[Bug rtl-optimization/112525] fail to eliminate unused store

["guojiufu at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112525

--- Comment #1 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
(In reply to Jiu Fu Guo from comment #0)
> For below code:
> ```
> typedef struct teststruct
> {
>   double d;
>   int arr[15]; /* for ppc64le example foo1, 14: foo is just blr. 15: foo has
> 8 'std's */
> } teststruct;

Here, if the code is "int arr[14];", the struct is just passed via registers
(in foo function); and in the expander pass, they are stored to frame area. 
If the code is "int arr[15];",  the struct is passed through registers
partially, and the other partial is through memory; and in the expander pass,
they are stored to the area which is pointed via arg pointer.

In DSE pass, the 'dead' stores to 'frame' can be eliminated.