Abstract: Simulating a hardware description language design including a core and a testbench can include performing, using a processor, a first compilation of the hardware description language design by generating a compiled core unit for the core, a compiled testbench for the testbench, and synchronization data describing signals crossing a compile checkpoint boundary. A subsequent compilation of the hardware description language design can be performed by reusing the compiled core unit from the first compilation and generating a new compiled testbench for the testbench using the synchronization data.

Abstract: Simulating a circuit design can include detecting, using a processor, an assignment for a signal of a circuit design during a delta cycle of a simulation of the circuit design and comparing, using the processor, a range of the assignment for the signal with a range of an existing event for the signal for the delta cycle. In response to determining that the range of the assignment for the signal and the range of the existing event meet a condition, the existing event is updated, using the processor, resulting in a merged event. The merged event is scheduled for execution for the delta cycle using the processor.

Abstract: An example method of generating a control and data flow graph for hardware description language (HDL) code specifying a circuit design is described. The method includes traversing an abstract syntax tree (AST) representation of the HDL code having a plurality of modules on a module-by-module basis. The method further includes adding an execution unit to the control and data flow graph for each module having concurrent paths. Each execution unit includes nodes in the control and data flow graph. The nodes include a loopback sink that merges the concurrent paths and a loopback source that receives feedback from the loopback sink and propagates the feedback to the concurrent paths.

Abstract: In one embodiment, a method for compiling an HDL specification for simulation of a circuit design is provided. Using one or more processors the circuit design is elaborated from the HDL specification. Two or more instances of a module of the elaborated design that have a same hardware configuration are determined. Simulation code that models the circuit design is generated. A first portion of the simulation code is configured to model the module having the hardware configuration. For each of the two or more instances, a second portion of the simulation code is configured to, in response to an indication to simulate the instance, execute the first portion of simulation code using a respective set of nets corresponding to the instance.

Abstract: In one embodiment, a method is provided for generating dataflow-driven simulation code of a circuit design described with a combination of first and second HDLs. The circuit description is elaborated and a simulation dataflow graph of the circuit description is generated. Simulation code, configured to model execution of the design in a data-driven manner according to the simulation dataflow graph, is generated from the dataflow graph using a first HDL signal representation having a format compatible with the first HDL and a second HDL signal representation having a format compatible with the second HDL. For each instantiated module of the circuit description at a cross language boundary in the simulation dataflow graph, ports of the instantiated module are mapped to the first HDL signal representation and mapped to the second HDL signal representation.

Abstract: One or more embodiments provide a load balancing solution for improving the runtime performance of parallel HDL simulators. During compilation each process is analyzed to determine a simulation cost based on complexity of the HDL processes. During simulation, processes to be executed in the same simulation cycle are scheduled using the simulation costs computed at compile-time in order to reduce the delay incurred during simulation.

Abstract: One or more embodiments provide a method of HDL simulation that determines dependencies, forcing characteristics, and strength characteristics of nets for the entire circuit design during compilation. Simulation code and data structures are generated for each net, individually, based on the determined characteristics of the respective net. As a result, rather than implementing code for simulation of each net capable of handling every possible combination of the characteristics, less complex code and data structures may be generated for simulation of the nets.

Abstract: A method for compiling an HDL specification for simulation includes elaborating the HDL specification and determining singly-driven and multiply-driven nets of the elaborated circuit design. For each singly-driven net, a respective memory location is assigned to store a value of a corresponding driver of the net at runtime. For each multiply-driven net, a contiguous block of memory is assigned to store values of corresponding drivers of the net at runtime. For mixed language designs, this contiguous block contains values for drivers from all HDL languages involved. Simulation code that models the circuit design is generated. For each singly-driven net, the simulation code is configured to store a value of the corresponding driver of the singly-driven net in the respective memory location. For each multiply-driven net, the simulation code is configured to store the values of the corresponding drivers in the assigned block of memory. The generated simulation code is stored.