Dmd doesn't allow load global variable in asm block

[ntysdd]

Dmd told me

cannot directly load global variable x with PIC or PIE code

on x86-64, which I think is wrong.

[ntysdd]

__gshared int x;

void f()
{
int *p = &x;
asm
{
mov RAX, p;
// lea RAX, x;
}
}

Got inefficient code

push rbp
mov rbp,rsp
sub rsp,0x10
mov rax,QWORD PTR [rip+0x0] # f <_D1a1fFZv+0xf>
mov QWORD PTR [rbp-0x8],rax
mov rax,QWORD PTR [rbp-0x8]
leave
ret

[maxhaton]

I don't think we should worry too much about dmd code quality.

We can probably add asm pattern although I'm not entirely sure how the assembler thing we have interacts with (say) the relocation tables and so on.

[ntysdd]

Isn't dmd frontend used by ldc and gdc? How do they solve this problem?

[maxhaton]

The inline assembler is not part of the frontend technically.

The dmd one is basically an ab initio assembler inside the compiler whereas LDC and GDC both translate into an internal format which is handled by the backends - GDC only supports GNU style inline ASM

[ntysdd]

Thanks.