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str_independent: add a fastpath with a single flag check

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If we assume that most strings we modify are not frozen and
are independent, then we can optimize this case by replacing
multiple flag checks by a single mask check.
This commit is contained in:
Jean Boussier 2024-08-08 12:14:50 +02:00
parent f57167d338
commit af44af238b
Notes: git 2024-08-09 13:21:16 +00:00 
Merged: https://github.com/ruby/ruby/pull/11350
1 changed files with 19 additions and 8 deletions
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27
string.c
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@ -2500,32 +2500,43 @@ rb_check_lockedtmp(VALUE str)
} }
} }
// If none of these flags are set, we know we have an modifiable string.
// If any is set, we need to do more detailed checks.
#define STR_UNMODIFIABLE_MASK (FL_FREEZE | STR_TMPLOCK | STR_CHILLED)
static inline void static inline void
str_modifiable(VALUE str) str_modifiable(VALUE str)
{ {
if (CHILLED_STRING_P(str)) { if (RB_UNLIKELY(FL_ANY_RAW(str, STR_UNMODIFIABLE_MASK))) {
CHILLED_STRING_MUTATED(str); if (CHILLED_STRING_P(str)) {
CHILLED_STRING_MUTATED(str);
}
rb_check_lockedtmp(str);
rb_check_frozen(str);
} }
rb_check_lockedtmp(str);
rb_check_frozen(str);
} }
static inline int static inline int
str_dependent_p(VALUE str) str_dependent_p(VALUE str)
{ {
if (STR_EMBED_P(str) || !FL_TEST(str, STR_SHARED|STR_NOFREE)) { if (STR_EMBED_P(str) || !FL_TEST(str, STR_SHARED|STR_NOFREE)) {
return 0; return FALSE;
} }
else { else {
return 1; return TRUE;
} }
} }
// If none of these flags are set, we know we have an independent string.
// If any is set, we need to do more detailed checks.
#define STR_DEPENDANT_MASK (STR_UNMODIFIABLE_MASK | STR_SHARED | STR_NOFREE)
static inline int static inline int
str_independent(VALUE str) str_independent(VALUE str)
{ {
str_modifiable(str); if (RB_UNLIKELY(FL_ANY_RAW(str, STR_DEPENDANT_MASK))) {
return !str_dependent_p(str); str_modifiable(str);
return !str_dependent_p(str);
}
return TRUE;
} }
static void static void