Partial continuations are RTL stubs

* libguile/control.c: Implement partial continuations as RTL programs.

* libguile/programs.c (scm_i_rtl_program_minimum_arity): Add partial
  continuation case.

* libguile/vm-engine.c (compose-continuation): Fix to look for vm_cont
  from the free variables.

* libguile/vm-i-system.c (abort): Poison continuations captured in the
  stack VM, as the can't be rewound by the RTL stubs.
VM has "builtins": primitives addressable by emitted RTL code

* libguile/Makefile.am:
* libguile/vm-builtins.h: New header, declaring stubs needed by the
  compiler like values, apply, and abort-to-prompt.

* libguile/vm.c: Adapt the apply and values stubs to conform to a
  standard interface.  Add an abort-to-prompt stub.  Add call/cc and
  call-with-values stubs.
  (scm_vm_builtin_ref): New helper, for the builtin-ref opcode.
  (scm_vm_builtin_name_to_index)
  (scm_vm_builtin_index_to_name): New helpers, for the compiler and
  disassembler, respectively.
  (scm_init_vm_builtins, scm_bootstrap_vm): Allow the compiler helpers
  to be loaded later into a module.
* module/language/rtl.scm: Export builtin-index->name and
  builtin-name->index.

* libguile/vm-engine.c (RETURN_VALUE_LIST): Update to use new names of
  "apply" and "values".
  (tail-call/shuffle): New opcode.
  (abort): Update to be a tail VM op, and reorder and renumber other
  ops.
  (builtin-ref): New opcode.

* libguile/continuations.h:
* libguile/continuations.c (scm_i_call_with_current_continuation):
  Move this to vm.[ch], implemented as a builtin.

* module/language/tree-il/compile-cps.scm (convert): Convert to
  'abort-to-prompt calls, possibly with 'apply, effectively undoing the
  tree-il transformation.

* module/language/cps/reify-primitives.scm (builtin-ref): New helper.
  (reify-primitives): Convert builtin primitives to builtin-ref.

* module/language/cps/dfg.scm (constant-needs-allocation?):
* module/language/cps/compile-rtl.scm (emit-rtl-sequence): Add support
  for compiling builtin-ref.

* module/system/vm/disassembler.scm (code-annotation): Add annotation
  for builtin-ref.
Resumable partial continuations in the RTL VM

* libguile/vm-engine.c (receive-values): Bugfix for the case where we
  want an exact number of values.
  (abort): Advance the IP before capturing.  The captured SP is fp - 1,
  not fp.

* libguile/vm.c (vm_reinstate_partial_continuation): Don't push on a
  number-of-values marker.
Walk the stack to determine extent of partial continuation

* libguile/control.c (reify_partial_continuation): Walk the stack to
  determine the bottom of the captured stack.
Dynamic-wind doesn't call thunk? on the out-guard.

* module/ice-9/boot-9.scm (dynamic-wind): Remove the thunk? check of the
  out-guard.
DWARF return arity fixen

* module/system/vm/dwarf.scm (read-die-abbrev): Fix return arity.
  (read-compilation-unit): Fix return arity of read-die.
Add "pop" field to $prompt

* 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.
DFG: Disable control-flow analysis.

* module/language/cps/dfg.scm (visit-fun): Disable control-flow analysis
  for now, as it is not used.
Fix primitive reification for class-of, bytevector-u8-ref, etc

* module/language/cps/reify-primitives.scm (primitive-module): Not all
  primitives are bound in (guile).
static-patch! replaces link-procedure!

* libguile/vm-engine.c (static-patch!): Replace link-procedure! with
  this more versatile primitive.
* module/system/vm/assembler.scm (intern-constant): Emit static-patch!
  for static procedures and for strings.
* module/system/vm/disassembler.scm (code-annotation): Remove annotation
  for link-procedure!.  There can be no annotation for static-patch!, as
  neither operand is guaranteed to be a SCM value.
DFG: $block no longer stores control-flow analysis

* module/language/cps/dfg.scm ($block): Remove dominator-related things
  from $block.
  (reverse-post-order, convert-predecessors): Be more abstract, taking
  arbitrary identifiers for nodes instead of assuming the nodes are
  continuation names.
  (make-block-mapping): New helper.
  ($cfa): New data type, for dominator and loop analysis.  Not yet
  public.
  (analyze-control-flow): Rewrite to only compute the dominator tree in
  one direction, but take that direction as an argument.  To be public
  once there is some code that uses it.
  ($dfa): Refactor function fields to be hash tables.
  (dfa-k-idx, dfa-var-idx): Adapt to refactor.
  (compute-live-variables): Adapt to refactor.
Compile-time debugging

* module/language/cps/compile-rtl.scm:
* module/language/cps/contification.scm: Add some compile-time
  printouts.  Will be removed later.
Support serialization of uniform vector literals

* libguile/uniform.h:
* libguile/uniform.c (scm_uniform_vector_element_type_code): New
  interface, returns a type code as an integer.

* module/system/vm/assembler.scm (<uniform-vector-backing-store>)
  (simple-vector?, uniform-array?, statically-allocatable?)
  (intern-constant, link-data, link-constants): Support uniform arrays,
  and punt on vectors aren't contiguous from 0.  Support for general
  arrays will come later.

* test-suite/tests/rtl.test ("load-constant"): Add tests.
Fix bytevector error messages.

* libguile/vm-engine.c (BV_FIXABLE_INT_SET, BV_INT_SET):
  (BV_FLOAT_SET): Fix instruction names in error messages.
Better compiler support for bytevector ops

* module/language/cps/compile-rtl.scm (emit-rtl-sequence): Add emitters
  for bytevector ops.  Add br-if-bytevector emitter.
* module/language/cps/primitives.scm (*branching-primcall-arities*):
  Mark bytevector? as a branching primitive.
* module/system/vm/assembler.scm (br-if-bytevector): New instruction
* module/system/vm/disassembler.scm (code-annotation): Add support for
  bytevector?.
Better aliased primcall compilation

* libguile/vm-engine.c (define!): Rename from define.
* module/language/cps/arities.scm (fix-clause-arities): If a prim
  aliases an RTL instruction with a different name and we reify a
  primcall, reify the instruction name.
* module/language/cps/compile-rtl.scm (emit-rtl-sequence): Update
  emit-define! for new name.
* module/language/cps/primitives.scm (*rtl-instruction-aliases*): Add
  bytevector native accessors.
Avoid calling procedure-name when doing a make-procedure-with-setter

* libguile/procs.c (scm_make_procedure_with_setter): Don't set the name
  of the procedure.  Instead rely on procedure-name to look it up from
  the wrapped procedure as needed.
* libguile/procprop.c (scm_procedure_name): If there was no override and
  the procedure is a procedure-with-setter, recurse on the procedure.
Default to compiling to RTL

* module/ice-9/eval-string.scm (eval-string)
* module/language/tree-il/spec.scm (tree-il)
* module/scripts/compile.scm (compile)
* module/system/base/compile.scm (compile-file, read-and-compile)
* module/system/repl/common.scm (repl-compile, repl-prepare-eval-thunk):
  Default to compiling to RTL.

* module/language/rtl/spec.scm (rtl->value): Add value compiler.
Better REPL support for disassembling RTL images

* module/system/repl/command.scm (load-image): New helper.
  (compile, disassemble): Handle bytevectors.
static-patch! for pair and vector fields

* module/system/vm/assembler.scm (intern-constant): Use static-patch!
  for fields.