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.