Methods and apparatus for preserving precise exceptions in code reordering by using control speculation

A system comprising:

• a memory to store a plurality of instructions;
• and
• a processor to:
• determine if a first instruction is an excepting instruction;
• determine if the first instruction is to be moved across a check instruction to an execution location that is before the check instruction;
• determine a second instruction in the plurality of instructions that is to compute a previous value of a target register associated with the first instruction when (1) the first instruction is not an excepting instruction and (2) the first instruction is to be moved across a check instruction to an execution location that is before the check instruction;
• determine if a source operand associated with the second instruction is available at the check instruction;
• insert a third instruction into the plurality of instructions to save the previous value of the target register if the source operand associated with the second instruction is not available at the check instruction;
• and
• insert a fourth instruction into a recovery block to restore the previous value of the target register.