simplify_transformation_to_array had the nested loop unrolled 7 times,
which is reasonable given that it iterates over arrays of size
GFC_MAX_DIMENSIONS == 7.
The problem is that the last iteration increments the index, tests
that it's less than result->rank, and then accesses the arrays with
the incremented index.
We did not optimize out that part in the 7th iteration, so VRP flagged
the unreachable code as accessing arrays past the end.
It couldn't possibly know that we'd never reach that part, since the
test was on result->rank, and it's not obvious (for the compiler) that
result->rank <= GFC_MAX_DIMENSIONS.
Even an assert to that effect before the enclosing loop didn't avoid
the warning turned to error, though; I suppose there might be some
aliasing at play, because moving the assert into the loop does, but
then, it's not as efficient as testing the index itself against the
limit.
Regstrapped on x86_64-linux-gnu and i686-linux-gnu. OK to install?
for gcc/fortran/ChangeLog
* simplify.c (simplify_transformation_to_array): Assert the
array access is in range. Fix whitespace.