flambda-backend: Backport 5 PRNG (#2069)

* upgrade runtime4 to 5 prng

* update tests

Makefile

@@ -646,6 +646,7 @@ runtime4_COMMON_C_SOURCES = \
   obj \
   parsing \
   printexc \
+  prng \
   signals \
   simd \
   skiplist \

ocamltest/.depend

@@ -260,12 +260,14 @@ ocaml_flags.cmi : \
     environments.cmi
 ocaml_modifiers.cmo : \
     ocamltest_stdlib.cmi \
+    ocamltest_config.cmi \
     ocaml_variables.cmi \
     ocaml_directories.cmi \
     environments.cmi \
     ocaml_modifiers.cmi
 ocaml_modifiers.cmx : \
     ocamltest_stdlib.cmx \
+    ocamltest_config.cmx \
     ocaml_variables.cmx \
     ocaml_directories.cmx \
     environments.cmx \

otherlibs/systhreads4/.depend

@@ -1,34 +1,8 @@
-condition.cmo : \
-    mutex.cmi \
-    condition.cmi
-condition.cmx : \
-    mutex.cmx \
-    condition.cmi
-condition.cmi : \
-    mutex.cmi
 event.cmo : \
-    mutex.cmi \
-    condition.cmi \
     event.cmi
 event.cmx : \
-    mutex.cmx \
-    condition.cmx \
     event.cmi
 event.cmi :
-mutex.cmo : \
-    mutex.cmi
-mutex.cmx : \
-    mutex.cmi
-mutex.cmi :
-semaphore.cmo : \
-    mutex.cmi \
-    condition.cmi \
-    semaphore.cmi
-semaphore.cmx : \
-    mutex.cmx \
-    condition.cmx \
-    semaphore.cmi
-semaphore.cmi :
 thread.cmo : \
     thread.cmi
 thread.cmx : \

runtime4/Makefile

@@ -22,7 +22,7 @@ include $(ROOTDIR)/Makefile.common
 BYTECODE_C_SOURCES := $(addsuffix .c, \
   interp misc stacks fix_code startup_aux startup_byt freelist major_gc \
   minor_gc memory alloc roots_byt globroots fail_byt signals \
-  signals_byt printexc backtrace_byt backtrace compare ints eventlog \
+  signals_byt printexc backtrace_byt backtrace compare ints eventlog prng \
   floats simd str array io extern intern hash sys meta parsing gc_ctrl md5 obj \
   lexing callback debugger weak compact finalise custom dynlink \
   afl $(UNIX_OR_WIN32) bigarray main memprof domain \
@@ -31,7 +31,7 @@ BYTECODE_C_SOURCES := $(addsuffix .c, \
 NATIVE_C_SOURCES := $(addsuffix .c, \
   startup_aux startup_nat main fail_nat roots_nat signals \
   signals_nat misc freelist major_gc minor_gc memory alloc compare ints \
-  floats simd str array io extern intern hash sys parsing gc_ctrl eventlog md5 obj \
+  floats simd str array io extern intern hash sys parsing gc_ctrl eventlog prng md5 obj \
   lexing $(UNIX_OR_WIN32) printexc callback weak compact finalise custom \
   globroots backtrace_nat backtrace dynlink_nat debugger meta \
   dynlink clambda_checks afl bigarray \

runtime4/dune

@@ -23,7 +23,7 @@
      callback.c weak.c
    finalise.c stacks.c dynlink.c backtrace_byt.c backtrace.c
      afl.c
-   bigarray.c eventlog.c misc.c domain.c)
+   bigarray.c prng.c eventlog.c misc.c domain.c)
  (action  (with-stdout-to %{targets} (run %{dep:gen_primitives.sh}))))
 
 (rule

runtime4/gen_primitives.sh

@@ -25,7 +25,7 @@ export LC_ALL=C
       alloc array compare extern floats gc_ctrl hash intern interp ints io \
       lexing md5 meta memprof obj parsing signals str sys callback weak \
       finalise stacks dynlink backtrace_byt backtrace afl \
-      bigarray eventlog misc domain
+      bigarray eventlog misc domain prng
   do
       sed -n -e 's/^CAMLprim value \([a-z0-9_][a-z0-9_]*\).*/\1/p' "$prim.c"
   done

