* module/language/cps/dfg.scm (reverse-post-order): Add an optional
"fold-all-conts" argument.
(compute-live-variables): Take the function as an arg instead of the
start continuation, and implement fold-all-conts so that nodes that
never reach the tail also get liveness information.
* module/language/cps.scm ($prompt): Add a "pop" field, indicating the
continuation at which this prompt is popped. The body of the prompt
is dominated by the prompt, and post-dominated by the pop. Adapt all
builders and users.
* module/language/cps/closure-conversion.scm:
* module/language/cps/compile-rtl.scm:
* module/language/cps/slot-allocation.scm:
* module/language/cps/verify.scm:
* module/language/tree-il/compile-cps.scm: Adapt.
* module/language/cps/dfg.scm (visit-fun): Add an arc from the pop to
the handler, to keep handler variables alive through the prompt body.
* module/language/cps/dfg.scm (control-point?): New interface, replaces
branch?.
(dead-after-def?, dead-after-use?, dead-after-branch?): Remove these.
The first one was fine; dead-after-use? was conservative but OK; but
dead-after-branch? was totally bogus. Instead we use precise liveness
information in the allocator.
* module/language/cps/slot-allocation.scm ($allocation): Remove "def"
and "dead" slots. We'll communicate liveness information in some
other way to the compiler.
(allocate-slots): Rework to use precise liveness information.
* libguile/vm-engine.c (prompt): Adapt to explicitly set the saved SP so
we know how many incoming values the handler will receive, and to make
escape-only? a flag.
* module/language/cps/compile-rtl.scm (emit-rtl-sequence): $prompt
should only be found in a "seq" context, as it just pushes on a prompt
and doesn't bind any values. On the other hand it should emit
appropriate code for the handler to bind its values, so do that.
* module/language/cps/slot-allocation.scm ($cont-allocation): Add a note
that proc-slot is used by prompts as well.
(allocate-slots): Compute the allocation of a prompt handler's args.
* module/language/tree-il/compile-cps.scm (convert): Use "unwind"
instead of the nonexistent "pop-prompt".
* module/system/vm/disassembler.scm (code-annotation): Adapt to change
in prompt VM op.
