Hash lookup of constant strings optimization:

Introduce SvREADONLY && SvFAKE to flag an SV which has SvPVX pointing
to string table (as per sharepvn). Add newSV_pvn_share to create such
a thing. Make hv.c compare addresses of strings and skip string compare
if equal. Make method_named and helem ops use these shared-string SVs
when arg is constant. Make keys op return shared-string SVs (less clearly
a win).

p4raw-id: //depot/perl@7016

1 files changed, 35 insertions, 34 deletions

diff --git a/pp_hot.c b/pp_hot.c
index 0a0c084144..4192f55b30 100644
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -253,7 +253,7 @@ PP(pp_readline)
     tryAMAGICunTARGET(iter, 0);
     PL_last_in_gv = (GV*)(*PL_stack_sp--);
     if (SvTYPE(PL_last_in_gv) != SVt_PVGV) {
-	if (SvROK(PL_last_in_gv) && SvTYPE(SvRV(PL_last_in_gv)) == SVt_PVGV) 
+	if (SvROK(PL_last_in_gv) && SvTYPE(SvRV(PL_last_in_gv)) == SVt_PVGV)
 	    PL_last_in_gv = (GV*)SvRV(PL_last_in_gv);
 	else {
 	    dSP;
@@ -268,7 +268,7 @@ PP(pp_readline)
 
 PP(pp_eq)
 {
-    djSP; tryAMAGICbinSET(eq,0); 
+    djSP; tryAMAGICbinSET(eq,0);
     {
       dPOPnv;
       SETs(boolSV(TOPn == value));
@@ -306,7 +306,7 @@ PP(pp_or)
 
 PP(pp_add)
 {
-    djSP; dATARGET; tryAMAGICbin(add,opASSIGN); 
+    djSP; dATARGET; tryAMAGICbin(add,opASSIGN);
     {
       dPOPTOPnnrl_ul;
       SETn( left + right );
@@ -374,7 +374,7 @@ PP(pp_print)
 	gv = PL_defoutgv;
     if ((mg = SvTIED_mg((SV*)gv, 'q'))) {
 	if (MARK == ORIGMARK) {
-	    /* If using default handle then we need to make space to 
+	    /* If using default handle then we need to make space to
 	     * pass object as 1st arg, so move other args up ...
 	     */
 	    MEXTEND(SP, 1);
@@ -495,7 +495,7 @@ PP(pp_rv2av)
 	}
 	else {
 	    GV *gv;
-	    
+	
 	    if (SvTYPE(sv) != SVt_PVGV) {
 		char *sym;
 		STRLEN len;
@@ -551,14 +551,14 @@ PP(pp_rv2av)
     if (GIMME == G_ARRAY) {
 	I32 maxarg = AvFILL(av) + 1;
 	(void)POPs;			/* XXXX May be optimized away? */
-	EXTEND(SP, maxarg);          
+	EXTEND(SP, maxarg);
 	if (SvRMAGICAL(av)) {
-	    U32 i; 
+	    U32 i;
 	    for (i=0; i < maxarg; i++) {
 		SV **svp = av_fetch(av, i, FALSE);
 		SP[i+1] = (svp) ? *svp : &PL_sv_undef;
 	    }
-	} 
+	}
 	else {
 	    Copy(AvARRAY(av), SP+1, maxarg, SV*);
 	}
@@ -599,7 +599,7 @@ PP(pp_rv2hv)
 	}
 	else {
 	    GV *gv;
-	    
+	
 	    if (SvTYPE(sv) != SVt_PVGV) {
 		char *sym;
 		STRLEN len;
@@ -1034,10 +1034,10 @@ PP(pp_match)
 	    MAGIC* mg = mg_find(TARG, 'g');
 	    if (mg && mg->mg_len >= 0) {
 		if (!(rx->reganch & ROPT_GPOS_SEEN))
-		    rx->endp[0] = rx->startp[0] = mg->mg_len; 
+		    rx->endp[0] = rx->startp[0] = mg->mg_len;
 		else if (rx->reganch & ROPT_ANCH_GPOS) {
 		    r_flags |= REXEC_IGNOREPOS;
-		    rx->endp[0] = rx->startp[0] = mg->mg_len; 
+		    rx->endp[0] = rx->startp[0] = mg->mg_len;
 		}
 		minmatch = (mg->mg_flags & MGf_MINMATCH);
 		update_minmatch = 0;
@@ -1047,7 +1047,7 @@ PP(pp_match)
     if ((gimme != G_ARRAY && !global && rx->nparens)
 	    || SvTEMP(TARG) || PL_sawampersand)
 	r_flags |= REXEC_COPY_STR;
-    if (SvSCREAM(TARG)) 
+    if (SvSCREAM(TARG))
 	r_flags |= REXEC_SCREAM;
 