runtime4/prng.c

@@ -0,0 +1,71 @@
+/**************************************************************************/
+/*                                                                        */
+/*                                 OCaml                                  */
+/*                                                                        */
+/*          Xavier Leroy, projet Cambium, College de France and Inria     */
+/*                                                                        */
+/*   Copyright 2021 Institut National de Recherche en Informatique et     */
+/*     en Automatique.                                                    */
+/*                                                                        */
+/*   All rights reserved.  This file is distributed under the terms of    */
+/*   the GNU Lesser General Public License version 2.1, with the          */
+/*   special exception on linking described in the file LICENSE.          */
+/*                                                                        */
+/**************************************************************************/
+
+#define CAML_INTERNALS
+
+#include <string.h>
+#include "caml/alloc.h"
+#include "caml/bigarray.h"
+#include "caml/mlvalues.h"
+
+/* The L64X128 member of the LXM family.  Taken from figure 1 in
+   "LXM: Better Splittable Pseudorandom Number Generators
+    (and Almost as Fast)" by Guy L. Steele Jr. and Sebastiano Vigna,
+    OOPSLA 2021.  */
+
+static const uint64_t M = 0xd1342543de82ef95;
+
+struct LXM_state {
+  uint64_t a;            /* per-instance additive parameter (odd) */
+  uint64_t s;            /* state of the LCG subgenerator */
+  uint64_t x[2];         /* state of the XBG subgenerator (not 0) */
+};
+
+/* In OCaml, states are represented as a 1D big array of 64-bit integers */
+
+#define LXM_val(v) ((struct LXM_state *) Caml_ba_data_val(v))
+
+Caml_inline uint64_t rotl(const uint64_t x, int k) {
+  return (x << k) | (x >> (64 - k));
+}
+
+CAMLprim uint64_t caml_lxm_next_unboxed(value v)
+{
+  uint64_t z, q0, q1;
+  struct LXM_state * st = LXM_val(v);
+
+  /* Combining operation */
+  z = st->s + st->x[0];
+  /* Mixing function */
+  z = (z ^ (z >> 32)) * 0xdaba0b6eb09322e3;
+  z = (z ^ (z >> 32)) * 0xdaba0b6eb09322e3;
+  z = (z ^ (z >> 32));
+  /* LCG update */
+  st->s = st->s * M + st->a;
+  /* XBG update */
+  q0 = st->x[0]; q1 = st->x[1];
+  q1 ^= q0;
+  q0 = rotl(q0, 24);
+  q0 = q0 ^ q1 ^ (q1 << 16);
+  q1 = rotl(q1, 37);
+  st->x[0] = q0; st->x[1] = q1;
+  /* Return result */
+  return z;
+}
+
+CAMLprim value caml_lxm_next(value v)
+{
+  return caml_copy_int64(caml_lxm_next_unboxed(v));
+}

stdlib/.depend

@@ -242,12 +242,15 @@ stdlib__Complex.cmx : complex.ml \
 stdlib__Complex.cmi : complex.mli \
     stdlib.cmi
 stdlib__Condition.cmo : condition.ml \
+    stdlib.cmi \
     stdlib__Mutex.cmi \
     stdlib__Condition.cmi
 stdlib__Condition.cmx : condition.ml \
+    stdlib.cmx \
     stdlib__Mutex.cmx \
     stdlib__Condition.cmi
 stdlib__Condition.cmi : condition.mli \
+    stdlib.cmi \
     stdlib__Mutex.cmi
 stdlib__Digest.cmo : digest.ml \
     stdlib__String.cmi \
@@ -751,25 +754,29 @@ stdlib__Queue.cmi : queue.mli \
     stdlib.cmi \
     stdlib__Seq.cmi
 stdlib__Random.cmo : random.ml \
+    stdlib__Sys.cmi \
     stdlib__String.cmi \
     stdlib.cmi \
     stdlib__Nativeint.cmi \
     stdlib__Int64.cmi \
     stdlib__Int32.cmi \
-    stdlib__Int.cmi \
+    stdlib__Domain.cmi \
     stdlib__Digest.cmi \
-    stdlib__Char.cmi \
+    stdlib__Bytes.cmi \
+    stdlib__Bigarray.cmi \
     stdlib__Array.cmi \
     stdlib__Random.cmi
 stdlib__Random.cmx : random.ml \
+    stdlib__Sys.cmx \
     stdlib__String.cmx \
     stdlib.cmx \
     stdlib__Nativeint.cmx \
     stdlib__Int64.cmx \
     stdlib__Int32.cmx \
-    stdlib__Int.cmx \
+    stdlib__Domain.cmx \
     stdlib__Digest.cmx \
-    stdlib__Char.cmx \
+    stdlib__Bytes.cmx \
+    stdlib__Bigarray.cmx \
     stdlib__Array.cmx \
     stdlib__Random.cmi
 stdlib__Random.cmi : random.mli \
@@ -811,14 +818,17 @@ stdlib__Scanf.cmx : scanf.ml \
 stdlib__Scanf.cmi : scanf.mli \
     stdlib.cmi
 stdlib__Semaphore.cmo : semaphore.ml \
+    stdlib.cmi \
     stdlib__Mutex.cmi \
     stdlib__Condition.cmi \
     stdlib__Semaphore.cmi
 stdlib__Semaphore.cmx : semaphore.ml \
+    stdlib.cmx \
     stdlib__Mutex.cmx \
     stdlib__Condition.cmx \
     stdlib__Semaphore.cmi
-stdlib__Semaphore.cmi : semaphore.mli
+stdlib__Semaphore.cmi : semaphore.mli \
+    stdlib.cmi
 stdlib__Seq.cmo : seq.ml \
     stdlib.cmi \
     stdlib__Lazy.cmi \