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Date: Thu, 21 Oct 2010 15:52:09 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] x86/mem for v2.6.37
Linus,
Please pull the latest x86-mem-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git x86-mem-for-linus
Thanks,
Ingo
------------------>
Ma Ling (2):
x86, mem: Optimize memcpy by avoiding memory false dependece
x86, mem: Optimize memmove for small size and unaligned cases
Ma, Ling (1):
x86, mem: Don't implement forward memmove() as memcpy()
arch/x86/lib/memcpy_32.c | 199 +++++++++++++++++++++++++++++++++++++++++----
arch/x86/lib/memcpy_64.S | 158 +++++++++++++++++++++++-------------
arch/x86/lib/memmove_64.c | 189 ++++++++++++++++++++++++++++++++++++++++--
3 files changed, 465 insertions(+), 81 deletions(-)
diff --git a/arch/x86/lib/memcpy_32.c b/arch/x86/lib/memcpy_32.c
index 5415a9d..b908a59 100644
--- a/arch/x86/lib/memcpy_32.c
+++ b/arch/x86/lib/memcpy_32.c
@@ -22,22 +22,187 @@ EXPORT_SYMBOL(memset);
void *memmove(void *dest, const void *src, size_t n)
{
- int d0, d1, d2;
-
- if (dest < src) {
- memcpy(dest, src, n);
- } else {
- __asm__ __volatile__(
- "std\n\t"
- "rep\n\t"
- "movsb\n\t"
- "cld"
- : "=&c" (d0), "=&S" (d1), "=&D" (d2)
- :"0" (n),
- "1" (n-1+src),
- "2" (n-1+dest)
- :"memory");
- }
- return dest;
+ int d0,d1,d2,d3,d4,d5;
+ char *ret = dest;
+
+ __asm__ __volatile__(
+ /* Handle more 16bytes in loop */
+ "cmp $0x10, %0\n\t"
+ "jb 1f\n\t"
+
+ /* Decide forward/backward copy mode */
+ "cmp %2, %1\n\t"
+ "jb 2f\n\t"
+
+ /*
+ * movs instruction have many startup latency
+ * so we handle small size by general register.
+ */
+ "cmp $680, %0\n\t"
+ "jb 3f\n\t"
+ /*
+ * movs instruction is only good for aligned case.
+ */
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 4f\n\t"
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts forward in each loop.
+ */
+ "3:\n\t"
+ "sub $0x10, %0\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov 2*4(%1), %3\n\t"
+ "mov 3*4(%1), %4\n\t"
+ "mov %3, 2*4(%2)\n\t"
+ "mov %4, 3*4(%2)\n\t"
+ "lea 0x10(%1), %1\n\t"
+ "lea 0x10(%2), %2\n\t"
+ "jae 3b\n\t"
+ "add $0x10, %0\n\t"
+ "jmp 1f\n\t"
+
+ /*
+ * Handle data forward by movs.
+ */
+ ".p2align 4\n\t"
+ "4:\n\t"
+ "mov -4(%1, %0), %3\n\t"
+ "lea -4(%2, %0), %4\n\t"
+ "shr $2, %0\n\t"
+ "rep movsl\n\t"
+ "mov %3, (%4)\n\t"
+ "jmp 11f\n\t"
+ /*
+ * Handle data backward by movs.
+ */
+ ".p2align 4\n\t"
+ "6:\n\t"
+ "mov (%1), %3\n\t"
+ "mov %2, %4\n\t"
+ "lea -4(%1, %0), %1\n\t"
+ "lea -4(%2, %0), %2\n\t"
+ "shr $2, %0\n\t"
+ "std\n\t"
+ "rep movsl\n\t"
+ "mov %3,(%4)\n\t"
+ "cld\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Start to prepare for backward copy.
+ */
+ ".p2align 4\n\t"
+ "2:\n\t"
+ "cmp $680, %0\n\t"
+ "jb 5f\n\t"
+ "mov %1, %3\n\t"
+ "xor %2, %3\n\t"
+ "and $0xff, %3\n\t"
+ "jz 6b\n\t"
+
+ /*
+ * Calculate copy position to tail.
+ */
+ "5:\n\t"
+ "add %0, %1\n\t"
+ "add %0, %2\n\t"
+ "sub $0x10, %0\n\t"
+
+ /*
+ * We gobble 16byts backward in each loop.
+ */
+ "7:\n\t"
+ "sub $0x10, %0\n\t"
+
+ "mov -1*4(%1), %3\n\t"
+ "mov -2*4(%1), %4\n\t"
+ "mov %3, -1*4(%2)\n\t"
+ "mov %4, -2*4(%2)\n\t"
+ "mov -3*4(%1), %3\n\t"
+ "mov -4*4(%1), %4\n\t"
+ "mov %3, -3*4(%2)\n\t"
+ "mov %4, -4*4(%2)\n\t"
+ "lea -0x10(%1), %1\n\t"
+ "lea -0x10(%2), %2\n\t"
+ "jae 7b\n\t"
+ /*
+ * Calculate copy position to head.
