Devices and techniques for non-blocking external device calls are described herein. Specifically, when a processor receives an instruction with a no-return indication from a thread for a device, the processor can increase a counter corresponding to the thread based on the no-return indication. The processor can then continue execution of the thread without waiting for a return value from the device. When a return value is received for the instruction, the processor can decrement the counter. While the counter is not zero, the processor prevents the thread from completing (exiting).

Systems, devices, circuitries, and methods are disclosed for identifying, within a call instruction, context registers for storing prior to a jump to another subroutine. In one example, a method includes receiving, while executing a first subroutine, a call instruction that includes a first opcode and identifies a first target address, wherein the first target address stores instructions for performing a second subroutine. A first set of context registers identified by the call instruction is determined and the content of the first set of context registers is stored in first memory allocated for context storage for the first subroutine prior to executing the instruction stored in the first target address.

Representative apparatus, method, and system embodiments are disclosed for a self-scheduling processor which also provides additional functionality. Representative embodiments include a self-scheduling processor, comprising: a processor core adapted to execute instructions; and a core control circuit adapted to automatically schedule an instruction for execution by the processor core in response to a received work descriptor data packet. In a representative embodiment, the processor core is further adapted to execute a non-cached load instruction to designate a general purpose register rather than a data cache for storage of data received from a memory circuit. The core control circuit is also adapted to schedule a fiber create instruction for execution by the processor core, and to generate one or more work descriptor data packets to another circuit for execution of corresponding execution threads. Event processing, data path management, system calls, memory requests, and other new instructions are also disclosed.

Processing circuitry has a handler mode and a thread mode. In response to an exception condition, a switch to handler mode is made. In response to an intermodal calling branch instruction specifying a branch target address when the processing circuitry is in the handler mode, an instruction decoder controls the processing circuitry to save a function return address to a function return address storage location; switch a current mode of the processing circuitry to the thread mode; and branch to an instruction identified by the branch target address. This can be useful for deprivileging of exceptions.

In one example, a method includes allocating separate portions of memory for a control stack and a data stack. The method also includes, upon detecting a call instruction, storing a first return address in the control stack and a second return address in the data stack; and upon detecting a return instruction, popping the first return address from the control stack and the second return address from the data stack and raising an exception if the two return addresses do not match. Otherwise, the return instruction returns the first return address. Additionally, the method includes executing an exception handler in response to the return instruction detecting an exception, wherein the exception handler is to pop one or more return addresses from the control stack until the return address on a top of the control stack matches the return address on a top of the data stack.

In an embodiment, dynamically-generated code may be supported in the system by ensuring that the code either remains executing within a predefined region of memory or exits to one of a set of valid exit addresses. Software embodiments are described in which the dynamically-generated code is scanned prior to permitting execution of the dynamically-generated code to ensure that various criteria are met including exclusion of certain disallowed instructions and control of branch target addresses. Hardware embodiments are described in which the dynamically-generated code is permitted to executed but is monitored to ensure that the execution criteria are met.

Systems and methods for managing optimized branching in executable instructions are disclosed. In one implementation, a processing device may identify, in a sequence of executable instructions, a branching instruction associated with a safe static key, the branching instruction specifying a first target location. The processing device may determine whether a value of the safe static key is initialized. Responsive to determining that the value of the safe static key is initialized, the processing device may further replace the branching instruction with an unconditional branching instruction specifying the first target location. Responsive to determining that the value of the safe static key is uninitialized, the processing device may replace the branching instruction with a conditional branching instruction specifying the first target location.

A memory circuit included in a computer system includes a memory array that stores multiple program instructions included in compressed program code. In response to receiving a fetch instruction from a processor circuit, the memory circuit may retrieve a particular instruction from the memory array. The memory circuit may, in response to a determination that the particular instruction is a particular type of instruction, retrieve additional program instructions from the memory array using an address included in the particular instruction, and send the particular program instruction and the additional program instructions to the processor circuit.

A processing circuitry having a secure domain and a less secure domain. A control storage location stores a domain transition disable configuration parameter specifying whether domain transitions between the secure domain and the less secure domain are enabled or disabled in at least one mode of the process-ing circuitry. In the at least one mode of the processing circuitry, when the domain transition disable configuration parameter specifies that said domain transitions are disabled in said at least one mode, a disabled domain transition fault is signalled in response to an attempt to transition between domains in either direction. This can help support lazy configuration of resources for the secure domain or less secure domain for a thread expected only to need the other domain.

A new approach is proposed to support hardware-based PCIe link up based on post silicon characterization of an electronic device. A non-volatile storage medium of a bootup unit on the electronic device maintains an initialization sequence for the physical layer of a PCIe link, and a non-volatile storage medium allows flexible programming. During operation, the bootup unit reads from the non-volatile storage medium instructions to program/override one or more PCIe physical layer settings and controller registers for the PCIe link based on the post silicon characterization of the electronic device. The bootup unit is limited to access and override only to the one or more physical layer settings and controller registers of the PCIe link. The entire process of reading the initialization sequence and programming the one or more PCIe physical layer settings and the controller registers happens within time limit constraints of the PCIe specification for latency reduction.