[Bug tree-optimization/64277] [4.9/5 Regression] Incorrect warning "array subscript is above array bounds"

["enkovich.gnu at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64277

Ilya Enkovich <enkovich.gnu at gmail dot com> changed:

           What    |Removed                     |Added
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                 CC|                            |enkovich.gnu at gmail dot com

--- Comment #7 from Ilya Enkovich <enkovich.gnu at gmail dot com> ---
Here is a reduced test case:

>cat test.c
int f1[10];
void foo(short a[], short m, unsigned short l)
{
  int i = l;
  for (i = i + 5; i < m; i++)
    f1[i] = a[i]++;
}
>gcc test.c -O3 -c -Wall
test.c: In function 'foo':
test.c:6:7: warning: array subscript is above array bounds [-Warray-bounds]
     f1[i] = a[i]++;
       ^
test.c:6:7: warning: array subscript is above array bounds [-Warray-bounds]
test.c:6:7: warning: array subscript is above array bounds [-Warray-bounds]
test.c:6:7: warning: array subscript is above array bounds [-Warray-bounds]
test.c:6:7: warning: array subscript is above array bounds [-Warray-bounds]

Here we have complete unroll of the loop by 10 due to f1 size.  Later vrp
complains of last five produced iterations accessing above array bounds.

Used GCC 5.0.