cmd/gc: rewrite argtype to substitute in a single pass
Substituting in multiple passes meant walking the type
multiple times, and worse, if a complex type was substituted
in an early pass, later passes would follow it, possibly recursively,
until hitting the depth 10 limit.
Change-Id: Ie61d6ec08438e297baabe932afe33d08f358e55f
Reviewed-on: https://go-review.googlesource.com/7625
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/src/cmd/internal/gc/subr.go b/src/cmd/internal/gc/subr.go
index f77d151..ec4958a 100644
--- a/src/cmd/internal/gc/subr.go
+++ b/src/cmd/internal/gc/subr.go
@@ -1369,66 +1369,57 @@
return r
}
-func subtype(stp **Type, t *Type, d int) bool {
-loop:
- st := *stp
- if st == nil {
- return false
+// substArgTypes substitutes the given list of types for
+// successive occurrences of the "any" placeholder in the
+// type syntax expression n.Type.
+func substArgTypes(n *Node, types ...*Type) {
+ for _, t := range types {
+ dowidth(t)
}
-
- d++
- if d >= 10 {
- return false
+ substAny(&n.Type, &types)
+ if len(types) > 0 {
+ Fatal("substArgTypes: too many argument types")
}
+}
- switch st.Etype {
- default:
- return false
-
- case TPTR32,
- TPTR64,
- TCHAN,
- TARRAY:
- stp = &st.Type
- goto loop
-
- case TANY:
- if st.Copyany == 0 {
- return false
+// substAny walks *tp, replacing instances of "any" with successive
+// elements removed from types.
+func substAny(tp **Type, types *[]*Type) {
+ for {
+ t := *tp
+ if t == nil {
+ return
}
- *stp = t
-
- case TMAP:
- if subtype(&st.Down, t, d) {
- break
- }
- stp = &st.Type
- goto loop
-
- case TFUNC:
- for {
- if subtype(&st.Type, t, d) {
- break
+ if t.Etype == TANY && t.Copyany != 0 {
+ if len(*types) == 0 {
+ Fatal("substArgTypes: not enough argument types")
}
- if subtype(&st.Type.Down.Down, t, d) {
- break
- }
- if subtype(&st.Type.Down, t, d) {
- break
- }
- return false
+ *tp = (*types)[0]
+ *types = (*types)[1:]
}
- case TSTRUCT:
- for st = st.Type; st != nil; st = st.Down {
- if subtype(&st.Type, t, d) {
- return true
+ switch t.Etype {
+ case TPTR32, TPTR64, TCHAN, TARRAY:
+ tp = &t.Type
+ continue
+
+ case TMAP:
+ substAny(&t.Down, types)
+ tp = &t.Type
+ continue
+
+ case TFUNC:
+ substAny(&t.Type, types)
+ substAny(&t.Type.Down.Down, types)
+ substAny(&t.Type.Down, types)
+
+ case TSTRUCT:
+ for t = t.Type; t != nil; t = t.Down {
+ substAny(&t.Type, types)
}
}
- return false
+ return
}
-
- return true
}
/*
@@ -1484,13 +1475,6 @@
return false
}
-func argtype(on *Node, t *Type) {
- dowidth(t)
- if !subtype(&on.Type, t, 0) {
- Fatal("argtype: failed %v %v\n", Nconv(on, 0), Tconv(t, 0))
- }
-}
-
func shallow(t *Type) *Type {
if t == nil {
return nil
@@ -2793,18 +2777,13 @@
fn = syslook("memequal", 1)
*needsize = 1
- case 1,
- 2,
- 4,
- 8,
- 16:
+ case 1, 2, 4, 8, 16:
buf := fmt.Sprintf("memequal%d", int(size)*8)
fn = syslook(buf, 1)
*needsize = 0
}
- argtype(fn, type_)
- argtype(fn, type_)
+ substArgTypes(fn, type_, type_)
return fn
}
