Multiply-subtracts scalar double-precision floating-point values using three float64 vectors. The corresponding FMA instruction is VFMSUB<XXX>SD, where XXX could be 132, 213, or 231.
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-subtract 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 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 VFMSUB213SD instruction and uses the other forms VFMSUB132SD or VFMSUB231SD 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-subtract operation.
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