Abstract: A microprocessor includes a plurality of execution units configured to receive instructions and operands thereof and to execute the instructions. An instruction scheduler issues the instructions to the execution units and selects sources of the instruction operands. At least one of the execution units detects one of the operands of one of the instructions is a denormal operand, generates an indication that the instruction needs to be replayed in response to detecting the denormal operand, and provides the denormal operand to the instruction scheduler in response to detecting the denormal operand, rather than normalizing the denormal operand. The instruction scheduler normalizes the denormal operand, in response to the indication, and causes the normalized operand, rather than the denormal operand, to be provided to the execution unit when the instruction is replayed.

Abstract: A microprocessor includes an instruction set architecture, comprising a call instruction type, a return instruction type, and other instruction types. Execution units correctly execute program instructions of the other instruction types. A call/return stack has a plurality of entries arranged in a last-in-first-out manner. The call/return stack is architectural state of the microprocessor not modifiable by program instructions of the other instruction types. The call/return stack is architectural state of the microprocessor indirectly modifiable by program instructions of the call and return instruction types. The microprocessor also includes a fetch unit that fetches program instructions and sends the program instructions of the other instruction types to the execution units to be correctly executed.

Abstract: A microprocessor having model specific registers (MSRs) includes, for each of the MSRs, an associated default value that indicates whether the MSR is protected or non-protected and an associated fuse that, if blown, toggles the associated default value from protected to non-protected or non-protected to protected. In one embodiment, microcode that does the following in response to the microprocessor encountering an instruction that accesses a specified MSR: determines whether the fuse associated with the specified MSR is blown or unblown, uses the default value associated with the MSR as an indicator of whether the MSR is protected if the associated fuse is unblown; toggles the associated default value to generate the indicator if the associated fuse is blown; protects access to the MSR if the indicator indicates the MSR is protected; and refrains from protecting access to the MSR if the indicator indicates the MSR is non-protected.

Abstract: A microprocessor capable of running both x86 instruction set architecture (ISA) machine language programs and Advanced RISC Machines (ARM) ISA machine language programs. The microprocessor includes a mode indicator that indicates whether the microprocessor is currently fetching instructions of an x86 ISA or ARM ISA machine language program. The microprocessor also includes a plurality of model-specific registers (MSRs) that control aspects of the operation of the microprocessor. When the mode indicator indicates the microprocessor is currently fetching x86 ISA machine language program instructions, each of the plurality of MSRs is accessible via an x86 ISA RDMSR/WRMSR instruction that specifies an address of the MSR. When the mode indicator indicates the microprocessor is currently fetching ARM ISA machine language program instructions, each of the plurality of MSRs is accessible via an ARM ISA MRRC/MCRR instruction that specifies the address of the MSR.

Abstract: A microprocessor processes conditional non-branch instructions that specify a condition and instruct the microprocessor to perform an operation if the condition is satisfied and otherwise to not perform the operation. A predictor provides a prediction about a conditional non-branch instruction. An instruction translator translates the conditional non-branch instruction into a no-operation microinstruction when the prediction predicts the condition will not be satisfied, and into a set of one or more microinstructions to unconditionally perform the operation when the prediction predicts the condition will be satisfied. An execution pipeline executes the no-operation microinstruction or the set of microinstructions. The predictor translates into a second set of one or more microinstructions to conditionally perform the operation when the prediction does not make a prediction.

Abstract: A microprocessor executes an instruction specifying a floating-point input operand having a predetermined size and that instructs the microprocessor to round the floating-point input operand to an integer value using a rounding mode and to return a floating-point result having the same predetermined size. An instruction translator translates the instruction into first and second microinstructions. An execution unit executes the first and second microinstructions. The first microinstruction receives as an input operand the instruction floating-point input operand and generates an intermediate result from the input operand. The second microinstruction receives as an input operand the intermediate result of the first microinstruction and generates the floating-point result of the instruction from the intermediate result. The intermediate result is the same predetermined size as the instruction floating-point input operand.

