Visible to Intel only — GUID: GUID-E9005553-33AA-4155-ABBF-ADB1FE8C48DC
Visible to Intel only — GUID: GUID-E9005553-33AA-4155-ABBF-ADB1FE8C48DC
_mm_fmsub_pd, _mm256_fmsub_pd
Multiply-subtracts packed double-precision floating-point values using three float64 vectors. The corresponding FMA instruction is VFMSUB<XXX>PD, where XXX could be 132, 213, or 231.
Syntax
For 128-bit vector
extern __m128d _mm_fmsub_pd(__m128d a, __m128d b, __m128d c); |
For 256-bit vector
extern __m256d _mm256_fmsub_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 multiply-subtract 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 infinite precision intermediate results are obtained. From the infinite precision intermediate results, the values in the third operand, c, are subtracted. The final results are rounded to the nearest float64 values.
The compiler defaults to using the VFMSUB213PD instruction and uses the other forms VFMSUB132PD or VFMSUB231PD only if a low level optimization decides it is 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 multiply-subtract operation.