On Mon, 2019-09-09 at 15:40 -0500, William Tambe wrote: > I use documentation for atomic_exchange from: > https://gcc.gnu.org/onlinedocs/gccint/Standard-Names.html#Standard-Names > > When defining machine description for atomic_exchange, I find that GCC > mark operands[1] as volatile such that (MEM_VOLATILE_P (operands[1])) > returns TRUE; even when the memory operand is not declared using the C > keyword "volatile". > > Is there a way to have atomic_exchange not marking operands[1] as > volatile unless the memory operand was declared volatile ? If you want to distinguish that, one way is to implement all atomic patterns in the backedn. Then you know that those come from __atomic__... calls. In the other patterns, you can then assume that MEM_VOLATILE_P must be a mem ref for everything else (that is considered a volatile mem ref). Cheers, Oleg
