bc: fix rationals as place messages

When an exact (non-integer) rational is reconstructed from a place
message, normalization could involve bignum operations --- and those
operations might use a cache, but the cache should not refer to the
pages that are specific to a place message being constructed.
Normalization isn't necessary, since the parts were already in a
rational, so the repair is just it skip it.

Relevant to #3456

pkgs/racket-test/tests/racket/place-msg-rational.rkt

@@ -0,0 +1,23 @@
+#lang racket/base
+(require racket/place)
+
+(define N 100)
+
+(define (go)
+  (place
+   pch
+   (for/fold ([v 0]) ([x (in-range N)])
+     (place-channel-put pch (for/vector ([l 1000])
+                              (/ (- (expt 2 300) (random 10))
+                                 (expt 2 81))))
+     (apply + (vector->list (place-channel-get pch))))))
+
+(module+ main
+  (define p1 (go))
+  (for ([i (in-range N)])
+    (define v (place-channel-get p1))
+    (place-channel-put p1 v))
+  (place-wait p1))
+
+(module+ test
+  (require (submod ".." main)))

racket/src/bc/src/bignum.c

@@ -146,7 +146,7 @@ void scheme_clear_bignum_cache(void)
 # define SCHEME_BIGDIG_SAFE(b, s) SCHEME_BIGDIG(b)
 
 # define PROTECT(digarray, len) /* no-op */
-#define RELEASE(digarray) /* no-op */
+# define RELEASE(digarray) /* no-op */
 
 # define PROTECT_RESULT(len) allocate_bigdig_array(len)
 # define FINISH_RESULT(digarray, len) /* no-op */

racket/src/bc/src/place.c

@@ -948,7 +948,7 @@ static Scheme_Object *shallow_types_copy(Scheme_Object *so, Scheme_Hash_Table *h
                                mode, can_raise_exn, master_chain, invalid_object);
         d = shallow_types_copy(d, NULL, fd_accumulators, delayed_err, delayed_errno, delayed_errkind,
                                mode, can_raise_exn, master_chain, invalid_object);
-        new_so = scheme_make_rational(n, d);
+        new_so = scheme_make_rational_pre_normalized(n, d);
       }
       break;
     case scheme_float_type:

racket/src/bc/src/rational.c

@@ -26,6 +26,11 @@ Scheme_Object *scheme_make_rational(const Scheme_Object *n, const Scheme_Object
 		       scheme_bignum_normalize(d), 1);
 }
 
+Scheme_Object *scheme_make_rational_pre_normalized(const Scheme_Object *n, const Scheme_Object *d)
+{
+  return make_rational(n, d, 0);
+}
+
 Scheme_Object *scheme_integer_to_rational(const Scheme_Object *n)
 {
   return make_rational(n, one, 0);

racket/src/bc/src/schpriv.h

@@ -2264,6 +2264,7 @@ typedef Scheme_Rational Small_Rational;
 
 XFORM_NONGCING Scheme_Object *scheme_make_small_rational(intptr_t n, Small_Rational *space);
 XFORM_NONGCING Scheme_Object *scheme_make_small_bn_rational(Scheme_Object *n, Small_Rational *space);
+Scheme_Object *scheme_make_rational_pre_normalized(const Scheme_Object *n, const Scheme_Object *d);
 Scheme_Object *scheme_integer_to_rational(const Scheme_Object *n);
 Scheme_Object *scheme_make_fixnum_rational(intptr_t n, intptr_t d);
 XFORM_NONGCING int scheme_rational_eq(const Scheme_Object *a, const Scheme_Object *b);