[Bug rtl-optimization/84101] [7/8/9 Regression] -O3 and -ftree-vectorize trying too hard for function returning trivial pair-of-uint64_t-structure

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84101

--- Comment #20 from Richard Biener <rguenth at gcc dot gnu.org> ---
Ah.

Index: gcc/expr.c
===================================================================
--- gcc/expr.c  (revision 269960)
+++ gcc/expr.c  (working copy)
@@ -7018,7 +7018,11 @@ store_field (rtx target, poly_int64 bits
            }
        }

-      temp = expand_normal (exp);
+      temp = expand_expr (exp,
+                         known_eq (bitpos, 0) ? target : NULL_RTX,
+                         VOIDmode, EXPAND_NORMAL);
+      if (temp == target)
+       return const0_rtx;

       /* We don't support variable-sized BLKmode bitfields, since our
         handling of BLKmode is bound up with the ability to break
@@ -7641,6 +7645,8 @@ safe_from_p (const_rtx x, tree exp, int
              return 0;
          return 1;
        }
+      else if (TREE_CODE (exp) == SSA_NAME)
+       return 1;
       else if (TREE_CODE (exp) == ERROR_MARK)
        return 1;       /* An already-visited SAVE_EXPR? */
       else