Visible to Intel only — GUID: GUID-5C49C874-1D89-4225-A969-8D3C3AB87E4B
Visible to Intel only — GUID: GUID-5C49C874-1D89-4225-A969-8D3C3AB87E4B
_mm_fnmadd_pd, _mm256_fnmadd_pd
Multiply-adds negated packed double-precision floating-point values of three float64 vectors. The corresponding FMA instruction is VFNMADD<XXX>PD, where XXX could be 132, 213, or 231.
Syntax
For 128-bit vector
extern __m128d _mm_fnmadd_pd(__m128d a, __m128d b, __m128d c); |
For 256-bit vector
extern __m256d _mm256_fnmadd_pd(__m256d a, __m256d b, __m256d c); |
Arguments
a |
float64 vector used for the operation |
b |
float64 vector also used for the operation |
c |
float64 vector also used for the operation |
Description
Performs a set of SIMD negated multiply-add computation on packed double-precision floating-point values using three source vectors/operands, a, b, and c. Corresponding values in two operands, a and b, are multiplied and the negated infinite precision intermediate results are added to the values in the third operand, c, after which the final results are rounded to the nearest float64 values.
The compiler defaults to using the VFNMADD213PD instruction and uses the other forms VFNMADD132PD or VFNMADD231PD only if a low level optimization decides it as useful or necessary. For example, the compiler could change the default if it finds that another instruction form saves a register or eliminates a move.
Returns
Result of the negated multiply-add operation.