Withdrawn: 8311010: C1 array access causes SIGSEGV due to lack of range check

[Yi Yang]

On Wed, 28 Jun 2023 09:02:10 GMT, Yi Yang <yyang at openjdk.org> wrote:

> int[] a = { 11 } ;
>         for (int i = -1; i <= 0; i++) {
>             // Insert deopt check
>             if (2147483646 * i >=1) { goto deopt_stub;}
>             for (int j = -3; j <= 2147483646 * i - 3; j++) {
>                 b += a[j + 3];
>             }
>         }
> 
> C1 eliminates range check before accessing array and inserts a deoptimization check before loop header, because he did the following deduction:
> 
>    lower - const <= x <= upper - const
>    lower <= x + const <= upper
> 
>  This is wrong, because (lower - const + const) and  (upper -  const + const) may overflow/underflow, e.g.
> 
>     -3 <= x     <= min_jint - 3
>     0  <= x + 3 <= min_jint    (wrong)
> 
> The proposed change is to assume the worst case whenever upper or lower is found, which may be somewhat conservative.

This pull request has been closed without being integrated.

-------------

PR: https://git.openjdk.org/jdk/pull/14689