Systems and methods for performing 16-bit floating-point vector dot product instructions

1. A processor comprising:

fetch circuitry to fetch a single instruction having fields to specify an opcode and locations of first source, second source, and destination vectors, the opcode to indicate execution circuitry is to multiply N pairs of elements of the specified first and second sources having a 16-bit floating-point format of a sign bit, an 8-bit exponent, and a mantissa comprising 7 explicit bits and an eighth implicit bit, and accumulate resulting products with previous contents of a corresponding single-precision element of the specified destination according to a rounding mode fixed for the single instruction regardless of any rounding mode set in a control register;

decode circuitry to decode the fetched instruction; and

the execution circuitry to respond to the decoded instruction as specified by the opcode.

2. The processor of claim 1 , wherein the locations of each of the specified source and destination vectors are either in registers or in memory.

3. The processor of claim 1 , wherein N is specified by the instruction and has a value of one of 4, 8, 16, and 32.

4. The processor of claim 1 , wherein the execution circuitry is to perform the multiplications without saturation and to saturate the result of the accumulation to plus or minus infinity in case of an overflow and to zero in case of any underflow.

5. The processor of claim 1 , wherein the 16-bit floating-point format is bfloat16.

6. The processor of claim 1 , wherein the execution circuitry is to generate all N elements of the specified destination in parallel.

7. A method comprising:

fetching, using fetch circuitry, a single instruction having fields to specify an opcode and locations of first source, second source, and destination vectors, the opcode to indicate execution circuitry is to multiply N pairs of elements of the specified first and second sources having a 16-bit floating-point format of a sign bit, an 8-bit exponent, and a mantissa comprising 7 explicit bits and an eighth implicit bit, and accumulate resulting products with previous contents of a corresponding single-precision element of the specified destination according to a rounding mode fixed for the single instruction regardless of any rounding mode set in a control register;

decoding, using decode circuitry, the fetched instruction; and

responding to the decoded instruction as specified by the opcode with the execution circuitry.

8. The method of claim 7 , wherein the locations of each of the specified source and destination vectors are either in registers or in memory.

9. The method of claim 7 , wherein N is specified by the instruction and has a value of one of 4, 8, 16.

10. The method of claim 7 , wherein the execution circuitry is to perform the multiplications without saturation and to saturate the result of the accumulation to plus or minus infinity in case of an overflow and to zero in case of any underflow.

11. The method of claim 7 , wherein the 16-bit floating-point format is bfloat16.

12. The method of claim 7 , wherein the execution circuitry is to generate all N elements of the specified destination in parallel.

13. A system comprising:

a memory; and

a processor coupled to the memory, the processor comprising:

fetch circuitry to fetch a single instruction having fields to specify an opcode and locations of first source, second source, and destination vectors, the opcode to indicate execution circuitry is to multiply N pairs of elements of the specified first and second sources having a 16-bit floating-point format of a sign bit, an 8-bit exponent, and a mantissa comprising 7 explicit bits and an eighth implicit bit, and accumulate resulting products with previous contents of a corresponding single-precision element of the specified destination according to a rounding mode fixed for the single instruction regardless of any rounding mode set in a control register;

decode circuitry to decode the fetched instruction; and

the execution circuitry to respond to the decoded instruction as specified by the opcode.

14. The system of claim 13 , wherein the locations of each of the specified source and destination vectors are either in registers in the processor or in the memory.

15. The system of claim 13 , wherein the 16-bit floating-point format is bfloat16.

16. A non-transitory machine-readable medium containing code to cause a processor to respond by:

fetching, using fetch circuitry, a single instruction having fields to specify an opcode and locations of first source, second source, and destination vectors, the opcode to indicate the processor is to multiply N pairs of elements of the specified first and second sources having a 16-bit floating-point format of a sign bit, an 8-bit exponent, and a mantissa comprising 7 explicit bits and an eighth implicit bit, and accumulate resulting products with previous contents of a corresponding single-precision element of the specified destination according to a rounding mode fixed for the single instruction regardless of any rounding mode set in a control register;

decoding, using decode circuitry, the fetched instruction; and

responding to the decoded instruction as specified by the opcode with execution circuitry.

17. The non-transitory machine-readable medium of claim 16 , wherein the instruction further includes a field to specify N, wherein N is an even number larger than 4.

18. The non-transitory machine-readable medium of claim 16 , wherein the execution circuitry is to perform the multiplications without saturation and to saturate the result of the accumulation to plus or minus infinity in case of an overflow and to zero in case of any underflow.

19. The non-transitory machine-readable medium of claim 16 , wherein the 16-bit floating-point format is bfloat16.