# CL 108030044 text/scanner: provide facility for custom identifiers, Robert Griesemer <******@****.***>
pkg text/scanner, type Scanner struct, IsIdentRune func(int32, int) bool

# CL 130620043 text/template: add back pointer to Nodes for better error generation, Rob Pike <******@****.***>
pkg text/template/parse, type DotNode struct, embedded NodeType
pkg text/template/parse, type NilNode struct, embedded NodeType

(CSINC [cc] _ y flag) && ccARM64Eval(cc, flag) < 0 => (ADDconst [1] y)
(CSETM [cc]     flag) && ccARM64Eval(cc, flag) > 0 => (MOVDconst [-1])
(CSETM [cc]     flag) && ccARM64Eval(cc, flag) < 0 => (MOVDconst [0])

// absorb flags back into boolean CSEL
(CSEL [cc] x y (CMPWconst [0] boolval)) && cc == OpARM64NotEqual && flagArg(boolval) != nil =>
      (CSEL [boolval.Op] x y flagArg(boolval))

(TESTLconst [-1] x) && x.Op != OpAMD64MOVLconst => (TESTL x x)
(TESTWconst [-1] x) && x.Op != OpAMD64MOVLconst => (TESTW x x)
(TESTBconst [-1] x) && x.Op != OpAMD64MOVLconst => (TESTB x x)

// Convert LEAQ1 back to ADDQ if we can
(LEAQ1 [0] x y) && v.Aux == nil => (ADDQ x y)

(MOVQstoreconst [c] {s} p1 x:(MOVQstoreconst [a] {s} p0 mem))
  && config.useSSE
  && x.Uses == 1

              (Const32 <typ.UInt32> [int32((1<<32)%c)])))
          (Const32 <typ.UInt32> [int32(c)]))))

// For 64-bit divides on 64-bit machines
// (64-bit divides on 32-bit machines are lowered to a runtime call by the walk pass.)
(Div64u x (Const64 [c])) && umagicOK64(c) && config.RegSize == 8 && umagic64(c).m&1 == 0 && config.useHmul =>
  (Rsh64Ux64 <typ.UInt64>
    (Hmul64u <typ.UInt64>

When Go 1.23 builds older programs, the old behaviors remain in effect.
The new [GODEBUG setting](/doc/godebug) [`asynctimerchan=1`](/pkg/time/#NewTimer)
can be used to revert back to asynchronous channel behaviors

CL 564035 - changed encoding/xml, but the change was too disrptive and rolled back in CL 570175, reopening tracking issue go.dev/issue/65691; nothing to document in Go 1.23 release notes

but may nonetheless break some existing programs,
we first engineer the change to keep as many existing programs working as possible.
For the remaining programs,
we define a new GODEBUG setting that
allows individual programs to opt back in to the old behavior.
A GODEBUG setting may not be added if doing so is infeasible,
but that should be extremely rare.

GODEBUG settings added for compatibility will be maintained

pkg container/list, func New() *List
pkg container/list, method (*Element) Next() *Element
pkg container/list, method (*Element) Prev() *Element
pkg container/list, method (*List) Back() *Element
pkg container/list, method (*List) Front() *Element
pkg container/list, method (*List) Init() *List
pkg container/list, method (*List) InsertAfter(interface{}, *Element) *Element

// ANDconst which clobbers CC.
(ANDconst [m] x) && isPPC64ValidShiftMask(m) => (RLDICL [encodePPC64RotateMask(0,m,64)] x)

// Likewise, trying converting RLDICLCC back to ANDCCconst as it is faster.