Developer Guide and Reference

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_mm_fmadd_ps, _mm256_fmadd_ps

Multiply-adds packed single-precision floating-point values using three float32 vectors. The corresponding FMA instruction is
VFMADD<XXX>PS
, where XXX could be 132, 213, or 231.

Syntax

For 128-bit vector
extern __m128 _mm_fmadd_ps(__m128 a, __m128 b, __m128 c);
For 256-bit vector
extern __m256 _mm256_fmadd_ps(__m256 a, __m256 b, __m256 c);
Arguments
a
float32 vector used for the operation
b
float32 vector also used for the operation
c
float32 vector also used for the operation
Description
Performs a set of SIMD multiply-add computation on packed single-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 float32 values.
The compiler defaults to using the
VFMADD213PS
instruction and uses the other forms
VFMADD132PS
or
VFMADD231PS
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.