reg.field1 = val1, reg.field2 = val2;would then turn into fetch, mask with a combined mask of field1 and field2, or val1, or val2, store.
You can also do the RMW yourself: declare the register volatile, but not the fields of it, and copy in/out of the register manually.
volatile struct reg x; ... { struct reg mine = x; mine.field1 = true; mine.field2 = 0; mine.field3++; x = mine; }
Is it a completely brain-dead idea?
If I understood it correctly, it would not be standard compliant. Paolo