Extended Description

clang at -O2 missed opportunity to generate memset for

unsigned** a;
void foo( int max )
{
  for (int i = 0; i <= max; ++i) 
  {
    a[i] = 0;
  }
}

and left the loop, while gcc succeeded to do this:
X86-64 https://godbolt.org/z/oK59vf66n
AArch64 https://godbolt.org/z/G53W1vz7W