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Add 'scm_c_make_char' and use it where appropriate.

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This reverts the change to SCM_MAKE_CHAR made in the previous commit
63818453ad, which used an arithmetic trick
to avoid evaluating its argument more than once.

Here, we restore the previous implementation of SCM_MAKE_CHAR, which
evaluates its argument twice.  Instead, we introduce a new inlinable
function 'scm_c_make_char' and replace uses of SCM_MAKE_CHAR with calls
to 'scm_c_make_char' where appropriate.

* libguile/chars.h (scm_c_make_char): New inline function.
* libguile/inline.c: Include chars.h.
* libguile/srfi-13.c (REF_IN_CHARSET, scm_string_any, scm_string_every)
(scm_string_trim, scm_string_trim_right, scm_string_trim_both)
(scm_string_index, scm_string_index_right, scm_string_skip)
(scm_string_skip_right, scm_string_count, string_titlecase_x)
(string_reverse_x, scm_string_fold, scm_string_fold_right)
(scm_string_for_each, scm_string_filter, scm_string_delete):
Use 'scm_c_make_char' instead of 'SCM_MAKE_CHAR' in cases where the
argument calls a function.
* libguile/chars.c (scm_char_upcase, scm_char_downcase, scm_char_titlecase),
libguile/ports.c (scm_port_decode_char),
libguile/print.c (scm_simple_format),
libguile/read.c (scm_read_character),
libguile/strings.c (scm_string_ref, scm_c_string_ref),
libguile/vm-engine.c ("string-ref"): Ditto.
This commit is contained in:
Mark H Weaver 2019-05-07 02:28:26 -04:00
parent 63818453ad
commit 2a1f22c00a
9 changed files with 59 additions and 47 deletions
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26
libguile/chars.h
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@ -41,14 +41,13 @@ typedef scm_t_int32 scm_t_wchar;
(0 to 255) to Latin-1 codepoints (0 to 255) while allowing higher
codepoints (256 to 1114111) to pass through unchanged.
To avoid evaluating X more than once, we use an arithmetic trick: we
compute (X mod 2^N) mod (2^N - 256), which is equal to the required
mapping in the range -256 .. (2^N - 257). Here, N is the number of
bits in scm_t_bits. Note that (scm_t_bits) (x) implicitly computes
(X mod 2^N), and (scm_t_bits) -256 equals (2^N - 256). GCC is able
to optimize away these operations in practice. */
#define SCM_MAKE_CHAR(x) \
(SCM_MAKE_ITAG8 ((scm_t_bits) (x) % (scm_t_bits) -256, scm_tc8_char))
This macro evaluates X twice, which may lead to side effects if used
incorrectly. It's also likely to be inefficient if X calls a
procedure. Use 'scm_c_make_char' in those cases. */
#define SCM_MAKE_CHAR(x) \
((x) <= 1 \
? SCM_MAKE_ITAG8 ((scm_t_bits) (unsigned char) (x), scm_tc8_char) \
: SCM_MAKE_ITAG8 ((scm_t_bits) (x), scm_tc8_char))
#define SCM_CODEPOINT_DOTTED_CIRCLE (0x25cc)
#define SCM_CODEPOINT_SURROGATE_START (0xd800)
@ -85,14 +84,25 @@ SCM_API SCM scm_char_upcase (SCM chr);
SCM_API SCM scm_char_downcase (SCM chr);
SCM_API SCM scm_char_titlecase (SCM chr);
SCM_API SCM scm_char_general_category (SCM chr);
SCM_INLINE SCM scm_c_make_char (scm_t_wchar c);
SCM_API scm_t_wchar scm_c_upcase (scm_t_wchar c);
SCM_API scm_t_wchar scm_c_downcase (scm_t_wchar c);
SCM_API scm_t_wchar scm_c_titlecase (scm_t_wchar c);
SCM_INTERNAL const char *scm_i_charname (SCM chr);
SCM_INTERNAL SCM scm_i_charname_to_char (const char *charname,
size_t charname_len);
SCM_INTERNAL void scm_init_chars (void);
#if SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES
SCM_INLINE_IMPLEMENTATION SCM
scm_c_make_char (scm_t_wchar c)
{
return SCM_MAKE_CHAR(c);
}
#endif
#endif /* SCM_CHARS_H */
/*