checkasm: Check register clobbering on aarch64

This is disabled on iOS, since iOS uses a slightly different ABI
for vararg parameters.
Signed-off-by: Martin Storsjö <martin@martin.st>

tests/checkasm/aarch64/Makefile

+CHECKASMOBJS += aarch64/checkasm.o

tests/checkasm/aarch64/checkasm.S

+/****************************************************************************
+ * Assembly testing and benchmarking tool
+ * Copyright (c) 2015 Martin Storsjo
+ * Copyright (c) 2015 Janne Grunau
+ *
+ * This file is part of Libav.
+ *
+ * Libav is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Libav is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02111, USA.
+ *****************************************************************************/
+
+#include "libavutil/aarch64/asm.S"
+
+const register_init
+    .quad 0x21f86d66c8ca00ce
+    .quad 0x75b6ba21077c48ad
+    .quad 0xed56bb2dcb3c7736
+    .quad 0x8bda43d3fd1a7e06
+    .quad 0xb64a9c9e5d318408
+    .quad 0xdf9a54b303f1d3a3
+    .quad 0x4a75479abd64e097
+    .quad 0x249214109d5d1c88
+    .quad 0x1a1b2550a612b48c
+    .quad 0x79445c159ce79064
+    .quad 0x2eed899d5a28ddcd
+    .quad 0x86b2536fcd8cf636
+    .quad 0xb0856806085e7943
+    .quad 0x3f2bf84fc0fcca4e
+    .quad 0xacbd382dcf5b8de2
+    .quad 0xd229e1f5b281303f
+    .quad 0x71aeaff20b095fd9
+    .quad 0xab63e2e11fa38ed9
+endconst
+
+
+const error_message
+    .asciz "failed to preserve register"
+endconst
+
+
+// max number of args used by any asm function.
+#define MAX_ARGS 15
+
+#define ARG_STACK ((8*(MAX_ARGS - 7) + 15) & ~15)
+
+function checkasm_checked_call, export=1
+    stp         x29, x30, [sp, #-16]!
+    mov         x29, sp
+    stp         x19, x20, [sp, #-16]!
+    stp         x21, x22, [sp, #-16]!
+    stp         x23, x24, [sp, #-16]!
+    stp         x25, x26, [sp, #-16]!
+    stp         x27, x28, [sp, #-16]!
+    stp         d8,  d9,  [sp, #-16]!
+    stp         d10, d11, [sp, #-16]!
+    stp         d12, d13, [sp, #-16]!
+    stp         d14, d15, [sp, #-16]!
+
+    movrel      x9, register_init
+    ldp         d8,  d9,  [x9], #16
+    ldp         d10, d11, [x9], #16
+    ldp         d12, d13, [x9], #16
+    ldp         d14, d15, [x9], #16
+    ldp         x19, x20, [x9], #16
+    ldp         x21, x22, [x9], #16
+    ldp         x23, x24, [x9], #16
+    ldp         x25, x26, [x9], #16
+    ldp         x27, x28, [x9], #16
+
+    sub         sp,  sp,  #ARG_STACK
+.equ pos, 0
+// the first stacked arg is copied to x7
+.rept MAX_ARGS-7
+    ldr         x9, [x29, #16 + 8 + pos]
+    str         x9, [sp, #pos]
+.equ pos, pos + 8
+.endr
+
+    mov         x12, x0
+    mov         x0,  x1
+    mov         x1,  x2
+    mov         x2,  x3
+    mov         x3,  x4
+    mov         x4,  x5
+    mov         x5,  x6
+    mov         x6,  x7
+    ldr         x7,  [x29, #16]
+    blr         x12
+    add         sp,  sp,  #ARG_STACK
+    stp         x0,  x1,  [sp, #-16]!
+    movrel      x9, register_init
+    movi        v3.8h,  #0
+
+.macro check_reg_neon reg1, reg2
+    ldr         q0,  [x9], #16
+    uzp1        v1.2d,  v\reg1\().2d, v\reg2\().2d
+    eor         v0.16b, v0.16b, v1.16b
+    orr         v3.16b, v3.16b, v0.16b
+.endm
+    check_reg_neon  8,  9
+    check_reg_neon  10, 11
+    check_reg_neon  12, 13
+    check_reg_neon  14, 15
+    uqxtn       v3.8b,  v3.8h
+    umov        x3,  v3.d[0]
+
+.macro check_reg reg1, reg2
+    ldp         x0,  x1,  [x9], #16
+    eor         x0,  x0,  \reg1
+    eor         x1,  x1,  \reg2
+    orr         x3,  x3,  x0
+    orr         x3,  x3,  x1
+.endm
+    check_reg   x19, x20
+    check_reg   x21, x22
+    check_reg   x23, x24
+    check_reg   x25, x26
+    check_reg   x27, x28
+
+    cbz         x3,  0f
+
+    movrel      x0, error_message
+    bl          X(checkasm_fail_func)
+0:
+    ldp         x0,  x1,  [sp], #16
+    ldp         d14, d15, [sp], #16
+    ldp         d12, d13, [sp], #16
+    ldp         d10, d11, [sp], #16
+    ldp         d8,  d9,  [sp], #16
+    ldp         x27, x28, [sp], #16
+    ldp         x25, x26, [sp], #16
+    ldp         x23, x24, [sp], #16
+    ldp         x21, x22, [sp], #16
+    ldp         x19, x20, [sp], #16
+    ldp         x29, x30, [sp], #16
+    ret
+endfunc

tests/checkasm/checkasm.h

@@ -125,6 +125,10 @@ void checkasm_checked_call_novfp(void *func, int dummy, ...);
 extern void (*checkasm_checked_call)(void *func, int dummy, ...);
 #define declare_new(ret, ...) ret (*checked_call)(void *, int dummy, __VA_ARGS__) = (void *)checkasm_checked_call;
 #define call_new(...) checked_call(func_new, 0, __VA_ARGS__)
+#elif ARCH_AARCH64 && !defined(__APPLE__)
+void checkasm_checked_call(void *func, ...);
+#define declare_new(ret, ...) ret (*checked_call)(void *, __VA_ARGS__) = (void *)checkasm_checked_call;
+#define call_new(...) checked_call(func_new, __VA_ARGS__)
 #else
 #define declare_new(ret, ...)
 #define declare_new_emms(cpu_flags, ret, ...)