From cd90698b541046c22544c2c057a4676368fd1d7f Mon Sep 17 00:00:00 2001 From: Will Newton Date: Wed, 7 Aug 2013 14:15:52 +0100 Subject: [PATCH] ARM: Improve armv7 memcpy performance. Only enter the aligned copy loop with buffers that can be 8-byte aligned. This improves performance slightly on Cortex-A9 and Cortex-A15 cores for large copies with buffers that are 4-byte aligned but not 8-byte aligned. ports/ChangeLog.arm: 2013-09-16 Will Newton * sysdeps/arm/armv7/multiarch/memcpy_impl.S: Tighten check on entry to aligned copy loop to improve performance. --- ports/ChangeLog.arm | 5 +++++ ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S | 11 +++++------ 2 files changed, 10 insertions(+), 6 deletions(-) diff --git a/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S b/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S index 3decad6..ad43a3d 100644 --- a/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S +++ b/ports/sysdeps/arm/armv7/multiarch/memcpy_impl.S @@ -24,7 +24,6 @@ ARMv6 (ARMv7-a if using Neon) ARM state Unaligned accesses - LDRD/STRD support unaligned word accesses */ @@ -369,8 +368,8 @@ ENTRY(memcpy) cfi_adjust_cfa_offset (FRAME_SIZE) cfi_rel_offset (tmp2, 0) cfi_remember_state - and tmp2, src, #3 - and tmp1, dst, #3 + and tmp2, src, #7 + and tmp1, dst, #7 cmp tmp1, tmp2 bne .Lcpy_notaligned @@ -381,9 +380,9 @@ ENTRY(memcpy) vmov.f32 s0, s0 #endif - /* SRC and DST have the same mutual 32-bit alignment, but we may + /* SRC and DST have the same mutual 64-bit alignment, but we may still need to pre-copy some bytes to get to natural alignment. - We bring DST into full 64-bit alignment. */ + We bring SRC and DST into full 64-bit alignment. */ lsls tmp2, dst, #29 beq 1f rsbs tmp2, tmp2, #0 @@ -515,7 +514,7 @@ ENTRY(memcpy) .Ltail63aligned: /* Count in tmp2. */ /* Copy up to 7 d-words of data. Similar to Ltail63unaligned, but - we know that the src and dest are 32-bit aligned so we can use + we know that the src and dest are 64-bit aligned so we can use LDRD/STRD to improve efficiency. */ /* TMP2 is now negative, but we don't care about that. The bottom six bits still tell us how many bytes are left to copy. */ -- 1.7.0.9.GIT