Author: timbo
Date: Fri Mar 2 07:47:57 2012
New Revision: 15201
Modified:
dbi/trunk/DBI.xs
Log:
[PATCH 8/8] XS_DBI_dispatch: optimise stack handling (David Mitchell)
Simplify the code the fixes up the stack and associated vars after a
method call. Note that ax is an offset from stack base rather than a
pointer, so it doesn't need to be restored afterwards. Also,
markix+1 == ax, so we can dispense with markix.
Modified: dbi/trunk/DBI.xs
==============================================================================
--- dbi/trunk/DBI.xs (original)
+++ dbi/trunk/DBI.xs Fri Mar 2 07:47:57 2012
@@ -3658,22 +3658,22 @@
/* If we are calling an XSUB we jump directly to its C code and
* bypass perl_call_sv(), pp_entersub() etc. This is fast.
- * This code is copied from a small section of pp_entersub().
+ * This code is based on a small section of pp_entersub().
*/
- I32 markix = TOPMARK;
(void)(*CvXSUB(meth_cv))(aTHXo_ meth_cv); /* Call the C code
directly */
if (gimme == G_SCALAR) { /* Enforce sanity in scalar context */
- if (++markix != PL_stack_sp - PL_stack_base ) {
- if (markix > PL_stack_sp - PL_stack_base)
- *(PL_stack_base + markix) = &PL_sv_undef;
- else *(PL_stack_base + markix) = *PL_stack_sp;
- PL_stack_sp = PL_stack_base + markix;
+ if (ax != PL_stack_sp - PL_stack_base ) { /* outitems != 1 */
+ ST(0) =
+ (ax > PL_stack_sp - PL_stack_base)
+ ? &PL_sv_undef /* outitems == 0 */
+ : *PL_stack_sp; /* outitems > 1 */
+ PL_stack_sp = PL_stack_base + ax;
}
outitems = 1;
}
else {
- outitems = PL_stack_sp - (PL_stack_base + markix);
+ outitems = PL_stack_sp - (PL_stack_base + ax - 1);
}
}
@@ -3682,11 +3682,8 @@
outitems = call_sv((SV*)meth_cv,
(is_DESTROY ? gimme | G_EVAL | G_KEEPERR : gimme) );
}
- SPAGAIN;
- /* XXX restore local vars so ST(n) works below */
- SP -= outitems;
- ax = (SP - PL_stack_base) + 1;
+ XSprePUSH; /* reset SP to base of stack frame */
#ifdef DBI_save_hv_fetch_ent
if (meth_type == methtype_FETCH)
