Add new optimized strlen for arm.
This optimized version is primarily targeted at cortex-a15.
Tested on all nexus devices using the system/extras/libc_test strlen test.
Tested alignments from 1 to 32 that are powers of 2.
Tested that strlen does not cross page boundaries at all alignments.
Speed improvements listed below:
cortex-a15
- Sizes >= 32 bytes, ~75% improvement.
- Sizes >= 1024 bytes, ~250% improvement.
cortex-a9
- Sizes >= 32 bytes, ~75% improvement.
- Sizes >= 1024 bytes, ~85% improvement.
krait
- Sizes >= 32 bytes, ~95% improvement.
- Sizes >= 1024 bytes, ~160% improvement.
Merge from internal master.
(cherry-picked from 2fc071797743b88a9a47427d46baed7c7b24f4d2)
Change-Id: I1ceceb4e745fd68e9d946f96d1d42e0cdaff6ccf
diff --git a/libc/arch-arm/krait/krait.mk b/libc/arch-arm/krait/krait.mk
index 4847f86..288afbb 100644
--- a/libc/arch-arm/krait/krait.mk
+++ b/libc/arch-arm/krait/krait.mk
@@ -1,5 +1,7 @@
$(call libc-add-cpu-variant-src,MEMCPY,arch-arm/krait/bionic/memcpy.S)
$(call libc-add-cpu-variant-src,MEMSET,arch-arm/krait/bionic/memset.S)
$(call libc-add-cpu-variant-src,STRCMP,arch-arm/krait/bionic/strcmp.S)
+# Use cortex-a15 version of strlen.
+$(call libc-add-cpu-variant-src,STRLEN,arch-arm/cortex-a15/bionic/strlen.S)
include bionic/libc/arch-arm/generic/generic.mk