cmd/compile/internal/gc: eliminate stringsCompare for stackvar sorting
Passes go build -a -toolexec 'toolstash -cmp' std cmd.
Change-Id: I2a87d31da74affdf3d0f358d0efdb3f1c646d917
Reviewed-on: https://go-review.googlesource.com/14759
Reviewed-by: Dave Cheney <dave@cheney.net>
diff --git a/src/cmd/compile/internal/gc/pgen.go b/src/cmd/compile/internal/gc/pgen.go
index 7c918c5..cd8e66c 100644
--- a/src/cmd/compile/internal/gc/pgen.go
+++ b/src/cmd/compile/internal/gc/pgen.go
@@ -165,10 +165,7 @@
}
// cmpstackvarlt reports whether the stack variable a sorts before b.
-func cmpstackvarlt(a, b *Node) bool {
- return cmpstackvar(a, b) < 0
-}
-
+//
// Sort the list of stack variables. Autos after anything else,
// within autos, unused after used, within used, things with
// pointers first, zeroed things first, and then decreasing size.
@@ -177,48 +174,48 @@
// really means, in memory, things with pointers needing zeroing at
// the top of the stack and increasing in size.
// Non-autos sort on offset.
-func cmpstackvar(a *Node, b *Node) int {
+func cmpstackvarlt(a, b *Node) bool {
if a.Class != b.Class {
if a.Class == PAUTO {
- return +1
+ return false
}
- return -1
+ return true
}
if a.Class != PAUTO {
if a.Xoffset < b.Xoffset {
- return -1
+ return true
}
if a.Xoffset > b.Xoffset {
- return +1
+ return false
}
- return 0
+ return false
}
if a.Used != b.Used {
- return obj.Bool2int(b.Used) - obj.Bool2int(a.Used)
+ return a.Used
}
- ap := obj.Bool2int(haspointers(a.Type))
- bp := obj.Bool2int(haspointers(b.Type))
+ ap := haspointers(a.Type)
+ bp := haspointers(b.Type)
if ap != bp {
- return bp - ap
+ return ap
}
- ap = obj.Bool2int(a.Name.Needzero)
- bp = obj.Bool2int(b.Name.Needzero)
+ ap = a.Name.Needzero
+ bp = b.Name.Needzero
if ap != bp {
- return bp - ap
+ return ap
}
if a.Type.Width < b.Type.Width {
- return +1
+ return false
}
if a.Type.Width > b.Type.Width {
- return -1
+ return true
}
- return stringsCompare(a.Sym.Name, b.Sym.Name)
+ return a.Sym.Name < b.Sym.Name
}
// stkdelta records the stack offset delta for a node
@@ -244,7 +241,7 @@
markautoused(ptxt)
- listsort(&Curfn.Func.Dcl, cmpstackvar)
+ listsort(&Curfn.Func.Dcl, cmpstackvarlt)
// Unused autos are at the end, chop 'em off.
ll := Curfn.Func.Dcl
diff --git a/src/cmd/compile/internal/gc/pgen_test.go b/src/cmd/compile/internal/gc/pgen_test.go
index ce8b2b3..ebc91011 100644
--- a/src/cmd/compile/internal/gc/pgen_test.go
+++ b/src/cmd/compile/internal/gc/pgen_test.go
@@ -4,7 +4,10 @@
package gc
-import "testing"
+import (
+ "reflect"
+ "testing"
+)
// Test all code paths for cmpstackvarlt.
func TestCmpstackvar(t *testing.T) {
@@ -100,3 +103,74 @@
}
}
}
+
+func slice2nodelist(s []*Node) *NodeList {
+ var nl *NodeList
+ for _, n := range s {
+ nl = list(nl, n)
+ }
+ return nl
+}
+
+func nodelist2slice(nl *NodeList) []*Node {
+ var s []*Node
+ for l := nl; l != nil; l = l.Next {
+ s = append(s, l.N)
+ }
+ return s
+}
+
+func TestListsort(t *testing.T) {
+ inp := []*Node{
+ {Class: PFUNC, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 0, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 10, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 20, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Used: true, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{Haspointers: 1}, Name: &Name{}, Sym: &Sym{}}, // haspointers -> false
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{Needzero: true}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{Width: 1}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{Width: 2}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{Name: "abc"}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{Name: "xyz"}},
+ }
+ want := []*Node{
+ {Class: PFUNC, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 0, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 10, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PFUNC, Xoffset: 20, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Used: true, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{Needzero: true}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{Width: 2}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{Width: 1}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{Name: "abc"}},
+ {Class: PAUTO, Type: &Type{}, Name: &Name{}, Sym: &Sym{Name: "xyz"}},
+ {Class: PAUTO, Type: &Type{Haspointers: 1}, Name: &Name{}, Sym: &Sym{}}, // haspointers -> false
+ }
+ // haspointers updates Type.Haspointers as a side effect, so
+ // exercise this function on all inputs so that reflect.DeepEqual
+ // doesn't produce false positives.
+ for i := range want {
+ haspointers(want[i].Type)
+ haspointers(inp[i].Type)
+ }
+
+ nl := slice2nodelist(inp)
+ listsort(&nl, cmpstackvarlt)
+ got := nodelist2slice(nl)
+ if !reflect.DeepEqual(want, got) {
+ t.Error("listsort failed")
+ for i := range got {
+ g := got[i]
+ w := want[i]
+ eq := reflect.DeepEqual(w, g)
+ if !eq {
+ t.Log(i, w, g)
+ }
+ }
+ }
+}
diff --git a/src/cmd/compile/internal/gc/syntax.go b/src/cmd/compile/internal/gc/syntax.go
index 5081ea0..dd185f1 100644
--- a/src/cmd/compile/internal/gc/syntax.go
+++ b/src/cmd/compile/internal/gc/syntax.go
@@ -409,9 +409,10 @@
return concat(l, list1(n))
}
-// listsort sorts *l in place according to the 3-way comparison function f.
+// listsort sorts *l in place according to the comparison function lt.
+// The algorithm expects lt(a, b) to be equivalent to a < b.
// The algorithm is mergesort, so it is guaranteed to be O(n log n).
-func listsort(l **NodeList, f func(*Node, *Node) int) {
+func listsort(l **NodeList, lt func(*Node, *Node) bool) {
if *l == nil || (*l).Next == nil {
return
}
@@ -436,10 +437,10 @@
(*l).End = l1
l1 = *l
- listsort(&l1, f)
- listsort(&l2, f)
+ listsort(&l1, lt)
+ listsort(&l2, lt)
- if f(l1.N, l2.N) < 0 {
+ if lt(l1.N, l2.N) {
*l = l1
} else {
*l = l2
@@ -451,7 +452,7 @@
var le *NodeList
for (l1 != nil) && (l2 != nil) {
- for (l1.Next != nil) && f(l1.Next.N, l2.N) < 0 {
+ for (l1.Next != nil) && lt(l1.Next.N, l2.N) {
l1 = l1.Next
}
