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Optimisation for 'my $x; my $y;' -> 'my ($x, $y)'.
[perl5.git] / op.c
diff --git a/op.c b/op.c
index dd43323..60aef44 100644 (file)
--- a/op.c
+++ b/op.c
@@ -11200,6 +11200,71 @@ Perl_rpeep(pTHX_ OP *o)
                }
            }
 
                }
            }
 
+           /* Optimise 'my $x; my $y;' into 'my ($x, $y);'
+             *
+            * This latter form is then suitable for conversion into padrange
+            * later on. Convert:
+            *
+            *   nextstate1 -> padop1 -> nextstate2 -> padop2 -> nextstate3
+            *
+            * into:
+            *
+            *   nextstate1 ->     listop     -> nextstate3
+            *                 /            \
+            *         pushmark -> padop1 -> padop2
+            */
+           if (o->op_next && (
+                   o->op_next->op_type == OP_PADSV
+                || o->op_next->op_type == OP_PADAV
+                || o->op_next->op_type == OP_PADHV
+               )
+               && !(o->op_next->op_private & ~OPpLVAL_INTRO)
+               && o->op_next->op_next && o->op_next->op_next->op_type == OP_NEXTSTATE
+               && o->op_next->op_next->op_next && (
+                   o->op_next->op_next->op_next->op_type == OP_PADSV
+                || o->op_next->op_next->op_next->op_type == OP_PADAV
+                || o->op_next->op_next->op_next->op_type == OP_PADHV
+               )
+               && !(o->op_next->op_next->op_next->op_private & ~OPpLVAL_INTRO)
+               && o->op_next->op_next->op_next->op_next && o->op_next->op_next->op_next->op_next->op_type == OP_NEXTSTATE
+               && (!CopLABEL((COP*)o)) /* Don't mess with labels */
+               && (!CopLABEL((COP*)o->op_next->op_next)) /* ... */
+           ) {
+               OP *first;
+               OP *last;
+               OP *newop;
+
+               first = o->op_next;
+               last = o->op_next->op_next->op_next;
+
+               newop = newLISTOP(OP_LIST, 0, first, last);
+               newop->op_flags |= OPf_PARENS;
+               newop->op_flags = (newop->op_flags & ~OPf_WANT) | OPf_WANT_VOID;
+
+               /* Kill nextstate2 between padop1/padop2 */
+               op_free(first->op_next);
+
+               first->op_next = last;                /* padop2 */
+               first->op_sibling = last;             /* ... */
+               o->op_next = cUNOPx(newop)->op_first; /* pushmark */
+               o->op_next->op_next = first;          /* padop1 */
+               o->op_next->op_sibling = first;       /* ... */
+               newop->op_next = last->op_next;       /* nextstate3 */
+               newop->op_sibling = last->op_sibling;
+               last->op_next = newop;                /* listop */
+               last->op_sibling = NULL;
+               o->op_sibling = newop;                /* ... */
+
+               newop->op_flags = (newop->op_flags & ~OPf_WANT) | OPf_WANT_VOID;
+
+               /* Ensure pushmark has this flag if padops do */
+               if (first->op_flags & OPf_MOD && last->op_flags & OPf_MOD) {
+                   o->op_next->op_flags |= OPf_MOD;
+               }
+
+               break;
+           }
+
            /* Two NEXTSTATEs in a row serve no purpose. Except if they happen
               to carry two labels. For now, take the easier option, and skip
               this optimisation if the first NEXTSTATE has a label.  */
            /* Two NEXTSTATEs in a row serve no purpose. Except if they happen
               to carry two labels. For now, take the easier option, and skip
               this optimisation if the first NEXTSTATE has a label.  */