ZeroExt(32|16|8)to64 x))
    93
    94// POPCNT treats the input register as a vector of 8 bytes, producing
    95// a population count for each individual byte. For inputs larger than
    96// a single byte we therefore need to sum the individual bytes produced
    97// by the POPCNT instruction. For example, the following instruction
    98// sequence could be used to calculate the population count of a 4-byte
    99// value:
   100//
   101//     MOVD   $0x12345678, R1 // R1=0x12345678 <-- input
   102//     POPCNT R1, R2          // R2=0x02030404
   103//     SRW    $16, R2, R3     // R3=0x00000203
   104//     ADDW   R2, R3, R4      // R4=0x02030607
   105//     SRW    $8, R4, R5      // R5=0x00020306
   106//     ADDW   R4, R5, R6      // R6=0x0205090d
   107//     MOVBZ  R6, R7          // R7=0x0000000d <-- result is 13
   108//
   109(PopCount8  x) => (POPCNT (MOVBZreg x))
   110(PopCount16 x) => (MOVBZreg (SumBytes2 (POPCNT <typ.UInt16> x)))
   111(PopCount32 x) => (MOVBZreg (SumBytes4 (POPCNT <typ.UInt32> x)))
   112(PopCount64 x) => (MOVBZreg (SumBytes8 (POPCNT <typ.UInt64> x)))
   113
   114// SumBytes{2,4,8} pseudo operations sum the values of the rightmost
   115// 2, 4 or 8 bytes respectively. The result is a single byte however
   116// other bytes might contain junk so a zero extension is required if
   117// the desired output type is larger than 1 byte.
   118(SumBytes2 x) => (ADDW (SRWconst <typ.UInt8> x [8]) x)
   119(SumBytes4 x) => (SumBytes2 (ADDW <typ.UInt16> (SRWconst <typ.UInt16> x [16]) x))
   120(SumBytes8 x) => (SumBytes4 (ADDW <typ.UInt32> (SRDconst <typ.UInt32> x [32]) x))
   121
   122(Bswap64 ...) => (MOVDBR ...)
   123(Bswap32 ...) => (MOVWBR ...)
   124
   125// add with carry
   126(Select0 (Add64carry x y c))
   127  => (Select0 <typ.UInt64> (ADDE x y (Select1 <types.TypeFlags> (ADDCconst c [-1]))))
   128(Select1 (Add64carry x y c))
   129  => (Select0 <typ.UInt64> (ADDE (MOVDconst [0]) (MOVDconst [0]) (Select1 <types.TypeFlags> (ADDE x y (Select1 <types.TypeFlags> (ADDCconst c [-1]))))))
   130
   131// subtract with borrow
   132(Select0 (Sub64borrow x y c))
   133  => (Select0 <typ.UInt64> (SUBE x y (Select1 <types.TypeFlags> (SUBC (MOVDconst [0]) c))))
   134(Select1 (Sub64borrow x y c))
   135  => (NEG (Select0 <typ.UInt64> (SUBE (MOVDconst [0]) (MOVDconst [0]) (Select1 <types.TypeFlags> (SUBE x y (Select1 <types.TypeFlags> (SUBC (MOVDconst [0]) c)))))))
   136
   137// math package intrinsics
   138(Sqrt      ...) => (FSQRT ...)
   139(Floor       x) => (FIDBR [7] x)
   140(Ceil        x) => (FIDBR [6] x)
   141(Trunc       x) => (FIDBR [5] x)
   142(RoundToEven x) => (FIDBR [4] x)
   143(Round       x) => (FIDBR [1] x)
   144(FMA     x y z) => (FMADD z x y)
   145
   146(Sqrt32    ...) => (FSQRTS ...)
   147
   148// Atomic loads and stores.
   149// The SYNC instruction (fast-BCR-serialization) prevents store-load
   150// reordering. Other sequences of memory operations (load-load,
   151// store-store and load-store) are already guaranteed not to be reordered.
   152(AtomicLoad(8|32|Acq32|64|Ptr) ptr mem) => (MOV(BZ|WZ|WZ|D|D)atomicload ptr mem)
   153(AtomicStore(8|32|64|PtrNoWB) ptr val mem) => (SYNC (MOV(B|W|D|D)atomicstore ptr val mem))
   154
   155// Store-release doesn't require store-load ordering.
   156(AtomicStoreRel32 ptr val mem) => (MOVWatomicstore ptr val mem)
   157
   158// Atomic adds.
   159(AtomicAdd32 ptr val mem) => (AddTupleFirst32 val (LAA ptr val mem))
   160(AtomicAdd64 ptr val mem) => (AddTupleFirst64 val (LAAG ptr val mem))
   161(Select0 <t> (AddTupleFirst32 val tuple)) => (ADDW val (Select0 <t> tuple))
   162(Select1     (AddTupleFirst32   _ tuple)) => (Select1 tuple)
   163(Select0 <t> (AddTupleFirst64 val tuple)) => (ADD val (Select0 <t> tuple))
   164(Select1     (AddTupleFirst64   _ tuple)) => (Select1 tuple)
   165
   166// Atomic exchanges.
   167(AtomicExchange32 ptr val mem) => (LoweredAtomicExchange32 ptr val mem)
   168(AtomicExchange64 ptr val mem) => (LoweredAtomicExchange64 ptr val mem)
   169
   170// Atomic compare and swap.
   171(AtomicCompareAndSwap32 ptr old new_ mem) => (LoweredAtomicCas32 ptr old new_ mem)
   172(AtomicCompareAndSwap64 ptr old new_ mem) => (LoweredAtomicCas64 ptr old new_ mem)
   173
   174// Atomic and: *(*uint8)(ptr) &= val
   175//
   176// Round pointer down to nearest word boundary and pad value with ones before
   177// applying atomic AND operation to target word.
   178//
   179// *(*uint32)(ptr &^ 3) &= rotateleft(uint32(val) | 0xffffff00, ((3 << 3) ^ ((ptr & 3) << 3))
   180//
   181(AtomicAnd8 ptr val mem)
   182  => (LANfloor
   183       ptr
   184       (RLL <typ.UInt32>
   185         (ORWconst <typ.UInt32> val [-1<<8])
   186         (RXSBG <typ.UInt32> {s390x.NewRotateParams(59, 60, 3)} (MOVDconst [3<<3]) ptr))
   187       mem)
   188
   189// Atomic or: *(*uint8)(ptr) |= val
   190//
   191// Round pointer down to nearest word boundary and pad value with zeros before
   192// applying atomic OR operation to target word.
   193//
   194// *(*uint32)(ptr &^ 3) |= uint32(val) << ((3 << 3) ^ ((ptr & 3) << 3))
   195//
   196(AtomicOr8  ptr val mem)
   197  => (LAOfloor
   198       ptr
   199       (SLW <typ.UInt32>
   200         (MOVBZreg <typ.UInt32> val)
   201         (RXSBG <typ.UInt32> {s390x.NewRotateParams(59, 60, 3)} (MOVDconst [3<<3]) ptr))
   202       mem)
   203
   204(AtomicAnd32 ...) => (LAN ...)
   205(AtomicOr32  ...) => (LAO ...)
   206
   207// Lowering extension
   208// Note: we always extend to 64 bits even though some ops don't need that many result bits.
   209(SignExt8to(16|32|64) ...) => (MOVBreg ...)
   210(SignExt16to(32|64) ...) => (MOVHreg ...)
   211(SignExt32to64 ...) => (MOVWreg ...)
   212
   213(ZeroExt8to(16|32|64) ...) => (MOVBZreg ...)
   214(ZeroExt16to(32|64) ...) => (MOVHZreg ...)
   215(ZeroExt32to64 ...) => (MOVWZreg ...)
   216
   217(Slicemask <t> x) => (SRADconst (NEG <t> x) [63])
   218
   219// Lowering truncation
   220// Because we ignore high parts of registers, truncates are just copies.
   221(Trunc(16|32|64)to8 ...) => (Copy ...)
   222(Trunc(32|64)to16 ...) => (Copy ...)
   223(Trunc64to32 ...) => (Copy ...)
   224
   225// Lowering float <-> int
   226(Cvt32to32F ...) => (CEFBRA ...)
   227(Cvt32to64F ...) => (CDFBRA ...)
   228(Cvt64to32F ...) => (CEGBRA ...)
   229(Cvt64to64F ...) => (CDGBRA ...)
   230
   231(Cvt32Fto32 ...) => (CFEBRA ...)
   232(Cvt32Fto64 ...) => (CGEBRA ...)
   233(Cvt64Fto32 ...) => (CFDBRA ...)
   234(Cvt64Fto64 ...) => (CGDBRA ...)
   235
   236// Lowering float <-> uint
   237(Cvt32Uto32F ...) => (CELFBR ...)
   238(Cvt32Uto64F ...) => (CDLFBR ...)
   239(Cvt64Uto32F ...) => (CELGBR ...)
   240(Cvt64Uto64F ...) => (CDLGBR ...)
   241
   242(Cvt32Fto32U ...) => (CLFEBR ...)
   243(Cvt32Fto64U ...) => (CLGEBR ...)
   244(Cvt64Fto32U ...) => (CLFDBR ...)
   245(Cvt64Fto64U ...) => (CLGDBR ...)
   246
   247// Lowering float32 <-> float64
   248(Cvt32Fto64F ...) => (LDEBR ...)
   249(Cvt64Fto32F ...) => (LEDBR ...)
   250
   251(CvtBoolToUint8 ...) => (Copy ...)
   252
   253(Round(32|64)F ...) => (LoweredRound(32|64)F ...)
   254
   255// Lowering shifts
   256
   257// Lower bounded shifts first. No need to check shift value.
   258(Lsh64x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLD x y)
   259(Lsh32x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLW x y)
   260(Lsh16x(64|32|16|8)  x y) && shiftIsBounded(v) => (SLW x y)
   261(Lsh8x(64|32|16|8)   x y) && shiftIsBounded(v) => (SLW x y)
   262(Rsh64Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRD x y)
   263(Rsh32Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRW x y)
   264(Rsh16Ux(64|32|16|8) x y) && shiftIsBounded(v) => (SRW (MOVHZreg x) y)
   265(Rsh8Ux(64|32|16|8)  x y) && shiftIsBounded(v) => (SRW (MOVBZreg x) y)
   266(Rsh64x(64|32|16|8)  x y) && shiftIsBounded(v) => (SRAD x y)
   267(Rsh32x(64|32|16|8)  x y) && shiftIsBounded(v) => (SRAW x y)
   268(Rsh16x(64|32|16|8)  x y) && shiftIsBounded(v) => (SRAW (MOVHreg x) y)
   269(Rsh8x(64|32|16|8)   x y) && shiftIsBounded(v) => (SRAW (MOVBreg x) y)
   270
   271// Unsigned shifts need to return 0 if shift amount is >= width of shifted value.
   272//   result = shift >= 64 ? 0 : arg << shift
   273(Lsh(64|32|16|8)x64 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SL(D|W|W|W) <t> x y) (MOVDconst [0]) (CMPUconst y [64]))
   274(Lsh(64|32|16|8)x32 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SL(D|W|W|W) <t> x y) (MOVDconst [0]) (CMPWUconst y [64]))
   275(Lsh(64|32|16|8)x16 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SL(D|W|W|W) <t> x y) (MOVDconst [0]) (CMPWUconst (MOVHZreg y) [64]))
   276(Lsh(64|32|16|8)x8  <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SL(D|W|W|W) <t> x y) (MOVDconst [0]) (CMPWUconst (MOVBZreg y) [64]))
   277
   278(Rsh(64|32)Ux64 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SR(D|W) <t> x y) (MOVDconst [0]) (CMPUconst y [64]))
   279(Rsh(64|32)Ux32 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SR(D|W) <t> x y) (MOVDconst [0]) (CMPWUconst y [64]))
   280(Rsh(64|32)Ux16 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SR(D|W) <t> x y) (MOVDconst [0]) (CMPWUconst (MOVHZreg y) [64]))
   281(Rsh(64|32)Ux8  <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SR(D|W) <t> x y) (MOVDconst [0]) (CMPWUconst (MOVBZreg y) [64]))
   282
   283(Rsh(16|8)Ux64 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SRW <t> (MOV(H|B)Zreg x) y) (MOVDconst [0]) (CMPUconst y [64]))
   284(Rsh(16|8)Ux32 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SRW <t> (MOV(H|B)Zreg x) y) (MOVDconst [0]) (CMPWUconst y [64]))
   285(Rsh(16|8)Ux16 <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SRW <t> (MOV(H|B)Zreg x) y) (MOVDconst [0]) (CMPWUconst (MOVHZreg y) [64]))
   286(Rsh(16|8)Ux8  <t> x y) => (LOCGR {s390x.GreaterOrEqual} <t> (SRW <t> (MOV(H|B)Zreg x) y) (MOVDconst [0]) (CMPWUconst (MOVBZreg y) [64]))
   287
   288// Signed right shift needs to return 0/-1 if shift amount is >= width of shifted value.
