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path: root/src/string/x86_64/memset.s
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Diffstat (limited to 'src/string/x86_64/memset.s')
-rw-r--r--src/string/x86_64/memset.s30
1 files changed, 16 insertions, 14 deletions
diff --git a/src/string/x86_64/memset.s b/src/string/x86_64/memset.s
index fc06eef8..263336b5 100644
--- a/src/string/x86_64/memset.s
+++ b/src/string/x86_64/memset.s
@@ -1,41 +1,43 @@
 .global memset
 .type memset,@function
 memset:
-	and $0xff,%esi
+	movzbl %sil,%esi
 	mov $0x101010101010101,%rax
-	mov %rdx,%rcx
-	mov %rdi,%r8
+	# 64-bit imul has 3-7 cycles latency, launch early
 	imul %rsi,%rax
-	cmp $16,%rcx
+
+	cmp $16,%rdx
 	jb 1f
 
-	mov %rax,-8(%rdi,%rcx)
+	mov %rdx,%rcx
+	mov %rdi,%r8
 	shr $3,%rcx
+	mov %rax,-8(%rdi,%rdx)
 	rep
 	stosq
 	mov %r8,%rax
 	ret
 
-1:	test %ecx,%ecx
+1:	test %edx,%edx
 	jz 1f
 
 	mov %al,(%rdi)
-	mov %al,-1(%rdi,%rcx)
-	cmp $2,%ecx
+	mov %al,-1(%rdi,%rdx)
+	cmp $2,%edx
 	jbe 1f
 
 	mov %al,1(%rdi)
-	mov %al,-2(%rdi,%rcx)
-	cmp $4,%ecx
+	mov %al,-2(%rdi,%rdx)
+	cmp $4,%edx
 	jbe 1f
 
 	mov %eax,(%rdi)
-	mov %eax,-4(%rdi,%rcx)
-	cmp $8,%ecx
+	mov %eax,-4(%rdi,%rdx)
+	cmp $8,%edx
 	jbe 1f
 
 	mov %eax,4(%rdi)
-	mov %eax,-8(%rdi,%rcx)
+	mov %eax,-8(%rdi,%rdx)
 
-1:	mov %r8,%rax
+1:	mov %rdi,%rax
 	ret