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-rw-r--r--arch/x86_64/lib/memcpy.S93
1 files changed, 91 insertions, 2 deletions
diff --git a/arch/x86_64/lib/memcpy.S b/arch/x86_64/lib/memcpy.S
index 92dd805..5554948 100644
--- a/arch/x86_64/lib/memcpy.S
+++ b/arch/x86_64/lib/memcpy.S
@@ -11,8 +11,6 @@
*
* Output:
* rax original destination
- *
- * TODO: check best memcpy for PSC
*/
.globl __memcpy
@@ -20,6 +18,95 @@
.p2align 4
__memcpy:
memcpy:
+ pushq %rbx
+ movq %rdi,%rax
+
+ movl %edx,%ecx
+ shrl $6,%ecx
+ jz .Lhandle_tail
+
+ .p2align 4
+.Lloop_64:
+ decl %ecx
+
+ movq (%rsi),%r11
+ movq 8(%rsi),%r8
+
+ movq %r11,(%rdi)
+ movq %r8,1*8(%rdi)
+
+ movq 2*8(%rsi),%r9
+ movq 3*8(%rsi),%r10
+
+ movq %r9,2*8(%rdi)
+ movq %r10,3*8(%rdi)
+
+ movq 4*8(%rsi),%r11
+ movq 5*8(%rsi),%r8
+
+ movq %r11,4*8(%rdi)
+ movq %r8,5*8(%rdi)
+
+ movq 6*8(%rsi),%r9
+ movq 7*8(%rsi),%r10
+
+ movq %r9,6*8(%rdi)
+ movq %r10,7*8(%rdi)
+
+ leaq 64(%rsi),%rsi
+ leaq 64(%rdi),%rdi
+ jnz .Lloop_64
+
+.Lhandle_tail:
+ movl %edx,%ecx
+ andl $63,%ecx
+ shrl $3,%ecx
+ jz .Lhandle_7
+ .p2align 4
+.Lloop_8:
+ decl %ecx
+ movq (%rsi),%r8
+ movq %r8,(%rdi)
+ leaq 8(%rdi),%rdi
+ leaq 8(%rsi),%rsi
+ jnz .Lloop_8
+
+.Lhandle_7:
+ movl %edx,%ecx
+ andl $7,%ecx
+ jz .Lende
+ .p2align 4
+.Lloop_1:
+ movb (%rsi),%r8b
+ movb %r8b,(%rdi)
+ incq %rdi
+ incq %rsi
+ decl %ecx
+ jnz .Lloop_1
+
+.Lende:
+ popq %rbx
+ ret
+.Lfinal:
+
+ /* Some CPUs run faster using the string copy instructions.
+ It is also a lot simpler. Use this when possible */
+
+ .section .altinstructions,"a"
+ .align 8
+ .quad memcpy
+ .quad memcpy_c
+ .byte X86_FEATURE_REP_GOOD
+ .byte .Lfinal-memcpy
+ .byte memcpy_c_end-memcpy_c
+ .previous
+
+ .section .altinstr_replacement,"ax"
+ /* rdi destination
+ * rsi source
+ * rdx count
+ */
+memcpy_c:
movq %rdi,%rax
movl %edx,%ecx
shrl $3,%ecx
@@ -30,3 +117,5 @@ memcpy:
rep
movsb
ret
+memcpy_c_end:
+ .previous
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