import (
"go/constant"
+ "go/token"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
}
}
}
+ if n.Op() == ir.OSWITCH {
+ n := n.(*ir.SwitchStmt)
+ // Use a closure wrapper here so we can use "return" to abort the analysis.
+ func() {
+ if n.Tag != nil && n.Tag.Op() == ir.OTYPESW {
+ return // no special type-switch case yet.
+ }
+ var x constant.Value // value we're switching on
+ if n.Tag != nil {
+ if ir.ConstType(n.Tag) == constant.Unknown {
+ return
+ }
+ x = n.Tag.Val()
+ } else {
+ x = constant.MakeBool(true) // switch { ... } => switch true { ... }
+ }
+ var def *ir.CaseClause
+ for _, cas := range n.Cases {
+ if len(cas.List) == 0 { // default case
+ def = cas
+ continue
+ }
+ for _, c := range cas.List {
+ if ir.ConstType(c) == constant.Unknown {
+ return // can't statically tell if it matches or not - give up.
+ }
+ if constant.Compare(x, token.EQL, c.Val()) {
+ for _, n := range cas.Body {
+ if n.Op() == ir.OFALL {
+ return // fallthrough makes it complicated - abort.
+ }
+ }
+ // This switch entry is the one that always triggers.
+ for _, cas2 := range n.Cases {
+ for _, c2 := range cas2.List {
+ if cas2 != cas || c2 != c {
+ ir.Visit(c2, markHiddenClosureDead)
+ }
+ }
+ if cas2 != cas {
+ ir.VisitList(cas2.Body, markHiddenClosureDead)
+ }
+ }
+
+ cas.List[0] = c
+ cas.List = cas.List[:1]
+ n.Cases[0] = cas
+ n.Cases = n.Cases[:1]
+ return
+ }
+ }
+ }
+ if def != nil {
+ for _, n := range def.Body {
+ if n.Op() == ir.OFALL {
+ return // fallthrough makes it complicated - abort.
+ }
+ }
+ for _, cas := range n.Cases {
+ if cas != def {
+ ir.VisitList(cas.List, markHiddenClosureDead)
+ ir.VisitList(cas.Body, markHiddenClosureDead)
+ }
+ }
+ n.Cases[0] = def
+ n.Cases = n.Cases[:1]
+ return
+ }
+
+ // TODO: handle case bodies ending with panic/return as we do in the IF case above.
+
+ // entire switch is a nop - no case ever triggers
+ for _, cas := range n.Cases {
+ ir.VisitList(cas.List, markHiddenClosureDead)
+ ir.VisitList(cas.Body, markHiddenClosureDead)
+ }
+ n.Cases = n.Cases[:0]
+ }()
+ }
if len(n.Init()) != 0 {
stmts(n.(ir.InitNode).PtrInit())
}
}
+// Test that switches on constant things, with constant cases, only cost anything for
+// the case that matches. See issue 50253.
+func switchConst1(p func(string)) { // ERROR "can inline switchConst" "p does not escape"
+ const c = 1
+ switch c {
+ case 0:
+ p("zero")
+ case 1:
+ p("one")
+ case 2:
+ p("two")
+ default:
+ p("other")
+ }
+}
+
+func switchConst2() string { // ERROR "can inline switchConst2"
+ switch runtime.GOOS {
+ case "linux":
+ return "Leenooks"
+ case "windows":
+ return "Windoze"
+ case "darwin":
+ return "MackBone"
+ case "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "100":
+ return "Numbers"
+ default:
+ return "oh nose!"
+ }
+}
+func switchConst3() string { // ERROR "can inline switchConst3"
+ switch runtime.GOOS {
+ case "Linux":
+ panic("Linux")
+ case "Windows":
+ panic("Windows")
+ case "Darwin":
+ panic("Darwin")
+ case "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", "30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40", "41", "42", "43", "44", "45", "46", "47", "48", "49", "50", "51", "52", "53", "54", "55", "56", "57", "58", "59", "60", "61", "62", "63", "64", "65", "66", "67", "68", "69", "70", "71", "72", "73", "74", "75", "76", "77", "78", "79", "80", "81", "82", "83", "84", "85", "86", "87", "88", "89", "90", "91", "92", "93", "94", "95", "96", "97", "98", "99", "100":
+ panic("Numbers")
+ default:
+ return "oh nose!"
+ }
+}
+
func inlineRangeIntoMe(data []int) { // ERROR "can inline inlineRangeIntoMe" "data does not escape"
rangeFunc(data, 12) // ERROR "inlining call to rangeFunc"
}