o2-diff

--- before.s    2015-09-06 13:07:24.972328499 +0200
+++ after.s 2015-09-06 13:07:34.880435965 +0200
@@ -24,29 +24,26 @@
    @ link register save eliminated.
-   ands    r3, r2, #1
-   push    {r4, r5}
-   beq .L2
-   ldrb    r4, [r1]    @ zero_extendqisi2
-   adds    r5, r1, #1
+   push    {r4}
+   lsls    r4, r2, #31
+   bpl .L2
+   ldrb    r3, [r1]    @ zero_extendqisi2
+   adds    r4, r1, #1
    lsls    r1, r2, #30
    it  pl
-   strbpl  r4, [r0]
+   strbpl  r3, [r0]
    bpl .L1
-   mov r1, r5
-   ldrh    r2, [r1]
-   cbz r3, .L5
-.L4:
-   strb    r4, [r0]
-   adds    r0, r0, #1
-.L5:
-   strh    r2, [r0]    @ movhi
+   mov r1, r4
+.L9:
+   ldrh    r1, [r1]
+   lsls    r2, r2, #31
+   itt mi
+   strbmi  r3, [r0]
+   addmi   r0, r0, #1
+   strh    r1, [r0]    @ movhi
 .L1:
-   pop {r4, r5}
+   ldr r4, [sp], #4
    bx  lr
 .L2:
-   lsls    r2, r2, #30
-   bpl .L1
-   ldrh    r2, [r1]
-   cmp r3, #0
-   bne .L4
-   b   .L5
+   lsls    r4, r2, #30
+   bmi .L9
+   b   .L1
    .size   f2, .-f2