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/*
__morestack
See i386/morestack.S for the lengthy, general explanation.
*/
.text
#if defined(__APPLE__) || defined(_WIN32)
#define UPCALL_NEW_STACK _upcall_new_stack
#define UPCALL_DEL_STACK _upcall_del_stack
#define UPCALL_CALL_C _upcall_call_shim_on_c_stack
#define MORESTACK ___morestack
#else
#define UPCALL_NEW_STACK upcall_new_stack
#define UPCALL_DEL_STACK upcall_del_stack
#define UPCALL_CALL_C upcall_call_shim_on_c_stack
#define MORESTACK __morestack
#endif
.globl UPCALL_NEW_STACK
.globl UPCALL_DEL_STACK
.globl UPCALL_CALL_C
.globl MORESTACK
#if defined(__linux__)
.hidden MORESTACK
#else
#if defined(__APPLE__)
.private_extern MORESTACK
#endif
#endif
#ifdef __ELF__
.type MORESTACK,@function
#endif
#if defined(__linux__) || defined(__APPLE__)
MORESTACK:
.cfi_startproc
pushq %rbp
// The CFA is 24 bytes above the register that it will
// be associated with for this frame (%rbp). That is 8
// bytes greater than a normal frame, to allow the unwinder
// to skip the partial frame of the original function.
.cfi_def_cfa_offset 24
// %rbp is -24 bytes from the CFA
.cfi_offset %rbp, -24
movq %rsp, %rbp
// Calculate the CFA as on offset from %ebp
.cfi_def_cfa_register %rbp
// Save the grandparent stack pointer for the unwinder
// FIXME: This isn't used
leaq 24(%rbp), %rax
pushq %rax
// FIXME: libgcc also saves rax. not sure if we need to
// Save argument registers of the original function
pushq %rdi
pushq %rsi
pushq %rdx
pushq %rcx
pushq %r8
pushq %r9
// Calculate the address of the stack arguments.
// We have the base pointer, __morestack's return address,
// and __morestack's caller's return address to skip
movq %rbp, %rcx
addq $24, %rcx // Base pointer, return address x2
// The arguments to __morestack are passed in %r10 & %r11
pushq %r11 // Size of stack arguments
pushq %rcx // Address of stack arguments
pushq %r10 // The amount of stack needed
pushq $0 // Out pointer
movq UPCALL_NEW_STACK@GOTPCREL(%rip), %rsi
movq %rsp, %rdi
#ifdef __APPLE__
call UPCALL_CALL_C
#endif
#ifdef __linux__
call UPCALL_CALL_C@PLT
#endif
// Pop the new_stack_args struct
popq %rax
addq $24, %rsp
// Pop the saved arguments
popq %r9
popq %r8
popq %rcx
popq %rdx
popq %rsi
popq %rdi
// Pop the unwinding %rsp
addq $8, %rsp
movq 8(%rbp),%r10 // Grab the return pointer.
incq %r10 // Skip past the `ret` in our parent frame
movq %rax,%rsp // Switch to the new stack.
call *%r10 // Reenter the caller function
// Switch back to the rust stack
movq %rbp, %rsp
// Align the stack again
pushq $0
// FIXME: Should preserve %rax here
movq UPCALL_DEL_STACK@GOTPCREL(%rip), %rsi
movq $0, %rdi
#ifdef __APPLE__
call UPCALL_CALL_C
#endif
#ifdef __linux__
call UPCALL_CALL_C@PLT
#endif
addq $8, %rsp
popq %rbp
// FIXME: I don't think these rules are necessary
// since the unwinder should never encounter an instruction
// pointer pointing here.
.cfi_restore %rbp
.cfi_def_cfa %rsp, 16
ret
.cfi_endproc
#else
MORESTACK:
ret
#endif
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