Texas Instruments Corporation

Todd T Hahn

Timothy David Anderson

Kai Chirca

Alan Davis

Mel Alan Phipps

Joseph R Zbiciak

Duc Quang Bui

Eric J Stotzer

Michael D Asal

Due Quang Bui

Dineel Diwakar Sule

The number of registers required is reduced by overlapping scalar and vector registers. This allows increased compiler flexibility when mixing scalar and vector instructions. Local register read ports are reduced by restricting read access. Dedicated predicate registers reduce requirements for general registers, and allows reduction of critical timing paths by allowing the predicate registers to be placed next to the predicate unit.

Register file structures combining vector and scalar data with global and local accesses

A method for compiling and executing a nested loop includes initializing a nested loop controller with an outer loop count value and an inner loop count value. The nested loop controller includes a predicate FIFO. The method also includes coalescing the nested loop and, during execution of the coalesced nested loop, causing the nested loop controller to populate the predicate FIFO and executing a get predicate instruction having an offset value, where the get predicate returns a value from the predicate FIFO specified by the offset value. The method further includes predicating an outer loop instruction on the returned value from the predicate FIFO.

Nested loop control

Techniques related to executing a plurality of instructions by a processor comprising receiving a first instruction for execution on an instruction execution pipeline, wherein the instruction execution pipeline is in a first execution mode, beginning execution of the first instruction on the instruction execution pipeline, receiving an execution mode instruction to switch the instruction execution pipeline to a second execution mode, switching the instruction execution pipeline to the second execution mode based on the received execution mode instruction, annulling the first instruction based on the execution mode instruction, receiving a second instruction for execution on the instruction execution pipeline, the second instruction, and executing the second instruction.

Entering protected pipeline mode with clearing

A nested loop controller includes a first register having a first value initialized to an initial first value, a second register having a second value initialized to an initial second value, and a third register configured as a predicate FIFO, initialized to have a third value. The second value is advanced in response to a tick instruction during execution of a loop. In response to the second value reaching a second threshold, the second register is reset to the initial second value. The nested loop controller further includes a comparator coupled to the second register and to the predicate FIFO and configured to provide an outer loop indicator value as input to the predicate FIFO when the second value is equal to the second threshold, and provide an inner loop indicator value as input to the predicate FIFO when the second value is not equal to the second threshold.

The number of registers required is reduced by overlapping scalar and vector registers. This also allows increased compiler flexibility when mixing scalar and vector instructions. Local register read ports are minimized by restricting read access. Dedicated predicate registers reduces requirements for general registers, and allows reduction of critical timing paths by allowing the predicate registers to be placed next to the predicate unit.

A statically scheduled processor compiler schedules a speculative load in the program before the data is needed. The compiler inserts a conditional instruction confirming or disaffirming the speculative load before the program behavior changes due to the speculative load. The condition is not based solely upon whether the speculative load address is correct but preferably includes dependence according to the original source code. The compiler may statically schedule two or more branches in parallel with orthogonal conditions.

Compiler-control method for load speculation in a statically scheduled microprocessor

A method of register allocation in complier using a computer instruction set having tiered instructions that accesses differing numbers of registers makes a first preliminary register allocation attempt using an initially specified register set for each instruction. If this fails, the method identifies instructions having an initially specified limited register having a variable not register allocatable. The method makes a second preliminary register allocation attempt except using a less restrictive register set for the identified instructions. This method employs a next less restrictive register set and re-attempts preliminary register allocations for instructions with more than two levels of register restriction.

Tiered register allocation

This invention is useful in a very long instruction word data processor that fetches a predetermined plural number of instructions each operation cycle. A predetermined one of these instructions is used as a special header. This special header has a unique encoding different from any normal instruction. When decoded this special header instructs decode hardware to decode this fetch packet in a special way. In one embodiment a bit field in the header signals the decode hardware whether to decode each instruction word normally or in an alternative way. The header may include extension opcode bits corresponding to each of the other instruction slots. In another embodiment another bit field signals whether to decode an instruction field as one normal length instruction or as two half-length instructions.

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Sugar Land, TX, United States of America

Todd T Hahn