Described herein are systems and methods for secure multithread execution. For example, some methods include fetching an instruction of a first thread from a memory into a processor pipeline that is configured to execute instructions from two or more threads in parallel using execution units of the processor pipeline; detecting that the instruction has been designated as a sensitive instruction; responsive to detection of the sensitive instruction, disabling execution of instructions of threads other than the first thread in the processor pipeline during execution of the sensitive instruction by an execution unit of the processor pipeline; executing the sensitive instruction using an execution unit of the processor pipeline; and, responsive to completion of execution of the sensitive instruction, enabling execution of instructions of threads other than the first thread in the processor pipeline.

Method for secure execution of code, including (a) on a CPU, where opcodes for the same executable instructions differ from one memory page to another, depending on memory tag, loading original static instructions from executable module <0> into non-tagged executable memory pages; (b) beginning execution of original static instructions of process <0>; (c) invoking a CPU instruction to start process <i>, where i=1 initially, in process <0>, to create a new memory tag <i>, its set of randomized opcodes and to return memory tag <i> and new randomized set of opcodes to process <0>; (d) loading executable module <i> for process <i> in process <0>, and transforming executable code using new randomized opcodes from step (c); (e) in process <0>, allocating tagged memory with tag <i> to process <i>, loading memory with compiled executable code from step (d) into process <i>, and running compiled code from step (d).

Methods of encoding and decoding are described which use a variable number of instruction words to encode instructions from an instruction set, such that different instructions within the instruction set may be encoded using different numbers of instruction words. To encode an instruction, the bits within the instruction are reordered and formed into instruction words based upon their variance as determined using empirical or simulation data. The bits in the instruction words are compared to corresponding predicted values and some or all of the instruction words that match the predicted values are omitted from the encoded instruction.

In one embodiment, a processor includes circuitry to decode an instruction referencing an encoded data pointer that includes a set of plaintext linear address bits and a set of encrypted linear address bits. The processor also includes circuitry to perform a speculative lookup in a translation lookaside buffer (TLB) using the plaintext linear address bits to obtain physical address, buffer a set of architectural predictor state values based on the speculative TLB lookup, and speculatively execute the instruction using the physical address obtained from the speculative TLB lookup. The processor also includes circuitry to determine whether the speculative TLB lookup was correct and update a set of architectural predictor state values of the core using the buffered architectural predictor state values based on a determination that the speculative TLB lookup was correct.

There is provided a data processing apparatus comprising decode circuitry responsive to receipt of a block of instructions to generate control signals indicative of each of the block of instructions, and to analyse the block of instructions to detect a potential hazard instruction. The data processing apparatus is provided with decode circuitry to encode information indicative of a clean restart point into the control signals associated with the potential hazard instruction. The data processing apparatus is provided with data processing circuity to perform out-of-order execution of at least some of the block of instructions, and control circuitry responsive to a determination, at execution of the potential hazard instruction, that data values used as operands for the potential hazard instruction have been modified by out-of-order execution of a subsequent instruction, to restart execution from the clean restart point and to flush held data values from the data processing circuitry.

Methods of encoding and decoding are described which use a variable number of instruction words to encode instructions from an instruction set, such that different instructions within the instruction set may be encoded using different numbers of instruction words. To encode an instruction, the bits within the instruction are re-ordered and formed into instruction words based upon their variance as determined using empirical or simulation data. The bits in the instruction words are compared to corresponding predicted values and some or all of the instruction words that match the predicted values are omitted from the encoded instruction.

Described herein are systems and methods for secure multithread execution. For example, some methods include fetching an instruction of a first thread from a memory into a processor pipeline that is configured to execute instructions from two or more threads in parallel using execution units of the processor pipeline; detecting that the instruction has been designated as a sensitive instruction; responsive to detection of the sensitive instruction, disabling execution of instructions of threads other than the first thread in the processor pipeline during execution of the sensitive instruction by an execution unit of the processor pipeline; executing the sensitive instruction using an execution unit of the processor pipeline; and, responsive to completion of execution of the sensitive instruction, enabling execution of instructions of threads other than the first thread in the processor pipeline.

Techniques for program execution in a parallel processing architecture using speculative encoding are disclosed. A two-dimensional array of compute elements is accessed, where each compute element within the array of compute elements is known to a compiler and is coupled to its neighboring compute elements within the array of compute elements. Control for the array of compute elements is provided on a cycle-by-cycle basis. The control is enabled by a stream of wide, variable length, control words generated by the compiler. Two or more operations are coalesced into a control word, where the control word includes a branch decision and operations associated with the branch decision. The coalesced control word includes speculatively encoded operations for at least two possible branch paths. The at least two possible branch paths generate independent side effects. Operations associated with the branch decision that are not indicated by the branch decision are suppressed.

Embodiments are provided for error mitigation in quantum programs. In some embodiments, a system can include a processor that executes computer-executable components stored in memory. The computer-executable components include a compilation component that causes encoding of one or more qubits according to a circular repetition code at a time after operations on the one or more qubits and before readout.

Described herein are systems and methods for dynamic designation of instructions as sensitive. For example, some methods include detecting that a first instruction of a first process has been designated as a sensitive instruction; checking whether a sensitive handling enable indicator in a process state register storing a state of the first process is enabled; responsive to detection of the sensitive instruction and enablement of the sensitive handling enable indicator, invoking a constraint for execution of the first instruction; executing the first instruction subject to the constraint; and executing a second instruction of the first process without the constraint.