reduce number of calls to add_cp_to_invlist()

[perl5.git] / sv.h

diff --git a/sv.h b/sv.h
index 7c67d8f..bfda6bf 100644 (file)
--- a/sv.h
+++ b/sv.h
@@ -467,7 +467,7 @@ perform the upgrade if necessary.  See C<L</svtype>>.
 /* PVHV */
 #define SVphv_HASKFLAGS        0x80000000  /* keys have flag byte after hash */
 /* PVGV when SVpbm_VALID is true */
-#define SVpbm_TAIL     0x80000000
+#define SVpbm_TAIL     0x80000000  /* string has a fake "\n" appended */
 /* RV upwards. However, SVf_ROK and SVp_IOK are exclusive  */
 #define SVprv_WEAKREF   0x80000000  /* Weak reference */
 /* pad name vars only */
@@ -838,7 +838,7 @@ Set the current length of the string which is in the SV.  See C<L</SvCUR>>
 and C<SvIV_set>>.
 
 =for apidoc Am|void|SvLEN_set|SV* sv|STRLEN len
-Set the actual length of the string which is in the SV.  See C<L</SvIV_set>>.
+Set the size of the string buffer for the SV. See C<L</SvLEN>>.
 
 =cut
 */
@@ -949,7 +949,7 @@ in gv.h: */
 
 #define SvOOK(sv)              (SvFLAGS(sv) & SVf_OOK)
 #define SvOOK_on(sv)           (SvFLAGS(sv) |= SVf_OOK)
-#define SvOOK_off(sv)          ((void)(SvOOK(sv) && sv_backoff(sv)))
+#define SvOOK_off(sv)          ((void)(SvOOK(sv) && (sv_backoff(sv),0)))
 
 #define SvFAKE(sv)             (SvFLAGS(sv) & SVf_FAKE)
 #define SvFAKE_on(sv)          (SvFLAGS(sv) |= SVf_FAKE)
@@ -1051,7 +1051,7 @@ For example, if your scalar is a reference and you want to modify the C<SvIVX>
 slot, you can't just do C<SvROK_off>, as that will leak the referent.
 
 This is used internally by various sv-modifying functions, such as
-C<sv_setsv>, C<sv_setiv> and C<sv_pvn_force..
+C<sv_setsv>, C<sv_setiv> and C<sv_pvn_force>.
 
 One case that this does not handle is a gv without SvFAKE set.  After
 
@@ -1473,10 +1473,9 @@ attention to precisely which outputs are influenced by which inputs.
 
 #define SvTAINT(sv)                    \
     STMT_START {                       \
-       if (UNLIKELY(TAINTING_get)) {   \
-           if (UNLIKELY(TAINT_get))    \
-               SvTAINTED_on(sv);       \
-       }                               \
+        assert(TAINTING_get || !TAINT_get); \
+        if (UNLIKELY(TAINT_get))       \
+            SvTAINTED_on(sv);          \
     } STMT_END
 
 /*
@@ -1575,13 +1574,13 @@ Returns a boolean indicating whether Perl would evaluate the SV as true or
 false.  See C<L</SvOK>> for a defined/undefined test.  Does not handle 'get' magic.
 
 =for apidoc Am|char*|SvPVutf8_force|SV* sv|STRLEN len
-Like C<SvPV_force>, but converts C<sv> to utf8 first if necessary.
+Like C<SvPV_force>, but converts C<sv> to UTF-8 first if necessary.
 
 =for apidoc Am|char*|SvPVutf8|SV* sv|STRLEN len
-Like C<SvPV>, but converts C<sv> to utf8 first if necessary.
+Like C<SvPV>, but converts C<sv> to UTF-8 first if necessary.
 
 =for apidoc Am|char*|SvPVutf8_nolen|SV* sv
-Like C<SvPV_nolen>, but converts C<sv> to utf8 first if necessary.
+Like C<SvPV_nolen>, but converts C<sv> to UTF-8 first if necessary.
 
 =for apidoc Am|char*|SvPVbyte_force|SV* sv|STRLEN len
 Like C<SvPV_force>, but converts C<sv> to byte representation first if necessary.
@@ -1593,12 +1592,12 @@ Like C<SvPV>, but converts C<sv> to byte representation first if necessary.
 Like C<SvPV_nolen>, but converts C<sv> to byte representation first if necessary.
 
 =for apidoc Am|char*|SvPVutf8x_force|SV* sv|STRLEN len
-Like C<SvPV_force>, but converts C<sv> to utf8 first if necessary.
+Like C<SvPV_force>, but converts C<sv> to UTF-8 first if necessary.
 Guarantees to evaluate C<sv> only once; use the more efficient C<SvPVutf8_force>
 otherwise.
 
 =for apidoc Am|char*|SvPVutf8x|SV* sv|STRLEN len
-Like C<SvPV>, but converts C<sv> to utf8 first if necessary.
+Like C<SvPV>, but converts C<sv> to UTF-8 first if necessary.
 Guarantees to evaluate C<sv> only once; use the more efficient C<SvPVutf8>
 otherwise.
 
@@ -2261,5 +2260,39 @@ Evaluates C<sv> more than once.  Sets C<len> to 0 if C<SvOOK(sv)> is false.
 #define SV_CONSTS_COUNT 35
 
 /*
+ * Bodyless IVs and NVs!
+ *
+ * Since 5.9.2, we can avoid allocating a body for SVt_IV-type SVs.
+ * Since the larger IV-holding variants of SVs store their integer
+ * values in their respective bodies, the family of SvIV() accessor
+ * macros would  naively have to branch on the SV type to find the
+ * integer value either in the HEAD or BODY. In order to avoid this
+ * expensive branch, a clever soul has deployed a great hack:
+ * We set up the SvANY pointer such that instead of pointing to a
+ * real body, it points into the memory before the location of the
+ * head. We compute this pointer such that the location of
+ * the integer member of the hypothetical body struct happens to
+ * be the same as the location of the integer member of the bodyless
+ * SV head. This now means that the SvIV() family of accessors can
+ * always read from the (hypothetical or real) body via SvANY.
+ *
+ * Since the 5.21 dev series, we employ the same trick for NVs
+ * if the architecture can support it (NVSIZE <= IVSIZE).
+ */
+
+/* The following two macros compute the necessary offsets for the above
+ * trick and store them in SvANY for SvIV() (and friends) to use. */
+
+#ifdef PERL_CORE
+#  define SET_SVANY_FOR_BODYLESS_IV(sv) \
+       SvANY(sv) =   (XPVIV*)((char*)&(sv->sv_u.svu_iv) \
+                    - STRUCT_OFFSET(XPVIV, xiv_iv))
+
+#  define SET_SVANY_FOR_BODYLESS_NV(sv) \
+       SvANY(sv) =   (XPVNV*)((char*)&(sv->sv_u.svu_nv) \
+                    - STRUCT_OFFSET(XPVNV, xnv_u.xnv_nv))
+#endif
+
+/*
  * ex: set ts=8 sts=4 sw=4 et:
  */