Walter Bright 
| Figuring out stdarg for the Arm.
```
#include <stdarg.h>
int square(float a, float b, ...)
{
va_list args;
va_start(args, b);
int i = va_arg(args, int);
va_end(args);
return i;
}
```
which compiles to, I kid you not:
```
0: d10383ff sub sp, sp, #0xe0 // function prolog
4: bd000fe0 str s0, [sp, #12]
8: bd000be1 str s1, [sp, #8]
c: f90053e0 str x0, [sp, #160]
10: f90057e1 str x1, [sp, #168]
14: f9005be2 str x2, [sp, #176]
18: f9005fe3 str x3, [sp, #184]
1c: f90063e4 str x4, [sp, #192]
20: f90067e5 str x5, [sp, #200]
24: f9006be6 str x6, [sp, #208]
28: f9006fe7 str x7, [sp, #216]
2c: 3d8013e2 str q2, [sp, #64]
30: 3d8017e3 str q3, [sp, #80]
34: 3d801be4 str q4, [sp, #96]
38: 3d801fe5 str q5, [sp, #112]
3c: 3d8023e6 str q6, [sp, #128]
40: 3d8027e7 str q7, [sp, #144] // initialize va_argsave
44: 910383e0 add x0, sp, #0xe0
48: f9000fe0 str x0, [sp, #24]
4c: 910383e0 add x0, sp, #0xe0
50: f90013e0 str x0, [sp, #32]
54: 910283e0 add x0, sp, #0xa0
58: f90017e0 str x0, [sp, #40]
5c: 128007e0 mov w0, #0xffffffc0 // #-64
60: b90033e0 str w0, [sp, #48]
64: 12800be0 mov w0, #0xffffffa0 // #-96
68: b90037e0 str w0, [sp, #52] // va_start(args, b); (filling in va_list)
6c: b94033e1 ldr w1, [sp, #48]
70: f9400fe0 ldr x0, [sp, #24]
74: 7100003f cmp w1, #0x0
78: 540000ab b.lt 8c <square+0x8c> // b.tstop
7c: 91002c01 add x1, x0, #0xb
80: 927df021 and x1, x1, #0xfffffffffffffff8
84: f9000fe1 str x1, [sp, #24]
88: 1400000d b bc <square+0xbc>
8c: 11002022 add w2, w1, #0x8
90: b90033e2 str w2, [sp, #48]
94: b94033e2 ldr w2, [sp, #48]
98: 7100005f cmp w2, #0x0
9c: 540000ad b.le b0 <square+0xb0>
a0: 91002c01 add x1, x0, #0xb
a4: 927df021 and x1, x1, #0xfffffffffffffff8
a8: f9000fe1 str x1, [sp, #24]
ac: 14000004 b bc <square+0xbc>
b0: f94013e2 ldr x2, [sp, #32]
b4: 93407c20 sxtw x0, w1
b8: 8b000040 add x0, x2, x0
bc: b9400000 ldr w0, [x0]
c0: b9003fe0 str w0, [sp, #60] // int i = va_arg(args, int)
c4: b9403fe0 ldr w0, [sp, #60] // return i
c8: 910383ff add sp, sp, #0xe0
cc: d65f03c0 ret // epilog
```
|
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