At the time being, memcmp() compares two chunks of memory
byte per byte.
This patch optimises the comparison by comparing word by word.
On the same way as commit 15c2d45d17418 ("powerpc: Add 64bit
optimised memcmp"), this patch moves memcmp() into a dedicated
file named memcmp_32.S
A small benchmark performed on an 8xx comparing two chuncks
of 512 bytes performed 100000 times gives:
Before : 5852274 TB ticks
After: 1488638 TB ticks
This is almost 4 times faster
Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
arch/powerpc/lib/Makefile | 4 ++--
arch/powerpc/lib/memcmp_32.S | 45 ++++++++++++++++++++++++++++++++++++++++++++
arch/powerpc/lib/string.S | 17 -----------------
3 files changed, 47 insertions(+), 19 deletions(-)
create mode 100644 arch/powerpc/lib/memcmp_32.S
diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index 2c9b8c0adf22..d0ca13ad8231 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -26,14 +26,14 @@ obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o
copypage_power7.o \
memcpy_power7.o
obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \
- memcpy_64.o memcmp_64.o pmem.o
+ memcpy_64.o pmem.o
obj64-$(CONFIG_SMP) += locks.o
obj64-$(CONFIG_ALTIVEC) += vmx-helper.o
obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
obj-y += checksum_$(BITS).o checksum_wrappers.o \
- string_$(BITS).o
+ string_$(BITS).o memcmp_$(BITS).o
obj-y += sstep.o ldstfp.o quad.o
obj64-y += quad.o
diff --git a/arch/powerpc/lib/memcmp_32.S b/arch/powerpc/lib/memcmp_32.S
new file mode 100644
index 000000000000..dcb6ab45be66
--- /dev/null
+++ b/arch/powerpc/lib/memcmp_32.S
@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * memcmp for PowerPC32
+ *
+ * Copyright (C) 1996 Paul Mackerras.
+ *
+ */
+
+#include <asm/ppc_asm.h>
+#include <asm/export.h>
+
+ .text
+
+_GLOBAL(memcmp)
+ srawi. r7, r5, 2 /* Divide len by 4 */
+ mr r6, r3
+ beq- 3f
+ mtctr r7
+ li r7, 0
+1: lwzx r3, r6, r7
+ lwzx r0, r4, r7
+ addi r7, r7, 4
+ cmplw cr0, r3, r0
+ bdnzt eq, 1b
+ bne 5f
+3: andi. r3, r5, 3
+ beqlr
+ cmplwi cr1, r3, 2
+ blt- cr1, 4f
+ lhzx r3, r6, r7
+ lhzx r0, r4, r7
+ addi r7, r7, 2
+ subf. r3, r0, r3
+ beqlr cr1
+ bnelr
+4: lbzx r3, r6, r7
+ lbzx r0, r4, r7
+ subf. r3, r0, r3
+ blr
+5: li r3, 1
+ bgtlr
+ li r3, -1
+ blr
+EXPORT_SYMBOL(memcmp)
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index 5343a88e619e..4b41970e9ed8 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -54,23 +54,6 @@ _GLOBAL(strncmp)
blr
EXPORT_SYMBOL(strncmp)
-#ifdef CONFIG_PPC32
-_GLOBAL(memcmp)
- PPC_LCMPI 0,r5,0
- beq- 2f
- mtctr r5
- addi r6,r3,-1
- addi r4,r4,-1
-1: lbzu r3,1(r6)
- lbzu r0,1(r4)
- subf. r3,r0,r3
- bdnzt 2,1b
- blr
-2: li r3,0
- blr
-EXPORT_SYMBOL(memcmp)
-#endif
-
_GLOBAL(memchr)
PPC_LCMPI 0,r5,0
beq- 2f
--
2.13.3
