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#include "Utils/Platform.h"
#ifdef X64
.text
.globl doStackCall
.type doStackCall, @function
.align 4
doStackCall:
# 'current' is in %rdi
# 'callOn' is in %rsi
# 'fn' is in %rdx
# 'fnCall' is in %rcx
# 'member' is in %r8
# 'result' is in %r9
# We may use %rax, %r10 and %r11 as a scratchpad
.cfi_startproc
# Prolog. Saves %rsp.
push %rbp
.cfi_def_cfa rsp, 16
.cfi_offset rbp, -16
movq %rsp, %rbp
.cfi_def_cfa rbp, 16
# We need to save 'current' for after the thread call.
push %rdi
# First, we need to make the old stack scannable. Thus, we need to store a Stack::Desc struct there.
pushq $0 # high
pushq $0 # dummy
leaq -8(%rsp), %rax
pushq %rax # low
movq %rsp, 16(%rdi) # current.desc = %rsp
movq %rsi, 32(%rdi) # current.detourTo = callOn
# Now, we can switch to the other stack.
movq 16(%rsi), %rax # %rax = callOn.desc
movq (%rax), %rsp # %rsp = desc.low
movq $0, 16(%rsi) # callOn.desc = null
# Finally, call 'os::FnCallRaw::callRaw'
movq %rcx, %rdi # this ptr
movq %rdx, %rsi # fn
movq %r8, %rdx # member
movq $0, %rcx # first
movq %r9, %r8 # result
callq *fnCallRaw@GOTPCREL(%rip)
# Done! Tear down. Start by unlinking the old stack, otherwise the GC might scan too much.
# Note that we can not set "desc" again, as we have lost the pointer to it.
movq -8(%rbp), %rdi # Load "current" back into %rdi.
movq $0, 32(%rdi) # current.detourTo = null
movq %rbp, %rsp # Reset %rsp, it is safe now.
movq $0, 16(%rdi) # current.desc = null
# Epilog!
pop %rbp
.cfi_restore rbp
.cfi_def_cfa rsp, 8
retq
.cfi_endproc
#endif
# No executable stack.
.section .note.GNU-stack,"",%progbits
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