cmd/compile: don't generate algs for [0]T and [1]T
All [0]T values are equal.
[1]T values are equal iff their sole components are.
This types show up most frequently as a by-product of variadic
function calls, such as fmt.Printf("abc") or fmt.Printf("%v", x).
Cuts 12k off cmd/go and 22k off golang.org/x/tools/cmd/godoc, approx 0.1% each.
For #6853 and #9930
Change-Id: Ic9b7aeb8cc945804246340f6f5e67bbf6008773e
Reviewed-on: https://go-review.googlesource.com/19766
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/cmd/compile/internal/gc/walk.go b/src/cmd/compile/internal/gc/walk.go
index e008317..f324d5e 100644
--- a/src/cmd/compile/internal/gc/walk.go
+++ b/src/cmd/compile/internal/gc/walk.go
@@ -3193,6 +3193,21 @@
return
}
+ if t.Etype == TARRAY {
+ // Zero- or single-element array, of any type.
+ switch t.Bound {
+ case 0:
+ finishcompare(np, n, Nodbool(n.Op == OEQ), init)
+ return
+ case 1:
+ l0 := Nod(OINDEX, l, Nodintconst(0))
+ r0 := Nod(OINDEX, r, Nodintconst(0))
+ a := Nod(n.Op, l0, r0)
+ finishcompare(np, n, a, init)
+ return
+ }
+ }
+
if t.Etype == TSTRUCT && countfield(t) <= 4 {
// Struct of four or fewer fields.
// Inline comparisons.
