모두의 코드
SQRTSS (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 710 번 읽혔습니다.

SQRTSS

Compute Square Root of Scalar Single-Precision Value

참고 사항

아래 표를 해석하는 방법은 x86-64 명령어 레퍼런스 읽는 법 글을 참조하시기 바랍니다.

Opcode/
Instruction

Op /
En

64/32
bit Mode
Support

CPUID
Feature
Flag

Description

F3 0F 51 /r
SQRTSS xmm1 xmm2/m32

RM

V/V

SSE

Computes square root of the low single-precision floating-point value in xmm2/m32 and stores the results in xmm1.

VEX.NDS.128.F3.0F.WIG 51 /r
VSQRTSS xmm1 xmm2 xmm3/m32

RVM

V/V

AVX

Computes square root of the low single-precision floating-point value in xmm3/m32 and stores the results in xmm1. Also, upper single-precision floating-point values (bits[127:32]) from xmm2 are copied to xmm1[127:32].

EVEX.NDS.LIG.F3.0F.W0 51 /r
VSQRTSS xmm1 {k1}{z} xmm2 xmm3/m32{er}

T1S

V/V

AVX512F

Computes square root of the low single-precision floating-point value in xmm3/m32 and stores the results in xmm1 under writemask k1. Also, upper single-precision floating-point values (bits[127:32]) from xmm2 are copied to xmm1[127:32].

Instruction Operand Encoding

Op/En

Operand 1

Operand 2

Operand 3

Operand 4

RM

ModRM:reg (w)

ModRM:r/m (r)

NA

NA

RVM

ModRM:reg (w)

VEX.vvvv (r)

ModRM:r/m (r)

NA

T1S

ModRM:reg (w)

EVEX.vvvv (r)

ModRM:r/m (r)

NA

Description

Computes the square root of the low single-precision floating-point value in the second source operand and stores the single-precision floating-point result in the destination operand. The second source operand can be an XMM register or a 32-bit memory location. The first source and destination operands is an XMM register.

128-bit Legacy SSE version: The first source operand and the destination operand are the same. Bits (MAXVL-1:32) of the corresponding YMM destination register remain unchanged.

VEX.128 and EVEX encoded versions: Bits 127:32 of the destination operand are copied from the corresponding bits of the first source operand. Bits (MAXVL-1:128) of the destination ZMM register are zeroed.

EVEX encoded version: The low doubleword element of the destination operand is updated according to the writemask.

Software should ensure VSQRTSS is encoded with VEX.L=0. Encoding VSQRTSS with VEX.L=1 may encounter unpredictable behavior across different processor generations.

Operation

VSQRTSS (EVEX encoded version)

IF (EVEX.b = 1) AND (SRC2 *is register*)
    THEN
          SET_RM(EVEX.RC);
    ELSE 
          SET_RM(MXCSR.RM);
FI;
IF k1[0] or *no writemask*
    THEN DEST[31:0] <-  SQRT(SRC2[31:0])
    ELSE 
          IF *merging-masking* ; merging-masking
                THEN *DEST[31:0] remains unchanged*
                ELSE  ; zeroing-masking
                      DEST[31:0] <-  0
          FI;
FI;
DEST[127:31] <-  SRC1[127:31]
DEST[MAX_VL-1:128] <-  0

VSQRTSS (VEX.128 encoded version)

DEST[31:0] <- SQRT(SRC2[31:0])
DEST[127:32] <- SRC1[127:32]
DEST[MAX_VL-1:128] <- 0

SQRTSS (128-bit Legacy SSE version)

DEST[31:0] <- SQRT(SRC2[31:0])
DEST[MAX_VL-1:32] (Unmodified)

Intel C/C++ Compiler Intrinsic Equivalent

VSQRTSS __m128 _mm_sqrt_round_ss(__m128 a, __m128 b, int r);
VSQRTSS __m128 _mm_mask_sqrt_round_ss(__m128 s, __mmask8 k, __m128 a, __m128 b,
                                      int r);
VSQRTSS __m128 _mm_maskz_sqrt_round_ss(__mmask8 k, __m128 a, __m128 b, int r);
SQRTSS __m128 _mm_sqrt_ss(__m128 a)

SIMD Floating-Point Exceptions

Invalid, Precision, Denormal

Other Exceptions

Non-EVEX-encoded instruction, see Exceptions Type 3.

EVEX-encoded instruction, see Exceptions Type E3.

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