   289// We implement this by setting the shift value to 63 (all ones) if the shift value is more than 63.
   290//   result = arg >> (shift >= 64 ? 63 : shift)
   291(Rsh(64|32)x64 x y) => (SRA(D|W) x (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPUconst  y [64])))
   292(Rsh(64|32)x32 x y) => (SRA(D|W) x (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst y [64])))
   293(Rsh(64|32)x16 x y) => (SRA(D|W) x (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst (MOVHZreg y) [64])))
   294(Rsh(64|32)x8  x y) => (SRA(D|W) x (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst (MOVBZreg y) [64])))
   295
   296(Rsh(16|8)x64 x y) => (SRAW (MOV(H|B)reg x) (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPUconst  y [64])))
   297(Rsh(16|8)x32 x y) => (SRAW (MOV(H|B)reg x) (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst y [64])))
   298(Rsh(16|8)x16 x y) => (SRAW (MOV(H|B)reg x) (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst (MOVHZreg y) [64])))
   299(Rsh(16|8)x8  x y) => (SRAW (MOV(H|B)reg x) (LOCGR {s390x.GreaterOrEqual} <y.Type> y (MOVDconst <y.Type> [63]) (CMPWUconst (MOVBZreg y) [64])))
   300
   301// Lowering rotates
   302(RotateLeft8 <t> x (MOVDconst [c])) => (Or8 (Lsh8x64 <t> x (MOVDconst [c&7])) (Rsh8Ux64 <t> x (MOVDconst [-c&7])))
   303(RotateLeft16 <t> x (MOVDconst [c])) => (Or16 (Lsh16x64 <t> x (MOVDconst [c&15])) (Rsh16Ux64 <t> x (MOVDconst [-c&15])))
   304(RotateLeft32 ...) => (RLL  ...)
   305(RotateLeft64 ...) => (RLLG ...)
   306
   307// Lowering comparisons
   308(Less64      x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMP x y))
   309(Less32      x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPW x y))
   310(Less(16|8)  x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPW (MOV(H|B)reg x) (MOV(H|B)reg y)))
   311(Less64U     x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPU x y))
   312(Less32U     x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPWU x y))
   313(Less(16|8)U x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPWU (MOV(H|B)Zreg x) (MOV(H|B)Zreg y)))
   314(Less64F     x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (FCMP x y))
   315(Less32F     x y) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (FCMPS x y))
   316
   317(Leq64      x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMP x y))
   318(Leq32      x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPW x y))
   319(Leq(16|8)  x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPW (MOV(H|B)reg x) (MOV(H|B)reg y)))
   320(Leq64U     x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPU x y))
   321(Leq32U     x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPWU x y))
   322(Leq(16|8)U x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPWU (MOV(H|B)Zreg x) (MOV(H|B)Zreg y)))
   323(Leq64F     x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (FCMP x y))
   324(Leq32F     x y) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (FCMPS x y))
   325
   326(Eq(64|Ptr) x y) => (LOCGR {s390x.Equal} (MOVDconst [0]) (MOVDconst [1]) (CMP x y))
   327(Eq32       x y) => (LOCGR {s390x.Equal} (MOVDconst [0]) (MOVDconst [1]) (CMPW x y))
   328(Eq(16|8|B) x y) => (LOCGR {s390x.Equal} (MOVDconst [0]) (MOVDconst [1]) (CMPW (MOV(H|B|B)reg x) (MOV(H|B|B)reg y)))
   329(Eq64F      x y) => (LOCGR {s390x.Equal} (MOVDconst [0]) (MOVDconst [1]) (FCMP x y))
   330(Eq32F      x y) => (LOCGR {s390x.Equal} (MOVDconst [0]) (MOVDconst [1]) (FCMPS x y))
   331
   332(Neq(64|Ptr) x y) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (CMP x y))
   333(Neq32       x y) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPW x y))
   334(Neq(16|8|B) x y) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPW (MOV(H|B|B)reg x) (MOV(H|B|B)reg y)))
   335(Neq64F      x y) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (FCMP x y))
   336(Neq32F      x y) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (FCMPS x y))
   337
   338// Lowering loads
   339(Load <t> ptr mem) && (is64BitInt(t) || isPtr(t)) => (MOVDload ptr mem)
   340(Load <t> ptr mem) && is32BitInt(t) &&  t.IsSigned() => (MOVWload ptr mem)
   341(Load <t> ptr mem) && is32BitInt(t) && !t.IsSigned() => (MOVWZload ptr mem)
   342(Load <t> ptr mem) && is16BitInt(t) &&  t.IsSigned() => (MOVHload ptr mem)
   343(Load <t> ptr mem) && is16BitInt(t) && !t.IsSigned() => (MOVHZload ptr mem)
   344(Load <t> ptr mem) && is8BitInt(t)  &&  t.IsSigned() => (MOVBload ptr mem)
   345(Load <t> ptr mem) && (t.IsBoolean() || (is8BitInt(t) && !t.IsSigned())) => (MOVBZload ptr mem)
   346(Load <t> ptr mem) && is32BitFloat(t) => (FMOVSload ptr mem)
   347(Load <t> ptr mem) && is64BitFloat(t) => (FMOVDload ptr mem)
   348
   349// Lowering stores
   350(Store {t} ptr val mem) && t.Size() == 8 &&  t.IsFloat() => (FMOVDstore ptr val mem)
   351(Store {t} ptr val mem) && t.Size() == 4 &&  t.IsFloat() => (FMOVSstore ptr val mem)
   352(Store {t} ptr val mem) && t.Size() == 8 && !t.IsFloat() => (MOVDstore ptr val mem)
   353(Store {t} ptr val mem) && t.Size() == 4 && !t.IsFloat() => (MOVWstore ptr val mem)
   354(Store {t} ptr val mem) && t.Size() == 2 => (MOVHstore ptr val mem)
   355(Store {t} ptr val mem) && t.Size() == 1 => (MOVBstore ptr val mem)
   356
   357// Lowering moves
   358
   359// Load and store for small copies.
   360(Move [0] _ _ mem) => mem
   361(Move [1] dst src mem) => (MOVBstore dst (MOVBZload src mem) mem)
   362(Move [2] dst src mem) => (MOVHstore dst (MOVHZload src mem) mem)
   363(Move [4] dst src mem) => (MOVWstore dst (MOVWZload src mem) mem)
   364(Move [8] dst src mem) => (MOVDstore dst (MOVDload src mem) mem)
   365(Move [16] dst src mem) =>
   366	(MOVDstore [8] dst (MOVDload [8] src mem)
   367		(MOVDstore dst (MOVDload src mem) mem))
   368(Move [24] dst src mem) =>
   369        (MOVDstore [16] dst (MOVDload [16] src mem)
   370	        (MOVDstore [8] dst (MOVDload [8] src mem)
   371                (MOVDstore dst (MOVDload src mem) mem)))
   372(Move [3] dst src mem) =>
   373	(MOVBstore [2] dst (MOVBZload [2] src mem)
   374		(MOVHstore dst (MOVHZload src mem) mem))
   375(Move [5] dst src mem) =>
   376	(MOVBstore [4] dst (MOVBZload [4] src mem)
   377		(MOVWstore dst (MOVWZload src mem) mem))
   378(Move [6] dst src mem) =>
   379	(MOVHstore [4] dst (MOVHZload [4] src mem)
   380		(MOVWstore dst (MOVWZload src mem) mem))
   381(Move [7] dst src mem) =>
   382	(MOVBstore [6] dst (MOVBZload [6] src mem)
   383		(MOVHstore [4] dst (MOVHZload [4] src mem)
   384			(MOVWstore dst (MOVWZload src mem) mem)))
   385
   386// MVC for other moves. Use up to 4 instructions (sizes up to 1024 bytes).
   387(Move [s] dst src mem) && s > 0 && s <= 256 && logLargeCopy(v, s) =>
   388	(MVC [makeValAndOff(int32(s), 0)] dst src mem)
   389(Move [s] dst src mem) && s > 256 && s <= 512 && logLargeCopy(v, s) =>
   390	(MVC [makeValAndOff(int32(s)-256, 256)] dst src (MVC [makeValAndOff(256, 0)] dst src mem))
   391(Move [s] dst src mem) && s > 512 && s <= 768 && logLargeCopy(v, s) =>
   392	(MVC [makeValAndOff(int32(s)-512, 512)] dst src (MVC [makeValAndOff(256, 256)] dst src (MVC [makeValAndOff(256, 0)] dst src mem)))
   393(Move [s] dst src mem) && s > 768 && s <= 1024 && logLargeCopy(v, s) =>
   394	(MVC [makeValAndOff(int32(s)-768, 768)] dst src (MVC [makeValAndOff(256, 512)] dst src (MVC [makeValAndOff(256, 256)] dst src (MVC [makeValAndOff(256, 0)] dst src mem))))
   395
   396// Move more than 1024 bytes using a loop.
   397(Move [s] dst src mem) && s > 1024 && logLargeCopy(v, s) =>
   398	(LoweredMove [s%256] dst src (ADD <src.Type> src (MOVDconst [(s/256)*256])) mem)
   399
   400// Lowering Zero instructions
   401(Zero [0] _ mem) => mem
   402(Zero [1] destptr mem) => (MOVBstoreconst [0] destptr mem)
   403(Zero [2] destptr mem) => (MOVHstoreconst [0] destptr mem)
   404(Zero [4] destptr mem) => (MOVWstoreconst [0] destptr mem)
   405(Zero [8] destptr mem) => (MOVDstoreconst [0] destptr mem)
   406(Zero [3] destptr mem) =>
   407	(MOVBstoreconst [makeValAndOff(0,2)] destptr
   408		(MOVHstoreconst [0] destptr mem))
   409(Zero [5] destptr mem) =>
   410	(MOVBstoreconst [makeValAndOff(0,4)] destptr
   411		(MOVWstoreconst [0] destptr mem))
   412(Zero [6] destptr mem) =>
   413	(MOVHstoreconst [makeValAndOff(0,4)] destptr
   414		(MOVWstoreconst [0] destptr mem))
   415(Zero [7] destptr mem) =>
   416	(MOVWstoreconst [makeValAndOff(0,3)] destptr
   417		(MOVWstoreconst [0] destptr mem))
   418
   419(Zero [s] destptr mem) && s > 0 && s <= 1024 =>
   420	(CLEAR [makeValAndOff(int32(s), 0)] destptr mem)
   421
   422// Zero more than 1024 bytes using a loop.
   423(Zero [s] destptr mem) && s > 1024 =>
   424	(LoweredZero [s%256] destptr (ADDconst <destptr.Type> destptr [(int32(s)/256)*256]) mem)
   425
   426// Lowering constants
   427(Const(64|32|16|8) [val]) => (MOVDconst [int64(val)])
   428(Const(32|64)F ...) => (FMOV(S|D)const ...)
   429(ConstNil) => (MOVDconst [0])
   430(ConstBool [t]) => (MOVDconst [b2i(t)])
   431
   432// Lowering calls
   433(StaticCall ...) => (CALLstatic ...)
   434(ClosureCall ...) => (CALLclosure ...)
   435(InterCall ...) => (CALLinter ...)
   436(TailCall ...) => (CALLtail ...)
   437
   438// Miscellaneous
   439(IsNonNil p) => (LOCGR {s390x.NotEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPconst p [0]))
   440(IsInBounds idx len) => (LOCGR {s390x.Less} (MOVDconst [0]) (MOVDconst [1]) (CMPU idx len))
   441(IsSliceInBounds idx len) => (LOCGR {s390x.LessOrEqual} (MOVDconst [0]) (MOVDconst [1]) (CMPU idx len))
   442(NilCheck ...) => (LoweredNilCheck ...)
