> From the above doc, the major difference between a memory_constraint and a > special_memory_constraint is: whether "reload can or cannot make them match > by reloading the address".
Right, i.e. by just changing the form of the address (instead of the address itself). > For memory_constraint, the reload is Okay, however, for > special_memory_constraint, the reload is NOT Okay. > > I am not sure whether the RELOAD includes Spill or not, if it is, then the > current handling of special_memory_constraint is NOT correct: > (lra-constraints.c) > > 2088 case CT_SPECIAL_MEMORY: > 2089 if (MEM_P (op) > 2090 && satisfies_memory_constraint_p (op, cn)) > 2091 win = true; > 2092 else if (spilled_pseudo_p (op)) > 2093 win = true; > 2094 break; > > line 2092-2093 permits the memory spill, which seems need to be avoided for > SPECIAL_MEMORY_Constraint. > > the thing I need to confirm is: > > whether “spill” is considered as RELOAD or NOT? Yes, spilling is part of reloading but is not reloading the address since it's changing the address, so I think it's OK. Why is that problematic for you? -- Eric Botcazou
