I searched online for a while and haven't seen any similar question.
So i am writing a small compiler to compile a language to x64 code.
But when I try to do clang generated-code.s, I get:
ld: in section __DATA,__data reloc 0: length < 2 and X86_64_RELOC_UNSIGNED not supported file '/var/folders/3g/ydlqd7bx3819pfrr9n52zjv80000gn/T/hello_world-795c7e.o' for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)
I don't really understand the meaning of this error message. Does it mean i have undefined symbol? Can anyone please explain to me?
Here is the code my compiler generated:
.data
.globl Main_protoObj
.globl Int_protoObj
.globl String_protoObj
.globl Main_init
.globl Int_init
.globl String_init
.globl Bool_init
.globl Main_main
class_objTab:
.word Object_protoObj
.word Object_init
.word IO_protoObj
.word IO_init
.word String_protoObj
.word String_init
.word Int_protoObj
.word Int_init
.word Bool_protoObj
.word Bool_init
.word Main_protoObj
.word Main_init
Object_protoObj:
.word 0
.word 1
.word Object_dispatch_table
IO_protoObj:
.word 1
.word 3
.word IO_dispatch_table
String_protoObj:
.word 2
.word 3
.word String_dispatch_table
.word 0
.asciz ""
.align 8
Int_protoObj:
.word 3
.word 2
.word Int_dispatch_table
.word 0
Bool_protoObj:
.word 4
.word 2
.word Bool_dispatch_table
.word 0
Main_protoObj:
.word 5
.word 1
.word Main_dispatch_table
String_dispatch_table:
.word Object_abort
.word Object_copy
.word String_length
.word String_concat
.word String_substr
Main_dispatch_table:
.word Object_abort
.word Object_copy
.word IO_out_string
.word IO_out_int
.word IO_in_string
.word IO_in_int
.word Main_main
Bool_dispatch_table:
.word Object_abort
.word Object_copy
Object_dispatch_table:
.word Object_abort
.word Object_copy
IO_dispatch_table:
.word Object_abort
.word Object_copy
.word IO_out_string
.word IO_out_int
.word IO_in_string
.word IO_in_int
Int_dispatch_table:
.word Object_abort
.word Object_copy
int_const0:
.word 3
.word 4
.word Int_dispatch_table
.word 22
string_const0:
.word 2
.word 6
.word String_dispatch_table
.word int_const0
.asciz "Hello, World.\n \n\n"
.align 8
.text
Object_init:
pushq %rbp
movq %rsp, %rbp
leave
ret
IO_init:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rdi
callq Object_init
leave
ret
String_init:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rdi
callq Object_init
movq '', 32(%rbp)
movq $0, 24(%rbp)
leave
ret
Int_init:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rdi
callq Object_init
movq $0, 24(%rbp)
leave
ret
Bool_init:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rdi
callq Object_init
movq $0, 24(%rbp)
leave
ret
Main_main:
pushq %rbp
movq %rsp, %rbp
subq $8, %rsp
movq %rdi, -8(%rbp)
movq -8(%rbp), %rdi
leaq string_const0(%rip), %rax
movq %rax, %rsi
movq 16(%rdi), %r10
movq 16(%r10), %r10
callq* %r10
leave
ret
Main_init:
pushq %rbp
movq %rsp, %rbp
movq %rdi, %rdi
callq IO_init
leave
ret
The error:
ld: in section __DATA,__data reloc 0: length < 2 and X86_64_RELOC_UNSIGNED not supported
looks like a rather obscure way of saying that your object has allocated space to store offsets into data items that likely can't hold the offset generated at link time.
A quick look at your code shows you use .word and a label for a value. An example .word Object_protoObj where Object_protoObj offset is a label. The directive .word allows values between 0x0000 and 0xffff (16-bits). The linker error is probably suggesting that the offsets of the labels it is generating can't fit into 16-bit words.
Maybe you should be using .quad (allowing 64-bit values) or .int (32-bit values)? I don't know how you'll accessing these offsets in the tables so you'll have to choose .quad or .int based on your usage requirements.