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cmd/compile: optimize type switch for a single runtime known type with a case var

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Change-Id: I03ba70076d6dd3c0b9624d14699b7dd91a3c0e9b
Reviewed-on: https://go-review.googlesource.com/c/go/+/618476
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Keith Randall <khr@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This commit is contained in:
Youlin Feng 2024-10-08 12:49:30 +08:00 committed by Gopher Robot
parent 15c5580160
commit 711552e98a
2 changed files with 52 additions and 5 deletions
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35
src/cmd/compile/internal/walk/switch.go
View File

@ -440,6 +440,13 @@ func walkSwitchType(sw *ir.SwitchStmt) {
// we're looking for is not a compile-time constant (typ.Type()
// will be its shape).
typ ir.Node
// For a single runtime known type with a case var, create a
// temporary variable to hold the value returned by the dynamic
// type assert expr, so that we do not need one more dynamic
// type assert expr later.
val ir.Node
idx int // index of the single runtime known type in sw.Cases
}
var cases []oneCase
var defaultGoto, nilGoto ir.Node
@ -459,10 +466,19 @@ func walkSwitchType(sw *ir.SwitchStmt) {
nilGoto = jmp
continue
}
idx := -1
var val ir.Node
// for a single runtime known type with a case var, create the tmpVar
if len(ncase.List) == 1 && ncase.List[0].Op() == ir.ODYNAMICTYPE && ncase.Var != nil {
val = typecheck.TempAt(ncase.Pos(), ir.CurFunc, ncase.Var.Type())
idx = i
}
cases = append(cases, oneCase{
pos: ncase.Pos(),
typ: n1,
jmp: jmp,
val: val,
idx: idx,
})
}
}
@ -570,6 +586,9 @@ caseLoop:
as := ir.NewAssignListStmt(c.pos, ir.OAS2, nil, nil)
as.Lhs = []ir.Node{ir.BlankNode, s.okName} // _, ok =
if c.val != nil {
as.Lhs[0] = c.val // tmpVar, ok =
}
as.Rhs = []ir.Node{dot}
typecheck.Stmt(as)
@ -640,10 +659,18 @@ caseLoop:
val = ifaceData(ncase.Pos(), s.srcName, t)
}
} else if ncase.List[0].Op() == ir.ODYNAMICTYPE { // single runtime known type
dt := ncase.List[0].(*ir.DynamicType)
x := ir.NewDynamicTypeAssertExpr(ncase.Pos(), ir.ODYNAMICDOTTYPE, val, dt.RType)
x.ITab = dt.ITab
val = x
var found bool
for _, c := range cases {
if c.idx == i {
val = c.val
found = val != nil
break
}
}
// the tmpVar must always be found
if !found {
base.Fatalf("an error occurred when processing type switch case %v", ncase.List[0])
}
} else if ir.IsNil(ncase.List[0]) {
} else {
base.Fatalf("unhandled type switch case %v", ncase.List[0])

22
test/codegen/typeswitch.go
View File

@ -37,11 +37,31 @@ func swGYZ[T any](a Ig[T]) {
t.Y()
case Iz: // amd64:-".*typeAssert"
t.Z()
case interface{ G() T }: // amd64:-".*typeAssert",".*assertE2I"
case interface{ G() T }: // amd64:-".*typeAssert",-".*assertE2I\\(",".*assertE2I2"
t.G()
}
}
func swE2G[T any](a any) {
switch t := a.(type) {
case Iy:
t.Y()
case Ig[T]: // amd64:-".*assertE2I\\(",".*assertE2I2"
t.G()
}
}
func swI2G[T any](a Ix) {
switch t := a.(type) {
case Iy:
t.Y()
case Ig[T]: // amd64:-".*assertE2I\\(",".*assertE2I2"
t.G()
}
}
func swCaller() {
swGYZ[int]((Ig[int])(nil))
swE2G[int]((Ig[int])(nil))
swI2G[int]((Ix)(nil))
}