[Bug middle-end/94541] [8/9/10 Regression] -mx32 gcc produces wrong code passing structs by value

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94541

--- Comment #9 from H.J. Lu <hjl.tools at gmail dot com> ---
I am testing this:

diff --git a/gcc/lra-spills.c b/gcc/lra-spills.c
index 0caa4acd3b5..bd4ee80245d 100644
--- a/gcc/lra-spills.c
+++ b/gcc/lra-spills.c
@@ -844,9 +844,14 @@ lra_final_code_change (void)

          struct lra_static_insn_data *static_id = id->insn_static_data;
          bool insn_change_p = false;
+         set = single_set (insn);

+         /* NB: Never change SUBREG in the source operand of a SET
+            insn to REG.  */
          for (i = id->insn_static_data->n_operands - 1; i >= 0; i--)
            if ((DEBUG_INSN_P (insn) || ! static_id->operand[i].is_operator)
+               && (set == NULL
+                   || !rtx_equal_p (SET_SRC (set), *id->operand_loc[i]))
                && alter_subregs (id->operand_loc[i], ! DEBUG_INSN_P (insn)))
              {
                lra_update_dup (id, i);
@@ -855,7 +860,7 @@ lra_final_code_change (void)
          if (insn_change_p)
            lra_update_operator_dups (id);

-         if ((set = single_set (insn)) != NULL
+         if (set != NULL
              && REG_P (SET_SRC (set)) && REG_P (SET_DEST (set))
              && REGNO (SET_SRC (set)) == REGNO (SET_DEST (set)))
            {