pp_sassign: explain the mix of left<=>right in the optree

[perl5.git] / pp_hot.c

diff --git a/pp_hot.c b/pp_hot.c
index 22afeb1..24edbdc 100644 (file)
--- a/pp_hot.c
+++ b/pp_hot.c
@@ -112,30 +112,34 @@ PP(pp_and)
 
 PP(pp_sassign)
 {
-    dVAR; dSP; dPOPTOPssrl;
+    dVAR; dSP;
+    /* sassign keeps its args in the optree traditionally backwards.
+       So we pop them differently.
+    */
+    SV *left = POPs; SV *right = TOPs;
 
     if (PL_op->op_private & OPpASSIGN_BACKWARDS) {
        SV * const temp = left;
        left = right; right = temp;
     }
-    if (PL_tainting && PL_tainted && !SvTAINTED(left))
+    if (PL_tainting && PL_tainted && !SvTAINTED(right))
        TAINT_NOT;
     if (PL_op->op_private & OPpASSIGN_CV_TO_GV) {
-       SV * const cv = SvRV(left);
+       SV * const cv = SvRV(right);
        const U32 cv_type = SvTYPE(cv);
-       const bool is_gv = isGV_with_GP(right);
+       const bool is_gv = isGV_with_GP(left);
        const bool got_coderef = cv_type == SVt_PVCV || cv_type == SVt_PVFM;
 
        if (!got_coderef) {
            assert(SvROK(cv));
        }
 
-       /* Can do the optimisation if right (LVALUE) is not a typeglob,
-          left (RVALUE) is a reference to something, and we're in void
+       /* Can do the optimisation if left (LVALUE) is not a typeglob,
+          right (RVALUE) is a reference to something, and we're in void
           context. */
        if (!got_coderef && !is_gv && GIMME_V == G_VOID) {
            /* Is the target symbol table currently empty?  */
-           GV * const gv = gv_fetchsv_nomg(right, GV_NOINIT, SVt_PVGV);
+           GV * const gv = gv_fetchsv_nomg(left, GV_NOINIT, SVt_PVGV);
            if (SvTYPE(gv) != SVt_PVGV && !SvOK(gv)) {
                /* Good. Create a new proxy constant subroutine in the target.
                   The gv becomes a(nother) reference to the constant.  */
@@ -145,7 +149,7 @@ PP(pp_sassign)
                SvPCS_IMPORTED_on(gv);
                SvRV_set(gv, value);
                SvREFCNT_inc_simple_void(value);
-               SETs(right);
+               SETs(left);
                RETURN;
            }
        }
@@ -153,7 +157,7 @@ PP(pp_sassign)
        /* Need to fix things up.  */
        if (!is_gv) {
            /* Need to fix GV.  */
-           right = MUTABLE_SV(gv_fetchsv_nomg(right,GV_ADD, SVt_PVGV));
+           left = MUTABLE_SV(gv_fetchsv_nomg(left,GV_ADD, SVt_PVGV));
        }
 
        if (!got_coderef) {
@@ -167,7 +171,7 @@ PP(pp_sassign)
                   all sorts of fun as the reference to our new sub is
                   donated to the GV that we're about to assign to.
                */
-               SvRV_set(left, MUTABLE_SV(newCONSTSUB(GvSTASH(right), NULL,
+               SvRV_set(right, MUTABLE_SV(newCONSTSUB(GvSTASH(left), NULL,
                                                      SvRV(cv))));
                SvREFCNT_dec(cv);
                LEAVE_with_name("sassign_coderef");
@@ -193,20 +197,20 @@ PP(pp_sassign)
 
                SvREFCNT_inc_void(source);
                SvREFCNT_dec(upgraded);
-               SvRV_set(left, MUTABLE_SV(source));
+               SvRV_set(right, MUTABLE_SV(source));
            }
        }
 
     }
     if (
-      SvTEMP(right) && !SvSMAGICAL(right) && SvREFCNT(right) == 1 &&
-      (!isGV_with_GP(right) || SvFAKE(right)) && ckWARN(WARN_MISC)
+      SvTEMP(left) && !SvSMAGICAL(left) && SvREFCNT(left) == 1 &&
+      (!isGV_with_GP(left) || SvFAKE(left)) && ckWARN(WARN_MISC)
     )
        Perl_warner(aTHX_
            packWARN(WARN_MISC), "Useless assignment to a temporary"
        );
-    SvSetMagicSV(right, left);
-    SETs(right);
+    SvSetMagicSV(left, right);
+    SETs(left);
     RETURN;
 }