[PATCH 3/7] powerpc/lib: optimise PPC32 memcmp

[Christophe Leroy]

At the time being, memcmp() compares two chunks of memory
byte per byte.

This patch optimised the comparison by comparing word by word.

A small benchmark performed on an 8xx based on the comparison
of two chuncks of 512 bytes performed 10 times gives:

Before : 5852274 TB ticks
After:   1488638 TB ticks

This is almost 4 times faster

Signed-off-by: Christophe Leroy 
---
 arch/powerpc/lib/string_32.S | 42 +++---
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/lib/string_32.S b/arch/powerpc/lib/string_32.S
index 94e9c9bc31c3..5b2a73fb07be 100644
--- a/arch/powerpc/lib/string_32.S
+++ b/arch/powerpc/lib/string_32.S
@@ -19,13 +19,41 @@ _GLOBAL(memcmp)
PPC_LCMPI 0,r5,0
beq-2f
 #endif
-   mtctr   r5
-   addir6,r3,-1
-   addir4,r4,-1
-1: lbzur3,1(r6)
-   lbzur0,1(r4)
-   subf.   r3,r0,r3
-   bdnzt   2,1b
+   srawi.  r7, r5, 2   /* Divide len by 4 */
+   mr  r6, r3
+   beq-3f
+   mtctr   r7
+   li  r7, 0
+1:
+#ifdef __LITTLE_ENDIAN__
+   lwbrx   r3, r6, r7
+   lwbrx   r0, r4, r7
+#else
+   lwzxr3, r6, r7
+   lwzxr0, r4, r7
+#endif
+   addir7, r7, 4
+   subf.   r3, r0, r3
+   bdnzt   eq, 1b
+   bnelr
+   andi.   r5, r5, 3
+   beqlr
+3: cmplwi  cr1, r5, 2
+   blt-cr1, 4f
+#ifdef __LITTLE_ENDIAN__
+   lhbrx   r3, r6, r7
+   lhbrx   r0, r4, r7
+#else
+   lhzxr3, r6, r7
+   lhzxr0, r4, r7
+#endif
+   addir7, r7, 2
+   subf.   r3, r0, r3
+   beqlr   cr1
+   bnelr
+4: lbzxr3, r6, r7
+   lbzxr0, r4, r7
+   subf.   r3, r0, r3
blr
 #ifdef CONFIG_FORTIFY_SOURCE
 2: li  r3,0
-- 
2.13.3

[PATCH 3/7] powerpc/lib: optimise PPC32 memcmp

[Christophe Leroy]

At the time being, memcmp() compares two chunks of memory
byte per byte.

This patch optimised the comparison by comparing word by word.

A small benchmark performed on an 8xx based on the comparison
of two chuncks of 512 bytes performed 10 times gives:

Before : 5852274 TB ticks
After:   1488638 TB ticks

This is almost 4 times faster

Signed-off-by: Christophe Leroy 
---
 arch/powerpc/lib/string_32.S | 42 +++---
 1 file changed, 35 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/lib/string_32.S b/arch/powerpc/lib/string_32.S
index 94e9c9bc31c3..5b2a73fb07be 100644
--- a/arch/powerpc/lib/string_32.S
+++ b/arch/powerpc/lib/string_32.S
@@ -19,13 +19,41 @@ _GLOBAL(memcmp)
PPC_LCMPI 0,r5,0
beq-2f
 #endif
-   mtctr   r5
-   addir6,r3,-1
-   addir4,r4,-1
-1: lbzur3,1(r6)
-   lbzur0,1(r4)
-   subf.   r3,r0,r3
-   bdnzt   2,1b
+   srawi.  r7, r5, 2   /* Divide len by 4 */
+   mr  r6, r3
+   beq-3f
+   mtctr   r7
+   li  r7, 0
+1:
+#ifdef __LITTLE_ENDIAN__
+   lwbrx   r3, r6, r7
+   lwbrx   r0, r4, r7
+#else
+   lwzxr3, r6, r7
+   lwzxr0, r4, r7
+#endif
+   addir7, r7, 4
+   subf.   r3, r0, r3
+   bdnzt   eq, 1b
+   bnelr
+   andi.   r5, r5, 3
+   beqlr
+3: cmplwi  cr1, r5, 2
+   blt-cr1, 4f
+#ifdef __LITTLE_ENDIAN__
+   lhbrx   r3, r6, r7
+   lhbrx   r0, r4, r7
+#else
+   lhzxr3, r6, r7
+   lhzxr0, r4, r7
+#endif
+   addir7, r7, 2
+   subf.   r3, r0, r3
+   beqlr   cr1
+   bnelr
+4: lbzxr3, r6, r7
+   lbzxr0, r4, r7
+   subf.   r3, r0, r3
blr
 #ifdef CONFIG_FORTIFY_SOURCE
 2: li  r3,0
-- 
2.13.3