   443(GetG ...) => (LoweredGetG ...)
   444(GetClosurePtr ...) => (LoweredGetClosurePtr ...)
   445(GetCallerSP ...) => (LoweredGetCallerSP ...)
   446(GetCallerPC ...) => (LoweredGetCallerPC ...)
   447(Addr {sym} base) => (MOVDaddr {sym} base)
   448(LocalAddr <t> {sym} base mem) && t.Elem().HasPointers() => (MOVDaddr {sym} (SPanchored base mem))
   449(LocalAddr <t> {sym} base _)  && !t.Elem().HasPointers() => (MOVDaddr {sym} base)
   450(ITab (Load ptr mem)) => (MOVDload ptr mem)
   451
   452// block rewrites
   453(If cond yes no) => (CLIJ {s390x.LessOrGreater} (MOVBZreg <typ.Bool> cond) [0] yes no)
   454
   455// Write barrier.
   456(WB ...) => (LoweredWB ...)
   457
   458(PanicBounds [kind] x y mem) && boundsABI(kind) == 0 => (LoweredPanicBoundsA [kind] x y mem)
   459(PanicBounds [kind] x y mem) && boundsABI(kind) == 1 => (LoweredPanicBoundsB [kind] x y mem)
   460(PanicBounds [kind] x y mem) && boundsABI(kind) == 2 => (LoweredPanicBoundsC [kind] x y mem)
   461
   462// ***************************
   463// Above: lowering rules
   464// Below: optimizations
   465// ***************************
   466// TODO: Should the optimizations be a separate pass?
   467
   468// Note: when removing unnecessary sign/zero extensions.
   469//
   470// After a value is spilled it is restored using a sign- or zero-extension
   471// to register-width as appropriate for its type. For example, a uint8 will
   472// be restored using a MOVBZ (llgc) instruction which will zero extend the
   473// 8-bit value to 64-bits.
   474//
   475// This is a hazard when folding sign- and zero-extensions since we need to
   476// ensure not only that the value in the argument register is correctly
   477// extended but also that it will still be correctly extended if it is
   478// spilled and restored.
   479//
   480// In general this means we need type checks when the RHS of a rule is an
   481// OpCopy (i.e. "(... x:(...) ...) -> x").
   482
   483// Merge double extensions.
   484(MOV(H|HZ)reg e:(MOV(B|BZ)reg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   485(MOV(W|WZ)reg e:(MOV(B|BZ)reg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   486(MOV(W|WZ)reg e:(MOV(H|HZ)reg x)) && clobberIfDead(e) => (MOV(H|HZ)reg x)
   487
   488// Bypass redundant sign extensions.
   489(MOV(B|BZ)reg e:(MOVBreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   490(MOV(B|BZ)reg e:(MOVHreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   491(MOV(B|BZ)reg e:(MOVWreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   492(MOV(H|HZ)reg e:(MOVHreg x)) && clobberIfDead(e) => (MOV(H|HZ)reg x)
   493(MOV(H|HZ)reg e:(MOVWreg x)) && clobberIfDead(e) => (MOV(H|HZ)reg x)
   494(MOV(W|WZ)reg e:(MOVWreg x)) && clobberIfDead(e) => (MOV(W|WZ)reg x)
   495
   496// Bypass redundant zero extensions.
   497(MOV(B|BZ)reg e:(MOVBZreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   498(MOV(B|BZ)reg e:(MOVHZreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   499(MOV(B|BZ)reg e:(MOVWZreg x)) && clobberIfDead(e) => (MOV(B|BZ)reg x)
   500(MOV(H|HZ)reg e:(MOVHZreg x)) && clobberIfDead(e) => (MOV(H|HZ)reg x)
   501(MOV(H|HZ)reg e:(MOVWZreg x)) && clobberIfDead(e) => (MOV(H|HZ)reg x)
   502(MOV(W|WZ)reg e:(MOVWZreg x)) && clobberIfDead(e) => (MOV(W|WZ)reg x)
   503
   504// Remove zero extensions after zero extending load.
   505// Note: take care that if x is spilled it is restored correctly.
   506(MOV(B|H|W)Zreg x:(MOVBZload    _   _)) && (!x.Type.IsSigned() || x.Type.Size() > 1) => x
   507(MOV(H|W)Zreg   x:(MOVHZload    _   _)) && (!x.Type.IsSigned() || x.Type.Size() > 2) => x
   508(MOVWZreg       x:(MOVWZload    _   _)) && (!x.Type.IsSigned() || x.Type.Size() > 4) => x
   509
   510// Remove sign extensions after sign extending load.
   511// Note: take care that if x is spilled it is restored correctly.
   512(MOV(B|H|W)reg x:(MOVBload    _   _)) && (x.Type.IsSigned() || x.Type.Size() == 8) => x
   513(MOV(H|W)reg   x:(MOVHload    _   _)) && (x.Type.IsSigned() || x.Type.Size() == 8) => x
   514(MOVWreg       x:(MOVWload    _   _)) && (x.Type.IsSigned() || x.Type.Size() == 8) => x
   515
   516// Remove sign extensions after zero extending load.
   517// These type checks are probably unnecessary but do them anyway just in case.
   518(MOV(H|W)reg x:(MOVBZload    _   _)) && (!x.Type.IsSigned() || x.Type.Size() > 1) => x
   519(MOVWreg     x:(MOVHZload    _   _)) && (!x.Type.IsSigned() || x.Type.Size() > 2) => x
   520
   521// Fold sign and zero extensions into loads.
   522//
   523// Note: The combined instruction must end up in the same block
   524// as the original load. If not, we end up making a value with
   525// memory type live in two different blocks, which can lead to
   526// multiple memory values alive simultaneously.
   527//
   528// Make sure we don't combine these ops if the load has another use.
   529// This prevents a single load from being split into multiple loads
   530// which then might return different values.  See test/atomicload.go.
   531(MOV(B|H|W)Zreg <t> x:(MOV(B|H|W)load [o] {s} p mem))
   532  && x.Uses == 1
   533  && clobber(x)
   534  => @x.Block (MOV(B|H|W)Zload <t> [o] {s} p mem)
   535(MOV(B|H|W)reg <t> x:(MOV(B|H|W)Zload [o] {s} p mem))
   536  && x.Uses == 1
   537  && clobber(x)
   538  => @x.Block (MOV(B|H|W)load <t> [o] {s} p mem)
   539
   540// Remove zero extensions after argument load.
   541(MOVBZreg x:(Arg <t>)) && !t.IsSigned() && t.Size() == 1 => x
   542(MOVHZreg x:(Arg <t>)) && !t.IsSigned() && t.Size() <= 2 => x
   543(MOVWZreg x:(Arg <t>)) && !t.IsSigned() && t.Size() <= 4 => x
   544
   545// Remove sign extensions after argument load.
   546(MOVBreg x:(Arg <t>)) && t.IsSigned() && t.Size() == 1 => x
   547(MOVHreg x:(Arg <t>)) && t.IsSigned() && t.Size() <= 2 => x
   548(MOVWreg x:(Arg <t>)) && t.IsSigned() && t.Size() <= 4 => x
   549
   550// Fold zero extensions into constants.
   551(MOVBZreg (MOVDconst [c])) => (MOVDconst [int64( uint8(c))])
   552(MOVHZreg (MOVDconst [c])) => (MOVDconst [int64(uint16(c))])
   553(MOVWZreg (MOVDconst [c])) => (MOVDconst [int64(uint32(c))])
   554
   555// Fold sign extensions into constants.
   556(MOVBreg (MOVDconst [c])) => (MOVDconst [int64( int8(c))])
   557(MOVHreg (MOVDconst [c])) => (MOVDconst [int64(int16(c))])
   558(MOVWreg (MOVDconst [c])) => (MOVDconst [int64(int32(c))])
   559
   560// Remove zero extension of conditional move.
   561// Note: only for MOVBZreg for now since it is added as part of 'if' statement lowering.
   562(MOVBZreg x:(LOCGR (MOVDconst [c]) (MOVDconst [d]) _))
   563  && int64(uint8(c)) == c
   564  && int64(uint8(d)) == d
   565  && (!x.Type.IsSigned() || x.Type.Size() > 1)
   566  => x
   567
   568// Fold boolean tests into blocks.
   569// Note: this must match If statement lowering.
   570(CLIJ {s390x.LessOrGreater} (LOCGR {d} (MOVDconst [0]) (MOVDconst [x]) cmp) [0] yes no)
   571  && int32(x) != 0
   572  => (BRC {d} cmp yes no)
   573
   574// Canonicalize BRC condition code mask by removing impossible conditions.
   575// Integer comparisons cannot generate the unordered condition.
   576(BRC {c} x:((CMP|CMPW|CMPU|CMPWU)    _ _) yes no) && c&s390x.Unordered != 0 => (BRC {c&^s390x.Unordered} x yes no)
   577(BRC {c} x:((CMP|CMPW|CMPU|CMPWU)const _) yes no) && c&s390x.Unordered != 0 => (BRC {c&^s390x.Unordered} x yes no)
   578
   579// Compare-and-branch.
   580// Note: bit 3 (unordered) must not be set so we mask out s390x.Unordered.
   581(BRC {c} (CMP   x y) yes no) => (CGRJ  {c&^s390x.Unordered} x y yes no)
   582(BRC {c} (CMPW  x y) yes no) => (CRJ   {c&^s390x.Unordered} x y yes no)
   583(BRC {c} (CMPU  x y) yes no) => (CLGRJ {c&^s390x.Unordered} x y yes no)
   584(BRC {c} (CMPWU x y) yes no) => (CLRJ  {c&^s390x.Unordered} x y yes no)
   585
   586// Compare-and-branch (immediate).
   587// Note: bit 3 (unordered) must not be set so we mask out s390x.Unordered.
   588(BRC {c} (CMPconst   x [y]) yes no) && y == int32( int8(y)) => (CGIJ  {c&^s390x.Unordered} x [ int8(y)] yes no)
   589(BRC {c} (CMPWconst  x [y]) yes no) && y == int32( int8(y)) => (CIJ   {c&^s390x.Unordered} x [ int8(y)] yes no)
   590(BRC {c} (CMPUconst  x [y]) yes no) && y == int32(uint8(y)) => (CLGIJ {c&^s390x.Unordered} x [uint8(y)] yes no)
   591(BRC {c} (CMPWUconst x [y]) yes no) && y == int32(uint8(y)) => (CLIJ  {c&^s390x.Unordered} x [uint8(y)] yes no)
   592
   593// Absorb immediate into compare-and-branch.
   594(C(R|GR)J  {c} x (MOVDconst [y]) yes no) && is8Bit(y)  => (C(I|GI)J  {c} x [ int8(y)] yes no)
   595(CL(R|GR)J {c} x (MOVDconst [y]) yes no) && isU8Bit(y) => (CL(I|GI)J {c} x [uint8(y)] yes no)
   596(C(R|GR)J  {c} (MOVDconst [x]) y yes no) && is8Bit(x)  => (C(I|GI)J  {c.ReverseComparison()} y [ int8(x)] yes no)
   597(CL(R|GR)J {c} (MOVDconst [x]) y yes no) && isU8Bit(x) => (CL(I|GI)J {c.ReverseComparison()} y [uint8(x)] yes no)
   598
   599// Prefer comparison with immediate to compare-and-branch.
   600(CGRJ  {c} x (MOVDconst [y]) yes no) && !is8Bit(y)  && is32Bit(y)  => (BRC {c} (CMPconst   x [int32(y)]) yes no)
   601(CRJ   {c} x (MOVDconst [y]) yes no) && !is8Bit(y)  && is32Bit(y)  => (BRC {c} (CMPWconst  x [int32(y)]) yes no)
   602(CLGRJ {c} x (MOVDconst [y]) yes no) && !isU8Bit(y) && isU32Bit(y) => (BRC {c} (CMPUconst  x [int32(y)]) yes no)
   603(CLRJ  {c} x (MOVDconst [y]) yes no) && !isU8Bit(y) && isU32Bit(y) => (BRC {c} (CMPWUconst x [int32(y)]) yes no)
   604(CGRJ  {c} (MOVDconst [x]) y yes no) && !is8Bit(x)  && is32Bit(x)  => (BRC {c.ReverseComparison()} (CMPconst   y [int32(x)]) yes no)
   605(CRJ   {c} (MOVDconst [x]) y yes no) && !is8Bit(x)  && is32Bit(x)  => (BRC {c.ReverseComparison()} (CMPWconst  y [int32(x)]) yes no)
   606(CLGRJ {c} (MOVDconst [x]) y yes no) && !isU8Bit(x) && isU32Bit(x) => (BRC {c.ReverseComparison()} (CMPUconst  y [int32(x)]) yes no)
   607(CLRJ  {c} (MOVDconst [x]) y yes no) && !isU8Bit(x) && isU32Bit(x) => (BRC {c.ReverseComparison()} (CMPWUconst y [int32(x)]) yes no)
   608
   609// Absorb sign/zero extensions into 32-bit compare-and-branch.
