Deluxe68 is a simple (stupid) register allocator frontend for 68k assembly. It is a source to source translator, so you'll need your regular assembler to assemble its output. All is does it automate some tedious register allocation for you.
Usage is simple:
deluxe68 input.s output.s
Marking up source code
The following extensions are provided:
To pull from the data register pool, use
@dreg a, b, [...] moveq #0,@a moveq #1,@b
@areg allocates address registers. The stack pointer is
automatically reserved and will never be allocated:
@areg ptr lea foo(pc),@ptr
@kill to return a register to the pool:
@dreg a [.. code using @a ..] @kill a moveq #0,@a ; now generates an error!
Renaming an allocated register
Often in assembly programming, the purpose of a register changes. You can express that by renaming the register:
; @xcoordptr = x coordinate buffer @dreg x0,x1 move.w (@xcoordptr)+,@x0 move.w (@xcoordptr)+,@x1 sub.w @x0,@x1 @rename @x1,@deltax ; @x1 is now no longer a coordinate ; ... @kill x0,deltax ; x1 is now gone, and using it will result in an error
Using allocated registers
You can subsitute
@name for a register in any instruction or macro
invokation. The only caveat is if the register has been spilled, in which case
you'll instead get a reference to the stack which can generate a
memory-to-memory instruction that doesn't assemble. In that case, rework the
Spilling and restoring registers
To explicitly spill a named register to the stack (returning it to the pool) you can use
@dreg a moveq #0,@a @spill a ; a is now on stack ... ... ; more code involving more data register allocation ... @restore a ; a is now back in the same register it lived in before
@restore can also work with real registers. Spilling a real register ensures that
there is nothing named in that real register. This is useful when calling external code.
Reserving and unreserving registers
To reserve a real register you can use
@reserve d0 ; d0 is no longer available to the allocator moveq #0,d0 ... @unreserve d0 ; return d0 to the register allocator
When you want to call a subroutine then you typically need to place arguments in specific registers.
@reserve pairs to prepare the registers for use, and
when you are done:
@spill a0,d1 @reserve a0,d1 move.l @foo,a0 move.l @bar,d1 bsr SomeExternalCode @unreserve a0,d1 @restore a0,d1
d1 are not allocated, the
@restore operations will do nothing.
@unreserve operations are for bookkeeping, and will generate no code.
Mark a procedure entry point with
@proc ProcedureName(<reg>: name, [<reg>: name ...]). You can
@proc ProcedureName (that is, omitting the register-name part
entirely) if your procedure has no arguments.
Doing so accomplishes two things:
- It generates an automatic
movem.lthat stores all touched registers to the stack
- All live registers are killed automatically
Similarly, instead of
@endproc. This puts the inverse
place, and also emits the
Any registers declared in the procedure header are automatically live and not
available for allocation in the procedure. You can however
@kill them to
return them to the pool.
@proc Foo(a0:ptr, d0:count) @dreg sum moveq #0,@sum subq #1,@count .loop add.w (@ptr)+,@sum dbf @count,.loop move.w @sum,d0 @endproc
Generates output similar to:
; @proc Foo(a0:ptr, d0:count) ; live reg a0 => ptr ; live reg d0 => count Foo: movem.l d1,-(sp) ; @dreg sum ; live reg d1 => sum moveq #0,d1 subq #1,d0 .loop add.w (a0)+,d1 dbf d0,.loop move.w d1,d0 ; @endproc movem.l (sp)+,d1 rts
This software is available under the BSD 2-clause license:
Copyright (c) 2016, Andreas Fredriksson All rights reserved.
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