+/// Examine constraint type and operand type and determine a weight value.
+/// This object must already have been set up with the operand type
+/// and the current alternative constraint selected.
+TargetLowering::ConstraintWeight
+BlackfinTargetLowering::getSingleConstraintMatchWeight(
+ AsmOperandInfo &info, const char *constraint) const {
+ ConstraintWeight weight = CW_Invalid;
+ Value *CallOperandVal = info.CallOperandVal;
+ // If we don't have a value, we can't do a match,
+ // but allow it at the lowest weight.
+ if (CallOperandVal == NULL)
+ return CW_Default;
+ // Look at the constraint type.
+ switch (*constraint) {
+ default:
+ weight = TargetLowering::getSingleConstraintMatchWeight(info, constraint);
+ break;
+
+ // Blackfin-specific constraints
+ case 'a':
+ case 'd':
+ case 'z':
+ case 'D':
+ case 'W':
+ case 'e':
+ case 'b':
+ case 'v':
+ case 'f':
+ case 'c':
+ case 't':
+ case 'u':
+ case 'k':
+ case 'x':
+ case 'y':
+ case 'w':
+ return CW_Register;
+ case 'A':
+ case 'B':
+ case 'C':
+ case 'Z':
+ case 'Y':
+ return CW_SpecificReg;
+ }
+ return weight;
+}
+