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cmd/compile: split genCaseClauses by switch type

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The implementations are going to start diverging more.
Instead of more if clauses and empty parameters,
specialize.

Change-Id: I44584450592e8c9f72a10d8ada859c07e9d9aa19
Reviewed-on: https://go-review.googlesource.com/26764
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Josh Bleecher Snyder 2016-06-03 12:05:32 -07:00
parent b046786528
commit b7ac426ee3
1 changed files with 49 additions and 32 deletions
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81
src/cmd/compile/internal/gc/swt.go
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@ -247,7 +247,7 @@ func (s *exprSwitch) walk(sw *Node) {
}
// Enumerate the cases and prepare the default case.
clauses := genCaseClauses(sw, s.kind)
clauses := s.genCaseClauses(sw.List.Slice())
sw.List.Set(nil)
cc := clauses.list
@ -414,12 +414,10 @@ func casebody(sw *Node, typeswvar *Node) {
lineno = lno
}
// genCaseClauses generates the caseClauses value
// corresponding to the clauses in the switch statement sw.
// Kind is the kind of switch statement.
func genCaseClauses(sw *Node, kind int) caseClauses {
// genCaseClauses generates the caseClauses value for clauses.
func (s *exprSwitch) genCaseClauses(clauses []*Node) caseClauses {
var cc caseClauses
for _, n := range sw.List.Slice() {
for _, n := range clauses {
if n.Left == nil {
// default case
if cc.defjmp != nil {
@ -428,8 +426,36 @@ func genCaseClauses(sw *Node, kind int) caseClauses {
cc.defjmp = n.Right
continue
}
c := caseClause{node: n, ordinal: len(cc.list)}
switch consttype(n.Left) {
case CTFLT, CTINT, CTRUNE, CTSTR:
c.isconst = true
}
cc.list = append(cc.list, c)
}
if kind == switchKindType && n.Left.Op == OLITERAL {
if cc.defjmp == nil {
cc.defjmp = Nod(OBREAK, nil, nil)
}
// diagnose duplicate cases
s.checkDupCases(cc.list)
return cc
}
// genCaseClauses generates the caseClauses value for clauses.
func (s *typeSwitch) genCaseClauses(clauses []*Node) caseClauses {
var cc caseClauses
for _, n := range clauses {
switch {
case n.Left == nil:
// default case
if cc.defjmp != nil {
Fatalf("duplicate default case not detected during typechecking")
}
cc.defjmp = n.Right
continue
case n.Left.Op == OLITERAL:
// nil case in type switch
if cc.niljmp != nil {
Fatalf("duplicate nil case not detected during typechecking")
@ -439,17 +465,11 @@ func genCaseClauses(sw *Node, kind int) caseClauses {
}
// general case
c := caseClause{node: n, ordinal: len(cc.list)}
if kind == switchKindType {
// type switch
c.isconst = !n.Left.Type.IsInterface()
c.hash = typehash(n.Left.Type)
} else {
// expression switch
switch consttype(n.Left) {
case CTFLT, CTINT, CTRUNE, CTSTR:
c.isconst = true
}
c := caseClause{
node: n,
ordinal: len(cc.list),
isconst: !n.Left.Type.IsInterface(),
hash: typehash(n.Left.Type),
}
cc.list = append(cc.list, c)
}
@ -458,21 +478,15 @@ func genCaseClauses(sw *Node, kind int) caseClauses {
cc.defjmp = Nod(OBREAK, nil, nil)
}
if cc.list == nil {
return cc
}
// sort by value and diagnose duplicate cases
if kind == switchKindType {
checkDupTypeCases(cc.list)
} else {
checkDupExprCases(cc.list)
}
// diagnose duplicate cases
s.checkDupCases(cc.list)
return cc
}
func checkDupTypeCases(cc []caseClause) {
func (s *typeSwitch) checkDupCases(cc []caseClause) {
if len(cc) < 2 {
return
}
// We store seen types in a map keyed by type hash.
// It is possible, but very unlikely, for multiple distinct types to have the same hash.
seen := make(map[uint32][]*Node)
@ -499,7 +513,10 @@ Outer:
}
}
func checkDupExprCases(cc []caseClause) {
func (s *exprSwitch) checkDupCases(cc []caseClause) {
if len(cc) < 2 {
return
}
sort.Sort(caseClauseByExpr(cc))
for i, c1 := range cc[:len(cc)-1] {
c2 := cc[i+1]
@ -556,7 +573,7 @@ func (s *typeSwitch) walk(sw *Node) {
// set up labels and jumps
casebody(sw, s.facename)
clauses := genCaseClauses(sw, switchKindType)
clauses := s.genCaseClauses(sw.List.Slice())
sw.List.Set(nil)
def := clauses.defjmp