Commit 615a52b9 authored by Josh Bleecher Snyder's avatar Josh Bleecher Snyder

cmd/compile: inline x, ok := y.(T) where T is a scalar

When T is a scalar, there are no runtime calls
required, which makes this a clear win.

encoding/binary:
WriteInts-8                958ns ± 3%     864ns ± 2%   -9.80%  (p=0.000 n=15+15)

This also considerably shrinks a core fmt
routine:

Before: "".(*pp).printArg t=1 size=3952 args=0x20 locals=0xf0
After:  "".(*pp).printArg t=1 size=2624 args=0x20 locals=0x98

Unfortunately, I find it very hard to get stable
numbers out of the fmt benchmarks due to thermal scaling.

Change-Id: I1278006b030253bf8e48dc7631d18985cdaa143d
Reviewed-on: https://go-review.googlesource.com/26659
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: default avatarKeith Randall <khr@golang.org>
parent 074d6a64
......@@ -184,7 +184,7 @@ func cgen_wb(n, res *Node, wb bool) {
n.Addable = n.Left.Addable
}
case OITAB:
case OITAB, OIDATA:
n.Addable = n.Left.Addable
}
......@@ -525,12 +525,20 @@ func cgen_wb(n, res *Node, wb bool) {
Thearch.Gmove(&n1, res)
Regfree(&n1)
// interface table is first word of interface value
case OITAB:
// interface table is first word of interface value
var n1 Node
Igen(nl, &n1, res)
n1.Type = n.Type
Thearch.Gmove(&n1, res)
Regfree(&n1)
case OIDATA:
// interface data is second word of interface value
var n1 Node
Igen(nl, &n1, res)
n1.Type = n.Type
n1.Xoffset += int64(Widthptr)
Thearch.Gmove(&n1, res)
Regfree(&n1)
......
......@@ -48,6 +48,7 @@ var (
func Ismem(n *Node) bool {
switch n.Op {
case OITAB,
OIDATA,
OSPTR,
OLEN,
OCAP,
......@@ -456,16 +457,29 @@ func Naddr(a *obj.Addr, n *Node) {
}
a.Type = obj.TYPE_ADDR
// itable of interface value
case OITAB:
// itable of interface value
Naddr(a, n.Left)
if a.Type == obj.TYPE_CONST && a.Offset == 0 {
break // itab(nil)
}
a.Etype = uint8(Tptr)
a.Width = int64(Widthptr)
case OIDATA:
// idata of interface value
Naddr(a, n.Left)
if a.Type == obj.TYPE_CONST && a.Offset == 0 {
break // idata(nil)
}
if isdirectiface(n.Type) {
a.Etype = uint8(Simtype[n.Type.Etype])
} else {
a.Etype = uint8(Tptr)
}
a.Offset += int64(Widthptr)
a.Width = int64(Widthptr)
// pointer in a string or slice
case OSPTR:
Naddr(a, n.Left)
......
......@@ -143,6 +143,7 @@ var opnames = []string{
OINLCALL: "INLCALL",
OEFACE: "EFACE",
OITAB: "ITAB",
OIDATA: "IDATA",
OSPTR: "SPTR",
OCLOSUREVAR: "CLOSUREVAR",
OCFUNC: "CFUNC",
......
......@@ -329,7 +329,7 @@ func instrumentnode(np **Node, init *Nodes, wr int, skip int) {
goto ret
case OITAB:
case OITAB, OIDATA:
instrumentnode(&n.Left, init, 0, 0)
goto ret
......
......@@ -2026,6 +2026,10 @@ func (s *state) expr(n *Node) *ssa.Value {
a := s.expr(n.Left)
return s.newValue1(ssa.OpITab, n.Type, a)
case OIDATA:
a := s.expr(n.Left)
return s.newValue1(ssa.OpIData, n.Type, a)
case OEFACE:
tab := s.expr(n.Left)
data := s.expr(n.Right)
......
......@@ -2327,6 +2327,25 @@ func itabType(itab *Node) *Node {
return typ
}
// ifaceData loads the data field from an interface.
// The concrete type must be known to have type t.
// It follows the pointer if !isdirectiface(t).
func ifaceData(n *Node, t *Type) *Node {
ptr := NodSym(OIDATA, n, nil)
if isdirectiface(t) {
ptr.Type = t
ptr.Typecheck = 1
return ptr
}
ptr.Type = Ptrto(t)
ptr.Bounded = true
ptr.Typecheck = 1
ind := Nod(OIND, ptr, nil)
ind.Type = t
ind.Typecheck = 1
