From 45d8d77ad396419c1b95f696c83bf97ceada0f3a Mon Sep 17 00:00:00 2001
From: Steve Ellcey <sellcey@mips.com>
Date: Fri, 16 Oct 2015 14:32:49 -0700
Subject:     Make performance improvement to MIPS memcpy for small copies.

	* sysdeps/mips/memcpy.S (memcpy):  Add word copies for small aligned
	data.
---
 sysdeps/mips/memcpy.S | 45 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

(limited to 'sysdeps/mips')

diff --git a/sysdeps/mips/memcpy.S b/sysdeps/mips/memcpy.S
index c85935b811..6f63405333 100644
--- a/sysdeps/mips/memcpy.S
+++ b/sysdeps/mips/memcpy.S
@@ -295,7 +295,7 @@ L(memcpy):
  * size, copy dst pointer to v0 for the return value.
  */
 	slti	t2,a2,(2 * NSIZE)
-	bne	t2,zero,L(lastb)
+	bne	t2,zero,L(lasts)
 #if defined(RETURN_FIRST_PREFETCH) || defined(RETURN_LAST_PREFETCH)
 	move	v0,zero
 #else
@@ -546,7 +546,7 @@ L(chkw):
  */
 L(chk1w):
 	andi	a2,t8,(NSIZE-1)	/* a2 is the reminder past one (d)word chunks */
-	beq	a2,t8,L(lastb)
+	beq	a2,t8,L(lastw)
 	PTR_SUBU a3,t8,a2	/* a3 is count of bytes in one (d)word chunks */
 	PTR_ADDU a3,a0,a3	/* a3 is the dst address after loop */
 
@@ -558,6 +558,20 @@ L(wordCopy_loop):
 	bne	a0,a3,L(wordCopy_loop)
 	C_ST	REG3,UNIT(-1)(a0)
 
+/* If we have been copying double words, see if we can copy a single word
+   before doing byte copies.  We can have, at most, one word to copy.  */
+
+L(lastw):
+#ifdef USE_DOUBLE
+	andi    t8,a2,3		/* a2 is the remainder past 4 byte chunks.  */
+	beq	t8,a2,L(lastb)
+	lw	REG3,0(a1)
+	sw	REG3,0(a0)
+	PTR_ADDIU a0,a0,4
+	PTR_ADDIU a1,a1,4
+	move	a2,t8
+#endif
+
 /* Copy the last 8 (or 16) bytes */
 L(lastb):
 	blez	a2,L(leave)
@@ -572,6 +586,33 @@ L(leave):
 	j	ra
 	nop
 
+/* We jump here with a memcpy of less than 8 or 16 bytes, depending on
+   whether or not USE_DOUBLE is defined.  Instead of just doing byte
+   copies, check the alignment and size and use lw/sw if possible.
+   Otherwise, do byte copies.  */
+
+L(lasts):
+	andi	t8,a2,3
+	beq	t8,a2,L(lastb)
+
+	andi	t9,a0,3
+	bne	t9,zero,L(lastb)
+	andi	t9,a1,3
+	bne	t9,zero,L(lastb)
+
+	PTR_SUBU a3,a2,t8
+	PTR_ADDU a3,a0,a3
+
+L(wcopy_loop):
+	lw	REG3,0(a1)
+	PTR_ADDIU a0,a0,4
+	PTR_ADDIU a1,a1,4
+	bne	a0,a3,L(wcopy_loop)
+	sw	REG3,-4(a0)
+
+	b	L(lastb)
+	move	a2,t8
+
 #ifndef R6_CODE
 /*
  * UNALIGNED case, got here with a3 = "negu a0"
-- 
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