[Guile-commits] 02/04: Do not assume that sizeof (long) == sizeof (void *) == sizeof (SCM).

[Andy Wingo]

wingo pushed a commit to branch master
in repository guile.

commit 1d257c27f004fe4db81d62033b5cf2d8fafcd68f
Author: Mark H Weaver <address@hidden>
Date:   Wed Apr 6 17:36:57 2016 -0400

    Do not assume that sizeof (long) == sizeof (void *) == sizeof (SCM).
    
    This assumption does not hold on systems that use the LLP64 data model.
    
    Partially fixes <https://debbugs.gnu.org/22406>.
    Reported by Peter TB Brett <address@hidden>.
    
    * libguile/numbers.h (scm_t_inum): Move here from numbers.c, and change
      to be equivalent to 'long' (formerly 'scm_t_signed_bits').
      (SCM_MOST_POSITIVE_FIXNUM, SCM_MOST_NEGATIVE_FIXNUM): Define based on
      SCM_I_FIXNUM_BIT instead of SCM_T_SIGNED_BITS_MAX.
      (SCM_I_INUM): Adjust definitions to return a 'scm_t_inum', and avoiding
      the assumption that SCM_UNPACK returns a 'long'.
    * libguile/numbers.c (scm_t_inum): Move definition to numbers.h.
      Verify that 'scm_t_inum' fits within a SCM value.
      (scm_i_inum2big): Remove preprocessor code that forced a compile error
      unless sizeof (long) == sizeof (void *).
---
 libguile/numbers.c | 10 +++-------
 libguile/numbers.h | 31 +++++++++++++++----------------
 2 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/libguile/numbers.c b/libguile/numbers.c
index 34980c6..3e0efc8 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -86,7 +86,9 @@
 /* FIXME: We assume that FLT_RADIX is 2 */
 verify (FLT_RADIX == 2);
 
-typedef scm_t_signed_bits scm_t_inum;
+/* Make sure that scm_t_inum fits within a SCM value.  */
+verify (sizeof (scm_t_inum) <= sizeof (scm_t_bits));
+
 #define scm_from_inum(x) (scm_from_signed_integer (x))
 
 /* Test an inum to see if it can be converted to a double without loss
@@ -271,13 +273,7 @@ scm_i_inum2big (scm_t_inum x)
 {
   /* Return a newly created bignum initialized to X. */
   SCM z = make_bignum ();
-#if SIZEOF_VOID_P == SIZEOF_LONG
   mpz_init_set_si (SCM_I_BIG_MPZ (z), x);
-#else
-  /* Note that in this case, you'll also have to check all mpz_*_ui and
-     mpz_*_si invocations in Guile. */
-#error creation of mpz not implemented for this inum size
-#endif
   return z;
 }
 
diff --git a/libguile/numbers.h b/libguile/numbers.h
index bba336b..d2799b1 100644
--- a/libguile/numbers.h
+++ b/libguile/numbers.h
@@ -3,8 +3,8 @@
 #ifndef SCM_NUMBERS_H
 #define SCM_NUMBERS_H
 
-/* Copyright (C) 1995,1996,1998,2000,2001,2002,2003,2004,2005, 2006,
- *   2008, 2009, 2010, 2011, 2013, 2014 Free Software Foundation, Inc.
+/* Copyright (C) 1995, 1996, 1998, 2000-2006, 2008-2011, 2013, 2014,
+ *   2016 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -38,16 +38,15 @@ typedef scm_t_int32 scm_t_wchar;
 
 /* Immediate Numbers, also known as fixnums
  *
- * Inums are exact integer data that fits within an SCM word.  */
-
-/* SCM_T_SIGNED_MAX is                 (- (expt 2 n) 1),
- * SCM_MOST_POSITIVE_FIXNUM should be  (- (expt 2 (- n 2)) 1)
- * which is the same as                (/ (- (expt 2 n) 4) 4)
- */
-
+ * Inums are exact integers that fit within an SCM word
+ * (along with two tagging bits).
+ *
+ * In the current implementation, Inums must also fit within a long
+ * because that's what GMP's mpz_*_si functions accept.  */
+typedef long scm_t_inum;
 #define SCM_I_FIXNUM_BIT         (SCM_LONG_BIT - 2)
-#define SCM_MOST_POSITIVE_FIXNUM ((SCM_T_SIGNED_BITS_MAX-3)/4)
-#define SCM_MOST_NEGATIVE_FIXNUM (-SCM_MOST_POSITIVE_FIXNUM-1)
+#define SCM_MOST_NEGATIVE_FIXNUM (-1L << (SCM_I_FIXNUM_BIT - 1))
+#define SCM_MOST_POSITIVE_FIXNUM (- (SCM_MOST_NEGATIVE_FIXNUM + 1))
 
 /* SCM_SRS (X, Y) is signed right shift, defined as floor (X / 2^Y),
    where Y must be non-negative and less than the width in bits of X.
@@ -74,12 +73,12 @@ typedef scm_t_int32 scm_t_wchar;
 
    NOTE: X must not perform side effects.  */
 #ifdef __GNUC__
-# define SCM_I_INUM(x)  (SCM_SRS ((scm_t_signed_bits) SCM_UNPACK (x), 2))
+# define SCM_I_INUM(x)  (SCM_SRS ((scm_t_inum) SCM_UNPACK (x), 2))
 #else
-# define SCM_I_INUM(x)                                \
-  (SCM_UNPACK (x) > LONG_MAX                          \
-   ? -1 - (scm_t_signed_bits) (~SCM_UNPACK (x) >> 2)  \
-   : (scm_t_signed_bits) (SCM_UNPACK (x) >> 2))
+# define SCM_I_INUM(x)                          \
+  (SCM_UNPACK (x) > SCM_T_SIGNED_BITS_MAX       \
+   ? -1 - (scm_t_inum) (~SCM_UNPACK (x) >> 2)   \
+   : (scm_t_inum) (SCM_UNPACK (x) >> 2))
 #endif
 
 #define SCM_I_INUMP(x) (2 & SCM_UNPACK (x))