MIPS: microMIPS: Optimise 'strncpy' core library function.

Optimise 'strncpy' to use microMIPS instructions and/or optimisations
for binary size reduction. When the microMIPS ISA is not being used,
the library function compiles to the original binary code.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

diff --git a/arch/mips/lib/strncpy_user.S b/arch/mips/lib/strncpy_user.S
index bad5394..92870b6 100644 (file)
--- a/arch/mips/lib/strncpy_user.S
+++ b/arch/mips/lib/strncpy_user.S
@@ -3,7 +3,8 @@
  * License.  See the file "COPYING" in the main directory of this archive
  * for more details.
  *
- * Copyright (c) 1996, 1999 by Ralf Baechle
+ * Copyright (C) 1996, 1999 by Ralf Baechle
+ * Copyright (C) 2011 MIPS Technologies, Inc.
  */
 #include <linux/errno.h>
 #include <asm/asm.h>
@@ -33,26 +34,27 @@ LEAF(__strncpy_from_user_asm)
        bnez            v0, .Lfault
 
 FEXPORT(__strncpy_from_user_nocheck_asm)
-       move            v0, zero
-       move            v1, a1
        .set            noreorder
-1:     EX(lbu, t0, (v1), .Lfault)
+       move            t0, zero
+       move            v1, a1
+1:     EX(lbu, v0, (v1), .Lfault)
        PTR_ADDIU       v1, 1
        R10KCBARRIER(0(ra))
-       beqz            t0, 2f
-        sb             t0, (a0)
-       PTR_ADDIU       v0, 1
-       .set            reorder
-       PTR_ADDIU       a0, 1
-       bne             v0, a2, 1b
-2:     PTR_ADDU        t0, a1, v0
-       xor             t0, a1
-       bltz            t0, .Lfault
+       beqz            v0, 2f
+        sb             v0, (a0)
+       PTR_ADDIU       t0, 1
+       bne             t0, a2, 1b
+        PTR_ADDIU      a0, 1
+2:     PTR_ADDU        v0, a1, t0
+       xor             v0, a1
+       bltz            v0, .Lfault
+        nop
        jr              ra                      # return n
+        move           v0, t0
        END(__strncpy_from_user_asm)
 
-.Lfault:       li              v0, -EFAULT
-       jr              ra
+.Lfault: jr            ra
+         li            v0, -EFAULT
 
        .section        __ex_table,"a"
        PTR             1b, .Lfault