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[Arm64/Linux] Use platform memset/memcpy #17536

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Apr 13, 2018
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[Arm64/Linux] Use platform memset/memcpy #17536

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2 changes: 1 addition & 1 deletion src/vm/amd64/crthelpers.S
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Expand Up @@ -8,7 +8,7 @@

// JIT_MemSet/JIT_MemCpy
//
// It is IMPORANT that the exception handling code is able to find these guys
// It is IMPORTANT that the exception handling code is able to find these guys
// on the stack, but on non-windows platforms we can just defer to the platform
// implementation.
//
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344 changes: 15 additions & 329 deletions src/vm/arm64/crthelpers.S
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Expand Up @@ -2,347 +2,33 @@
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

// ==++==
//

#include "unixasmmacros.inc"

// JIT_MemSet/JIT_MemCpy
//
// ==--==

// Calls to JIT_MemSet is emitted by jit for initialization of large structs.
// We need to provide our own implementation of memset instead of using the ones in crt because crt implementation does not gurantee
// that aligned 8/4/2 - byte memory will be written atomically. This is required because members in a struct can be read atomically
// and their values should be written atomically.
//
//
//void JIT_MemSet(void *dst, int val, SIZE_T count)
//
// uint64_t valEx = (unsigned char)val;
// valEx = valEx | valEx << 8;
// valEx = valEx | valEx << 16;
// valEx = valEx | valEx << 32;
//
// size_t dc_zva_size = 4ULL << DCZID_EL0.BS;
//
// uint64_t use_dc_zva = (val == 0) && !DCZID_EL0.p ? count / (2 * dc_zva_size) : 0; // ~Minimum size (assumes worst case alignment)
//
// // If not aligned then make it 8-byte aligned
// if(((uint64_t)dst&0xf) != 0)
// {
// // Calculate alignment we can do without exceeding count
// // Use math to avoid introducing more unpredictable branches
// // Due to inherent mod in lsr, ~7 is used instead of ~0 to handle count == 0
// // Note logic will fail is count >= (1 << 61). But this exceeds max physical memory for arm64
// uint8_t align = (dst & 0x7) & (~uint64_t(7) >> (countLeadingZeros(count) mod 64))
//
// if(align&0x1)
// {
// *(unit8_t*)dst = (unit8_t)valEx;
// dst = (unit8_t*)dst + 1;
// count-=1;
// }
//
// if(align&0x2)
// {
// *(unit16_t*)dst = (unit16_t)valEx;
// dst = (unit16_t*)dst + 1;
// count-=2;
// }
//
// if(align&0x4)
// {
// *(unit32_t*)dst = (unit32_t)valEx;
// dst = (unit32_t*)dst + 1;
// count-=4;
// }
// }
//
// if(use_dc_zva)
// {
// // If not aligned then make it aligned to dc_zva_size
// if(dst&0x8)
// {
// *(uint64_t*)dst = (uint64_t)valEx;
// dst = (uint64_t*)dst + 1;
// count-=8;
// }
// It is IMPORTANT that the exception handling code is able to find these guys
// on the stack, but on non-windows platforms we can just defer to the platform
// implementation.
//
// while(dst & (dc_zva_size - 1))
// {
// *(uint64_t*)dst = valEx;
// dst = (uint64_t*)dst + 1;
// *(uint64_t*)dst = valEx;
// dst = (uint64_t*)dst + 1;
// count-=16;
// }
//
// count -= dc_zva_size;
//
// while(count >= 0)
// {
// dc_zva(dst);
// dst = (uint8_t*)dst + dc_zva_size;
// count-=dc_zva_size;
// }
//
// count += dc_zva_size;
// }
//
// count-=16;
//
// while(count >= 0)
// {
// *(uint64_t*)dst = valEx;
// dst = (uint64_t*)dst + 1;
// *(uint64_t*)dst = valEx;
// dst = (uint64_t*)dst + 1;
// count-=16;
// }
//
// if(count & 8)
// {
// *(uint64_t*)dst = valEx;
// dst = (uint64_t*)dst + 1;
// }
//
// if(count & 4)
// {
// *(uint32_t*)dst = (uint32_t)valEx;
// dst = (uint32_t*)dst + 1;
// }
//
// if(count & 2)
// {
// *(uint16_t*)dst = (uint16_t)valEx;
// dst = (uint16_t*)dst + 1;
// }
//
// if(count & 1)
// {
// *(uint8_t*)dst = (uint8_t)valEx;
// }
//
//

// Assembly code corresponding to above C++ method. JIT_MemSet can AV and clr exception personality routine needs to
// determine if the exception has taken place inside JIT_Memset in order to throw corresponding managed exception.
// Determining this is slow if the method were implemented as C++ method (using unwind info). In .asm file by adding JIT_MemSet_End
// marker it can be easily determined if exception happened in JIT_MemSet. Therefore, JIT_MemSet has been written in assembly instead of
// as C++ method.

