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/* AArch64 support code for fibers and multithreading.
Copyright (C) 2019-2021 Free Software Foundation, Inc.
This file is part of GCC.
GCC 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 3, or (at your option) any later
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<>. */
#include "../common/threadasm.S"
* preserve/restore AAPCS64 registers
* x19-x28 5.1.1 64-bit callee saved
* x29 fp, or possibly callee saved reg - depends on platform choice 5.2.3)
* x30 lr
* d8-d15 5.1.2 says callee only must save bottom 64-bits (the "d" regs)
* saved regs on stack will look like:
* 19: x19
* 18: x20
* ...
* 10: x28
* 9: x29 (fp) <-- oldp / *newp save stack top
* 8: x30 (lr)
* 7: d8
* ...
* 0: d15 <-- sp
.global CSYM(fiber_switchContext)
.type CSYM(fiber_switchContext), %function
.align 4
stp d15, d14, [sp, #-20*8]!
stp d13, d12, [sp, #2*8]
stp d11, d10, [sp, #4*8]
stp d9, d8, [sp, #6*8]
stp x30, x29, [sp, #8*8] // lr, fp
stp x28, x27, [sp, #10*8]
stp x26, x25, [sp, #12*8]
stp x24, x23, [sp, #14*8]
stp x22, x21, [sp, #16*8]
stp x20, x19, [sp, #18*8]
// oldp is set above saved lr (x30) to hide it and float regs
// from GC
add x19, sp, #9*8
str x19, [x0] // *oldp tstack
sub sp, x1, #9*8 // switch to newp sp
ldp x20, x19, [sp, #18*8]
ldp x22, x21, [sp, #16*8]
ldp x24, x23, [sp, #14*8]
ldp x26, x25, [sp, #12*8]
ldp x28, x27, [sp, #10*8]
ldp x30, x29, [sp, #8*8] // lr, fp
ldp d9, d8, [sp, #6*8]
ldp d11, d10, [sp, #4*8]
ldp d13, d12, [sp, #2*8]
ldp d15, d14, [sp], #20*8
.size CSYM(fiber_switchContext),.-CSYM(fiber_switchContext)
* When generating any kind of backtrace (gdb, exception handling) for
* a function called in a Fiber, we need to tell the unwinder to stop
* at our Fiber main entry point, i.e. we need to mark the bottom of
* the call stack. This can be done by clearing the link register lr
* prior to calling fiber_entryPoint (i.e. in fiber_switchContext) or
* using a .cfi_undefined directive for the link register in the
* Fiber entry point. cfi_undefined seems to yield better results in gdb.
* Unfortunately we can't place it into fiber_entryPoint using inline
* asm, so we use this trampoline instead.
.global CSYM(fiber_trampoline)
.p2align 2
.type CSYM(fiber_trampoline), %function
.cfi_undefined x30
// fiber_entryPoint never returns
bl CSYM(fiber_entryPoint)
.size CSYM(fiber_trampoline),.-CSYM(fiber_trampoline)