Multiply-adds scalar double-precision floating-point values using three float64 vectors. The corresponding FMA instruction is VFMADD<XXX>SD, where XXX could be 132, 213, or 231.
extern __m128d _mm_fmadd_sd(__m128d a, __m128d b, __m128d c); |
a |
float64 vector used for the operation |
b |
float64 vector also used for the operation |
c |
float64 vector also used for the operation |
Performs a set of SIMD multiply-add computation on scalar 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 added to corresponding values in the third operand, after which the final results are rounded to the nearest float64 values.
The compiler defaults to using the VFMADD213SD instruction and uses the other forms VFMADD132SD or VFMADD231SD only if a low level optimization decides it is useful/necessary. For example, the compiler could change the default if it finds that another instruction form saves a register or eliminates a move.
Result of the multiply-add operation.
Copyright © 1996-2010, Intel Corporation. All rights reserved.