[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 #10 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to Andrew Pinski from comment #8)
> (In reply to H.J. Lu from comment #7)
> > After 284r.ira:
> 
> That is fine according to the rules as long as TARGET_TRULY_NOOP_TRUNCATION 
> is true.

We can't turn

(insn 13 12 14 3 (set (reg:SI 4 si)
        (subreg:SI (reg/v:DI 85 [ b ]) 0)) "y.i":14:14 67 {*movsi_internal}
     (expr_list:REG_DEAD (reg/v:DI 85 [ b ])
        (nil)))

into


(insn 13 12 14 3 (set (reg:SI 4 si)
        (reg:SI 4 si [orig:85 b ] [85])) "y.i":14:14 67 {*movsi_internal}
     (expr_list:REG_DEAD (reg/v:DI 4 si [orig:85 b ] [85])
        (nil)))

This is simple wrong.