     if (pm->op_pmflags & (PMf_MULTILINE|PMf_SINGLELINE)) {
@@ -1069,7 +1069,7 @@ play_it_again:
 	if (!s)
 	    goto nope;
 	if ( (rx->reganch & ROPT_CHECK_ALL)
-	     && !PL_sawampersand 
+	     && !PL_sawampersand
 	     && ((rx->reganch & ROPT_NOSCAN)
 		 || !((rx->reganch & RE_INTUIT_TAIL)
 		      && (r_flags & REXEC_SCREAM)))
@@ -1165,7 +1165,7 @@ yup:					/* Confirmed by INTUIT */
 	rx->endp[0] = s - truebase + rx->minlen;
 	rx->sublen = strend - truebase;
 	goto gotcha;
-    } 
+    }
     if (PL_sawampersand) {
 	I32 off;
 
@@ -1541,15 +1541,16 @@ PP(pp_helem)
     U32 lval = PL_op->op_flags & OPf_MOD;
     U32 defer = PL_op->op_private & OPpLVAL_DEFER;
     SV *sv;
+    U32 hash = (SvFAKE(keysv) && SvREADONLY(keysv)) ? SvUVX(keysv) : 0;
 
     if (SvTYPE(hv) == SVt_PVHV) {
-	he = hv_fetch_ent(hv, keysv, lval && !defer, 0);
+	he = hv_fetch_ent(hv, keysv, lval && !defer, hash);
 	svp = he ? &HeVAL(he) : 0;
     }
     else if (SvTYPE(hv) == SVt_PVAV) {
 	if (PL_op->op_private & OPpLVAL_INTRO)
 	    DIE(aTHX_ "Can't localize pseudo-hash element");
-	svp = avhv_fetch_ent((AV*)hv, keysv, lval && !defer, 0);
+	svp = avhv_fetch_ent((AV*)hv, keysv, lval && !defer, hash);
     }
     else {
 	RETPUSHUNDEF;
@@ -1678,7 +1679,7 @@ PP(pp_iter)
 		    /* safe to reuse old SV */
 		    sv_setsv(*itersvp, cur);
 		}
-		else 
+		else
 #endif
 		{
 		    /* we need a fresh SV every time so that loop body sees a
@@ -1704,7 +1705,7 @@ PP(pp_iter)
 	    /* safe to reuse old SV */
 	    sv_setiv(*itersvp, cx->blk_loop.iterix++);
 	}
-	else 
+	else
 #endif
 	{
 	    /* we need a fresh SV every time so that loop body sees a
@@ -1723,7 +1724,7 @@ PP(pp_iter)
     SvREFCNT_dec(*itersvp);
 
     if ((sv = SvMAGICAL(av)
-	      ? *av_fetch(av, ++cx->blk_loop.iterix, FALSE) 
+	      ? *av_fetch(av, ++cx->blk_loop.iterix, FALSE)
 	      : AvARRAY(av)[++cx->blk_loop.iterix]))
 	SvTEMP_off(sv);
     else
@@ -1783,7 +1784,7 @@ PP(pp_subst)
     else {
 	TARG = DEFSV;
 	EXTEND(SP,1);
-    }                  
+    }
     if (SvREADONLY(TARG)
 	|| (SvTYPE(TARG) > SVt_PVLV
 	    && !(SvTYPE(TARG) == SVt_PVGV && SvFAKE(TARG))))
@@ -1804,7 +1805,7 @@ PP(pp_subst)
 	DIE(aTHX_ "panic: do_subst");
 
     strend = s + len;
-    maxiters = 2*(strend - s) + 10;	/* We can match twice at each 
+    maxiters = 2*(strend - s) + 10;	/* We can match twice at each
 					   position, once with zero-length,
 					   second time with non-zero. */
 
@@ -1828,7 +1829,7 @@ PP(pp_subst)
 	    goto nope;
 	/* How to do it in subst? */
 /*	if ( (rx->reganch & ROPT_CHECK_ALL)
-	     && !PL_sawampersand 
+	     && !PL_sawampersand
 	     && ((rx->reganch & ROPT_NOSCAN)
 		 || !((rx->reganch & RE_INTUIT_TAIL)
 		      && (r_flags & REXEC_SCREAM))))
@@ -2006,7 +2007,7 @@ PP(pp_subst)
     goto ret_no;
 
 nope:
-ret_no:         
+ret_no:
     SPAGAIN;
     PUSHs(&PL_sv_no);
     LEAVE_SCOPE(oldsave);
@@ -2065,7 +2066,7 @@ PP(pp_leavesub)
     SV *sv;
 