return ind
}
// iet returns 'T' if t is a concrete type,
// 'I' if t is an interface type, and 'E' if t is an empty interface type.
// It is used to build calls to the conv* and assert* runtime routines.
......
......@@ -383,7 +383,7 @@ const (
OINDEX // Left[Right] (index of array or slice)
OINDEXMAP // Left[Right] (index of map)
OKEY // Left:Right (key:value in struct/array/map literal, or slice index pair)
_ // was OPARAM, but cannot remove without breaking binary blob in builtin.go
OIDATA // data word of an interface value in Left; TODO: move next to OITAB once it is easier to regenerate the binary blob in builtin.go (issues 15835, 15839)
OLEN // len(Left)
OMAKE // make(List) (before type checking converts to one of the following)
OMAKECHAN // make(Type, Left) (type is chan)
......
......@@ -1912,6 +1912,12 @@ OpSwitch:
n.Type = Ptrto(Types[TUINTPTR])
break OpSwitch
case OIDATA:
// Whoever creates the OIDATA node must know a priori the concrete type at that moment,
// usually by just having checked the OITAB.
Fatalf("cannot typecheck interface data %v", n)
break OpSwitch
case OSPTR:
ok |= Erv
n.Left = typecheck(n.Left, Erv)
......
......@@ -555,7 +555,7 @@ opswitch:
n.Left = walkexpr(n.Left, init)
n.Right = walkexpr(n.Right, init)
case OSPTR, OITAB:
case OSPTR, OITAB, OIDATA:
n.Left = walkexpr(n.Left, init)
case OLEN, OCAP:
......@@ -961,11 +961,13 @@ opswitch:
toKind := t.iet()
res := n.List.First()
scalar := !haspointers(res.Type)
// Avoid runtime calls in a few cases of the form _, ok := i.(T).
// This is faster and shorter and allows the corresponding assertX2X2
// routines to skip nil checks on their last argument.
if isblank(res) {
// Also avoid runtime calls for converting interfaces to scalar concrete types.
if isblank(res) || (scalar && toKind == 'T') {
var fast *Node
switch toKind {
case 'T':
......@@ -985,11 +987,27 @@ opswitch:
fast = Nod(ONE, nodnil(), tab)
}
if fast != nil {
if Debug_typeassert > 0 {
Warn("type assertion (ok only) inlined")
if isblank(res) {
if Debug_typeassert > 0 {
Warn("type assertion (ok only) inlined")
}
n = Nod(OAS, ok, fast)
n = typecheck(n, Etop)
} else {
if Debug_typeassert > 0 {
Warn("type assertion (scalar result) inlined")
}
n = Nod(OIF, ok, nil)
n.Likely = 1
if isblank(ok) {
n.Left = fast
} else {
n.Ninit.Set1(Nod(OAS, ok, fast))
}
n.Nbody.Set1(Nod(OAS, res, ifaceData(from, res.Type)))
n.Rlist.Set1(Nod(OAS, res, nil))
n = typecheck(n, Etop)
}
n = Nod(OAS, ok, fast)
n = typecheck(n, Etop)
break
}
}
......
......@@ -43,7 +43,7 @@ func assertbig(x interface{}) complex128 {
}
func assertbig2(x interface{}) (complex128, bool) {
z, ok := x.(complex128) // ERROR "type assertion not inlined"
z, ok := x.(complex128) // ERROR "type assertion .scalar result. inlined"
return z, ok
}
......@@ -51,3 +51,17 @@ func assertbig2ok(x interface{}) (complex128, bool) {
_, ok := x.(complex128) // ERROR "type assertion [(]ok only[)] inlined"
return 0, ok
}
func assertslice(x interface{}) []int {
return x.([]int) // ERROR "type assertion not inlined"
}
func assertslice2(x interface{}) ([]int, bool) {
z, ok := x.([]int) // ERROR "type assertion not inlined"
return z, ok
}
func assertslice2ok(x interface{}) ([]int, bool) {
_, ok := x.([]int) // ERROR "type assertion [(]ok only[)] inlined"
return nil, ok
}
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