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

Fixes buggy memset implementation
Use heavily optimized platform implementation
Follows amd64 & arm precedent

2 files changed, 16 insertions, 330 deletions

diff --git a/src/vm/amd64/crthelpers.S b/src/vm/amd64/crthelpers.S
index 168359e192..a9b54e4d3b 100644
--- a/src/vm/amd64/crthelpers.S
+++ b/src/vm/amd64/crthelpers.S
@@ -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.
 //
diff --git a/src/vm/arm64/crthelpers.S b/src/vm/arm64/crthelpers.S
index c8b108ca8f..c0317edf57 100644
--- a/src/vm/arm64/crthelpers.S
+++ b/src/vm/arm64/crthelpers.S
@@ -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