Local stall/hazard detect in superscalar, pipelined microprocessor to avoid re-read of register file

An apparatus for avoiding a re-read of a register due to a data hazard in a pipeline with multiple stages, comprising:

• a simplified hazard detection that detects data-dependency hazards for an instruction within the pipeline and determines whether to assert a local stall, wherein the simplified hazard detection re-uses comparators that are used for data-forwarding in the pipeline;
• and
• a logic circuitry capable of determining whether the local stall has been asserted by the simplified hazard detection, wherein the logic circuit holds the instruction in a stage of the pipeline when the local stall is asserted and wherein non-assertion of the local stall indicates that the instruction data is correct and that a re-read of a register file is not necessary.

An apparatus for avoiding a re-read of a register due to a data hazard in a pipeline with multiple stages, comprising:

• a simplified hazard detection that detects data-dependency hazards for an instruction within the pipeline and determines whether to assert a local stall;
• and
• a logic circuitry capable of determining whether the local stall has been asserted by the simplified hazard detection, wherein the logic circuitry holds the instruction in a REG stage when the local stall is asserted and wherein non-assertion of the local stall indicates that the instruction data is correct and that a re-read of a register file is not necessary.

An apparatus for avoiding a re-read of a register due to a data hazard in a pipeline with multiple stages, comprising:

• a simplified hazard detection that detects data-dependency hazards for an instruction within the pipeline and determines whether to assert a local stall;
• and
• a logic circuitry capable of determining whether the local stall has been asserted by the simplified hazard detection and wherein non-assertion of the local stall indicates that the instruction data is correct and that a re-read of a register file is not necessary and wherein the local stall is asserted sufficiently long enough to allow the instruction to receive data from a producer through a data-forwarding architecture when the producer data is available.