Overview of Assembly Procedures

Quxlang provides the ASM_PROCEDURE keyword for declaring assembly procedures. Assembly procedures allow the programmer precise control over the exact machine instructions emitted by the program. System-call wrappers and early runtime startup are typical applications:

::exit_process INCLUDE_IF(OS_LINUX) ASM_PROCEDURE X64
  CALLABLE(@code I32)
{
  MOV RAX, 60
  SYSCALL
  RET
}

The CALLABLE clause defines the typed interface visible to Quxlang code. The assembly body follows the platform ABI, which determines the register containing code in this example.

Architecture-specific definitions

The same procedure can have a separate definition for each architecture:

::exit_process INCLUDE_IF(OS_LINUX) ASM_PROCEDURE ARM64
  CALLABLE(@code I32)
{
  MOV X8, 93
  SVC 0
  RET
}

The active target selects the matching declaration. An INCLUDE_IF condition is required when the operation also depends on an operating system, environment, or binary format.

Assembly provides exact instruction control and requires a separate implementation for every supported architecture. Assembly procedures are primarily applicable to small platform-specific operations. Portable Quxlang code permits the backend to select and optimize instructions for each target.

Assembly can refer to emitted Quxlang procedures and global objects through PROCEDURE_REF and OBJECT_REF; those forms avoid spelling generated linker names.

The Assembly Procedures Reference lists the declaration grammar, callable forms, symbolic operands, architecture support, and current implementation limits.