cmd/internal/obj/arm64: omit stack check for no-frame leafs

For leaf functions with zero-sized frames, there's no point in doing a
stack check, so omit it.

This aligns arm64 with other architectures.

Change-Id: I1fb483d62f1736af10c5110815d3f5a875a46d7f
Reviewed-on: https://go-review.googlesource.com/92037
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/internal/obj/arm64/obj7.go

@@ -552,6 +552,13 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 				c.cursym.Func.Text.Mark |= LEAF
 			}
 
+			if c.cursym.Func.Text.Mark&LEAF != 0 {
+				c.cursym.Set(obj.AttrLeaf, true)
+				if c.autosize == 0 {
+					break
+				}
+			}
+
 			if !p.From.Sym.NoSplit() {
 				p = c.stacksplit(p, c.autosize) // emit split check
 			}
@@ -560,12 +567,6 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
 			if aoffset > 0xF0 {
 				aoffset = 0xF0
 			}
-			if c.cursym.Func.Text.Mark&LEAF != 0 {
-				c.cursym.Set(obj.AttrLeaf, true)
-				if c.autosize == 0 {
-					break
-				}
-			}
 
 			// Frame is non-empty. Make sure to save link register, even if
 			// it is a leaf function, so that traceback works.