create itervar_u union in struct block_loop

make it clearer what types of pointer to the iterator variable can be
stored, reduce the amount of #ifdef USE_ITHREADS, get rid of some macros,
and generally make the code easier to follow. No change to the size of the
structure.

3 files changed, 25 insertions, 37 deletions

diff --git a/cop.h b/cop.h
index 4c269a72de..c91e9a4a09 100644
--- a/cop.h
+++ b/cop.h
@@ -447,11 +447,11 @@ struct block_eval {
 struct block_loop {
     I32		resetsp;
     LOOP *	my_op;	/* My op, that contains redo, next and last ops.  */
-#ifdef USE_ITHREADS
-    PAD		*oldcomppad; /* Also used for the GV, if my_op->op_targ is 0 */
-#else
-    SV **	itervar;
-#endif
+    union {	/* different ways of locating the iteration variable */
+	SV      **svp;
+	GV      *gv;
+	PAD     *oldcomppad; /* only used in ITHREADS */
+    } itervar_u;
     union {
 	struct { /* valid if type is LOOP_FOR or LOOP_PLAIN (but {NULL,0})*/
 	    AV * ary; /* use the stack if this is NULL */
@@ -470,20 +470,13 @@ struct block_loop {
 
 #ifdef USE_ITHREADS
 #  define CxITERVAR(c)							\
-	((c)->blk_loop.oldcomppad					\
+	((c)->blk_loop.itervar_u.oldcomppad				\
 	 ? (CxPADLOOP(c) 						\
-	    ? &CX_CURPAD_SV( (c)->blk_loop, (c)->blk_loop.my_op->op_targ) \
-	    : &GvSV((GV*)(c)->blk_loop.oldcomppad))			\
+	    ? &CX_CURPAD_SV( (c)->blk_loop.itervar_u, (c)->blk_loop.my_op->op_targ) \
+	    : &GvSV((c)->blk_loop.itervar_u.gv))			\
 	 : (SV**)NULL)
-#  define CX_ITERDATA_SET(cx,idata,o)					\
-	if (cx->blk_loop.my_op->op_targ)				\
-	    CX_CURPAD_SAVE(cx->blk_loop);				\
-	else								\
-	    cx->blk_loop.oldcomppad = (idata);
 #else
-#  define CxITERVAR(c)		((c)->blk_loop.itervar)
-#  define CX_ITERDATA_SET(cx,ivar,o)					\
-	cx->blk_loop.itervar = (SV**)(ivar);
+#  define CxITERVAR(c)		((c)->blk_loop.itervar_u.svp)
 #endif
 #define CxLABEL(c)	(0 + CopLABEL((c)->blk_oldcop))
 #define CxHASARGS(c)	(((c)->cx_type & CXp_HASARGS) == CXp_HASARGS)
@@ -494,14 +487,14 @@ struct block_loop {
 	cx->blk_loop.my_op = cLOOP;					\
 	cx->blk_loop.state_u.ary.ary = NULL;				\
 	cx->blk_loop.state_u.ary.ix = 0;				\
-	CX_ITERDATA_SET(cx, NULL, 0);
+	cx->blk_loop.itervar_u.svp = NULL;
 
-#define PUSHLOOP_FOR(cx, dat, s, offset)				\
+#define PUSHLOOP_FOR(cx, ivar, s)					\
 	cx->blk_loop.resetsp = s - PL_stack_base;			\
 	cx->blk_loop.my_op = cLOOP;					\
 	cx->blk_loop.state_u.ary.ary = NULL;				\
 	cx->blk_loop.state_u.ary.ix = 0;				\
-	CX_ITERDATA_SET(cx, dat, offset);
+	cx->blk_loop.itervar_u.svp = (SV**)(ivar);
 
 #define POPLOOP(cx)							\
 	if (CxTYPE(cx) == CXt_LOOP_LAZYSV) {				\
diff --git a/pp_ctl.c b/pp_ctl.c
index 93d167545b..9673d1290f 100644
--- a/pp_ctl.c
+++ b/pp_ctl.c
@@ -1946,11 +1946,8 @@ PP(pp_enteriter)
     dVAR; dSP; dMARK;
     register PERL_CONTEXT *cx;
     const I32 gimme = GIMME_V;
-    SV **svp;
+    void *itervar; /* location of the iteration variable */
     U8 cxtype = CXt_LOOP_FOR;
-#ifdef USE_ITHREADS
-    PAD *iterdata;
-#endif
 
     ENTER_with_name("loop1");
     SAVETMPS;
@@ -1963,18 +1960,20 @@ PP(pp_enteriter)
 	}
 	SAVEPADSVANDMORTALIZE(PL_op->op_targ);
 #ifndef USE_ITHREADS
-	svp = &PAD_SVl(PL_op->op_targ);		/* "my" variable */
+	itervar = &PAD_SVl(PL_op->op_targ);	/* "my" variable */
 #else
-	iterdata = NULL;
+	itervar = PL_comppad;
 #endif
     }
     else {
 	GV * const gv = MUTABLE_GV(POPs);
-	svp = &GvSV(gv);			/* symbol table variable */
+	SV** svp = &GvSV(gv);			/* symbol table variable */
 	SAVEGENERICSV(*svp);
 	*svp = newSV(0);
 #ifdef USE_ITHREADS
-	iterdata = (PAD*)gv;
+	itervar = (void *)gv;
+#else
+	itervar = (void *)svp;
 #endif
     }
 
@@ -1984,11 +1983,7 @@ PP(pp_enteriter)
     ENTER_with_name("loop2");
 
     PUSHBLOCK(cx, cxtype, SP);
-#ifdef USE_ITHREADS
-    PUSHLOOP_FOR(cx, iterdata, MARK, PL_op->op_targ);
-#else
-    PUSHLOOP_FOR(cx, svp, MARK, 0);
-#endif
+    PUSHLOOP_FOR(cx, itervar, MARK);
     if (PL_op->op_flags & OPf_STACKED) {
 	SV *maybe_ary = POPs;
 	if (SvTYPE(maybe_ary) != SVt_PVAV) {
diff --git a/sv.c b/sv.c
index d6af5ce445..8bf7cbaabe 100644
--- a/sv.c
+++ b/sv.c
@@ -11660,13 +11660,13 @@ Perl_cx_dup(pTHX_ PERL_CONTEXT *cxs, I32 ix, I32 max, CLONE_PARAMS* param)
 	    case CXt_LOOP_LAZYIV:
 	    case CXt_LOOP_PLAIN:
 		if (CxPADLOOP(ncx)) {
-		    ncx->blk_loop.oldcomppad
+		    ncx->blk_loop.itervar_u.oldcomppad
 			= (PAD*)ptr_table_fetch(PL_ptr_table,
-						ncx->blk_loop.oldcomppad);
+					ncx->blk_loop.itervar_u.oldcomppad);
 		} else {
-		    ncx->blk_loop.oldcomppad
-			= (PAD*)gv_dup((const GV *)ncx->blk_loop.oldcomppad,
-				       param);
+		    ncx->blk_loop.itervar_u.gv
+			= gv_dup((const GV *)ncx->blk_loop.itervar_u.gv,
+				    param);
 		}
 		break;
 	    case CXt_FORMAT: