On Tue, Jan 20, 2009 at 12:06 PM, Martin Jambor <mjam...@suse.cz> wrote:
> Hi,
>
> I have found the testcase gcc/testsuite/gcc.dg/noncompile/920507-1.c
> failing when I was testing my new SRA. The testcase is quite simple,
> should error out but no longer does:
>
> ----------------------------------------
> int *
> x(void)
> {
> register int *a asm("unknown_register"); /* { dg-error "invalid register" }
> */
> int *v[1] = {a};
> return v[1];
> }
> ----------------------------------------
>
> The problem is the array index in the return statement. My SRA
> replaces both accesses with separate scalars, the initialization which
> is never used then gets eliminated and thus there is no failure.
>
> The first question is: Is the testcase correct or is that out of
> bounds index simply a mistake?
I have fixed that testcase on alias-improvements branch already ;)
There we otherwise simply DSE the store and return some
uninitialized memory.
> The current implementation of SRA checks in_array_bounds_p() for every
> ARRAY_REF and disables for scalarization of the array if it returns
> false. The second question is whether this is for some reason
> necessary or whether this was done only because of how the current SRA
> works. Is this useful because of warnings?
I think simply scalarizing for the above testcase is ok - the behavior
is undefined anyway.
Richard.
> Thanks for any insight,
>
> Martin
>
