Store xio_ifp in sv_u in the SV head, reducing XPVIO by 1 pointer.

When accessing a file handle for reading, this reduces pointer dereferences by
1, which will reduce CPU cache pressure.

As SVt_PVIO is also the default type provided to source filters, the code needs
to allow them to continue to use the sv_u for SvPVX(). Re-use the existing
IOf_FAKE_DIRP to signal this, as it's only set when a source filter is added.

1 files changed, 18 insertions, 3 deletions

diff --git a/sv.h b/sv.h
index adadab36cb..bc75d1e199 100644
--- a/sv.h
+++ b/sv.h
@@ -106,6 +106,7 @@ typedef struct hek HEK;
 	SV**    svu_array;		\
 	HE**	svu_hash;		\
 	GP*	svu_gp;			\
+	PerlIO *svu_fp;			\
     }	sv_u
 
 
@@ -509,8 +510,8 @@ struct xpvfm {
 struct xpvio {
     _XPV_HEAD;
     union _xivu xiv_u;
-    PerlIO *	xio_ifp;	/* ifp and ofp are normally the same */
-    PerlIO *	xio_ofp;	/* but sockets need separate streams */
+    /* ifp and ofp are normally the same, but sockets need separate streams */
+    PerlIO *	xio_ofp;
     /* Cray addresses everything by word boundaries (64 bits) and
      * code and data pointers cannot be mixed (which is exactly what
      * Perl_filter_add() tries to do with the dirp), hence the
@@ -1054,6 +1055,8 @@ the scalar's value cannot change unless written to.
 	    assert(SvTYPE(_svcur) != SVt_PVAV);				\
 	    assert(SvTYPE(_svcur) != SVt_PVHV);				\
 	    assert(!isGV_with_GP(_svcur));				\
+	    assert(!(SvTYPE(_svcur) == SVt_PVIO				\
+		     && !(IoFLAGS(_svcur) & IOf_FAKE_DIRP)));		\
 	    &(((XPV*) MUTABLE_PTR(SvANY(_svcur)))->xpv_cur);		\
 	 }))
 #    define SvIVX(sv)							\
@@ -1100,6 +1103,8 @@ the scalar's value cannot change unless written to.
 	    assert(SvTYPE(_svrv) != SVt_PVCV);				\
 	    assert(SvTYPE(_svrv) != SVt_PVFM);				\
 	    assert(!isGV_with_GP(_svrv));				\
+	    assert(!(SvTYPE(_svrv) == SVt_PVIO				\
+		     && !(IoFLAGS(_svrv) & IOf_FAKE_DIRP)));		\
 	    &((_svrv)->sv_u.svu_rv);					\
 	 }))
 #    define SvRV_const(sv)						\
@@ -1110,6 +1115,8 @@ the scalar's value cannot change unless written to.
 	    assert(SvTYPE(_svrv) != SVt_PVCV);				\
 	    assert(SvTYPE(_svrv) != SVt_PVFM);				\
 	    assert(!isGV_with_GP(_svrv));				\
+	    assert(!(SvTYPE(_svrv) == SVt_PVIO				\
+		     && !(IoFLAGS(_svrv) & IOf_FAKE_DIRP)));		\
 	    (_svrv)->sv_u.svu_rv;					\
 	 })
 #    define SvMAGIC(sv)							\
@@ -1185,6 +1192,8 @@ the scalar's value cannot change unless written to.
 		assert(SvTYPE(sv) != SVt_PVAV);		\
 		assert(SvTYPE(sv) != SVt_PVHV);		\
 		assert(!isGV_with_GP(sv));		\
+		assert(!(SvTYPE(sv) == SVt_PVIO		\
+		     && !(IoFLAGS(sv) & IOf_FAKE_DIRP))); \
 		((sv)->sv_u.svu_pv = (val)); } STMT_END
 #define SvUV_set(sv, val) \
 	STMT_START { assert(SvTYPE(sv) == SVt_IV || SvTYPE(sv) >= SVt_PVIV); \
@@ -1200,6 +1209,8 @@ the scalar's value cannot change unless written to.
 		assert(SvTYPE(sv) != SVt_PVCV);		\
 		assert(SvTYPE(sv) != SVt_PVFM);		\
 		assert(!isGV_with_GP(sv));		\
+		assert(!(SvTYPE(sv) == SVt_PVIO		\
+		     && !(IoFLAGS(sv) & IOf_FAKE_DIRP))); \
                 ((sv)->sv_u.svu_rv = (val)); } STMT_END
 #define SvMAGIC_set(sv, val) \
         STMT_START { assert(SvTYPE(sv) >= SVt_PVMG); \
@@ -1212,12 +1223,16 @@ the scalar's value cannot change unless written to.
 		assert(SvTYPE(sv) != SVt_PVAV);		\
 		assert(SvTYPE(sv) != SVt_PVHV);		\
 		assert(!isGV_with_GP(sv));		\
+		assert(!(SvTYPE(sv) == SVt_PVIO		\
+		     && !(IoFLAGS(sv) & IOf_FAKE_DIRP))); \
 		(((XPV*)  SvANY(sv))->xpv_cur = (val)); } STMT_END
 #define SvLEN_set(sv, val) \
 	STMT_START { assert(SvTYPE(sv) >= SVt_PV); \
 		assert(SvTYPE(sv) != SVt_PVAV);	\
 		assert(SvTYPE(sv) != SVt_PVHV);	\
 		assert(!isGV_with_GP(sv));	\
+		assert(!(SvTYPE(sv) == SVt_PVIO		\
+		     && !(IoFLAGS(sv) & IOf_FAKE_DIRP))); \
 		(((XPV*)  SvANY(sv))->xpv_len = (val)); } STMT_END
 #define SvEND_set(sv, val) \
 	STMT_START { assert(SvTYPE(sv) >= SVt_PV); \
@@ -1311,7 +1326,7 @@ the scalar's value cannot change unless written to.
 #define LvTARGOFF(sv)	((XPVLV*)  SvANY(sv))->xlv_targoff
 #define LvTARGLEN(sv)	((XPVLV*)  SvANY(sv))->xlv_targlen
 
-#define IoIFP(sv)	((XPVIO*)  SvANY(sv))->xio_ifp
+#define IoIFP(sv)	(sv)->sv_u.svu_fp
 #define IoOFP(sv)	((XPVIO*)  SvANY(sv))->xio_ofp
 #define IoDIRP(sv)	((XPVIO*)  SvANY(sv))->xio_dirp
 #define IoANY(sv)	((XPVIO*)  SvANY(sv))->xio_any