Define a newPADxVOP() convenience function

This function conveniently sets the ->op_targ field of the returned op,
making it neater to use inline in larger trees of new*OP functions used
to build optree fragments.

This function is implemented as `static inline`, for speed and code-size
reasons.

Author: leonerd

embed.fnc

@@ -1519,6 +1519,7 @@ AxpdRT	|PADNAMELIST *|newPADNAMELIST|size_t max
 #ifdef USE_ITHREADS
 ApdR	|OP*	|newPADOP	|I32 type|I32 flags|NN SV* sv
 #endif
+ApdRi	|OP*	|newPADxVOP	|I32 type|I32 flags|PADOFFSET padix
 ApdR	|OP*	|newPMOP	|I32 type|I32 flags
 ApdR	|OP*	|newPVOP	|I32 type|I32 flags|NULLOK char* pv
 ApdR	|SV*	|newRV		|NN SV *const sv

embed.h

@@ -368,6 +368,7 @@
 #define newPADNAMELIST		Perl_newPADNAMELIST
 #define newPADNAMEouter		Perl_newPADNAMEouter
 #define newPADNAMEpvn		Perl_newPADNAMEpvn
+#define newPADxVOP(a,b,c)	Perl_newPADxVOP(aTHX_ a,b,c)
 #define newPMOP(a,b)		Perl_newPMOP(aTHX_ a,b)
 #define newPROG(a)		Perl_newPROG(aTHX_ a)
 #define newPVOP(a,b,c)		Perl_newPVOP(aTHX_ a,b,c)

inline.h

@@ -3086,6 +3086,36 @@ Perl_cx_popgiven(pTHX_ PERL_CONTEXT *cx)
     SvREFCNT_dec(sv);
 }
 
+/*
+=for apidoc newPADxVOP
+
+Constructs, checks and returns an op containing a pad offset.  C<type> is
+the opcode, which should be one of C<OP_PADSV>, C<OP_PADAV>, C<OP_PADHV>
+or C<OP_PADCV>.  The returned op will have the C<op_targ> field set by
+the C<padix> argument.
+
+This is convenient when constructing a large optree in nested function
+calls, as it avoids needing to store the pad op directly to set the
+C<op_targ> field as a side-effect. For example
+
+    o = op_append_elem(OP_LINESEQ, o,
+        newPADxVOP(OP_PADSV, 0, padix));
+
+=cut
+*/
+
+PERL_STATIC_INLINE OP *
+Perl_newPADxVOP(pTHX_ I32 type, I32 flags, PADOFFSET padix)
+{
+    PERL_ARGS_ASSERT_NEWPADXVOP;
+
+    assert(type == OP_PADSV || type == OP_PADAV || type == OP_PADHV
+            || type == OP_PADCV);
+    OP *o = newOP(type, flags);
+    o->op_targ = padix;
+    return o;
+}
+
 /* ------------------ util.h ------------------------------------------- */
 
 /*

proto.h

@@ -2763,6 +2763,12 @@ PERL_CALLCONV PADNAME *	Perl_newPADNAMEpvn(const char *s, STRLEN len)
 #define PERL_ARGS_ASSERT_NEWPADNAMEPVN	\
 	assert(s)
 
+#ifndef PERL_NO_INLINE_FUNCTIONS
+PERL_STATIC_INLINE OP*	Perl_newPADxVOP(pTHX_ I32 type, I32 flags, PADOFFSET padix)
+			__attribute__warn_unused_result__;
+#define PERL_ARGS_ASSERT_NEWPADXVOP
+#endif
+
 PERL_CALLCONV OP*	Perl_newPMOP(pTHX_ I32 type, I32 flags)
 			__attribute__warn_unused_result__;
 #define PERL_ARGS_ASSERT_NEWPMOP