gnu: chez-scheme-for-racket: Support all systems.

On systems for which Racket's variant of Chez Scheme cannot generate
native code, it can use a 'pbarch' machine type: a variant of the
``portable bytecode'' backend specialized to word size and endianness.
This allows Racket CS to replace Racket BC on those systems while
maintaining comparable performance. (Racket BC lacks JIT support for
those systems anyway.) It also lets us provide a Chez Scheme package on
all systems Guix supports.

This patch adds 'pbarch' support to both 'chez-scheme-for-racket' and
'racket-vm-cs', but it does not change the Racket VM implementation used
for the 'racket' and 'racket-minimal' packages.

* gnu/packages/chez.scm (nix-system->pbarch-machine-type): New variable.
(chez-scheme-for-racket)[inputs]: Use 'libffi' for non-native systems.
[arguments]<#:configure-flags>: Always supply '-m='. Add applicable
flags for non-native systems.
[supported-systems]: Use '%supported-systems'.
[description]: Update.
(chez-scheme-for-racket-bootstrap-bootfiles)[arguments]<#:phases>: Adapt
'build' phase for non-native systems.
* gnu/packages/racket.scm (racket-vm-bc)[description]: Update.
(racket-vm-cs)[description]: Likewise.
[inputs]: Use 'libffi' for non-native systems.
[arguments]<#:configure-flags>: Add applicable flags for non-native
systems.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

1 files changed, 57 insertions, 19 deletions

diff --git a/gnu/packages/chez.scm b/gnu/packages/chez.scm
index 26f653ea9d..5d152b3db5 100644
--- a/gnu/packages/chez.scm
+++ b/gnu/packages/chez.scm
@@ -37,6 +37,7 @@
   #:use-module (gnu packages compression)
   #:use-module (gnu packages ncurses)
   #:use-module (gnu packages ghostscript)
+  #:use-module (gnu packages libffi)
   #:use-module (gnu packages linux)
   #:use-module (gnu packages netpbm)
   #:use-module (gnu packages racket)
@@ -49,6 +50,7 @@
   #:use-module (srfi srfi-26)
   #:export (chez-scheme-for-system
             racket-cs-native-supported-system?
+            nix-system->pbarch-machine-type
             unpack-nanopass+stex))
 
 ;; Commentary:
@@ -231,6 +233,28 @@ future."
     (and=> (assoc-ref %chez-features-table chez-os)
            (cut assoc-ref <> chez-arch))))
 
+(define* (nix-system->pbarch-machine-type #:optional
+                                          (system
+                                           (or (%current-target-system)
+                                               (%current-system)))
+                                          #:key (threads? #t))
+  "Return a string naming the pseudo–machine type used by Racket's variant of
+Chez Scheme to represent the appropriate ``pbarch'' backend for SYSTEM: that
+is, the ``portable bytecode'' backend specialized for SYSTEM's word size and
+endianness.  The result will name the threaded machine type unless THREADS? is
+provided and is #f."
+  (string-append (if threads?
+                     "t"
+                     "")
+                 "pb"
+                 (if (target-64bit? system)
+                     "64"
+                     "32")
+                 ;; missing (guix utils) predicate target-little-endian?
+                 (if (target-ppc32? system)
+                     "b"
+                     "l")))
+
 (define* (racket-cs-native-supported-system? #:optional
                                              (system
                                               (or (%current-target-system)
@@ -449,10 +473,14 @@ and 32-bit PowerPC architectures.")
     ;; When updating, remember to also update %racket-version in racket.scm.
     (source #f) ; avoid problematic cycle with racket.scm
     (inputs
-     (modify-inputs (package-inputs chez-scheme)
-       (delete "libx11" "util-linux:lib")
-        (replace "chez-scheme-bootstrap-bootfiles"
-          chez-scheme-for-racket-bootstrap-bootfiles)))
+     (let ((inputs (modify-inputs (package-inputs chez-scheme)
+                     (replace "chez-scheme-bootstrap-bootfiles"
+                       chez-scheme-for-racket-bootstrap-bootfiles)
+                     (delete "libx11" "util-linux:lib"))))
+       (if (racket-cs-native-supported-system?)
+           inputs
+           (modify-inputs inputs
+             (prepend libffi)))))
     (native-inputs
      (let ((native-inputs (modify-inputs (package-native-inputs chez-scheme)
                             (prepend zuo))))
@@ -473,10 +501,16 @@ and 32-bit PowerPC architectures.")
        ((#:configure-flags cfg-flags #~'())
         #~`("--disable-x11"
             "--threads" ;; ok to potentially duplicate
-            #$@(if (%current-target-system)
-                   (list (string-append "-m="
-                                        (racket-cs-native-supported-system?)))
-                   '())
+            #$(string-append "-m=" (or (racket-cs-native-supported-system?)
+                                       (nix-system->pbarch-machine-type)))
+            ;; ^ could skip -m= for non-cross non-pbarch builds
+            #$@(if (racket-cs-native-supported-system?)
+                   #~()
+                   ;; not inferred on non-native platforms: see
+                   ;; https://racket.discourse.group/t/950/9
+                   #~("--enable-libffi"
+                      "CFLAGS=-g -O2 -D_REENTRANT -pthread"
+                      "LIBS=-lm -ldl -lrt -lffi -lncurses"))
             #$@(if (%current-target-system)
                    (list (string-append "--toolprefix="
                                         (%current-target-system)
@@ -543,10 +577,7 @@ and 32-bit PowerPC architectures.")
               (add-after 'unpack 'chdir
                 (lambda args
                   (chdir "racket/src/ChezScheme"))))))))
-    ;; TODO: How to build pbarch/pbchunks for other systems?
-    ;; See https://racket.discourse.group/t/950
-    (supported-systems (filter racket-cs-native-supported-system?
-                               %supported-systems))
+    (supported-systems %supported-systems)
     (home-page "https://github.com/racket/ChezScheme")
     ;; ^ This is downstream of https://github.com/racket/racket,
     ;; but it's designed to be a friendly landing place for people
@@ -559,13 +590,17 @@ supported by upstream Chez Scheme.
 Main additions to Chez Scheme in the Racket variant:
 @itemize @bullet
 @item
-AArch64 support
+AArch64 code generation
 @item
-Portable bytes (@code{pb}) support, which is mainly useful for bootstrapping
-a build on any supported platform
+Portable bytecode (@code{pb}) mode, which is mainly useful for bootstrapping a
+build on any platform, but can also be used on platforms without native-code
+generation, compiled via Emscripten, linked with @code{libffi}, or used with
+bytecode partially compiled to C
 @item
 Unboxed floating-point arithmetic and flvectors
 @item
+Faster multiplication and division for large exact numbers
+@item
 Type reconstruction during optimization (especially for safe code)
 @item
 Continuation attachments
@@ -576,8 +611,6 @@ accounting
 @item
 Ordered finalization, immobile (but collectable) objects, weak/ephemeron
 generic hash tables, and reference bytevectors
-@item
-Faster multiplication and division for large exact numbers
 @end itemize")
     (license asl2.0)))
 
@@ -655,13 +688,18 @@ source.")))
                          "makefiles/boot.zuo"
                          (search-input-file (or native-inputs inputs)
                                             "/bin/scheme")
-                         #$(racket-cs-native-supported-system?)))
+                         #$(or (racket-cs-native-supported-system?)
+                               (nix-system->pbarch-machine-type))))
                      (else
                       ;; bootstrapping
                       #~(invoke
                          (search-input-file (or native-inputs inputs)
                                             "/opt/racket-vm/bin/racket")
-                         "rktboot/main.rkt"))))))))))
+                         "rktboot/main.rkt"
+                         #$@(if (racket-cs-native-supported-system?)
+                                #~()
+                                (let ((m (nix-system->pbarch-machine-type)))
+                                  #~("--machine" #$m)))))))))))))
     (supported-systems
      (package-supported-systems chez-scheme-for-racket))
     (home-page "https://github.com/racket/ChezScheme")