diff options
| author | John Hawthorn <john@hawthorn.email> | 2025-11-02 21:13:37 -0800 |
|---|---|---|
| committer | John Hawthorn <john@hawthorn.email> | 2025-12-05 06:21:17 -0800 |
| commit | b0c9286d98929db56514d8009040fe206b3d310f (patch) | |
| tree | c76a9a0f71280d190dcd66115d85a8337d89d245 /internal | |
| parent | ea415e9636d3be8890d5dc97cf0b67fc95403a46 (diff) | |
Use VWA for bignum
Previously we only allocated bignums from the 40 byte sizepool, and
embedded bignum used a fixed size.
Diffstat (limited to 'internal')
| -rw-r--r-- | internal/bignum.h | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/internal/bignum.h b/internal/bignum.h index 0ba21a4923..e5b6b42563 100644 --- a/internal/bignum.h +++ b/internal/bignum.h @@ -9,6 +9,7 @@ * @brief Internal header for Bignums. */ #include "ruby/internal/config.h" /* for HAVE_LIBGMP */ +#include "internal/compilers.h" /* for FLEX_ARY_LEN */ #include <stddef.h> /* for size_t */ #ifdef HAVE_SYS_TYPES_H @@ -76,18 +77,17 @@ #define RBIGNUM(obj) ((struct RBignum *)(obj)) #define BIGNUM_SIGN_BIT FL_USER1 #define BIGNUM_EMBED_FLAG ((VALUE)FL_USER2) -#define BIGNUM_EMBED_LEN_NUMBITS 3 + +/* This is likely more bits than we need today and will also need adjustment if + * we change GC slot sizes. + */ +#define BIGNUM_EMBED_LEN_NUMBITS 9 #define BIGNUM_EMBED_LEN_MASK \ - (~(~(VALUE)0U << BIGNUM_EMBED_LEN_NUMBITS) << BIGNUM_EMBED_LEN_SHIFT) + (RUBY_FL_USER11 | RUBY_FL_USER10 | RUBY_FL_USER9 | RUBY_FL_USER8 | RUBY_FL_USER7 | \ + RUBY_FL_USER6 | RUBY_FL_USER5 | RUBY_FL_USER4 | RUBY_FL_USER3) #define BIGNUM_EMBED_LEN_SHIFT \ (FL_USHIFT+3) /* bit offset of BIGNUM_EMBED_LEN_MASK */ -#ifndef BIGNUM_EMBED_LEN_MAX -# if (SIZEOF_VALUE*RBIMPL_RVALUE_EMBED_LEN_MAX/SIZEOF_ACTUAL_BDIGIT) < (1 << BIGNUM_EMBED_LEN_NUMBITS)-1 -# define BIGNUM_EMBED_LEN_MAX (SIZEOF_VALUE*RBIMPL_RVALUE_EMBED_LEN_MAX/SIZEOF_ACTUAL_BDIGIT) -# else -# define BIGNUM_EMBED_LEN_MAX ((1 << BIGNUM_EMBED_LEN_NUMBITS)-1) -# endif -#endif +#define BIGNUM_EMBED_LEN_MAX (BIGNUM_EMBED_LEN_MASK >> BIGNUM_EMBED_LEN_SHIFT) enum rb_int_parse_flags { RB_INT_PARSE_SIGN = 0x01, @@ -104,7 +104,12 @@ struct RBignum { size_t len; BDIGIT *digits; } heap; - BDIGIT ary[BIGNUM_EMBED_LEN_MAX]; + /* This is a length 1 array because: + * 1. GCC has a bug that does not optimize C flexible array members + * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102452) + * 2. Zero length arrays are not supported by all compilers + */ + BDIGIT ary[1]; } as; }; |