def RFP : RegisterClass<f80, 32, [FP0, FP1, FP2, FP3, FP4, FP5, FP6]>;
-// Floating point stack registers.
-def RST : RegisterClass<f80, 32, [ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7]>;
+// Floating point stack registers (these are not allocatable by the
+// register allocator - the floating point stackifier is responsible
+// for transforming FPn allocations to STn registers)
+def RST : RegisterClass<f80, 32, [ST0, ST1, ST2, ST3, ST4, ST5, ST6, ST7]> {
+ let Methods = [{
+ iterator allocation_order_end(MachineFunction &MF) const {
+ return begin();
+ }
+ }];
+}