On 09/01/2015 12:44 AM, DJ Delorie wrote: > I expected gcc to see that the operation doesn't meet the constraints, > and move operands into registers to make it work (alternative 1, > "v/v/v").
It did match the first alternative (alternative 0), but it matched the constraints Y/Y/m. Operands 1 and 2 are OK, so don't need reloads. It did create optional reloads, which it always does for mem, but these reloads are irrelevant. The interesting one is for operand 0. Since Y accepts mem, and operand 0 is a mem but doesn't match, reload assumes that we can fix it by reloading the address to make it an offsettable address. But a far mem is still not acceptable even with a reloaded address, and you get an ICE. Reload doesn't have any concept of two different kinds of memory operands which can't be converted via reloads. If the constraint accepts mem, and we have a mem operand, then it will always assume that the problem is with the address and reload it. I don't think that there is an easy solution to this, but my reload skills are a bit rusty too. Jim