   610(CIJ  {c} (MOV(W|WZ)reg x) [y] yes no) => (CIJ  {c} x [y] yes no)
   611(CLIJ {c} (MOV(W|WZ)reg x) [y] yes no) => (CLIJ {c} x [y] yes no)
   612
   613// Bring out-of-range signed immediates into range by varying branch condition.
   614(BRC {s390x.Less}           (CMPconst  x [ 128]) yes no) => (CGIJ {s390x.LessOrEqual}    x [ 127] yes no)
   615(BRC {s390x.Less}           (CMPWconst x [ 128]) yes no) => (CIJ  {s390x.LessOrEqual}    x [ 127] yes no)
   616(BRC {s390x.LessOrEqual}    (CMPconst  x [-129]) yes no) => (CGIJ {s390x.Less}           x [-128] yes no)
   617(BRC {s390x.LessOrEqual}    (CMPWconst x [-129]) yes no) => (CIJ  {s390x.Less}           x [-128] yes no)
   618(BRC {s390x.Greater}        (CMPconst  x [-129]) yes no) => (CGIJ {s390x.GreaterOrEqual} x [-128] yes no)
   619(BRC {s390x.Greater}        (CMPWconst x [-129]) yes no) => (CIJ  {s390x.GreaterOrEqual} x [-128] yes no)
   620(BRC {s390x.GreaterOrEqual} (CMPconst  x [ 128]) yes no) => (CGIJ {s390x.Greater}        x [ 127] yes no)
   621(BRC {s390x.GreaterOrEqual} (CMPWconst x [ 128]) yes no) => (CIJ  {s390x.Greater}        x [ 127] yes no)
   622
   623// Bring out-of-range unsigned immediates into range by varying branch condition.
   624(BRC {s390x.Less}           (CMP(WU|U)const  x [256]) yes no) => (C(L|LG)IJ {s390x.LessOrEqual} x [255] yes no)
   625(BRC {s390x.GreaterOrEqual} (CMP(WU|U)const  x [256]) yes no) => (C(L|LG)IJ {s390x.Greater}     x [255] yes no)
   626
   627// Bring out-of-range immediates into range by switching signedness (only == and !=).
   628(BRC {c} (CMPconst   x [y]) yes no) && y == int32(uint8(y)) && (c == s390x.Equal || c == s390x.LessOrGreater) => (CLGIJ {c} x [uint8(y)] yes no)
   629(BRC {c} (CMPWconst  x [y]) yes no) && y == int32(uint8(y)) && (c == s390x.Equal || c == s390x.LessOrGreater) => (CLIJ  {c} x [uint8(y)] yes no)
   630(BRC {c} (CMPUconst  x [y]) yes no) && y == int32( int8(y)) && (c == s390x.Equal || c == s390x.LessOrGreater) => (CGIJ  {c} x [ int8(y)] yes no)
   631(BRC {c} (CMPWUconst x [y]) yes no) && y == int32( int8(y)) && (c == s390x.Equal || c == s390x.LessOrGreater) => (CIJ   {c} x [ int8(y)] yes no)
   632
   633// Fold constants into instructions.
   634(ADD x (MOVDconst <t> [c])) && is32Bit(c) && !t.IsPtr() => (ADDconst [int32(c)] x)
   635(ADDW x (MOVDconst [c])) => (ADDWconst [int32(c)] x)
   636
   637(SUB x (MOVDconst [c])) && is32Bit(c) => (SUBconst x [int32(c)])
   638(SUB (MOVDconst [c]) x) && is32Bit(c) => (NEG (SUBconst <v.Type> x [int32(c)]))
   639(SUBW x (MOVDconst [c])) => (SUBWconst x [int32(c)])
   640(SUBW (MOVDconst [c]) x) => (NEGW (SUBWconst <v.Type> x [int32(c)]))
   641
   642(MULLD x (MOVDconst [c])) && is32Bit(c) => (MULLDconst [int32(c)] x)
   643(MULLW x (MOVDconst [c])) => (MULLWconst [int32(c)] x)
   644
   645// NILF instructions leave the high 32 bits unchanged which is
   646// equivalent to the leftmost 32 bits being set.
   647// TODO(mundaym): modify the assembler to accept 64-bit values
   648// and use isU32Bit(^c).
   649(AND x (MOVDconst [c]))
   650  && s390x.NewRotateParams(0, 63, 0).OutMerge(uint64(c)) != nil
   651  => (RISBGZ x {*s390x.NewRotateParams(0, 63, 0).OutMerge(uint64(c))})
   652(AND x (MOVDconst [c]))
   653  && is32Bit(c)
   654  && c < 0
   655  => (ANDconst [c] x)
   656(AND x (MOVDconst [c]))
   657  && is32Bit(c)
   658  && c >= 0
   659  => (MOVWZreg (ANDWconst <typ.UInt32> [int32(c)] x))
   660
   661(ANDW x (MOVDconst [c])) => (ANDWconst [int32(c)] x)
   662
   663((AND|ANDW)const [c] ((AND|ANDW)const [d] x)) => ((AND|ANDW)const [c&d] x)
   664
   665((OR|XOR) x (MOVDconst [c])) && isU32Bit(c) => ((OR|XOR)const [c] x)
   666((OR|XOR)W x (MOVDconst [c])) => ((OR|XOR)Wconst [int32(c)] x)
   667
   668// Constant shifts.
   669(S(LD|RD|RAD) x (MOVDconst [c])) => (S(LD|RD|RAD)const x [uint8(c&63)])
   670(S(LW|RW|RAW) x (MOVDconst [c])) && c&32 == 0 => (S(LW|RW|RAW)const x [uint8(c&31)])
   671(S(LW|RW)     _ (MOVDconst [c])) && c&32 != 0 => (MOVDconst [0])
   672(SRAW         x (MOVDconst [c])) && c&32 != 0 => (SRAWconst x [31])
   673
   674// Shifts only use the rightmost 6 bits of the shift value.
   675(S(LD|RD|RAD|LW|RW|RAW) x (RISBGZ y {r}))
   676  && r.Amount == 0
   677  && r.OutMask()&63 == 63
   678  => (S(LD|RD|RAD|LW|RW|RAW) x y)
   679(S(LD|RD|RAD|LW|RW|RAW) x (AND (MOVDconst [c]) y))
   680  => (S(LD|RD|RAD|LW|RW|RAW) x (ANDWconst <typ.UInt32> [int32(c&63)] y))
   681(S(LD|RD|RAD|LW|RW|RAW) x (ANDWconst [c] y)) && c&63 == 63
   682  => (S(LD|RD|RAD|LW|RW|RAW) x y)
   683(SLD  x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SLD  x y)
   684(SRD  x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SRD  x y)
   685(SRAD x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SRAD x y)
   686(SLW  x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SLW  x y)
   687(SRW  x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SRW  x y)
   688(SRAW x (MOV(W|H|B|WZ|HZ|BZ)reg y)) => (SRAW x y)
   689
   690// Match rotate by constant.
   691(RLLG x (MOVDconst [c])) => (RISBGZ x {s390x.NewRotateParams(0, 63, uint8(c&63))})
   692(RLL  x (MOVDconst [c])) => (RLLconst x [uint8(c&31)])
   693
   694// Signed 64-bit comparison with immediate.
   695(CMP x (MOVDconst [c])) && is32Bit(c) => (CMPconst x [int32(c)])
   696(CMP (MOVDconst [c]) x) && is32Bit(c) => (InvertFlags (CMPconst x [int32(c)]))
   697
   698// Unsigned 64-bit comparison with immediate.
   699(CMPU x (MOVDconst [c])) && isU32Bit(c) => (CMPUconst x [int32(c)])
   700(CMPU (MOVDconst [c]) x) && isU32Bit(c) => (InvertFlags (CMPUconst x [int32(c)]))
   701
   702// Signed and unsigned 32-bit comparison with immediate.
   703(CMP(W|WU) x (MOVDconst [c])) => (CMP(W|WU)const x [int32(c)])
   704(CMP(W|WU) (MOVDconst [c]) x) => (InvertFlags (CMP(W|WU)const x [int32(c)]))
   705
   706// Match (x >> c) << d to 'rotate then insert selected bits [into zero]'.
   707(SLDconst (SRDconst x [c]) [d]) => (RISBGZ x {s390x.NewRotateParams(uint8(max(0, int8(c-d))), 63-d, uint8(int8(d-c)&63))})
   708
   709// Match (x << c) >> d to 'rotate then insert selected bits [into zero]'.
   710(SRDconst (SLDconst x [c]) [d]) => (RISBGZ x {s390x.NewRotateParams(d, uint8(min(63, int8(63-c+d))), uint8(int8(c-d)&63))})
   711
   712// Absorb input zero extension into 'rotate then insert selected bits [into zero]'.
   713(RISBGZ (MOVWZreg x) {r}) && r.InMerge(0xffffffff) != nil => (RISBGZ x {*r.InMerge(0xffffffff)})
   714(RISBGZ (MOVHZreg x) {r}) && r.InMerge(0x0000ffff) != nil => (RISBGZ x {*r.InMerge(0x0000ffff)})
   715(RISBGZ (MOVBZreg x) {r}) && r.InMerge(0x000000ff) != nil => (RISBGZ x {*r.InMerge(0x000000ff)})
   716
   717// Absorb 'rotate then insert selected bits [into zero]' into zero extension.
   718(MOVWZreg (RISBGZ x {r})) && r.OutMerge(0xffffffff) != nil => (RISBGZ x {*r.OutMerge(0xffffffff)})
   719(MOVHZreg (RISBGZ x {r})) && r.OutMerge(0x0000ffff) != nil => (RISBGZ x {*r.OutMerge(0x0000ffff)})
   720(MOVBZreg (RISBGZ x {r})) && r.OutMerge(0x000000ff) != nil => (RISBGZ x {*r.OutMerge(0x000000ff)})
   721
   722// Absorb shift into 'rotate then insert selected bits [into zero]'.
   723//
   724// Any unsigned shift can be represented as a rotate and mask operation:
   725//
   726//   x << c => RotateLeft64(x, c) & (^uint64(0) << c)
   727//   x >> c => RotateLeft64(x, -c) & (^uint64(0) >> c)
   728//
   729// Therefore when a shift is used as the input to a rotate then insert
   730// selected bits instruction we can merge the two together. We just have
   731// to be careful that the resultant mask is representable (non-zero and
   732// contiguous). For example, assuming that x is variable and c, y and m
   733// are constants, a shift followed by a rotate then insert selected bits
   734// could be represented as:
   735//
   736//   RotateLeft64(RotateLeft64(x, c) & (^uint64(0) << c), y) & m
   737//
   738// We can split the rotation by y into two, one rotate for x and one for
   739// the mask:
   740//
   741//   RotateLeft64(RotateLeft64(x, c), y) & (RotateLeft64(^uint64(0) << c, y)) & m
   742//
   743// The rotations of x by c followed by y can then be combined:
   744//
   745//   RotateLeft64(x, c+y) & (RotateLeft64(^uint64(0) << c, y)) & m
   746//   ^^^^^^^^^^^^^^^^^^^^   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   747//          rotate                          mask
   748//
   749// To perform this optimization we therefore just need to check that it
   750// is valid to merge the shift mask (^(uint64(0)<<c)) into the selected
   751// bits mask (i.e. that the resultant mask is non-zero and contiguous).
