Controlling the number of powered vector lanes via a register field
In an example, a device includes a memory, a register, a data path including a set of lanes, and a processor that executes a program. The following operations are performed in response to execution of the program: write data to a field of the register, in which the data specifies that at least one lane of the set of lanes is powered on; execute an instruction on the at least one powered on lane; receive an interrupt; based on the interrupt, copy the data from the register to the memory; service the interrupt; and based on completing the service, copy data the data from the memory to the register.
1. A device comprising:
a memory;
a register;
a data path including a set of lanes; and
a processor configured to execute a program to:
write data to a field of the register, the data specifying that at least one lane of the set of lanes is powered on;
execute an instruction on the at least one lane of the set of lanes that is powered on;
receive an interrupt;
based on the interrupt, copy the data from the register to the memory;
service the interrupt; and
based on completion of the service of the interrupt, copy the data from the memory to the register.
2. The device of claim 1 , wherein:
the at least one lane of the set of lanes is a first subset of the set of lanes; and
the processor, in executing the program, is further configured to cause a second subset of the set of lanes to be powered on during servicing of the interrupt.
3. The device of claim 1 , wherein the data is configured to specify a number of the at least one lane of the set of lanes as a power of two.
4. The device of claim 1 , wherein the data has fewer bits than the number of lanes in the set of lanes.
5. The device of claim 1 , wherein the at least one lane of the set of lanes is a first subset of the set of lanes that is a contiguous set of least significant lanes.
6. The device of claim 1 , wherein the processor, in executing the program, is further configured to cause the set of lanes to be powered on from least significant to most significant.
7. The device of claim 1 , wherein:
the register configured to store an instruction; and
the data that specifies the at least one lane of the set of lanes that is powered on is a field of the instruction.
8. The device of claim 1 , further comprising:
a decoder coupled to the register and configured to generate a control word based on the data in the field of the register, to cause the at least one lane of the set of lanes to be powered on.
9. The device of claim 8 , wherein the control word includes a set of bits such that each bit of the set of bits corresponds to a respective lane of the set of vector lanes.
10. A non-transitory device-readable medium storing instructions that when executed by a processor cause the processor to:
store data in a register that specifies at least one lane of a set of vector lanes to power on;
cause the at least one lane of the set of vector lanes to be powered on based on the data;
receive an interrupt;
based on the interrupt, copy the data from the register to a memory;
service the interrupt; and
based on the service of the interrupt being complete, copy the data from the memory to the register.
11. The non-transitory device-readable medium of claim 10 , wherein:
the at least one lane of the set of vector lanes is a first subset of the set of vector lanes; and
the instructions when executed by the processor further cause the processor to cause a second subset of the set of vector lanes to be powered on during the service of the interrupt.
12. The non-transitory device-readable medium of claim 10 , wherein the data specifies a number of the at least one lane of the set of vector lanes by a power of two.
13. The non-transitory device-readable medium of claim 10 , wherein the data has fewer bits than the number of lanes in the set of vector lanes.
14. The non-transitory device-readable medium of claim 10 , wherein the at least one lane of the set of vector lanes is a first subset of the set of vector lanes that is a contiguous set of least significant lanes.
15. The non-transitory device-readable medium of claim 10 , wherein the instructions when executed by the processor further cause to processor to:
receive an instruction that includes a field that specifies the data that specifies the at least one lane of the set of vector lanes that is powered on; and
store the instruction.
16. A device comprising:
a memory;
a register;
a data path including a set of lanes; and
a processor configured to execute a program to:
write data to a field in the register, the data specifying that at least one lane of the set of lanes is powered on;
execute an instruction on the at least one of the set of lanes that is powered on;
receive an interrupt;
based on the interrupt, copy contents of the register including the data from the register to the memory;
service the interrupt; and
based on completion of the service of the interrupt, set the register to a default value.
17. The device of claim 16 , wherein the default value specifies to power on one lane of the set of lanes or to power on all lanes of the set of lanes.
18. The device of claim 16 , wherein the data is configured to specify a number of the at least one lane of the set of lanes as a power of two.
19. The device of claim 16 , wherein the data has fewer bits than the number of lanes in the set of lanes.