+ */
+ "add $0x10, %0\n\t"
+ "sub %0, %1\n\t"
+ "sub %0, %2\n\t"
+
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ ".p2align 4\n\t"
+ "1:\n\t"
+ "cmp $8, %0\n\t"
+ "jb 8f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov 1*4(%1), %4\n\t"
+ "mov -2*4(%1, %0), %5\n\t"
+ "mov -1*4(%1, %0), %1\n\t"
+
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, 1*4(%2)\n\t"
+ "mov %5, -2*4(%2, %0)\n\t"
+ "mov %1, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ ".p2align 4\n\t"
+ "8:\n\t"
+ "cmp $4, %0\n\t"
+ "jb 9f\n\t"
+ "mov 0*4(%1), %3\n\t"
+ "mov -1*4(%1, %0), %4\n\t"
+ "mov %3, 0*4(%2)\n\t"
+ "mov %4, -1*4(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data from 2 bytes to 3 bytes.
+ */
+ ".p2align 4\n\t"
+ "9:\n\t"
+ "cmp $2, %0\n\t"
+ "jb 10f\n\t"
+ "movw 0*2(%1), %%dx\n\t"
+ "movw -1*2(%1, %0), %%bx\n\t"
+ "movw %%dx, 0*2(%2)\n\t"
+ "movw %%bx, -1*2(%2, %0)\n\t"
+ "jmp 11f\n\t"
+
+ /*
+ * Move data for 1 byte.
+ */
+ ".p2align 4\n\t"
+ "10:\n\t"
+ "cmp $1, %0\n\t"
+ "jb 11f\n\t"
+ "movb (%1), %%cl\n\t"
+ "movb %%cl, (%2)\n\t"
+ ".p2align 4\n\t"
+ "11:"
+ : "=&c" (d0), "=&S" (d1), "=&D" (d2),
+ "=r" (d3),"=r" (d4), "=r"(d5)
+ :"0" (n),
+ "1" (src),
+ "2" (dest)
+ :"memory");
+
+ return ret;
+
}
EXPORT_SYMBOL(memmove);
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index bcbcd1e..75ef61e 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -40,84 +40,132 @@
ENTRY(__memcpy)
ENTRY(memcpy)
CFI_STARTPROC
+ movq %rdi, %rax
/*
- * Put the number of full 64-byte blocks into %ecx.
- * Tail portion is handled at the end:
+ * Use 32bit CMP here to avoid long NOP padding.
*/
- movq %rdi, %rax
- movl %edx, %ecx
- shrl $6, %ecx
- jz .Lhandle_tail
+ cmp $0x20, %edx
+ jb .Lhandle_tail
- .p2align 4
-.Lloop_64:
/*
- * We decrement the loop index here - and the zero-flag is
- * checked at the end of the loop (instructions inbetween do
- * not change the zero flag):
+ * We check whether memory false dependece could occur,
+ * then jump to corresponding copy mode.
*/
- decl %ecx
+ cmp %dil, %sil
+ jl .Lcopy_backward
+ subl $0x20, %edx
+.Lcopy_forward_loop:
+ subq $0x20, %rdx
/*
- * Move in blocks of 4x16 bytes:
+ * Move in blocks of 4x8 bytes:
*/
- movq 0*8(%rsi), %r11
- movq 1*8(%rsi), %r8
- movq %r11, 0*8(%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
+ movq 0*8(%rsi), %r8
+ movq 1*8(%rsi), %r9
+ movq 2*8(%rsi), %r10
+ movq 3*8(%rsi), %r11
+ leaq 4*8(%rsi), %rsi
+
+ movq %r8, 0*8(%rdi)
+ movq %r9, 1*8(%rdi)
+ movq %r10, 2*8(%rdi)
+ movq %r11, 3*8(%rdi)
+ leaq 4*8(%rdi), %rdi
+ jae .Lcopy_forward_loop
+ addq $0x20, %rdx
+ jmp .Lhandle_tail
+
+.Lcopy_backward:
+ /*
+ * Calculate copy position to tail.
+ */
+ addq %rdx, %rsi
+ addq %rdx, %rdi
+ subq $0x20, %rdx
+ /*
+ * At most 3 ALU operations in one cycle,
+ * so append NOPS in the same 16bytes trunk.