Abstract: A microprocessor having an instruction set architecture (ISA) that specifies at least one architected data format (ADF) for floating-point operands. The microprocessor includes a plurality of floating-point units, each comprising an arithmetic unit configured to receive non-ADF source operands and to perform a floating-point operation on the non-ADF source operands to generate a non-ADF result. The microprocessor also includes forwarding buses, configured to forward the non-ADF result generated by each arithmetic unit of the plurality of floating-point units to each of the plurality of floating-point units for selective use as one of the non-ADF source operands.

Abstract: An apparatus including a microprocessor and a secure non-volatile memory. The microprocessor executes non-secure application programs and a secure application program. The microprocessor has secure execution mode initialization logic and an authorized public key. The secure execution mode initialization logic provides for initialization of a secure execution mode within the microprocessor. The secure execution mode initialization logic employs an asymmetric key algorithm to decrypt an enable parameter directing entry into the secure execution mode. The authorized public key is used to decrypt the enable parameter, the enable parameter having been encrypted according to the asymmetric key algorithm using an authorized private key that corresponds to the authorized public key.

Abstract: A microprocessor having a control register to which the manufacturer of the microprocessor may limit access. The microprocessor includes a manufacturing identifier that uniquely identifies the microprocessor and that is externally readable from the microprocessor by a user. The microprocessor also includes a secret key, manufactured internally within the microprocessor and externally invisible. The microprocessor also includes an encryption engine, coupled to the secret key, configured to decrypt a user-supplied password using the secret key to generate a decrypted result in response to a user instruction instructing the microprocessor to access the control register. The user-supplied password is unique to the microprocessor.

Abstract: An out-of-order execution microprocessor includes a register alias table configured to generate a first indicator that indicates whether an instruction is dependent upon a condition code result of a shift instruction. The microprocessor also includes a first execution unit configured to execute the shift instruction and to generate a second indicator that indicates whether a shift amount of the shift instruction is zero. The microprocessor also includes a second execution unit configured to receive the first and second indicators and to generate a replay signal to cause the instruction to be replayed if the first indicator indicates the instruction is dependent upon the condition code result of the shift instruction and a second indicator indicates the shift amount of the shift instruction is zero.

Abstract: A microprocessor includes a manufacturing ID that is stored in the microprocessor during manufacture thereof in a non-volatile manner. The manufacturing ID is unique to the microprocessor. The microprocessor also includes a secret encryption key that is stored internally within the microprocessor and unreadable externally from the microprocessor. The microprocessor also includes an AES encryption engine, coupled to receive the manufacturing ID and the secret encryption key, configured to encrypt the manufacturing ID using the secret encryption key to generate an unpredictable key that is unique to the microprocessor.

Abstract: A microprocessor including a random number generator within its instruction set architecture and made selectively available to program instructions of the instruction set architecture depending upon results of a self-test of the random number generator performed is disclosed. The microprocessor also includes a self-test unit that performs the self-test in response to a reset. The microprocessor also includes an instruction translator that translates instructions of the instruction set architecture, including instructions related exclusively to operation of the random number generator. The microprocessor generates a fault defined by the instruction set architecture in response to execution of one of the plurality of instructions related exclusively to operation of the random number generator if the self-test unit previously determined the random number generator is not operating properly.

Abstract: A microprocessor capable of running both x86 instruction set architecture (ISA) machine language programs and Advanced RISC Machines (ARM) ISA machine language programs includes a mode indicator that indicates whether the microprocessor is currently fetching instructions of an x86 ISA or ARM ISA machine language program and a plurality of hardware registers. When the mode indicator indicates the microprocessor is currently fetching x86 ISA machine language program instructions, the plurality of hardware registers store x86 ISA architectural state; when the mode indicator indicates the microprocessor is currently fetching ARM ISA machine language program instructions, the plurality of hardware registers store ARM ISA architectural state.

Abstract: A microprocessor having performs an architectural instruction that instructs it to perform an operation on first and second source operands to generate a result and to write the result to a destination register only if its architectural condition flags satisfy a condition specified in the architectural instruction. A hardware instruction translator translates the instruction into first and second microinstructions. To execute the first microinstruction, an execution pipeline performs the operation on the source operands to generate the result. To execute the second microinstruction, it writes the destination register with the result generated by the first microinstruction if the architectural condition flags satisfy the condition, and writes the destination register with the current value of the destination register if the architectural condition flags do not satisfy the condition.

