Re: Fix PR69752, insn with REG_INC being removed as equiv_init insn

[Jeff Law <law at redhat dot com>]

On 02/11/2016 06:28 PM, Bernd Schmidt wrote:
> This seems fairly straightforward:
>
> (insn 213 455 216 6 (set (reg:SI 266)
>          (mem/u/c:SI (post_inc:SI (reg/f:SI 267)) [4  S4 A32])) 748
> {*thumb1_movsi_insn}
>       (expr_list:REG_EQUAL (const_int -1044200508 [0xffffffffc1c2c3c4])
>          (expr_list:REG_INC (reg/f:SI 267)
>              (nil))))
>
> We don't notice that the SET_SRC has a side effect, record the insn as
> an equivalencing one, and later remove it because we replaced the reg
> with the constant everywhere. Thus, the increment doesn't take place.
>
> Fixed as follows. Bootstrapped and tested on x86_64-linux. Also compared
> before/after dumps for the testcase with arm-elf. Ok?
>
>
> Bernd
>
> equiv-inc.diff
>
>
> 	PR rtl-optimization/69752
> 	* ira.c (update_equiv_regs): When looking for more than a single SET,
> 	also take other side effects into account.
Also note that the reporter says gcc-4.9 didn't have this problem, so 
there's a reasonable chance this is a latent regression exposed by 
codegen changes prior to IRA.


OK for the trunk.

Jeff