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_var_arg

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This commit is contained in:
Antoni Piasecki
2026-04-04 13:14:58 +02:00
parent bb42e1fcf7
commit a17ffa184a
7 changed files with 75 additions and 58 deletions
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61
src/codegen_x86_64.rs
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@@ -151,21 +151,6 @@ _builtin_syscall:
mov r9, [rsp+8]
syscall
ret
section .text.io.printf
io.printf:
push rbp
mov rbp, rsp
sub rsp, 48
mov [rsp], rsi
mov [rsp + 8], rdx
mov [rsp + 16], rcx
mov [rsp + 24], r8
mov [rsp + 32], r9
lea rsi, [rsp]
call io._printf_impl
leave
ret
"
);
@@ -337,7 +322,16 @@ _builtin_environ:
}
}
}
Params::Variadic(_name) => todo!(),
Params::Variadic => {
emit!(&mut self.output, " sub rsp, 48");
emit!(&mut self.output, " mov [rbp - 8], rdi");
emit!(&mut self.output, " mov [rbp - 16], rsi");
emit!(&mut self.output, " mov [rbp - 24], rdx");
emit!(&mut self.output, " mov [rbp - 32], rcx");
emit!(&mut self.output, " mov [rbp - 40], r8");
emit!(&mut self.output, " mov [rbp - 48], r9");
env.next_offset += 48;
}
}
self.compile_stmt(env, body)?;
@@ -626,6 +620,12 @@ _builtin_environ:
paren: _,
args,
} => {
if let Expr::Variable(callee_name) = &**callee
&& callee_name.lexeme == "_var_arg"
{
return self.emit_var_arg(env, &args[0]);
}
for arg in args {
self.compile_expr(env, arg)?;
emit!(&mut self.output, " push rax");
@@ -795,4 +795,33 @@ _builtin_environ:
Ok(field.offset)
}
fn emit_var_arg(&mut self, env: &mut Env, index_expr: &Expr) -> Result<(), ZernError> {
self.compile_expr(env, index_expr)?;
emit!(&mut self.output, " mov r10, rax");
let stack_label = self.label();
let done_label = self.label();
emit!(&mut self.output, " cmp r10, 6");
emit!(&mut self.output, " jge {}", stack_label);
// < 6
emit!(&mut self.output, " mov rax, r10");
emit!(&mut self.output, " inc rax");
emit!(&mut self.output, " shl rax, 3");
emit!(&mut self.output, " neg rax");
emit!(&mut self.output, " mov rax, [rbp + rax]");
emit!(&mut self.output, " jmp {}", done_label);
// >= 6
emit!(&mut self.output, "{}:", stack_label);
emit!(&mut self.output, " mov rax, r10");
emit!(&mut self.output, " sub rax, 6");
emit!(&mut self.output, " shl rax, 3");
emit!(&mut self.output, " mov rax, [rbp + 16 + rax]");
emit!(&mut self.output, "{}:", done_label);
Ok(())
}
}