+ */
+ .p2align 4
+.Lcopy_backward_loop:
+ subq $0x20, %rdx
+ movq -1*8(%rsi), %r8
+ movq -2*8(%rsi), %r9
+ movq -3*8(%rsi), %r10
+ movq -4*8(%rsi), %r11
+ leaq -4*8(%rsi), %rsi
+ movq %r8, -1*8(%rdi)
+ movq %r9, -2*8(%rdi)
+ movq %r10, -3*8(%rdi)
+ movq %r11, -4*8(%rdi)
+ leaq -4*8(%rdi), %rdi
+ jae .Lcopy_backward_loop
+ /*
+ * Calculate copy position to head.
+ */
+ addq $0x20, %rdx
+ subq %rdx, %rsi
+ subq %rdx, %rdi
.Lhandle_tail:
- movl %edx, %ecx
- andl $63, %ecx
- shrl $3, %ecx
- jz .Lhandle_7
+ cmpq $16, %rdx
+ jb .Lless_16bytes
+ /*
+ * Move data from 16 bytes to 31 bytes.
+ */
+ movq 0*8(%rsi), %r8
+ movq 1*8(%rsi), %r9
+ movq -2*8(%rsi, %rdx), %r10
+ movq -1*8(%rsi, %rdx), %r11
+ movq %r8, 0*8(%rdi)
+ movq %r9, 1*8(%rdi)
+ movq %r10, -2*8(%rdi, %rdx)
+ movq %r11, -1*8(%rdi, %rdx)
+ retq
.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 .Lend
+.Lless_16bytes:
+ cmpq $8, %rdx
+ jb .Lless_8bytes
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ movq 0*8(%rsi), %r8
+ movq -1*8(%rsi, %rdx), %r9
+ movq %r8, 0*8(%rdi)
+ movq %r9, -1*8(%rdi, %rdx)
+ retq
+ .p2align 4
+.Lless_8bytes:
+ cmpq $4, %rdx
+ jb .Lless_3bytes
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ movl (%rsi), %ecx
+ movl -4(%rsi, %rdx), %r8d
+ movl %ecx, (%rdi)
+ movl %r8d, -4(%rdi, %rdx)
+ retq
.p2align 4
+.Lless_3bytes:
+ cmpl $0, %edx
+ je .Lend
+ /*
+ * Move data from 1 bytes to 3 bytes.
+ */
.Lloop_1:
movb (%rsi), %r8b
movb %r8b, (%rdi)
incq %rdi
incq %rsi
- decl %ecx
+ decl %edx
jnz .Lloop_1
.Lend:
- ret
+ retq
CFI_ENDPROC
ENDPROC(memcpy)
ENDPROC(__memcpy)
diff --git a/arch/x86/lib/memmove_64.c b/arch/x86/lib/memmove_64.c
index 0a33909..6d0f0ec 100644
--- a/arch/x86/lib/memmove_64.c
+++ b/arch/x86/lib/memmove_64.c
@@ -8,14 +8,185 @@
#undef memmove
void *memmove(void *dest, const void *src, size_t count)
{
- if (dest < src) {
- return memcpy(dest, src, count);
- } else {
- char *p = dest + count;
- const char *s = src + count;
- while (count--)
- *--p = *--s;
- }
- return dest;
+ unsigned long d0,d1,d2,d3,d4,d5,d6,d7;
+ char *ret;
+
+ __asm__ __volatile__(
+ /* Handle more 32bytes in loop */
+ "mov %2, %3\n\t"
+ "cmp $0x20, %0\n\t"
+ "jb 1f\n\t"
+
+ /* Decide forward/backward copy mode */
+ "cmp %2, %1\n\t"
+ "jb 2f\n\t"
+
+ /*
+ * movsq instruction have many startup latency
+ * so we handle small size by general register.
+ */
+ "cmp $680, %0\n\t"
+ "jb 3f\n\t"
+ /*
+ * movsq instruction is only good for aligned case.
+ */
+ "cmpb %%dil, %%sil\n\t"
+ "je 4f\n\t"
+ "3:\n\t"
+ "sub $0x20, %0\n\t"
+ /*
+ * We gobble 32byts forward in each loop.
+ */
+ "5:\n\t"
+ "sub $0x20, %0\n\t"
+ "movq 0*8(%1), %4\n\t"
+ "movq 1*8(%1), %5\n\t"
+ "movq 2*8(%1), %6\n\t"
+ "movq 3*8(%1), %7\n\t"
+ "leaq 4*8(%1), %1\n\t"
+
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, 1*8(%2)\n\t"
+ "movq %6, 2*8(%2)\n\t"
+ "movq %7, 3*8(%2)\n\t"
+ "leaq 4*8(%2), %2\n\t"
+ "jae 5b\n\t"
+ "addq $0x20, %0\n\t"
+ "jmp 1f\n\t"
+ /*
+ * Handle data forward by movsq.
