V4FMADDPS/V4FNMADDPS — Packed Single-Precision Floating-Point Fused Multiply-Add (4-iterations)

Instruction Operand Encoding ¶

Description ¶

This instruction computes 4 sequential packed fused single-precision floating-point multiply-add instructions with a sequentially selected memory operand in each of the four steps.

In the above box, the notation of “+3” is used to denote that the instruction accesses 4 source registers based on that operand; sources are consecutive, start in a multiple of 4 boundary, and contain the encoded register operand.

This instruction supports memory fault suppression. The entire memory operand is loaded if any of the 16 lowest significant mask bits is set to 1 or if a “no masking” encoding is used.

The tuple type Tuple1_4X implies that four 32-bit elements (16 bytes) are referenced by the memory operation portion of this instruction.

Rounding is performed at every FMA (fused multiply and add) boundary. Exceptions are also taken sequentially. Pre- and post-computational exceptions of the first FMA take priority over the pre- and post-computational exceptions of the second FMA, etc.

Operation ¶

src_reg_id is the 5 bit index of the vector register specified in the instruction as the src1 register.
define NFMA_PS(kl, vl, dest, k1, msrc, regs_loaded, src_base, posneg):
    tmpdest ← dest
    // reg[] is an array representing the SIMD register file.
    FOR j ← 0 to regs_loaded-1:
        FOR i ← 0 to kl-1:
            IF k1[i] or *no writemask*:
                IF posneg = 0:
                    tmpdest.single[i] ← RoundFPControl_MXCSR(tmpdest.single[i] - reg[src_base + j ].single[i] * msrc.single[j])
            ELSE:
                    tmpdest.single[i] ← RoundFPControl_MXCSR(tmpdest.single[i] + reg[src_base + j ].single[i] * msrc.single[j])
        ELSE IF *zeroing*:
            tmpdest.single[i] ← 0
    dest ← tmpdst
    dest[MAX_VL-1:VL] ← 0
V4FMADDPS and V4FNMADDPS dest{k1}, src1, msrc (AVX512)
KL, VL = (16,512)
regs_loaded ← 4
src_base ← src_reg_id & ~3 // for src1 operand
posneg ← 0 if negative form, 1 otherwise
NFMA_PS(kl, vl, dest, k1, msrc, regs_loaded, src_base, posneg)

Intel C/C++ Compiler Intrinsic Equivalent ¶

V4FMADDPS __m512 _mm512_4fmadd_ps( __m512, __m512x4, __m128 *);

V4FMADDPS __m512 _mm512_mask_4fmadd_ps(__m512, __mmask16, __m512x4, __m128 *);

V4FMADDPS __m512 _mm512_maskz_4fmadd_ps(__mmask16, __m512, __m512x4, __m128 *);

V4FNMADDPS __m512 _mm512_4fnmadd_ps(__m512, __m512x4, __m128 *);

V4FNMADDPS __m512 _mm512_mask_4fnmadd_ps(__m512, __mmask16, __m512x4, __m128 *);

V4FNMADDPS __m512 _mm512_maskz_4fnmadd_ps(__mmask16, __m512, __m512x4, __m128 *);

SIMD Floating-Point Exceptions ¶

Overflow, Underflow, Invalid, Precision, Denormal.

Other Exceptions ¶

See Type E2; additionally