   752//
   753(RISBGZ (SLDconst x [c]) {r}) && r.InMerge(^uint64(0)<<c) != nil => (RISBGZ x {(*r.InMerge(^uint64(0)<<c)).RotateLeft(c)})
   754(RISBGZ (SRDconst x [c]) {r}) && r.InMerge(^uint64(0)>>c) != nil => (RISBGZ x {(*r.InMerge(^uint64(0)>>c)).RotateLeft(-c)})
   755
   756// Absorb 'rotate then insert selected bits [into zero]' into left shift.
   757(SLDconst (RISBGZ x {r}) [c])
   758  && s390x.NewRotateParams(0, 63-c, c).InMerge(r.OutMask()) != nil
   759  => (RISBGZ x {(*s390x.NewRotateParams(0, 63-c, c).InMerge(r.OutMask())).RotateLeft(r.Amount)})
   760
   761// Absorb 'rotate then insert selected bits [into zero]' into right shift.
   762(SRDconst (RISBGZ x {r}) [c])
   763  && s390x.NewRotateParams(c, 63, -c&63).InMerge(r.OutMask()) != nil
   764  => (RISBGZ x {(*s390x.NewRotateParams(c, 63, -c&63).InMerge(r.OutMask())).RotateLeft(r.Amount)})
   765
   766// Merge 'rotate then insert selected bits [into zero]' instructions together.
   767(RISBGZ (RISBGZ x {y}) {z})
   768  && z.InMerge(y.OutMask()) != nil
   769  => (RISBGZ x {(*z.InMerge(y.OutMask())).RotateLeft(y.Amount)})
   770
   771// Convert RISBGZ into 64-bit shift (helps CSE).
   772(RISBGZ x {r}) && r.End == 63 && r.Start == -r.Amount&63 => (SRDconst x [-r.Amount&63])
   773(RISBGZ x {r}) && r.Start == 0 && r.End == 63-r.Amount => (SLDconst x [r.Amount])
   774
   775// Optimize single bit isolation when it is known to be equivalent to
   776// the most significant bit due to mask produced by arithmetic shift.
   777// Simply isolate the most significant bit itself and place it in the
   778// correct position.
   779//
   780// Example: (int64(x) >> 63) & 0x8 -> RISBGZ $60, $60, $4, Rsrc, Rdst
   781(RISBGZ (SRADconst x [c]) {r})
   782  && r.Start == r.End           // single bit selected
   783  && (r.Start+r.Amount)&63 <= c // equivalent to most significant bit of x
   784  => (RISBGZ x {s390x.NewRotateParams(r.Start, r.Start, -r.Start&63)})
   785
   786// Canonicalize the order of arguments to comparisons - helps with CSE.
   787((CMP|CMPW|CMPU|CMPWU) x y) && canonLessThan(x,y) => (InvertFlags ((CMP|CMPW|CMPU|CMPWU) y x))
   788
   789// Use sign/zero extend instead of RISBGZ.
   790(RISBGZ x {r}) && r == s390x.NewRotateParams(56, 63, 0) => (MOVBZreg x)
   791(RISBGZ x {r}) && r == s390x.NewRotateParams(48, 63, 0) => (MOVHZreg x)
   792(RISBGZ x {r}) && r == s390x.NewRotateParams(32, 63, 0) => (MOVWZreg x)
   793
   794// Use sign/zero extend instead of ANDW.
   795(ANDWconst [0x00ff] x) => (MOVBZreg x)
   796(ANDWconst [0xffff] x) => (MOVHZreg x)
   797
   798// Strength reduce multiplication to the sum (or difference) of two powers of two.
   799//
   800// Examples:
   801//     5x -> 4x + 1x
   802//    10x -> 8x + 2x
   803//   120x -> 128x - 8x
   804//  -120x -> 8x - 128x
   805//
   806// We know that the rightmost bit of any positive value, once isolated, must either
   807// be a power of 2 (because it is a single bit) or 0 (if the original value is 0).
   808// In all of these rules we use a rightmost bit calculation to determine one operand
   809// for the addition or subtraction. We then just need to calculate if the other
   810// operand is a valid power of 2 before we can match the rule.
   811//
   812// Notes:
   813//   - the generic rules have already matched single powers of two so we ignore them here
   814//   - isPowerOfTwo asserts that its argument is greater than 0
   815//   - c&(c-1) = clear rightmost bit
   816//   - c&^(c-1) = isolate rightmost bit
   817
   818// c = 2ˣ + 2ʸ => c - 2ˣ = 2ʸ
   819(MULL(D|W)const <t> x [c]) && isPowerOfTwo(c&(c-1))
   820  => ((ADD|ADDW) (SL(D|W)const <t> x [uint8(log32(c&(c-1)))])
   821                 (SL(D|W)const <t> x [uint8(log32(c&^(c-1)))]))
   822
   823// c = 2ʸ - 2ˣ => c + 2ˣ = 2ʸ
   824(MULL(D|W)const <t> x [c]) && isPowerOfTwo(c+(c&^(c-1)))
   825  => ((SUB|SUBW) (SL(D|W)const <t> x [uint8(log32(c+(c&^(c-1))))])
   826                 (SL(D|W)const <t> x [uint8(log32(c&^(c-1)))]))
   827
   828// c = 2ˣ - 2ʸ => -c + 2ˣ = 2ʸ
   829(MULL(D|W)const <t> x [c]) && isPowerOfTwo(-c+(-c&^(-c-1)))
   830  => ((SUB|SUBW) (SL(D|W)const <t> x [uint8(log32(-c&^(-c-1)))])
   831                 (SL(D|W)const <t> x [uint8(log32(-c+(-c&^(-c-1))))]))
   832
   833// Fold ADD into MOVDaddr. Odd offsets from SB shouldn't be folded (LARL can't handle them).
   834(ADDconst [c] (MOVDaddr [d] {s} x:(SB))) && ((c+d)&1 == 0) && is32Bit(int64(c)+int64(d)) => (MOVDaddr [c+d] {s} x)
   835(ADDconst [c] (MOVDaddr [d] {s} x)) && x.Op != OpSB && is20Bit(int64(c)+int64(d)) => (MOVDaddr [c+d] {s} x)
   836(ADD idx (MOVDaddr [c] {s} ptr)) && ptr.Op != OpSB => (MOVDaddridx [c] {s} ptr idx)
   837
   838// fold ADDconst into MOVDaddrx
   839(ADDconst [c] (MOVDaddridx [d] {s} x y)) && is20Bit(int64(c)+int64(d)) => (MOVDaddridx [c+d] {s} x y)
   840(MOVDaddridx [c] {s} (ADDconst [d] x) y) && is20Bit(int64(c)+int64(d)) => (MOVDaddridx [c+d] {s} x y)
   841(MOVDaddridx [c] {s} x (ADDconst [d] y)) && is20Bit(int64(c)+int64(d)) => (MOVDaddridx [c+d] {s} x y)
   842
   843// reverse ordering of compare instruction
   844(LOCGR {c} x y (InvertFlags cmp)) => (LOCGR {c.ReverseComparison()} x y cmp)
   845
   846// replace load from same location as preceding store with copy
   847(MOVDload  [off] {sym} ptr1 (MOVDstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => x
   848(MOVWload  [off] {sym} ptr1 (MOVWstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVWreg x)
   849(MOVHload  [off] {sym} ptr1 (MOVHstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVHreg x)
   850(MOVBload  [off] {sym} ptr1 (MOVBstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVBreg x)
   851(MOVWZload [off] {sym} ptr1 (MOVWstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVWZreg x)
   852(MOVHZload [off] {sym} ptr1 (MOVHstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVHZreg x)
   853(MOVBZload [off] {sym} ptr1 (MOVBstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (MOVBZreg x)
   854(MOVDload  [off] {sym} ptr1 (FMOVDstore [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (LGDR x)
   855(FMOVDload [off] {sym} ptr1 (MOVDstore  [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => (LDGR x)
   856(FMOVDload [off] {sym} ptr1 (FMOVDstore [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => x
   857(FMOVSload [off] {sym} ptr1 (FMOVSstore [off] {sym} ptr2 x _)) && isSamePtr(ptr1, ptr2) => x
   858
   859// prefer FPR <-> GPR moves over combined load ops
   860(MULLDload <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (MULLD x (LGDR <t> y))
   861(ADDload   <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (ADD   x (LGDR <t> y))
   862(SUBload   <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (SUB   x (LGDR <t> y))
   863(ORload    <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (OR    x (LGDR <t> y))
   864(ANDload   <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (AND   x (LGDR <t> y))
   865(XORload   <t> [off] {sym} x ptr1 (FMOVDstore [off] {sym} ptr2 y _)) && isSamePtr(ptr1, ptr2) => (XOR   x (LGDR <t> y))
   866
   867// detect attempts to set/clear the sign bit
   868// may need to be reworked when NIHH/OIHH are added
   869(RISBGZ (LGDR <t> x) {r}) && r == s390x.NewRotateParams(1, 63, 0) => (LGDR <t> (LPDFR <x.Type> x))
   870(LDGR <t> (RISBGZ x {r})) && r == s390x.NewRotateParams(1, 63, 0) => (LPDFR (LDGR <t> x))
   871(OR (MOVDconst [-1<<63]) (LGDR <t> x)) => (LGDR <t> (LNDFR <x.Type> x))
   872(LDGR <t> (OR (MOVDconst [-1<<63]) x)) => (LNDFR (LDGR <t> x))
   873
   874// detect attempts to set the sign bit with load
   875(LDGR <t> x:(ORload <t1> [off] {sym} (MOVDconst [-1<<63]) ptr mem)) && x.Uses == 1 && clobber(x) => @x.Block (LNDFR <t> (LDGR <t> (MOVDload <t1> [off] {sym} ptr mem)))
   876
   877// detect copysign
   878(OR (RISBGZ (LGDR x) {r}) (LGDR (LPDFR <t> y)))
   879  && r == s390x.NewRotateParams(0, 0, 0)
   880  => (LGDR (CPSDR <t> y x))
   881(OR (RISBGZ (LGDR x) {r}) (MOVDconst [c]))
   882  && c >= 0
   883  && r == s390x.NewRotateParams(0, 0, 0)
   884  => (LGDR (CPSDR <x.Type> (FMOVDconst <x.Type> [math.Float64frombits(uint64(c))]) x))
   885(CPSDR y (FMOVDconst [c])) && !math.Signbit(c) => (LPDFR y)
   886(CPSDR y (FMOVDconst [c])) && math.Signbit(c)  => (LNDFR y)
   887
   888// absorb negations into set/clear sign bit
   889(FNEG  (LPDFR x)) => (LNDFR x)
   890(FNEG  (LNDFR x)) => (LPDFR x)
   891(FNEGS (LPDFR x)) => (LNDFR x)
   892(FNEGS (LNDFR x)) => (LPDFR x)
   893
   894// no need to convert float32 to float64 to set/clear sign bit
   895(LEDBR (LPDFR (LDEBR x))) => (LPDFR x)
   896(LEDBR (LNDFR (LDEBR x))) => (LNDFR x)
   897
   898// remove unnecessary FPR <-> GPR moves
   899(LDGR (LGDR x)) => x
   900(LGDR (LDGR x)) => x
   901
   902// Don't extend before storing
   903(MOVWstore [off] {sym} ptr (MOVWreg x) mem) => (MOVWstore [off] {sym} ptr x mem)
   904(MOVHstore [off] {sym} ptr (MOVHreg x) mem) => (MOVHstore [off] {sym} ptr x mem)
   905(MOVBstore [off] {sym} ptr (MOVBreg x) mem) => (MOVBstore [off] {sym} ptr x mem)
   906(MOVWstore [off] {sym} ptr (MOVWZreg x) mem) => (MOVWstore [off] {sym} ptr x mem)
   907(MOVHstore [off] {sym} ptr (MOVHZreg x) mem) => (MOVHstore [off] {sym} ptr x mem)
   908(MOVBstore [off] {sym} ptr (MOVBZreg x) mem) => (MOVBstore [off] {sym} ptr x mem)
   909
   910// Fold constants into memory operations.
   911// Note that this is not always a good idea because if not all the uses of
   912// the ADDconst get eliminated, we still have to compute the ADDconst and we now
   913// have potentially two live values (ptr and (ADDconst [off] ptr)) instead of one.
   914// Nevertheless, let's do it!