Abstract: An ISA-defined instruction includes an immediate field having a first and second portions specifying first and second values, which instructs the microprocessor to perform an operation using a constant value as one of its source operands. The constant value is the first value rotated/shifted by a number of bits based on the second value. An instruction translator translates the instruction into one or more microinstructions. An execution pipeline executes the microinstructions generated by the instruction translator. The instruction translator, rather than the execution pipeline, generates the constant value for the execution pipeline as a source operand of at least one of the microinstructions for execution by the execution pipeline.

Abstract: A microprocessor supports an instruction set architecture that specifies: processor modes, architectural registers associated with each mode, and a load multiple instruction that instructs the microprocessor to load data from memory into specified ones of the registers. Direct storage holds data associated with a first portion of the registers and is coupled to an execution unit to provide the data thereto. Indirect storage holds data associated with a second portion of the registers and cannot directly provide the data to the execution unit. Which architectural registers are in the first and second portions varies dynamically based upon the current processor mode. If a specified register is currently in the first portion, the microprocessor loads data from memory into the direct storage, whereas if in the second portion, the microprocessor loads data from memory into the direct storage and then stores the data from the direct storage to the indirect storage.

Abstract: A microprocessor includes processor modes comprising a user mode and a plurality of exception modes. An execution unit performs arithmetic operations on operands specified by program instructions. A first set of storage elements holds a first subset of the operands and provides them to the execution unit coupled thereto. A second set of storage elements associated with each of the modes hold a second subset of the operands and are incapable of directly providing the second operand subset to the execution unit. To enter a new mode from a current mode, logic saves the first operand subset held in the first set of storage elements to the second set of storage elements associated with the current mode and restores to the first set of storage elements the second operand subset held in the second set of storage elements associated with the new mode.

Abstract: A microprocessor includes a hardware instruction translator that translates x86 ISA and ARM ISA machine language program instructions into microinstructions, which are encoded in a distinct manner from the x86 and ARM instructions. An execution pipeline executes the microinstructions to generate x86/ARM-defined results. The microinstructions are distinct from the results generated by the execution of the microinstructions by the execution pipeline. The translator directly provides the microinstructions to the execution pipeline for execution. Each time the microprocessor performs one of the x86 ISA and ARM ISA instructions, the translator translates it into the microinstructions. An indicator indicates either x86 or ARM as a boot ISA. After reset, the microprocessor initializes its architectural state, fetches its first instructions from a reset address, and translates them all as defined by the boot ISA. An instruction cache caches the x86 and ARM instructions and provides them to the translator.

Abstract: A microprocessor capable of operating as both an x86 ISA and an ARM ISA microprocessor includes first, second, and third storage that stores x86 ISA-specific, ARM ISA-specific, and non-ISA-specific state, respectively. When reset, the microprocessor initializes the first storage to default values specified by the x86 ISA, initializes the second storage to default values specified by the ARM ISA, initializes the third storage to predetermined values, and begins fetching instructions of a first ISA. The first ISA is the x86 ISA or the ARM ISA and a second ISA is the other ISA. The microprocessor updates the third storage in response to the first ISA instructions. In response to a subsequent one of the first ISA instructions that instructs the microprocessor to reset to the second ISA, the microprocessor refrains from modifying the non-ISA-specific state stored in the third storage and begins fetching instructions of the second ISA.

Abstract: A microprocessor includes a plurality of processing cores each including a hardware instruction translator that translates instructions of x86 instruction set architecture (ISA) machine language programs and Advanced RISC Machines (ARM) ISA machine language programs into microinstructions defined by a microinstruction set of the microprocessor. The microinstructions are encoded in a distinct manner from the manner in which the instructions of the x86 and ARM instruction sets are defined. Each core includes an execution pipeline that executes the microinstructions to generate results defined by the x86 ISA and ARM ISA instructions. Each core uses and associated indicator to determine whether it will boot as an x86 ISA core or an ARM ISA core when reset. The indicators are configurable to indicate that at least one of the cores will boot as an x86 ISA core and at least one other of the cores will boot as an ARM ISA core.