go/ir: emit Low expression before High in *ast.Slice

Author: dominikh

go/ir/UPSTREAM

@@ -5,5 +5,5 @@ The changes are too many to list here, and it is best to consider this package i
 Upstream changes still get applied when they address bugs in portions of code we have inherited.
 
 The last upstream commit we've looked at was:
-915f6209478fe61eb90dbe155a8a1c58655b931f
+b900e8804030b22a099f187ef7bdc65bed470c7f
 

go/ir/builder.go

@@ -680,12 +680,12 @@ func (b *builder) expr0(fn *Function, e ast.Expr, tv types.TypeAndValue) Value {
 		}
 
 		var low, high, max Value
-		if e.High != nil {
-			high = b.expr(fn, e.High)
-		}
 		if e.Low != nil {
 			low = b.expr(fn, e.Low)
 		}
+		if e.High != nil {
+			high = b.expr(fn, e.High)
+		}
 		if e.Slice3 {
 			max = b.expr(fn, e.Max)
 		}