Opcode/ Instruction |
Op / En |
64/32 bit Mode Support |
CPUID Feature Flag |
Description |
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EVEX.128.66.0F3A.W1 56 /r ib VREDUCEPD xmm1 {k1}{z}, xmm2/m128/m64bcst, imm8 |
A |
V/V |
AVX512VL AVX512DQ |
Perform reduction transformation on packed double precision floating-point values in xmm2/m128/m32bcst by subtracting a number of fraction bits specified by the imm8 field. Stores the result in xmm1 register under writemask k1. |
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EVEX.256.66.0F3A.W1 56 /r ib VREDUCEPD ymm1 {k1}{z}, ymm2/m256/m64bcst, imm8 |
A |
V/V |
AVX512VL AVX512DQ |
Perform reduction transformation on packed double precision floating-point values in ymm2/m256/m32bcst by subtracting a number of fraction bits specified by the imm8 field. Stores the result in ymm1 register under writemask k1. |
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EVEX.512.66.0F3A.W1 56 /r ib VREDUCEPD zmm1 {k1}{z}, zmm2/m512/m64bcst{sae}, imm8 |
A |
V/V |
AVX512DQ |
Perform reduction transformation on double precision floating-point values in zmm2/m512/m32bcst by subtracting a number of fraction bits specified by the imm8 field. Stores the result in zmm1 register under writemask k1. |
Op/En |
Tuple Type |
Operand 1 |
Operand 2 |
Operand 3 |
Operand 4 |
|
A |
Full |
ModRM:reg (w) |
ModRM:r/m (r) |
imm8 |
N/A |
Perform reduction transformation of the packed binary encoded double precision floating-point values in the source operand (the second operand) and store the reduced results in binary floating-point format to the destination operand (the first operand) under the writemask k1.
The reduction transformation subtracts the integer part and the leading M fractional bits from the binary floating- point source value, where M is a unsigned integer specified by imm8[7:4], see Figure 5-28. Specifically, the reduc- tion transformation can be expressed as: dest = src - (ROUND(2M*src))*2-M; where "Round()" treats "src", "2M", and their product as binary floating-point numbers with normalized signifi- cand and biased exponents. The magnitude of the reduced result can be expressed by considering src= 2p*man2, where ‘man2' is the normalized significand and ‘p' is the unbiased exponent Then if RC = RNE: 0<=|Reduced Result|<=2p-M-1 Then if RC != RNE: 0<=|Reduced Result|<2p-M
This instruction might end up with a precision exception set. However, in case of SPE set (i.e., Suppress Precision Exception, which is imm8[3]=1), no precision exception is reported.
EVEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.
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7 6 5 4 3 2 1 0 imm8 SPE RS Fixed point length Round Control Override Suppress Precision Exception: Imm8[3] Imm8[1:0] = 00b : Round nearest even Imm8[3] = 0b : Use MXCSR exception mask Round Select: Imm8[2] Imm8[7:4] : Number of fixed points to subtract Imm8[1:0] = 01b : Round down Imm8[2] = 0b : Use Imm8[1:0] Imm8[3] = 1b : Suppress Imm8[1:0] = 10b : Round up Imm8[2] = 1b : Use MXCSR Imm8[1:0] = 11b : Truncate |
Handling of special case of input values are listed in Table 5-19.
Round Mode |
Returned value | |
|
|Src1| < 2-M-1 |
RNE |
Src1 |
|
RPI, Src1 > 0 |
Round (Src1-2-M) * | |
|
RPI, Src1 <= 0 |
Src1 | |
|
RNI, Src1 >= 0 |
Src1 | |
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|Src1| < 2-M |
RNI, Src1 < 0 |
Round (Src1+2-M) * |
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Src1 = +-0, or |
NOT RNI |
+0.0 |
|
Dest = +-0 (Src1!=INF) |
RNI |
-0.0 |
|
Src1 = +-INF |
any |
+0.0 |
|
Src1= +-NAN |
n/a |
QNaN(Src1) |
* Round control = (imm8.MS1)? MXCSR.RC: imm8.RC
ReduceArgumentDP(SRC[63:0], imm8[7:0])
{
// Check for NaN
IF (SRC [63:0] = NAN) THEN
RETURN (Convert SRC[63:0] to QNaN); FI;
M := imm8[7:4]; // Number of fraction bits of the normalized significand to be subtracted
RC := imm8[1:0];// Round Control for ROUND() operation
RC source := imm[2];
SPE := imm[3];// Suppress Precision Exception
TMP[63:0] := 2-M *{ROUND(2M*SRC[63:0], SPE, RC_source, RC)}; // ROUND() treats SRC and 2M as standard binary FP values
TMP[63:0] := SRC[63:0] - TMP[63:0]; // subtraction under the same RC,SPE controls
RETURN TMP[63:0]; // binary encoded FP with biased exponent and normalized significand
}
(KL, VL) = (2, 128), (4, 256), (8, 512)
FOR j := 0 TO KL-1
i := j * 64
IF k1[j] OR *no writemask* THEN
IF (EVEX.b == 1) AND (SRC *is memory*)
THEN DEST[i+63:i] := ReduceArgumentDP(SRC[63:0], imm8[7:0]);
ELSE DEST[i+63:i] := ReduceArgumentDP(SRC[i+63:i], imm8[7:0]);
FI;
ELSE
IF *merging-masking* ; merging-masking
THEN *DEST[i+63:i] remains unchanged*
ELSE ; zeroing-masking
DEST[i+63:i] = 0
FI;
FI;
ENDFOR;
DEST[MAXVL-1:VL] := 0
VREDUCEPD __m512d _mm512_mask_reduce_pd( __m512d a, int imm, int sae) VREDUCEPD __m512d _mm512_mask_reduce_pd(__m512d s, __mmask8 k, __m512d a, int imm, int sae) VREDUCEPD __m512d _mm512_maskz_reduce_pd(__mmask8 k, __m512d a, int imm, int sae) VREDUCEPD __m256d _mm256_mask_reduce_pd( __m256d a, int imm) VREDUCEPD __m256d _mm256_mask_reduce_pd(__m256d s, __mmask8 k, __m256d a, int imm) VREDUCEPD __m256d _mm256_maskz_reduce_pd(__mmask8 k, __m256d a, int imm) VREDUCEPD __m128d _mm_mask_reduce_pd( __m128d a, int imm) VREDUCEPD __m128d _mm_mask_reduce_pd(__m128d s, __mmask8 k, __m128d a, int imm) VREDUCEPD __m128d _mm_maskz_reduce_pd(__mmask8 k, __m128d a, int imm)
Invalid, Precision.
If SPE is enabled, precision exception is not reported (regardless of MXCSR exception mask).
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See Table 2-46, "Type E2 Class Exception Conditions." |
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Additionally: |
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#UD |
If EVEX.vvvv != 1111B. |