   915(MOVDload   [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVDload  [off1+off2] {sym} ptr mem)
   916(MOVWload   [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVWload  [off1+off2] {sym} ptr mem)
   917(MOVHload   [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVHload  [off1+off2] {sym} ptr mem)
   918(MOVBload   [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVBload  [off1+off2] {sym} ptr mem)
   919(MOVWZload  [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVWZload [off1+off2] {sym} ptr mem)
   920(MOVHZload  [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVHZload [off1+off2] {sym} ptr mem)
   921(MOVBZload  [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (MOVBZload [off1+off2] {sym} ptr mem)
   922(FMOVSload  [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (FMOVSload [off1+off2] {sym} ptr mem)
   923(FMOVDload  [off1] {sym} (ADDconst [off2] ptr) mem) && is20Bit(int64(off1)+int64(off2)) => (FMOVDload [off1+off2] {sym} ptr mem)
   924
   925(MOVDstore  [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (MOVDstore  [off1+off2] {sym} ptr val mem)
   926(MOVWstore  [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (MOVWstore  [off1+off2] {sym} ptr val mem)
   927(MOVHstore  [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (MOVHstore  [off1+off2] {sym} ptr val mem)
   928(MOVBstore  [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (MOVBstore  [off1+off2] {sym} ptr val mem)
   929(FMOVSstore [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (FMOVSstore [off1+off2] {sym} ptr val mem)
   930(FMOVDstore [off1] {sym} (ADDconst [off2] ptr) val mem) && is20Bit(int64(off1)+int64(off2)) => (FMOVDstore [off1+off2] {sym} ptr val mem)
   931
   932(ADDload   [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ADDload   [off1+off2] {sym} x ptr mem)
   933(ADDWload  [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ADDWload  [off1+off2] {sym} x ptr mem)
   934(MULLDload [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (MULLDload [off1+off2] {sym} x ptr mem)
   935(MULLWload [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (MULLWload [off1+off2] {sym} x ptr mem)
   936(SUBload   [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (SUBload   [off1+off2] {sym} x ptr mem)
   937(SUBWload  [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (SUBWload  [off1+off2] {sym} x ptr mem)
   938
   939(ANDload   [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ANDload   [off1+off2] {sym} x ptr mem)
   940(ANDWload  [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ANDWload  [off1+off2] {sym} x ptr mem)
   941(ORload    [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ORload    [off1+off2] {sym} x ptr mem)
   942(ORWload   [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (ORWload   [off1+off2] {sym} x ptr mem)
   943(XORload   [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (XORload   [off1+off2] {sym} x ptr mem)
   944(XORWload  [off1] {sym} x (ADDconst [off2] ptr) mem) && ptr.Op != OpSB && is20Bit(int64(off1)+int64(off2)) => (XORWload  [off1+off2] {sym} x ptr mem)
   945
   946// Fold constants into stores.
   947(MOVDstore [off] {sym} ptr (MOVDconst [c]) mem) && is16Bit(c) && isU12Bit(int64(off)) && ptr.Op != OpSB =>
   948	(MOVDstoreconst [makeValAndOff(int32(c),off)] {sym} ptr mem)
   949(MOVWstore [off] {sym} ptr (MOVDconst [c]) mem) && is16Bit(c) && isU12Bit(int64(off)) && ptr.Op != OpSB =>
   950	(MOVWstoreconst [makeValAndOff(int32(c),off)] {sym} ptr mem)
   951(MOVHstore [off] {sym} ptr (MOVDconst [c]) mem) && isU12Bit(int64(off)) && ptr.Op != OpSB =>
   952	(MOVHstoreconst [makeValAndOff(int32(int16(c)),off)] {sym} ptr mem)
   953(MOVBstore [off] {sym} ptr (MOVDconst [c]) mem) && is20Bit(int64(off)) && ptr.Op != OpSB =>
   954	(MOVBstoreconst [makeValAndOff(int32(int8(c)),off)] {sym} ptr mem)
   955
   956// Fold address offsets into constant stores.
   957(MOVDstoreconst [sc] {s} (ADDconst [off] ptr) mem) && isU12Bit(sc.Off64()+int64(off)) =>
   958	(MOVDstoreconst [sc.addOffset32(off)] {s} ptr mem)
   959(MOVWstoreconst [sc] {s} (ADDconst [off] ptr) mem) && isU12Bit(sc.Off64()+int64(off)) =>
   960	(MOVWstoreconst [sc.addOffset32(off)] {s} ptr mem)
   961(MOVHstoreconst [sc] {s} (ADDconst [off] ptr) mem) && isU12Bit(sc.Off64()+int64(off)) =>
   962	(MOVHstoreconst [sc.addOffset32(off)] {s} ptr mem)
   963(MOVBstoreconst [sc] {s} (ADDconst [off] ptr) mem) && is20Bit(sc.Off64()+int64(off)) =>
   964	(MOVBstoreconst [sc.addOffset32(off)] {s} ptr mem)
   965
   966// Merge address calculations into loads and stores.
   967// Offsets from SB must not be merged into unaligned memory accesses because
   968// loads/stores using PC-relative addressing directly must be aligned to the
   969// size of the target.
   970(MOVDload   [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%8 == 0 && (off1+off2)%8 == 0)) =>
   971	(MOVDload  [off1+off2] {mergeSym(sym1,sym2)} base mem)
   972(MOVWZload  [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%4 == 0 && (off1+off2)%4 == 0)) =>
   973	(MOVWZload  [off1+off2] {mergeSym(sym1,sym2)} base mem)
   974(MOVHZload  [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%2 == 0 && (off1+off2)%2 == 0)) =>
   975	(MOVHZload  [off1+off2] {mergeSym(sym1,sym2)} base mem)
   976(MOVBZload  [off1] {sym1} (MOVDaddr [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   977	(MOVBZload  [off1+off2] {mergeSym(sym1,sym2)} base mem)
   978(FMOVSload [off1] {sym1} (MOVDaddr [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   979	(FMOVSload [off1+off2] {mergeSym(sym1,sym2)} base mem)
   980(FMOVDload [off1] {sym1} (MOVDaddr [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   981	(FMOVDload [off1+off2] {mergeSym(sym1,sym2)} base mem)
   982
   983(MOVWload [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%4 == 0 && (off1+off2)%4 == 0)) =>
   984	(MOVWload [off1+off2] {mergeSym(sym1,sym2)} base mem)
   985(MOVHload [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%2 == 0 && (off1+off2)%2 == 0)) =>
   986	(MOVHload [off1+off2] {mergeSym(sym1,sym2)} base mem)
   987(MOVBload [off1] {sym1} (MOVDaddr [off2] {sym2} base) mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   988	(MOVBload [off1+off2] {mergeSym(sym1,sym2)} base mem)
   989
   990(MOVDstore  [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%8 == 0 && (off1+off2)%8 == 0)) =>
   991	(MOVDstore  [off1+off2] {mergeSym(sym1,sym2)} base val mem)
   992(MOVWstore  [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%4 == 0 && (off1+off2)%4 == 0)) =>
   993	(MOVWstore  [off1+off2] {mergeSym(sym1,sym2)} base val mem)
   994(MOVHstore  [off1] {sym1} (MOVDaddr <t> [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && (base.Op != OpSB || (t.IsPtr() && t.Elem().Alignment()%2 == 0 && (off1+off2)%2 == 0)) =>
   995	(MOVHstore  [off1+off2] {mergeSym(sym1,sym2)} base val mem)
   996(MOVBstore  [off1] {sym1} (MOVDaddr [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   997	(MOVBstore  [off1+off2] {mergeSym(sym1,sym2)} base val mem)
   998(FMOVSstore [off1] {sym1} (MOVDaddr [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
   999	(FMOVSstore [off1+off2] {mergeSym(sym1,sym2)} base val mem)
  1000(FMOVDstore [off1] {sym1} (MOVDaddr [off2] {sym2} base) val mem) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) =>
  1001	(FMOVDstore [off1+off2] {mergeSym(sym1,sym2)} base val mem)
  1002
  1003(ADDload   [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ADDload   [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1004(ADDWload  [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ADDWload  [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1005(MULLDload [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (MULLDload [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1006(MULLWload [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (MULLWload [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1007(SUBload   [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (SUBload   [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1008(SUBWload  [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (SUBWload  [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1009
  1010(ANDload   [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ANDload   [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1011(ANDWload  [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ANDWload  [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1012(ORload    [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ORload    [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1013(ORWload   [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (ORWload   [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1014(XORload   [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (XORload   [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1015(XORWload  [o1] {s1} x (MOVDaddr [o2] {s2} ptr) mem) && ptr.Op != OpSB && is20Bit(int64(o1)+int64(o2)) && canMergeSym(s1, s2) => (XORWload  [o1+o2] {mergeSym(s1, s2)} x ptr mem)
  1016
  1017// Cannot store constant to SB directly (no 'move relative long immediate' instructions).
  1018(MOVDstoreconst [sc] {sym1} (MOVDaddr [off] {sym2} ptr) mem) && ptr.Op != OpSB && canMergeSym(sym1, sym2) && sc.canAdd32(off) =>
  1019	(MOVDstoreconst [sc.addOffset32(off)] {mergeSym(sym1, sym2)} ptr mem)
  1020(MOVWstoreconst [sc] {sym1} (MOVDaddr [off] {sym2} ptr) mem) && ptr.Op != OpSB && canMergeSym(sym1, sym2) && sc.canAdd32(off) =>
  1021	(MOVWstoreconst [sc.addOffset32(off)] {mergeSym(sym1, sym2)} ptr mem)
  1022(MOVHstoreconst [sc] {sym1} (MOVDaddr [off] {sym2} ptr) mem) && ptr.Op != OpSB && canMergeSym(sym1, sym2) && sc.canAdd32(off) =>
  1023	(MOVHstoreconst [sc.addOffset32(off)] {mergeSym(sym1, sym2)} ptr mem)
  1024(MOVBstoreconst [sc] {sym1} (MOVDaddr [off] {sym2} ptr) mem) && ptr.Op != OpSB && canMergeSym(sym1, sym2) && sc.canAdd32(off) =>
  1025	(MOVBstoreconst [sc.addOffset32(off)] {mergeSym(sym1, sym2)} ptr mem)
  1026
  1027// MOVDaddr into MOVDaddridx
  1028(MOVDaddridx [off1] {sym1} (MOVDaddr [off2] {sym2} x) y) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && x.Op != OpSB =>
  1029       (MOVDaddridx [off1+off2] {mergeSym(sym1,sym2)} x y)
  1030(MOVDaddridx [off1] {sym1} x (MOVDaddr [off2] {sym2} y)) && is32Bit(int64(off1)+int64(off2)) && canMergeSym(sym1, sym2) && y.Op != OpSB =>
  1031       (MOVDaddridx [off1+off2] {mergeSym(sym1,sym2)} x y)
  1032
  1033// Absorb InvertFlags into branches.
  1034(BRC {c} (InvertFlags cmp) yes no) => (BRC {c.ReverseComparison()} cmp yes no)
  1035
  1036// Constant comparisons.
