[MIPS] Optimize flow of csum_partial

Delete dead codes at end of the function and move small_csumcopy
there.  This makes some labels (maybe_end_cruft, small_memcpy,
end_bytes, out) needless and eliminates some branches.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 54 insertions, 75 deletions

diff --git a/arch/mips/lib/csum_partial.S b/arch/mips/lib/csum_partial.S
index 3bffdbb1c1f9..b04475d76f3c 100644
--- a/arch/mips/lib/csum_partial.S
+++ b/arch/mips/lib/csum_partial.S
@@ -65,64 +65,6 @@
 
         .text
         .set    noreorder
-
-/* unknown src alignment and < 8 bytes to go  */
-small_csumcpy:
-        move    a1, t2
-
-        andi    t0, a1, 4
-        beqz    t0, 1f
-         andi   t0, a1, 2
-
-        /* Still a full word to go  */
-        ulw     t1, (src)
-        PTR_ADDIU       src, 4
-        ADDC(sum, t1)
-
-1:      move    t1, zero
-        beqz    t0, 1f
-         andi   t0, a1, 1
-
-        /* Still a halfword to go  */
-        ulhu    t1, (src)
-        PTR_ADDIU       src, 2
-
-1:      beqz    t0, 1f
-         sll    t1, t1, 16
-
-        lbu     t2, (src)
-         nop
-
-#ifdef __MIPSEB__
-        sll     t2, t2, 8
-#endif
-        or      t1, t2
-
-1:      ADDC(sum, t1)
-
-        /* fold checksum */
-        sll     v1, sum, 16
-        addu    sum, v1
-        sltu    v1, sum, v1
-        srl     sum, sum, 16
-        addu    sum, v1
-
-        /* odd buffer alignment? */
-        beqz    t7, 1f
-         nop
-        sll     v1, sum, 8
-        srl     sum, sum, 8
-        or      sum, v1
-        andi    sum, 0xffff
-1:
-        .set    reorder
-        /* Add the passed partial csum.  */
-        ADDC(sum, a2)
-        jr      ra
-        .set    noreorder
-
-/* ------------------------------------------------------------------------- */
-
         .align  5
 LEAF(csum_partial)
         move    sum, zero
@@ -132,8 +74,7 @@ LEAF(csum_partial)
         bnez    t8, small_csumcpy               /* < 8 bytes to copy */
          move   t2, a1
 
-        beqz    a1, out
-         andi   t7, src, 0x1                    /* odd buffer? */
+        andi    t7, src, 0x1                    /* odd buffer? */
 
 hword_align:
         beqz    t7, word_align
@@ -232,8 +173,9 @@ move_32bytes:
         PTR_ADDU        src, src, 0x20
 
 do_end_words:
-        beqz    t8, maybe_end_cruft
-         LONG_SRL       t8, t8, 0x2
+        beqz    t8, small_csumcpy
+         andi   t2, a1, 0x3
+        LONG_SRL        t8, t8, 0x2
 
 end_words:
         lw      t0, (src)
@@ -242,21 +184,58 @@ end_words:
         bnez    t8, end_words
          PTR_ADDU       src, src, 0x4
 
-maybe_end_cruft:
-        andi    t2, a1, 0x3
+/* unknown src alignment and < 8 bytes to go  */
+small_csumcpy:
+        move    a1, t2
 
-small_memcpy:
- j small_csumcpy; move a1, t2           /* XXX ??? */
-        beqz    t2, out
-         move   a1, t2
+        andi    t0, a1, 4
+        beqz    t0, 1f
+         andi   t0, a1, 2
 
-end_bytes:
-        lb      t0, (src)
-        LONG_SUBU       a1, a1, 0x1
-        bnez    a2, end_bytes
-         PTR_ADDU       src, src, 0x1
+        /* Still a full word to go  */
+        ulw     t1, (src)
+        PTR_ADDIU       src, 4
+        ADDC(sum, t1)
+
+1:      move    t1, zero
+        beqz    t0, 1f
+         andi   t0, a1, 1
+
+        /* Still a halfword to go  */
+        ulhu    t1, (src)
+        PTR_ADDIU       src, 2
+
+1:      beqz    t0, 1f
+         sll    t1, t1, 16
+
+        lbu     t2, (src)
+         nop
+
+#ifdef __MIPSEB__
+        sll     t2, t2, 8
+#endif
+        or      t1, t2
+
+1:      ADDC(sum, t1)
 
-out:
+        /* fold checksum */
+        sll     v1, sum, 16
+        addu    sum, v1
+        sltu    v1, sum, v1
+        srl     sum, sum, 16
+        addu    sum, v1
+
+        /* odd buffer alignment? */
+        beqz    t7, 1f
+         nop
+        sll     v1, sum, 8
+        srl     sum, sum, 8
+        or      sum, v1
+        andi    sum, 0xffff
+1:
+        .set    reorder
+        /* Add the passed partial csum.  */
+        ADDC(sum, a2)
         jr      ra
-         move   v0, sum
+        .set    noreorder
         END(csum_partial)