+ */
+ ".p2align 4\n\t"
+ "4:\n\t"
+ "movq %0, %8\n\t"
+ "movq -8(%1, %0), %4\n\t"
+ "lea -8(%2, %0), %5\n\t"
+ "shrq $3, %8\n\t"
+ "rep movsq\n\t"
+ "movq %4, (%5)\n\t"
+ "jmp 13f\n\t"
+ /*
+ * Handle data backward by movsq.
+ */
+ ".p2align 4\n\t"
+ "7:\n\t"
+ "movq %0, %8\n\t"
+ "movq (%1), %4\n\t"
+ "movq %2, %5\n\t"
+ "leaq -8(%1, %0), %1\n\t"
+ "leaq -8(%2, %0), %2\n\t"
+ "shrq $3, %8\n\t"
+ "std\n\t"
+ "rep movsq\n\t"
+ "cld\n\t"
+ "movq %4, (%5)\n\t"
+ "jmp 13f\n\t"
+
+ /*
+ * Start to prepare for backward copy.
+ */
+ ".p2align 4\n\t"
+ "2:\n\t"
+ "cmp $680, %0\n\t"
+ "jb 6f \n\t"
+ "cmp %%dil, %%sil\n\t"
+ "je 7b \n\t"
+ "6:\n\t"
+ /*
+ * Calculate copy position to tail.
+ */
+ "addq %0, %1\n\t"
+ "addq %0, %2\n\t"
+ "subq $0x20, %0\n\t"
+ /*
+ * We gobble 32byts backward in each loop.
+ */
+ "8:\n\t"
+ "subq $0x20, %0\n\t"
+ "movq -1*8(%1), %4\n\t"
+ "movq -2*8(%1), %5\n\t"
+ "movq -3*8(%1), %6\n\t"
+ "movq -4*8(%1), %7\n\t"
+ "leaq -4*8(%1), %1\n\t"
+
+ "movq %4, -1*8(%2)\n\t"
+ "movq %5, -2*8(%2)\n\t"
+ "movq %6, -3*8(%2)\n\t"
+ "movq %7, -4*8(%2)\n\t"
+ "leaq -4*8(%2), %2\n\t"
+ "jae 8b\n\t"
+ /*
+ * Calculate copy position to head.
+ */
+ "addq $0x20, %0\n\t"
+ "subq %0, %1\n\t"
+ "subq %0, %2\n\t"
+ "1:\n\t"
+ "cmpq $16, %0\n\t"
+ "jb 9f\n\t"
+ /*
+ * Move data from 16 bytes to 31 bytes.
+ */
+ "movq 0*8(%1), %4\n\t"
+ "movq 1*8(%1), %5\n\t"
+ "movq -2*8(%1, %0), %6\n\t"
+ "movq -1*8(%1, %0), %7\n\t"
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, 1*8(%2)\n\t"
+ "movq %6, -2*8(%2, %0)\n\t"
+ "movq %7, -1*8(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ ".p2align 4\n\t"
+ "9:\n\t"
+ "cmpq $8, %0\n\t"
+ "jb 10f\n\t"
+ /*
+ * Move data from 8 bytes to 15 bytes.
+ */
+ "movq 0*8(%1), %4\n\t"
+ "movq -1*8(%1, %0), %5\n\t"
+ "movq %4, 0*8(%2)\n\t"
+ "movq %5, -1*8(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "10:\n\t"
+ "cmpq $4, %0\n\t"
+ "jb 11f\n\t"
+ /*
+ * Move data from 4 bytes to 7 bytes.
+ */
+ "movl (%1), %4d\n\t"
+ "movl -4(%1, %0), %5d\n\t"
+ "movl %4d, (%2)\n\t"
+ "movl %5d, -4(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "11:\n\t"
+ "cmp $2, %0\n\t"
+ "jb 12f\n\t"
+ /*
+ * Move data from 2 bytes to 3 bytes.
+ */
+ "movw (%1), %4w\n\t"
+ "movw -2(%1, %0), %5w\n\t"
+ "movw %4w, (%2)\n\t"
+ "movw %5w, -2(%2, %0)\n\t"
+ "jmp 13f\n\t"
+ "12:\n\t"
+ "cmp $1, %0\n\t"
+ "jb 13f\n\t"
+ /*
+ * Move data for 1 byte.
+ */
+ "movb (%1), %4b\n\t"
+ "movb %4b, (%2)\n\t"
+ "13:\n\t"
+ : "=&d" (d0), "=&S" (d1), "=&D" (d2), "=&a" (ret) ,
+ "=r"(d3), "=r"(d4), "=r"(d5), "=r"(d6), "=&c" (d7)
+ :"0" (count),
+ "1" (src),
+ "2" (dest)
+ :"memory");
+
+ return ret;
+
}
EXPORT_SYMBOL(memmove);
--
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