45 lines
1.1 KiB
ArmAsm
45 lines
1.1 KiB
ArmAsm
// This file is part of libfringe, a low-level green threading library.
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// Copyright (c) 2015, edef <edef@edef.eu>
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// See the LICENSE file included in this distribution.
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//! switch to a new context
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//! arguments:
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//! * rdi: stack pointer pointer
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// make sure we leave the red zone alone
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sub $$128, %rsp
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// save the Rust stack limit and the frame pointer, respectively
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pushq %fs:0x70
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pushq %rbp
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// save the return address to the stack, control flow continues at label 1
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call 1f
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// we arrive here once this context is reactivated
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// restore the frame pointer and the Rust stack limit, respectively
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popq %rbp
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popq %fs:0x70
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// give back the red zone
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add $$128, %rsp
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// and we merrily go on our way, back into Rust-land
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jmp 2f
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1:
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// retrieve the new stack pointer
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movq (%rdi), %rax
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// save the old stack pointer
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movq %rsp, (%rdi)
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// switch to the new stack pointer
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movq %rax, %rsp
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// jump into the new context (return to the call point)
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// doing this instead of a straight `ret` is 8ns slower,
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// presumably because the branch predictor tries to be clever about it
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popq %rax
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jmpq *%rax
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2:
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