Abstract: Instruction decoder circuitry decodes processing instructions each generating an output multi-bit data item in a destination architectural register by applying a processing operation to source data item(s) in respective source architectural register(s). The decoder circuitry detects whether an instruction defines a predicated merge operation that propagates a set of zero or more portions of the prevailing contents of the destination architectural register as respective portions of the output multi-bit data item. The portions are defined by predicate data. Register allocation circuitry associates physical registers with the destination architectural register and the source architectural register(s). When detector circuitry detects that an instruction defines a predicated merge operation, the register allocation circuitry associates a further physical register with that instruction to store a copy of the prevailing contents.

Abstract: Instruction decoder circuitry decodes processing instructions each generating an output multi-bit data item in a destination architectural register by applying a processing operation to source data item(s) in respective source architectural register(s). The decoder circuitry detects whether an instruction defines a predicated merge operation that propagates a set of zero or more portions of the prevailing contents of the destination architectural register as respective portions of the output multi-bit data item. The portions are defined by predicate data. Register allocation circuitry associates physical registers with the destination architectural register and the source architectural register(s). When detector circuitry detects that an instruction defines a predicated merge operation, the register allocation circuitry associates a further physical register with that instruction to store a copy of the prevailing contents.

Abstract: A data processing apparatus comprises register rename circuitry for mapping architectural register specifiers specified by instructions to physical registers to be accessed in response to the instructions. Available register control circuitry controls which physical registers are available for mapping to an architectural register specifier by the register rename circuitry. For at least one group of two or more physical registers, the available register control circuitry controls availability of the registers based on a group tracking indication indicative of whether there is at least one pending access to any of the physical registers in the group.

Abstract: A data processing apparatus and method of operating a data processing apparatus are disclosed. Comparisons are made between first and second floating-point operands received. A more significant portion of the first floating-point operand and of the second floating-point operand are subject to comparison. The more significant portion of the first floating-point operand minus a least significant bit in the more significant portion is subject to comparison with the more significant portion of the second floating-point operand. A less significant portion of the first floating-point operand and of the second floating-point operand are also subject to comparison. In dependence on the outcome of these comparisons, right-shift circuitry is used selectively to perform a 1-bit right shift on a difference calculated between the first floating-point operand and the second floating-point operand.

Abstract: A data processing apparatus and method of operating a data processing apparatus are disclosed. Comparisons are made between first and second floating-point operands received. A more significant portion of the first floating-point operand and of the second floating-point operand are subject to comparison. The more significant portion of the first floating-point operand minus a least significant bit in the more significant portion is subject to comparison with the more significant portion of the second floating-point operand. A less significant portion of the first floating-point operand and of the second floating-point operand are also subject to comparison. In dependence on the outcome of these comparisons, right-shift circuitry is used selectively to perform a 1-bit right shift on a difference calculated between the first floating-point operand and the second floating-point operand.

Abstract: An apparatus has register rename circuitry to map architectural register specifiers specified by instructions to physical register specifiers identifying physical registers. A restoration table identifies at least one restoration mapping between an architectural register specifier and a previously mapped physical register specifier. Register reserving circuitry indicates one or more reserved register specifiers. In response to detecting that a speculative instruction corresponding to a restoration mapping has been committed when that instruction or an older instruction still could potentially read a register, the register reserving circuitry indicates the physical register specifier of that restoration mapping as reserved.

Abstract: A data processing system 2 includes multiple out-of-order issue queues 8, 10. A master serialization instruction MSI received by a first issue queue 8 is detected by slave generation circuitry 24 which generates a slave serialization instruction SSI added to a second issue queue 10. The master serialization instruction MSI manages serialization relative to the instructions within the first issue queue 8. The slave serialization instruction SSI manages serialization relative to the instructions within the second issue queue 10. The master serialization instruction MSI and the slave serialization instruction SSI are removed when both have met their serialization conditions and are respectively the oldest instructions within their issue queues.

Abstract: An apparatus has register rename circuitry to map architectural register specifiers specified by instructions to physical register specifiers identifying physical registers. A restoration table identifies at least one restoration mapping between an architectural register specifier and a previously mapped physical register specifier. Register reserving circuitry indicates one or more reserved register specifiers. In response to detecting that a speculative instruction corresponding to a restoration mapping has been committed when that instruction or an older instruction still could potentially read a register, the register reserving circuitry indicates the physical register specifier of that restoration mapping as reserved.

Abstract: A data processing apparatus comprises register rename circuitry for mapping architectural register specifiers specified by instructions to physical registers to be accessed in response to the instructions. Available register control circuitry controls which physical registers are available for mapping to an architectural register specifier by the register rename circuitry. For at least one group of two or more physical registers, the available register control circuitry controls availability of the registers based on a group tracking indication indicative of whether there is at least one pending access to any of the physical registers in the group.

Abstract: A data processing system 2 includes multiple out-of-order issue queues 8, 10. A master serialisation instruction MSI received by a first issue queue 8 is detected by slave generation circuitry 24 which generates a slave serialisation instruction SSI added to a second issue queue 10. The master serialisation instruction MSI manages serialisation relative to the instructions within the first issue queue 8. The slave serialisation instruction SSI manages serialisation relative to the instructions within the second issue queue 10. The master serialisation instruction MSI and the slave serialisation instruction SSI are removed when both have met their serialisation conditions and are respectively the oldest instructions within their issue queues.