  1037(CMPconst (MOVDconst [x]) [y]) && x==int64(y) => (FlagEQ)
  1038(CMPconst (MOVDconst [x]) [y]) && x<int64(y) => (FlagLT)
  1039(CMPconst (MOVDconst [x]) [y]) && x>int64(y) => (FlagGT)
  1040(CMPUconst (MOVDconst [x]) [y]) && uint64(x)==uint64(y) => (FlagEQ)
  1041(CMPUconst (MOVDconst [x]) [y]) && uint64(x)<uint64(y) => (FlagLT)
  1042(CMPUconst (MOVDconst [x]) [y]) && uint64(x)>uint64(y) => (FlagGT)
  1043
  1044(CMPWconst (MOVDconst [x]) [y]) && int32(x)==int32(y) => (FlagEQ)
  1045(CMPWconst (MOVDconst [x]) [y]) && int32(x)<int32(y) => (FlagLT)
  1046(CMPWconst (MOVDconst [x]) [y]) && int32(x)>int32(y) => (FlagGT)
  1047(CMPWUconst (MOVDconst [x]) [y]) && uint32(x)==uint32(y) => (FlagEQ)
  1048(CMPWUconst (MOVDconst [x]) [y]) && uint32(x)<uint32(y) => (FlagLT)
  1049(CMPWUconst (MOVDconst [x]) [y]) && uint32(x)>uint32(y) => (FlagGT)
  1050
  1051(CMP(W|WU)const (MOVBZreg _) [c]) &&   0xff < c => (FlagLT)
  1052(CMP(W|WU)const (MOVHZreg _) [c]) && 0xffff < c => (FlagLT)
  1053
  1054(CMPconst  (SRDconst _ [c]) [n]) && c > 0 && n < 0 => (FlagGT)
  1055(CMPWconst (SRWconst _ [c]) [n]) && c > 0 && n < 0 => (FlagGT)
  1056
  1057(CMPUconst  (SRDconst _ [c]) [n]) && c > 0 && c < 64 && (1<<uint(64-c)) <= uint64(n) => (FlagLT)
  1058(CMPWUconst (SRWconst _ [c]) [n]) && c > 0 && c < 32 && (1<<uint(32-c)) <= uint32(n) => (FlagLT)
  1059
  1060(CMPWconst  (ANDWconst _ [m]) [n]) && int32(m) >= 0 &&  int32(m) <  int32(n) => (FlagLT)
  1061(CMPWUconst (ANDWconst _ [m]) [n]) && uint32(m) < uint32(n) => (FlagLT)
  1062
  1063(CMPconst  (RISBGZ x {r}) [c]) && c > 0 && r.OutMask() < uint64(c) => (FlagLT)
  1064(CMPUconst (RISBGZ x {r}) [c]) && r.OutMask() < uint64(uint32(c)) => (FlagLT)
  1065
  1066// Constant compare-and-branch with immediate.
  1067(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   != 0 &&  int64(x) ==  int64(y) => (First yes no)
  1068(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    != 0 &&  int64(x) <   int64(y) => (First yes no)
  1069(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater != 0 &&  int64(x) >   int64(y) => (First yes no)
  1070(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   != 0 &&  int32(x) ==  int32(y) => (First yes no)
  1071(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    != 0 &&  int32(x) <   int32(y) => (First yes no)
  1072(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater != 0 &&  int32(x) >   int32(y) => (First yes no)
  1073(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   != 0 && uint64(x) == uint64(y) => (First yes no)
  1074(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    != 0 && uint64(x) <  uint64(y) => (First yes no)
  1075(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater != 0 && uint64(x) >  uint64(y) => (First yes no)
  1076(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   != 0 && uint32(x) == uint32(y) => (First yes no)
  1077(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    != 0 && uint32(x) <  uint32(y) => (First yes no)
  1078(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater != 0 && uint32(x) >  uint32(y) => (First yes no)
  1079(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   == 0 &&  int64(x) ==  int64(y) => (First no yes)
  1080(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    == 0 &&  int64(x) <   int64(y) => (First no yes)
  1081(CGIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater == 0 &&  int64(x) >   int64(y) => (First no yes)
  1082(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   == 0 &&  int32(x) ==  int32(y) => (First no yes)
  1083(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    == 0 &&  int32(x) <   int32(y) => (First no yes)
  1084(CIJ   {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater == 0 &&  int32(x) >   int32(y) => (First no yes)
  1085(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   == 0 && uint64(x) == uint64(y) => (First no yes)
  1086(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    == 0 && uint64(x) <  uint64(y) => (First no yes)
  1087(CLGIJ {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater == 0 && uint64(x) >  uint64(y) => (First no yes)
  1088(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Equal   == 0 && uint32(x) == uint32(y) => (First no yes)
  1089(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Less    == 0 && uint32(x) <  uint32(y) => (First no yes)
  1090(CLIJ  {c} (MOVDconst [x]) [y] yes no) && c&s390x.Greater == 0 && uint32(x) >  uint32(y) => (First no yes)
  1091
  1092// Constant compare-and-branch with immediate when unsigned comparison with zero.
  1093(C(L|LG)IJ {s390x.GreaterOrEqual} _ [0] yes no) => (First yes no)
  1094(C(L|LG)IJ {s390x.Less}           _ [0] yes no) => (First no yes)
  1095
  1096// Constant compare-and-branch when operands match.
  1097(C(GR|R|LGR|LR)J {c} x y yes no) && x == y && c&s390x.Equal != 0 => (First yes no)
  1098(C(GR|R|LGR|LR)J {c} x y yes no) && x == y && c&s390x.Equal == 0 => (First no yes)
  1099
  1100// Convert 64-bit comparisons to 32-bit comparisons and signed comparisons
  1101// to unsigned comparisons.
  1102// Helps simplify constant comparison detection.
  1103(CM(P|PU)const (MOV(W|WZ)reg x) [c]) => (CMP(W|WU)const x [c])
  1104(CM(P|P|PU|PU)const x:(MOV(H|HZ|H|HZ)reg _) [c]) => (CMP(W|W|WU|WU)const x [c])
  1105(CM(P|P|PU|PU)const x:(MOV(B|BZ|B|BZ)reg _) [c]) => (CMP(W|W|WU|WU)const x [c])
  1106(CMPconst  (MOV(WZ|W)reg x:(ANDWconst [m] _)) [c]) && int32(m) >= 0 && c >= 0 => (CMPWUconst x [c])
  1107(CMPUconst (MOV(WZ|W)reg x:(ANDWconst [m] _)) [c]) && int32(m) >= 0           => (CMPWUconst x [c])
  1108(CMPconst  x:(SRDconst _ [c]) [n]) && c > 0 && n >= 0 => (CMPUconst  x [n])
  1109(CMPWconst x:(SRWconst _ [c]) [n]) && c > 0 && n >= 0 => (CMPWUconst x [n])
  1110
  1111// Absorb sign and zero extensions into 32-bit comparisons.
  1112(CMP(W|W|WU|WU)      x (MOV(W|WZ|W|WZ)reg y))   => (CMP(W|W|WU|WU) x y)
  1113(CMP(W|W|WU|WU)      (MOV(W|WZ|W|WZ)reg x) y)   => (CMP(W|W|WU|WU) x y)
  1114(CMP(W|W|WU|WU)const (MOV(W|WZ|W|WZ)reg x) [c]) => (CMP(W|W|WU|WU)const x [c])
  1115
  1116// Absorb flag constants into branches.
  1117(BRC {c} (FlagEQ) yes no) && c&s390x.Equal     != 0 => (First yes no)
  1118(BRC {c} (FlagLT) yes no) && c&s390x.Less      != 0 => (First yes no)
  1119(BRC {c} (FlagGT) yes no) && c&s390x.Greater   != 0 => (First yes no)
  1120(BRC {c} (FlagOV) yes no) && c&s390x.Unordered != 0 => (First yes no)
  1121
  1122(BRC {c} (FlagEQ) yes no) && c&s390x.Equal     == 0 => (First no yes)
  1123(BRC {c} (FlagLT) yes no) && c&s390x.Less      == 0 => (First no yes)
  1124(BRC {c} (FlagGT) yes no) && c&s390x.Greater   == 0 => (First no yes)
  1125(BRC {c} (FlagOV) yes no) && c&s390x.Unordered == 0 => (First no yes)
  1126
  1127// Absorb flag constants into SETxx ops.
  1128(LOCGR {c} _ x (FlagEQ)) && c&s390x.Equal     != 0 => x
  1129(LOCGR {c} _ x (FlagLT)) && c&s390x.Less      != 0 => x
  1130(LOCGR {c} _ x (FlagGT)) && c&s390x.Greater   != 0 => x
  1131(LOCGR {c} _ x (FlagOV)) && c&s390x.Unordered != 0 => x
  1132
  1133(LOCGR {c} x _ (FlagEQ)) && c&s390x.Equal     == 0 => x
  1134(LOCGR {c} x _ (FlagLT)) && c&s390x.Less      == 0 => x
  1135(LOCGR {c} x _ (FlagGT)) && c&s390x.Greater   == 0 => x
  1136(LOCGR {c} x _ (FlagOV)) && c&s390x.Unordered == 0 => x
  1137
  1138// Remove redundant *const ops
  1139(ADDconst [0] x) => x
  1140(ADDWconst [c] x) && int32(c)==0 => x
  1141(SUBconst [0] x) => x
  1142(SUBWconst [c] x) && int32(c) == 0 => x
  1143(ANDconst [0] _)                 => (MOVDconst [0])
  1144(ANDWconst [c] _) && int32(c)==0  => (MOVDconst [0])
  1145(ANDconst [-1] x)                => x
  1146(ANDWconst [c] x) && int32(c)==-1 => x
  1147(ORconst [0] x)                  => x
  1148(ORWconst [c] x) && int32(c)==0   => x
  1149(ORconst [-1] _)                 => (MOVDconst [-1])
  1150(ORWconst [c] _) && int32(c)==-1  => (MOVDconst [-1])
  1151(XORconst [0] x)                  => x
  1152(XORWconst [c] x) && int32(c)==0   => x
  1153
  1154// Shifts by zero (may be inserted during multiplication strength reduction).
  1155((SLD|SLW|SRD|SRW|SRAD|SRAW)const x [0]) => x
  1156
  1157// Convert constant subtracts to constant adds.
