Revert "cmd/compile: improve equality algs for arrays of interfaces"

This reverts commit 7eab9506c92562fe49861597e7bf1fcb28f2fd40.

Reason for revert: Undoing to get back to semantics discussed in #8606.

Change-Id: If0cd7518c10c37a81fdbb4ae112239e04c0b1448
Reviewed-on: https://go-review.googlesource.com/c/go/+/236278
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
diff --git a/src/cmd/compile/internal/gc/alg.go b/src/cmd/compile/internal/gc/alg.go
index b55109b..ecbed1a 100644
--- a/src/cmd/compile/internal/gc/alg.go
+++ b/src/cmd/compile/internal/gc/alg.go
@@ -591,24 +591,6 @@
 		}
 
 		switch t.Elem().Etype {
-		case TINTER:
-			// Do two loops. First, check that all the types match (cheap).
-			// Second, check that all the data match (expensive).
-			// TODO: when the array size is small, unroll the tab match checks.
-			checkAll(3, func(pi, qi *Node) *Node {
-				// Compare types.
-				pi = typecheck(pi, ctxExpr)
-				qi = typecheck(qi, ctxExpr)
-				eqtab, _ := eqinterface(pi, qi)
-				return eqtab
-			})
-			checkAll(1, func(pi, qi *Node) *Node {
-				// Compare data.
-				pi = typecheck(pi, ctxExpr)
-				qi = typecheck(qi, ctxExpr)
-				_, eqdata := eqinterface(pi, qi)
-				return eqdata
-			})
 		case TSTRING:
 			// Do two loops. First, check that all the lengths match (cheap).
 			// Second, check that all the contents match (expensive).