[Bug tree-optimization/89518] New: missed optimisation for array address calculations

[arnaud02 at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89518

            Bug ID: 89518
           Summary: missed optimisation for array address calculations
           Product: gcc
           Version: 8.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: arnaud02 at users dot sourceforge.net
  Target Milestone: ---

Considering:

int f(int index, int stride) {
    const int i1 = index / stride;
    const int i2 = index % stride;
    const int index2 = i1*stride+i2;
    return index2; // expect: index2 = index
}

gcc 8.3 with "-O3" on x84_64 emits:
f(int, int):
        mov     eax, edi
        cdq
        idiv    esi
        imul    eax, esi
        add     eax, edx
        ret

By contrast, clang 7 with "-O3" emits
f(int, int):
        mov     eax, edi
        ret

MSVC 2017 with "/O2" emits:
int f(int,int)
        mov     eax, ecx
        ret     0

Is there a way to persuade gcc to simplify this expression at compile time?