  1158(SUBconst [c] x) && c != -(1<<31) => (ADDconst [-c] x)
  1159(SUBWconst [c] x) => (ADDWconst [-int32(c)] x)
  1160
  1161// generic constant folding
  1162// TODO: more of this
  1163(ADDconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)+d])
  1164(ADDWconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)+d])
  1165(ADDconst [c] (ADDconst [d] x)) && is32Bit(int64(c)+int64(d)) => (ADDconst [c+d] x)
  1166(ADDWconst [c] (ADDWconst [d] x)) => (ADDWconst [int32(c+d)] x)
  1167(SUBconst (MOVDconst [d]) [c]) => (MOVDconst [d-int64(c)])
  1168(SUBconst (SUBconst x [d]) [c]) && is32Bit(-int64(c)-int64(d)) => (ADDconst [-c-d] x)
  1169(SRADconst [c] (MOVDconst [d])) => (MOVDconst [d>>uint64(c)])
  1170(SRAWconst [c] (MOVDconst [d])) => (MOVDconst [int64(int32(d))>>uint64(c)])
  1171(NEG (MOVDconst [c])) => (MOVDconst [-c])
  1172(NEGW (MOVDconst [c])) => (MOVDconst [int64(int32(-c))])
  1173(MULLDconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)*d])
  1174(MULLWconst [c] (MOVDconst [d])) => (MOVDconst [int64(c*int32(d))])
  1175(AND (MOVDconst [c]) (MOVDconst [d])) => (MOVDconst [c&d])
  1176(ANDconst [c] (MOVDconst [d])) => (MOVDconst [c&d])
  1177(ANDWconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)&d])
  1178(OR (MOVDconst [c]) (MOVDconst [d])) => (MOVDconst [c|d])
  1179(ORconst [c] (MOVDconst [d])) => (MOVDconst [c|d])
  1180(ORWconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)|d])
  1181(XOR (MOVDconst [c]) (MOVDconst [d])) => (MOVDconst [c^d])
  1182(XORconst [c] (MOVDconst [d])) => (MOVDconst [c^d])
  1183(XORWconst [c] (MOVDconst [d])) => (MOVDconst [int64(c)^d])
  1184(LoweredRound32F x:(FMOVSconst)) => x
  1185(LoweredRound64F x:(FMOVDconst)) => x
  1186
  1187// generic simplifications
  1188// TODO: more of this
  1189(ADD x (NEG y)) => (SUB x y)
  1190(ADDW x (NEGW y)) => (SUBW x y)
  1191(SUB x (NEG y)) => (ADD x y)
  1192(SUBW x (NEGW y)) => (ADDW x y)
  1193(SUB x x) => (MOVDconst [0])
  1194(SUBW x x) => (MOVDconst [0])
  1195(AND x x) => x
  1196(ANDW x x) => x
  1197(OR x x) => x
  1198(ORW x x) => x
  1199(XOR x x) => (MOVDconst [0])
  1200(XORW x x) => (MOVDconst [0])
  1201(NEG (NEG x)) => x
  1202(NEG (ADDconst [c] (NEG x))) && c != -(1<<31) => (ADDconst [-c] x)
  1203(MOVBZreg (ANDWconst [m] x)) => (MOVWZreg (ANDWconst <typ.UInt32> [int32( uint8(m))] x))
  1204(MOVHZreg (ANDWconst [m] x)) => (MOVWZreg (ANDWconst <typ.UInt32> [int32(uint16(m))] x))
  1205(MOVBreg  (ANDWconst [m] x)) &&  int8(m) >= 0 => (MOVWZreg (ANDWconst <typ.UInt32> [int32( uint8(m))] x))
  1206(MOVHreg  (ANDWconst [m] x)) && int16(m) >= 0 => (MOVWZreg (ANDWconst <typ.UInt32> [int32(uint16(m))] x))
  1207
  1208// carry flag generation
  1209// (only constant fold carry of zero)
  1210(Select1 (ADDCconst (MOVDconst [c]) [d]))
  1211  && uint64(c+int64(d)) >= uint64(c) && c+int64(d) == 0
  1212  => (FlagEQ)
  1213(Select1 (ADDCconst (MOVDconst [c]) [d]))
  1214  && uint64(c+int64(d)) >= uint64(c) && c+int64(d) != 0
  1215  => (FlagLT)
  1216
  1217// borrow flag generation
  1218// (only constant fold borrow of zero)
  1219(Select1 (SUBC (MOVDconst [c]) (MOVDconst [d])))
  1220  && uint64(d) <= uint64(c) && c-d == 0
  1221  => (FlagGT)
  1222(Select1 (SUBC (MOVDconst [c]) (MOVDconst [d])))
  1223  && uint64(d) <= uint64(c) && c-d != 0
  1224  => (FlagOV)
  1225
  1226// add with carry
  1227(ADDE x y (FlagEQ)) => (ADDC x y)
  1228(ADDE x y (FlagLT)) => (ADDC x y)
  1229(ADDC x (MOVDconst [c])) && is16Bit(c) => (ADDCconst x [int16(c)])
  1230(Select0 (ADDCconst (MOVDconst [c]) [d])) => (MOVDconst [c+int64(d)])
  1231
  1232// subtract with borrow
  1233(SUBE x y (FlagGT)) => (SUBC x y)
  1234(SUBE x y (FlagOV)) => (SUBC x y)
  1235(Select0 (SUBC (MOVDconst [c]) (MOVDconst [d]))) => (MOVDconst [c-d])
  1236
  1237// collapse carry chain
  1238(ADDE x y (Select1 (ADDCconst [-1] (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) c)))))
  1239  => (ADDE x y c)
  1240
  1241// collapse borrow chain
  1242(SUBE x y (Select1 (SUBC (MOVDconst [0]) (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) c))))))
  1243  => (SUBE x y c)
  1244
  1245// branch on carry
  1246(C(G|LG)IJ {s390x.Equal}         (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) carry)) [0]) => (BRC {s390x.NoCarry} carry)
  1247(C(G|LG)IJ {s390x.Equal}         (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) carry)) [1]) => (BRC {s390x.Carry}   carry)
  1248(C(G|LG)IJ {s390x.LessOrGreater} (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) carry)) [0]) => (BRC {s390x.Carry}   carry)
  1249(C(G|LG)IJ {s390x.LessOrGreater} (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) carry)) [1]) => (BRC {s390x.NoCarry} carry)
  1250(C(G|LG)IJ {s390x.Greater}       (Select0 (ADDE (MOVDconst [0]) (MOVDconst [0]) carry)) [0]) => (BRC {s390x.Carry}   carry)
  1251
  1252// branch on borrow
  1253(C(G|LG)IJ {s390x.Equal}         (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) borrow))) [0]) => (BRC {s390x.NoBorrow} borrow)
  1254(C(G|LG)IJ {s390x.Equal}         (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) borrow))) [1]) => (BRC {s390x.Borrow}   borrow)
  1255(C(G|LG)IJ {s390x.LessOrGreater} (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) borrow))) [0]) => (BRC {s390x.Borrow}   borrow)
  1256(C(G|LG)IJ {s390x.LessOrGreater} (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) borrow))) [1]) => (BRC {s390x.NoBorrow} borrow)
  1257(C(G|LG)IJ {s390x.Greater}       (NEG (Select0 (SUBE (MOVDconst [0]) (MOVDconst [0]) borrow))) [0]) => (BRC {s390x.Borrow}   borrow)
  1258
  1259// fused multiply-add
  1260(Select0 (F(ADD|SUB) (FMUL y z) x)) && x.Block.Func.useFMA(v) => (FM(ADD|SUB) x y z)
  1261(Select0 (F(ADDS|SUBS) (FMULS y z) x)) && x.Block.Func.useFMA(v) => (FM(ADDS|SUBS) x y z)
  1262
  1263// Convert floating point comparisons against zero into 'load and test' instructions.
  1264(F(CMP|CMPS) x (FMOV(D|S)const [0.0])) => (LT(D|E)BR x)
  1265(F(CMP|CMPS) (FMOV(D|S)const [0.0]) x) => (InvertFlags (LT(D|E)BR <v.Type> x))
  1266
  1267// FSUB, FSUBS, FADD, FADDS now produce a condition code representing the
  1268// comparison of the result with 0.0. If a compare with zero instruction
  1269// (e.g. LTDBR) is following one of those instructions, we can use the
  1270// generated flag and remove the comparison instruction.
  1271// Note: when inserting Select1 ops we need to ensure they are in the
  1272// same block as their argument. We could also use @x.Block for this
  1273// but moving the flag generating value to a different block seems to
  1274// increase the likelihood that the flags value will have to be regenerated
  1275// by flagalloc which is not what we want.
  1276(LTDBR (Select0 x:(F(ADD|SUB) _ _)))   && b == x.Block => (Select1 x)
  1277(LTEBR (Select0 x:(F(ADDS|SUBS) _ _))) && b == x.Block => (Select1 x)
  1278
  1279// Fold memory operations into operations.
  1280// Exclude global data (SB) because these instructions cannot handle relative addresses.
  1281// TODO(mundaym): indexed versions of these?
  1282((ADD|SUB|MULLD|AND|OR|XOR) <t> x g:(MOVDload [off] {sym} ptr mem))
  1283  && ptr.Op != OpSB
  1284  && is20Bit(int64(off))
  1285  && canMergeLoadClobber(v, g, x)
  1286  && clobber(g)
  1287  => ((ADD|SUB|MULLD|AND|OR|XOR)load <t> [off] {sym} x ptr mem)
  1288((ADD|SUB|MULL|AND|OR|XOR)W <t> x g:(MOVWload [off] {sym} ptr mem))
  1289  && ptr.Op != OpSB
  1290  && is20Bit(int64(off))
  1291  && canMergeLoadClobber(v, g, x)
  1292  && clobber(g)
  1293  => ((ADD|SUB|MULL|AND|OR|XOR)Wload <t> [off] {sym} x ptr mem)
  1294((ADD|SUB|MULL|AND|OR|XOR)W <t> x g:(MOVWZload [off] {sym} ptr mem))
  1295  && ptr.Op != OpSB
  1296  && is20Bit(int64(off))
  1297  && canMergeLoadClobber(v, g, x)
  1298  && clobber(g)
  1299  => ((ADD|SUB|MULL|AND|OR|XOR)Wload <t> [off] {sym} x ptr mem)
  1300
  1301// Combine stores into store multiples.
  1302// 32-bit
  1303(MOVWstore [i] {s} p w1 x:(MOVWstore [i-4] {s} p w0 mem))
  1304  && p.Op != OpSB
  1305  && x.Uses == 1
  1306  && is20Bit(int64(i)-4)
  1307  && setPos(v, x.Pos)
  1308  && clobber(x)
  1309  => (STM2 [i-4] {s} p w0 w1 mem)
  1310(MOVWstore [i] {s} p w2 x:(STM2 [i-8] {s} p w0 w1 mem))
  1311  && x.Uses == 1
  1312  && is20Bit(int64(i)-8)
  1313  && setPos(v, x.Pos)
  1314  && clobber(x)
  1315  => (STM3 [i-8] {s} p w0 w1 w2 mem)
  1316(MOVWstore [i] {s} p w3 x:(STM3 [i-12] {s} p w0 w1 w2 mem))
  1317  && x.Uses == 1
  1318  && is20Bit(int64(i)-12)
  1319  && setPos(v, x.Pos)
  1320  && clobber(x)
  1321  => (STM4 [i-12] {s} p w0 w1 w2 w3 mem)
  1322(STM2 [i] {s} p w2 w3 x:(STM2 [i-8] {s} p w0 w1 mem))
  1323  && x.Uses == 1
  1324  && is20Bit(int64(i)-8)
  1325  && setPos(v, x.Pos)
  1326  && clobber(x)
  1327  => (STM4 [i-8] {s} p w0 w1 w2 w3 mem)
  1328// 64-bit
  1329(MOVDstore [i] {s} p w1 x:(MOVDstore [i-8] {s} p w0 mem))
  1330  && p.Op != OpSB
  1331  && x.Uses == 1
  1332  && is20Bit(int64(i)-8)
  1333  && setPos(v, x.Pos)
  1334  && clobber(x)
  1335  => (STMG2 [i-8] {s} p w0 w1 mem)
  1336(MOVDstore [i] {s} p w2 x:(STMG2 [i-16] {s} p w0 w1 mem))
  1337  && x.Uses == 1
  1338  && is20Bit(int64(i)-16)
  1339  && setPos(v, x.Pos)
  1340  && clobber(x)
  1341  => (STMG3 [i-16] {s} p w0 w1 w2 mem)
  1342(MOVDstore [i] {s} p w3 x:(STMG3 [i-24] {s} p w0 w1 w2 mem))
  1343  && x.Uses == 1
  1344  && is20Bit(int64(i)-24)
  1345  && setPos(v, x.Pos)
  1346  && clobber(x)
  1347  => (STMG4 [i-24] {s} p w0 w1 w2 w3 mem)
  1348(STMG2 [i] {s} p w2 w3 x:(STMG2 [i-16] {s} p w0 w1 mem))
  1349  && x.Uses == 1
  1350  && is20Bit(int64(i)-16)
  1351  && setPos(v, x.Pos)
  1352  && clobber(x)
  1353  => (STMG4 [i-16] {s} p w0 w1 w2 w3 mem)
  1354
  1355// Convert 32-bit store multiples into 64-bit stores.
  1356(STM2 [i] {s} p (SRDconst [32] x) x mem) => (MOVDstore [i] {s} p x mem)
  1357
  1358// Fold bit reversal into loads.
  1359(MOVWBR x:(MOVWZload    [off] {sym} ptr     mem)) && x.Uses == 1 => @x.Block (MOVWZreg (MOVWBRload    [off] {sym} ptr     mem)) // need zero extension?
  1360(MOVWBR x:(MOVWZloadidx [off] {sym} ptr idx mem)) && x.Uses == 1 => @x.Block (MOVWZreg (MOVWBRloadidx [off] {sym} ptr idx mem)) // need zero extension?
  1361(MOVDBR x:(MOVDload     [off] {sym} ptr     mem)) && x.Uses == 1 => @x.Block (MOVDBRload    [off] {sym} ptr     mem)
  1362(MOVDBR x:(MOVDloadidx  [off] {sym} ptr idx mem)) && x.Uses == 1 => @x.Block (MOVDBRloadidx [off] {sym} ptr idx mem)
  1363
  1364// Fold bit reversal into stores.
  1365(MOV(D|W)store    [off] {sym} ptr     r:(MOV(D|W)BR x) mem) && r.Uses == 1 => (MOV(D|W)BRstore    [off] {sym} ptr     x mem)
  1366(MOV(D|W)storeidx [off] {sym} ptr idx r:(MOV(D|W)BR x) mem) && r.Uses == 1 => (MOV(D|W)BRstoreidx [off] {sym} ptr idx x mem)
  1367
  1368// Special bswap16 rules
  1369(Bswap16 x:(MOVHZload    [off] {sym} ptr     mem)) => @x.Block (MOVHZreg (MOVHBRload    [off] {sym} ptr     mem))
  1370(Bswap16 x:(MOVHZloadidx [off] {sym} ptr idx mem)) => @x.Block (MOVHZreg (MOVHBRloadidx [off] {sym} ptr idx mem))
  1371(MOVHstore    [off] {sym} ptr     (Bswap16 val) mem) => (MOVHBRstore    [off] {sym} ptr     val mem)
  1372(MOVHstoreidx [off] {sym} ptr idx (Bswap16 val) mem) => (MOVHBRstoreidx [off] {sym} ptr idx val mem)

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