# SQRTPD (Compute Square Roots of Packed Double-Precision Floating-Point Values)

## Opcodes

Opcode*/Instruction | Op/En | 64/32 bit Mode Support | CPUID Feature Flag | Description |
---|---|---|---|---|

66 0F 51 /r
SQRTPD xmm1, xmm2/m128 |
RM | V/V | SSE2 | Computes square roots of the packed double-precision floating-point values in xmm2/m128 and stores the results in xmm1. |

VEX.128.66.0F.WIG 51 /r
VSQRTPD xmm1, xmm2/m128 |
RM | V/V | AVX | Computes Square Roots of the packed double-precision floating-point values in xmm2/m128 and stores the result in xmm1. |

VEX.256.66.0F.WIG 51/r
VSQRTPD ymm1, ymm2/m256 |
RM | V/V | AVX | Computes Square Roots of the packed double-precision floating-point values in ymm2/m256 and stores the result in ymm1. |

## Instruction Operand Encoding

Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
---|---|---|---|---|

RM | ModRM:reg (w) | ModRM:r/m (r) | NA | NA |

## Description

Performs a SIMD computation of the square roots of the two packed double-precision floating-point values in the source operand (second operand) stores the packed double-precision floating-point results in the destination operand. The source operand can be an XMM register or a 128-bit memory location. The destination operand is an XMM register. See Figure 11-3 in the *Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1*, for an illustration of a SIMD double-precision floating-point operation.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

128-bit Legacy SSE version: The second source can be an XMM register or 128-bit memory location. The destina-tion is not distinct from the first source XMM register and the upper bits (VLMAX-1:128) of the corresponding YMM register destination are unmodified.

VEX.128 encoded version: the source operand second source operand or a 128-bit memory location. The destina-tion operand is an XMM register. The upper bits (VLMAX-1:128) of the corresponding YMM register destination are zeroed.

VEX.256 encoded version: The source operand is a YMM register or a 256-bit memory location. The destination operand is a YMM register.

Note: In VEX-encoded versions, VEX.vvvv is reserved and must be 1111b otherwise instructions will #UD.

## Operation

**SQRTPD (128-bit Legacy SSE version)**

DEST[63:0] ← SQRT(SRC[63:0]) DEST[127:64] ← SQRT(SRC[127:64]) DEST[VLMAX-1:128] (Unmodified)

**VSQRTPD (VEX.128 encoded version)**

DEST[63:0] ← SQRT(SRC[63:0]) DEST[127:64] ← SQRT(SRC[127:64]) DEST[VLMAX-1:128] ← 0

**VSQRTPD (VEX.256 encoded version)**

DEST[63:0] ← SQRT(SRC[63:0]) DEST[127:64] ← SQRT(SRC[127:64]) DEST[191:128] ← SQRT(SRC[191:128]) DEST[255:192] ← SQRT(SRC[255:192])

## Intel C/C++ Compiler Intrinsic Equivalent

SQRTPD:

__m128d _mm_sqrt_pd (m128d a)

SQRTPD:

__m256d _mm256_sqrt_pd (__m256d a);

## SIMD Floating-Point Exceptions

Invalid, Precision, Denormal.

## Other Exceptions

See Exceptions Type 2; additionally

#UD | If VEX.vvvv ≠ 1111B. |
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