     POPBLOCK(cx,newpm);
- 
+
     TAINT_NOT;
     if (gimme == G_SCALAR) {
 	MARK = newsp + 1;
@@ -2101,7 +2102,7 @@ PP(pp_leavesub)
 	}
     }
     PUTBACK;
-    
+
     POPSUB(cx,sv);	/* Stack values are safe: release CV and @_ ... */
     PL_curpm = newpm;	/* ... and pop $1 et al */
 
@@ -2123,7 +2124,7 @@ PP(pp_leavesublv)
     SV *sv;
 
     POPBLOCK(cx,newpm);
- 
+
     TAINT_NOT;
 
     if (cx->blk_sub.lval & OPpENTERSUB_INARGS) {
@@ -2254,7 +2255,7 @@ PP(pp_leavesublv)
 	}
     }
     PUTBACK;
-    
+
     POPSUB(cx,sv);	/* Stack values are safe: release CV and @_ ... */
     PL_curpm = newpm;	/* ... and pop $1 et al */
 
@@ -2275,7 +2276,7 @@ S_get_db_sub(pTHX_ SV **svp, CV *cv)
 
 	save_item(dbsv);
 	if ( (CvFLAGS(cv) & (CVf_ANON | CVf_CLONED))
-	     || strEQ(GvNAME(gv), "END") 
+	     || strEQ(GvNAME(gv), "END")
 	     || ((GvCV(gv) != cv) && /* Could be imported, and old sub redefined. */
 		 !( (SvTYPE(*svp) == SVt_PVGV) && (GvCV((GV*)*svp) == cv)
 		    && (gv = (GV*)*svp) ))) {
@@ -2553,7 +2554,7 @@ try_autoload:
 	    }
 	    PL_stack_sp = mark + 1;
 	    fp3 = (I32(*)(int,int,int))CvXSUB(cv);
-	    items = (*fp3)(CvXSUBANY(cv).any_i32, 
+	    items = (*fp3)(CvXSUBANY(cv).any_i32,
 			   MARK - PL_stack_base + 1,
 			   items);
 	    PL_stack_sp = PL_stack_base + items;
@@ -2583,7 +2584,7 @@ try_autoload:
 		    EXTEND(SP, items);
 		    Copy(AvARRAY(av), SP + 1, items, SV*);
 		    SP += items;
-		    PUTBACK ;		    
+		    PUTBACK ;		
 		}
 	    }
 	    /* We assume first XSUB in &DB::sub is the called one. */
@@ -2677,7 +2678,7 @@ try_autoload:
 		EXTEND(SP, items);
 		Copy(AvARRAY(av), SP + 1, items, SV*);
 		SP += items;
-		PUTBACK ;		    
+		PUTBACK ;		
 	    }
 	}
 #endif /* USE_THREADS */		
@@ -2725,7 +2726,7 @@ try_autoload:
 	    }
 	    Copy(MARK,AvARRAY(av),items,SV*);
 	    AvFILLp(av) = items - 1;
-	    
+	
 	    while (items--) {
 		if (*MARK)
 		    SvTEMP_off(*MARK);
@@ -2755,7 +2756,7 @@ Perl_sub_crush_depth(pTHX_ CV *cv)
     else {
 	SV* tmpstr = sv_newmortal();
 	gv_efullname3(tmpstr, CvGV(cv), Nullch);
-	Perl_warner(aTHX_ WARN_RECURSION, "Deep recursion on subroutine \"%s\"", 
+	Perl_warner(aTHX_ WARN_RECURSION, "Deep recursion on subroutine \"%s\"",
 		SvPVX(tmpstr));
     }
 }
@@ -2888,7 +2889,7 @@ S_method_common(pTHX_ SV* meth, U32* hashp)
 	    !(iogv = gv_fetchpv(packname, FALSE, SVt_PVIO)) ||
 	    !(ob=(SV*)GvIO(iogv)))
 	{
-	    if (!packname || 
+	    if (!packname ||
 		((*(U8*)packname >= 0xc0 && DO_UTF8(sv))
 		    ? !isIDFIRST_utf8((U8*)packname)
 		    : !isIDFIRST(*packname)