Clean up the atomic opcodes in SelectionDAG.

This removes all the _8, _16, _32, and _64 opcodes and replaces each
group with an unsuffixed opcode. The MemoryVT field of the AtomicSDNode
is now used to carry the size information. In tablegen, the size-specific
opcodes are replaced by size-independent opcodes that utilize the
ability to compose them with predicates.

This shrinks the per-opcode tables and makes the code that handles
atomics much more concise.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61389 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/ScheduleDAGInstrs.cpp

@@ -413,6 +413,7 @@ MachineBasicBlock *ScheduleDAGInstrs::EmitSchedule() {
   while (!BB->empty())
     BB->remove(BB->begin());
 
+  // Then re-insert them according to the given schedule.
   for (unsigned i = 0, e = Sequence.size(); i != e; i++) {
     SUnit *SU = Sequence[i];
     if (!SU) {