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+// *****************************************************************
+//
+// The Compcert verified compiler
+//
+// Xavier Leroy, Collège de France and INRIA Paris
+//
+// Copyright (c) Institut National de Recherche en Informatique et
+// en Automatique.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+// * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright
+// notice, this list of conditions and the following disclaimer in the
+// documentation and/or other materials provided with the distribution.
+// * Neither the name of the <organization> nor the
+// names of its contributors may be used to endorse or promote products
+// derived from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT
+// HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// *********************************************************************
+
+// Helper functions for variadic functions <stdarg.h>. AArch64 version.
+
+#include "sysdeps.h"
+
+// typedef struct __va_list {
+// void *__stack; // next stack parameter
+// void *__gr_top; // top of the save area for int regs
+// void *__vr_top; // top of the save area for float regs
+// int__gr_offs; // offset from gr_top to next int reg
+// int__vr_offs; // offset from gr_top to next FP reg
+// }
+// typedef struct __va_list va_list; // struct passed by reference
+// unsigned int __compcert_va_int32(va_list * ap);
+// unsigned long long __compcert_va_int64(va_list * ap);
+// double __compcert_va_float64(va_list * ap);
+
+FUNCTION(__compcert_va_int32)
+ ldr w1, [x0, #24] // w1 = gr_offs
+ cbz w1, 1f
+ // gr_offs is not zero: load from int save area and update gr_offs
+ ldr x2, [x0, #8] // x2 = gr_top
+ ldr w2, [x2, w1, sxtw] // w2 = the next integer
+ add w1, w1, #8
+ str w1, [x0, #24] // update gr_offs
+ mov w0, w2
+ ret
+ // gr_offs is zero: load from stack save area and update stack pointer
+1: ldr x1, [x0, #0] // x1 = stack
+ ldr w2, [x1, #0] // w2 = the next integer
+ add x1, x1, #8
+ str x1, [x0, #0] // update stack
+ mov w0, w2
+ ret
+ENDFUNCTION(__compcert_va_int32)
+
+FUNCTION(__compcert_va_int64)
+ ldr w1, [x0, #24] // w1 = gr_offs
+ cbz w1, 1f
+ // gr_offs is not zero: load from int save area and update gr_offs
+ ldr x2, [x0, #8] // x2 = gr_top
+ ldr x2, [x2, w1, sxtw] // w2 = the next long integer
+ add w1, w1, #8
+ str w1, [x0, #24] // update gr_offs
+ mov x0, x2
+ ret
+ // gr_offs is zero: load from stack save area and update stack pointer
+1: ldr x1, [x0, #0] // x1 = stack
+ ldr x2, [x1, #0] // w2 = the next long integer
+ add x1, x1, #8
+ str x1, [x0, #0] // update stack
+ mov x0, x2
+ ret
+ENDFUNCTION(__compcert_va_int64)
+
+FUNCTION(__compcert_va_float64)
+ ldr w1, [x0, #28] // w1 = vr_offs
+ cbz w1, 1f
+ // vr_offs is not zero: load from float save area and update vr_offs
+ ldr x2, [x0, #16] // x2 = vr_top
+ ldr d0, [x2, w1, sxtw] // d0 = the next float
+ add w1, w1, #16
+ str w1, [x0, #28] // update vr_offs
+ ret
+ // gr_offs is zero: load from stack save area and update stack pointer
+1: ldr x1, [x0, #0] // x1 = stack
+ ldr d0, [x1, #0] // d0 = the next float
+ add x1, x1, #8
+ str x1, [x0, #0] // update stack
+ ret
+ENDFUNCTION(__compcert_va_float64)
+
+// Right now we pass structs by reference. This is not ABI conformant.
+FUNCTION(__compcert_va_composite)
+ b __compcert_va_int64
+ENDFUNCTION(__compcert_va_composite)