LEAF_ENTRY JIT_MemSet, _TEXT
ands w8, w1, #0xff
mrs x3, DCZID_EL0 // x3 = DCZID_EL0
mov x6, #4
lsr x11, x2, #3 // x11 = count >> 3

orr w8, w8, w8, lsl #8
and x5, x3, #0xf // x5 = dczid_el0.bs
csel x11, x11, xzr, eq // x11 = (val == 0) ? count >> 3 : 0
tst x3, (1 << 4)

orr w8, w8, w8, lsl #0x10
csel x11, x11, xzr, eq // x11 = (val == 0) && !DCZID_EL0.p ? count >> 3 : 0
ands x3, x0, #7 // x3 = dst & 7
lsl x9, x6, x5 // x9 = size

orr x8, x8, x8, lsl #0x20
lsr x11, x11, x5 // x11 = (val == 0) && !DCZID_EL0.p ? count >> (3 + DCZID_EL0.bs) : 0
sub x10, x9, #1 // x10 = mask

b.eq LOCAL_LABEL(JIT_MemSet_0x80)

movn x4, #7
clz x5, x2
lsr x4, x4, x5
and x3, x3, x4
cbz x2, LOCAL_LABEL(JIT_MemSet_ret)

tbz x3, #0, LOCAL_LABEL(JIT_MemSet_0x2c)
strb w8, [x0], #1
sub x2, x2, #1
LOCAL_LABEL(JIT_MemSet_0x2c):
tbz x3, #1, LOCAL_LABEL(JIT_MemSet_0x5c)
strh w8, [x0], #2
sub x2, x2, #2
LOCAL_LABEL(JIT_MemSet_0x5c):
tbz x3, #2, LOCAL_LABEL(JIT_MemSet_0x80)
str w8, [x0], #4
sub x2, x2, #4
LOCAL_LABEL(JIT_MemSet_0x80):
cbz x11, LOCAL_LABEL(JIT_MemSet_0x9c)
tbz x0, #3, LOCAL_LABEL(JIT_MemSet_0x84)
str x8, [x0], #8
sub x2, x2, #8
strb w1, [x0]

b LOCAL_LABEL(JIT_MemSet_0x85)
LOCAL_LABEL(JIT_MemSet_0x84):
stp x8, x8, [x0], #16
sub x2, x2, #16
LOCAL_LABEL(JIT_MemSet_0x85):
tst x0, x10
b.ne LOCAL_LABEL(JIT_MemSet_0x84)
b C_PLTFUNC(memset)

b LOCAL_LABEL(JIT_MemSet_0x8a)
LOCAL_LABEL(JIT_MemSet_0x88):
dc zva, x0
add x0, x0, x9
LOCAL_LABEL(JIT_MemSet_0x8a):
subs x2, x2, x9
b.ge LOCAL_LABEL(JIT_MemSet_0x88)

LOCAL_LABEL(JIT_MemSet_0x8c):
add x2, x2, x9

LOCAL_LABEL(JIT_MemSet_0x9c):
b LOCAL_LABEL(JIT_MemSet_0xa8)
LOCAL_LABEL(JIT_MemSet_0xa0):
stp x8, x8, [x0], #16
LOCAL_LABEL(JIT_MemSet_0xa8):
subs x2, x2, #16
b.ge LOCAL_LABEL(JIT_MemSet_0xa0)

LOCAL_LABEL(JIT_MemSet_0xb0):
tbz x2, #3, LOCAL_LABEL(JIT_MemSet_0xb4)
str x8, [x0], #8
LOCAL_LABEL(JIT_MemSet_0xb4):
tbz x2, #2, LOCAL_LABEL(JIT_MemSet_0xc8)
str w8, [x0], #4
LOCAL_LABEL(JIT_MemSet_0xc8):
tbz x2, #1, LOCAL_LABEL(JIT_MemSet_0xdc)
strh w8, [x0], #2
LOCAL_LABEL(JIT_MemSet_0xdc):
tbz x2, #0, LOCAL_LABEL(JIT_MemSet_0xe8)
strb w8, [x0]
LOCAL_LABEL(JIT_MemSet_0xe8):
LOCAL_LABEL(JIT_MemSet_ret):
ret lr
LEAF_END_MARKED JIT_MemSet, _TEXT

// See comments above for JIT_MemSet
LEAF_ENTRY JIT_MemCpy, _TEXT
cbz x2, LOCAL_LABEL(JIT_MemCpy_ret)

