runtime: simplify amd64 memmove of 3/4 bytes

Change-Id: I132d3627ae301b68bf87eacb5bf41fd1ba2dcd91
Reviewed-on: https://go-review.googlesource.com/94025
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s
index 3462bc43fcb80a0ab41cd7fac926b3c63da3c3aa..924b11b97b7aae746799eba70db4e72e3b143d4a 100644 (file)
--- a/src/runtime/memmove_amd64.s
+++ b/src/runtime/memmove_amd64.s
@@ -48,7 +48,8 @@ tail:
        CMPQ    BX, $2
        JBE     move_1or2
        CMPQ    BX, $4
-       JBE     move_3or4
+       JB      move_3
+       JBE     move_4
        CMPQ    BX, $8
        JB      move_5through7
        JE      move_8
@@ -145,9 +146,7 @@ move_1or2:
        RET
 move_0:
        RET
-move_3or4:
-       CMPQ    BX, $4
-       JB      move_3
+move_4:
        MOVL    (SI), AX
        MOVL    AX, (DI)
        RET