https://gcc.gnu.org/bugzilla/show_bug.cgi?id=126941
--- Comment #3 from Alfie Richards <alfierichards at gcc dot gnu.org> ---
So to take a really simple case, the below generates code that looks like:
> unsigned long foo (char);
> int bad_addressing (char *arr1, unsigned long n) {
> for (unsigned long i = 0; i < n;) {
> *arr1 += 1;
> unsigned long advance = foo (*arr1);
> arr1 += advance;
> i += advance;
> }
> }
Generates the following loop body
> .L3:
> ldrb w0, [x19]
> add w0, w0, 1
> strb w0, [x19]
> bl foo
> add x20, x20, x0
> add x19, x19, x0
> cmp x21, x20
> bhi .L3
Where it could do
> .L3:
> ldrb w0, [x19, x20]
> add w0, w0, 1
> strb w0, [x19, x20]
> bl foo
> add x20, x20, x0
> cmp x21, x20
> bhi .L3
As arr1 can be safely expressed as arr1_base + advance (even with overflow
considerations)
