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objc_msgSend.x86-64.S
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objc_msgSend.x86-64.S
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#define DTABLE_OFFSET 64
#define SMALLOBJ_MASK 7
#define SHIFT_OFFSET 4
#define DATA_OFFSET 16
#define SLOT_OFFSET 32
.macro MSGSEND receiver, sel
.cfi_startproc # Start emitting unwind data. We
# don't actually care about any of
# the stuff except the slow call,
# because that's the only one that
# can throw.
test \receiver, \receiver # If the receiver is nil
jz 4f # return nil
movq $SMALLOBJ_MASK, %r10 # Load the small object mask
test \receiver, %r10 # Check if the receiver is a small object
jnz 6f # Get the small object class
mov (\receiver), %r10 # Load the dtable from the class
1: # classLoaded
mov DTABLE_OFFSET(%r10), %r10 # Load the dtable from the class
cmpq uninstalled_dtable(%rip), %r10 # If this is not (yet) a valid dtable
je 5f # Do a slow lookup
push %r12
push %r13
mov (\sel), %r11 # Load the selector index
mov SHIFT_OFFSET(%r10), %r13 # Load the shift (dtable size)
mov DATA_OFFSET(%r10), %r12 # load the address of the start of the array
cmpl $8, %r13d # If this is a small dtable, jump to the small dtable handlers
je 2f
cmpl $0, %r13d
je 3f
mov %r11, %r13
and $0xff0000, %r13
shrl $13, %r13d # Right shift 16, but then left shift by 3 *sizeof(void*)
add %r13, %r12
mov (%r12), %r12
mov DATA_OFFSET(%r12), %r12
2: # dtable16:
mov %r11, %r13
and $0xff00, %r13
shrl $5, %r13d
add %r13, %r12
mov (%r12), %r12
mov DATA_OFFSET(%r12), %r12
3: # dtable8:
mov %r11, %r13
and $0xff, %r13
shll $3, %r13d
add %r13, %r12
mov (%r12), %r10
pop %r13
pop %r12
test %r10, %r10
jz 5f # Nil slot - invoke some kind of forwarding mechanism
mov SLOT_OFFSET(%r10), %r10
jmp *%r10
4: # returnNil:
# Both of the return registers are
# callee-save on x86-64, so we can
# return 0 in both in the same code:
xor %rax, %rax # Return 0 as an integer
pxor %xmm0, %xmm0 # Return 0 as a floating point value
ret
5: # slowSend:
push %rax # We need to preserve all registers that may contain arguments:
push %rbx
push %rcx
push %r8
push %r9
sub $0x98, %rsp
movups %xmm0, 0x80(%rsp)
movups %xmm1, 0x70(%rsp)
movups %xmm2, 0x60(%rsp)
movups %xmm3, 0x50(%rsp)
movups %xmm4, 0x40(%rsp)
movups %xmm5, 0x30(%rsp)
movups %xmm6, 0x20(%rsp)
movups %xmm7, 0x10(%rsp)
#rdi rsi rdx
# We're (potentially) modifying the self argument with the lookup, so we don't want to be
.ifc "\receiver", "%rdi"
push %rdi
mov %rsp, %rdi
push %rsi # Save _cmd (not preserved across calls)
push %rdx
.else
push %rdi # Save the sret pointer
push %rsi # Save self where it can be modified
mov %rsp, %rdi
push %rdx
mov %rdx, %rsi # move _cmd to where the callee expects it to be
.endif
.cfi_adjust_cfa_offset 0xD8
call slowMsgLookup # Call the slow lookup function
mov %rax, %r10 # Load the returned IMP
pop %rdx
pop %rsi
pop %rdi
movups 0x80(%rsp), %xmm0
movups 0x70(%rsp), %xmm1
movups 0x60(%rsp), %xmm2
movups 0x50(%rsp), %xmm3
movups 0x40(%rsp), %xmm4
movups 0x30(%rsp), %xmm5
movups 0x20(%rsp), %xmm6
movups 0x10(%rsp), %xmm7
add $0x98, %rsp
pop %r9
pop %r8
pop %rcx
pop %rbx
pop %rax
jmp *%r10
6: # smallObject:
and \receiver, %r10 # Find the small int type
shll $3, %r10d
lea SmallObjectClasses(%rip), %r11
add %r11, %r10
mov (%r10), %r10
jmp 1b
.cfi_endproc
.endm
.globl objc_msgSend
.type objc_msgSend, @function
.globl objc_msgSend_fpret
.type objc_msgSend_fpret, @function
objc_msgSend_fpret:
objc_msgSend:
MSGSEND %rdi, %rsi
.globl objc_msgSend_stret
.type objc_msgSend_stret, @function
objc_msgSend_stret:
MSGSEND %rsi, %rdx