Method and apparatus for handling out of order exceptions in a pipelined data unit

In a pipelined data unit for use in a data processor, the data unit comprising:

• an input stage for selectively receiving input operands from said data processor;
• an operation stage for performing a selected operation on said input operands to produce an output result;
• and
• an output stage for selectively providing said output result to said data processor;
• the method comprising the steps of:
• performing a predetermined input operand test on said input operands, and selectively providing a precise exception signal to said data processor if any of said input operands fails said input operand test;
• and
• performing a predetermined output result test on said output result, and selectively providing an imprecise exception signal to said data processor if said output result fails said output result test.

In a data processor, a pipelined data unit comprising:

• an input stage for receiving input operands, performing a predetermined input operand test on said input operands, and providing a precise exception signal if any of said input operands fails said input operand test;
• an operation stage for performing a selected operation on said input operands to produce an output result;
• an output stage for receiving said output result, performing a predetermined output result test on said output result, and providing an imprecise exception signal if said output result fails said output result test;
• and
• exception handling means for providing selected information to said data processor relating to said exception signals, said exception handling means comprising:
• precise exception handling means for selectively providing to said data processor said input operands and a precise error signal that characterizes said failure of said input operand test;
• and
• imprecise exception handling means for selectively providing to said data processor said output result and an imprecise error signal that characterizes said failure of said output result test.