> But here too the point is that we don't assume the same thing at the > tree level or during register allocation. It seems a bit silly for > the scheduler to assume that all hard registers are clobbered when the > register allocator itself doesn't assume that. And most rtl passes > assume that changes to pseudo registers are explicitly modelled via SETs > or CLOBBERs.
OK, let's declare volatile asms dead as full optimization barriers then, which means that they will need to be taken out of volatile_insn_p eventually and the comments in the RTL middle-end adjusted. In the short term, i.e. for 4.8.x/4.9.x, we cannot simply revert the patch because it has been written to catch UNSPEC_VOLATILE. So we could devise another, temporary predicate in rtlanal.c that would be volatile_insn_p minus volatile asms and invoke it from the places in cse.c, cselib.c and dse.c which have been changed by the patch. -- Eric Botcazou
