| Opcode/Instruction | Op /En | 64/32 bit Mode Support | CPUID Feature Flag | Description |
|---|---|---|---|---|
|
EVEX.512.66.0F38.W1 C8 /r VEXP2PD zmm1 {k1}{z}, zmm2/m512/m64bcst {sae} |
FV | V/V | AVX512ER | Computes approximations to the exponential 2^x (with less than 2^-23 of maximum relative error) of the packed double-precision floating-point values from zmm2/m512/m64bcst and stores the floating-point result in zmm1with writemask k1. |
| Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
| FV | ModRM:reg (r, w) | ModRM:r/m (r) | NA | NA |
Description
Computes the approximate base-2 exponential evaluation of the double-precision floating-point values in the source operand (the second operand) and stores the results to the destination operand (the first operand) using the writemask k1. The approximate base-2 exponential is evaluated with less than 2^-23 of relative error.
Denormal input values are treated as zeros and do not signal #DE, irrespective of MXCSR.DAZ. Denormal results are flushed to zeros and do not signal #UE, irrespective of MXCSR.FZ.
The source operand is a ZMM register, a 512-bit memory location or a 512-bit vector broadcasted from a 64-bit memory location. The destination operand is a ZMM register, conditionally updated using writemask k1.
EVEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.
A numerically exact implementation of VEXP2xx can be found at https://software.intel.com/en-us/articles/refer-ence-implementations-for-IA-approximation-instructions-vrcp14-vrsqrt14-vrcp28-vrsqrt28-vexp2.
Operation
VEXP2PD
(KL, VL) = (8, 512)
FOR j (cid:197) 0 TO KL-1
i (cid:197) j * 64
IF k1[j] OR *no writemask* THEN
IF (EVEX.b = 1) AND (SRC *is memory*)
THEN DEST[i+63:i] (cid:197) EXP2_23_DP(SRC[63:0])
ELSE DEST[i+63:i] (cid:197) EXP2_23_DP(SRC[i+63:i])
FI;
ELSE
IF *merging-masking*
; merging-masking
THEN *DEST[i+63:i] remains unchanged*
ELSE
; zeroing-masking
DEST[i+63:i] (cid:197) 0
FI;
FI;
ENDFOR;
| Source Input | Result | Comments |
|---|---|---|
| NaN | QNaN(src) | If (SRC = SNaN) then #I |
| +∞ | +∞ | |
| +/-0 | 1.0f | Exact result |
| -∞ | +0.0f | |
| Integral value N | 2^ (N) | Exact result |
Intel C/C++ Compiler Intrinsic Equivalent
VEXP2PD __m512d _mm512_exp2a23_round_pd (__m512d a, int sae);
VEXP2PD __m512d _mm512_mask_exp2a23_round_pd (__m512d a, __mmask8 m, __m512d b, int sae);
VEXP2PD __m512d _mm512_maskz_exp2a23_round_pd ( __mmask8 m, __m512d b, int sae);
SIMD Floating-Point Exceptions
Invalid (if SNaN input), Overflow
Other Exceptions
See Exceptions Type E2.