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return-values opcode resets the frame

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* libguile/vm-engine.c (return-values): Change to also reset the frame,
  if nlocals is nonzero.

* doc/ref/vm.texi (Procedure Call and Return Instructions): Updated
  docs.

* module/language/cps/compile-bytecode.scm (compile-function): Adapt to
  call emit-return-values with the right number of arguments.
This commit is contained in:
Andy Wingo 2015-10-28 10:47:18 +00:00
parent 34f3fb78e0
commit 7aee3c74f5
3 changed files with 15 additions and 8 deletions
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7
doc/ref/vm.texi
View file

@ -763,12 +763,13 @@ has run, the values can be copied down via @code{mov}, or used in place.
Return a value.
@end deftypefn
@deftypefn Instruction {} return-values x24:@var{_}
@deftypefn Instruction {} return-values c24:@var{nlocals}
Return a number of values from a call frame. This opcode corresponds to
an application of @code{values} in tail position. As with tail calls,
we expect that the values have already been shuffled down to a
contiguous array starting at slot 1. We also expect the frame has
already been reset.
contiguous array starting at slot 1. If @var{nlocals} is nonzero, reset
the frame to hold that number of locals. Note that a frame reset to 1
local returns 0 values.
@end deftypefn
@deftypefn Instruction {} call/cc x24:@var{_}

12
libguile/vm-engine.c
View file

@ -747,20 +747,26 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
RETURN_ONE_VALUE (SP_REF (src));
}
/* return-values _:24
/* return-values nlocals:24
*
* Return a number of values from a call frame. This opcode
* corresponds to an application of `values' in tail position. As
* with tail calls, we expect that the values have already been
* shuffled down to a contiguous array starting at slot 1.
* We also expect the frame has already been reset.
* If NLOCALS is not zero, we also reset the frame to hold NLOCALS
* values.
*/
VM_DEFINE_OP (9, return_values, "return-values", OP1 (X32))
VM_DEFINE_OP (9, return_values, "return-values", OP1 (X8_C24))
{
union scm_vm_stack_element *old_fp;
scm_t_uint32 nlocals;
VM_HANDLE_INTERRUPTS;
UNPACK_24 (op, nlocals);
if (nlocals)
RESET_FRAME (nlocals);
old_fp = vp->fp;
ip = SCM_FRAME_RETURN_ADDRESS (vp->fp);
vp->fp = SCM_FRAME_DYNAMIC_LINK (vp->fp);

4
module/language/cps/compile-bytecode.scm
View file

@ -124,7 +124,7 @@
(emit-tail-call-label asm (1+ (length args)) k))
(($ $values ())
(emit-reset-frame asm 1)
(emit-return-values asm))
(emit-return-values asm 1))
(($ $values (arg))
(if (maybe-slot arg)
(emit-return asm (from-sp (slot arg)))
@ -138,7 +138,7 @@
((src . dst) (emit-mov asm (from-sp dst) (from-sp src))))
(lookup-parallel-moves label allocation))
(emit-reset-frame asm (1+ (length args)))
(emit-return-values asm))
(emit-return-values asm (1+ (length args))))
(($ $primcall 'return (arg))
(emit-return asm (from-sp (slot arg))))))