//void JIT_MemCpy(void *dst, const void *src, SIZE_T count)
//
// // If not aligned then make it 8-byte aligned
// if(((uintptr_t)dst&0x7) != 0)
// {
// // Calculate alignment we can do without exceeding count
// // Use math to avoid introducing more unpredictable branches
// // Due to inherent mod in lsr, ~7 is used instead of ~0 to handle count == 0
// // Note logic will fail is count >= (1 << 61). But this exceeds max physical memory for arm64
// uint8_t align = (dst & 0x7) & (~uint64_t(7) >> (countLeadingZeros(count) mod 64))
//
// if(align&0x1)
// {
// *(unit8_t*)dst = *(unit8_t*)src;
// dst = (unit8_t*)dst + 1;
// src = (unit8_t*)src + 1;
// count-=1;
// }
//
// if(align&0x2)
// {
// *(unit16_t*)dst = *(unit16_t*)src;
// dst = (unit16_t*)dst + 1;
// src = (unit16_t*)src + 1;
// count-=2;
// }
//
// if(align&0x4)
// {
// *(unit32_t*)dst = *(unit32_t*)src;
// dst = (unit32_t*)dst + 1;
// src = (unit32_t*)src + 1;
// count-=4;
// }
// }
//
// count-=16;
//
// while(count >= 0)
// {
// *(unit64_t*)dst = *(unit64_t*)src;
// dst = (unit64_t*)dst + 1;
// src = (unit64_t*)src + 1;
// *(unit64_t*)dst = *(unit64_t*)src;
// dst = (unit64_t*)dst + 1;
// src = (unit64_t*)src + 1;
// count-=16;
// }
//
// if(count & 8)
// {
// *(unit64_t*)dst = *(unit64_t*)src;
// dst = (unit64_t*)dst + 1;
// src = (unit64_t*)src + 1;
// }
//
// if(count & 4)
// {
// *(unit32_t*)dst = *(unit32_t*)src;
// dst = (unit32_t*)dst + 1;
// src = (unit32_t*)src + 1;
// }
//
// if(count & 2)
// {
// *(unit16_t*)dst = *(unit16_t*)src;
// dst = (unit16_t*)dst + 1;
// src = (unit16_t*)src + 1;
// }
//
// if(count & 1)
// {
// *(unit8_t*)dst = *(unit8_t*)src;
// }
//
//
strb wzr, [x0]
ldrb wzr, [x1]

// Assembly code corresponding to above C++ method.
// See comments above for JIT_MemSet method
LEAF_ENTRY JIT_MemCpy, _TEXT
ands x3, x0, #7
movn x4, #7
clz x5, x2
b.eq LOCAL_LABEL(JIT_MemCpy_0xa8)
lsr x4, x4, x5
and x3, x3, x4
tbz x3, #0, LOCAL_LABEL(JIT_MemCpy_0x2c)
ldrsb w8, [x1], #1
strb w8, [x0], #1
sub x2, x2, #1
LOCAL_LABEL(JIT_MemCpy_0x2c):
tbz x3, #1, LOCAL_LABEL(JIT_MemCpy_0x5c)
ldrsh w8, [x1], #2
strh w8, [x0], #2
sub x2, x2, #2
LOCAL_LABEL(JIT_MemCpy_0x5c):
tbz x3, #2, LOCAL_LABEL(JIT_MemCpy_0xa8)
ldr w8, [x1], #4
str w8, [x0], #4
sub x2, x2, #4
b LOCAL_LABEL(JIT_MemCpy_0xa8)
LOCAL_LABEL(JIT_MemCpy_0xa0):
ldp x8, x9, [x1], #16
stp x8, x9, [x0], #16
LOCAL_LABEL(JIT_MemCpy_0xa8):
subs x2, x2, #16
b.ge LOCAL_LABEL(JIT_MemCpy_0xa0)
LOCAL_LABEL(JIT_MemCpy_0xb0):
tbz x2, #3, LOCAL_LABEL(JIT_MemCpy_0xb4)
ldr x8, [x1], #8
str x8, [x0], #8
LOCAL_LABEL(JIT_MemCpy_0xb4):
tbz x2, #2, LOCAL_LABEL(JIT_MemCpy_0xc8)
ldr w8, [x1], #4
str w8, [x0], #4
LOCAL_LABEL(JIT_MemCpy_0xc8):
tbz x2, #1, LOCAL_LABEL(JIT_MemCpy_0xdc)
ldrsh w8, [x1], #2
strh w8, [x0], #2
LOCAL_LABEL(JIT_MemCpy_0xdc):
tbz x2, #0, LOCAL_LABEL(JIT_MemCpy_0xe8)
ldrsb w8, [x1]
strb w8, [x0]
LOCAL_LABEL(JIT_MemCpy_0xe8):
b C_PLTFUNC(memcpy)

LOCAL_LABEL(JIT_MemCpy_ret):
ret lr
LEAF_END_MARKED JIT_MemCpy, _TEXT