image/svg+xmlRSQRTSS—Compute Reciprocal of Square Root of Scalar Single-Precision Floating-Point ValueInstruction Operand EncodingDescriptionComputes an approximate reciprocal of the square root of the low single-precision floating-point value in the source operand (second operand) stores the single-precision floating-point result in the destination operand. The source operand can be an XMM register or a 32-bit memory location. The destination operand is an XMM register. The three high-order doublewords of the destination operand remain unchanged. See Figure 10-6 in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1, for an illustration of a scalar single-precision floating-point operation.The relative error for this approximation is:|Relative Error| ≤ 1.5 ∗ 2−12 The RSQRTSS instruction is not affected by the rounding control bits in the MXCSR register. When a source value is a 0.0, an ∞ of the sign of the source value is returned. A denormal source value is treated as a 0.0 (of the same sign). When a source value is a negative value (other than −0.0), a floating-point indefinite is returned. When a source value is an SNaN or QNaN, the SNaN is converted to a QNaN or the source QNaN is returned. 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 first source operand and the destination operand are the same. Bits (MAXVL-1:32) of the corresponding YMM destination register remain unchanged.VEX.128 encoded version: Bits (MAXVL-1:128) of the destination YMM register are zeroed.OperationRSQRTSS (128-bit Legacy SSE version)DEST[31:0] := APPROXIMATE(1/SQRT(SRC2[31:0]))DEST[MAXVL-1:32] (Unmodified)VRSQRTSS (VEX.128 encoded version)DEST[31:0] := APPROXIMATE(1/SQRT(SRC2[31:0]))DEST[127:32] := SRC1[127:32]DEST[MAXVL-1:128] := 0Opcode*/InstructionOp/ En64/32 bit Mode SupportCPUID Feature FlagDescriptionF3 0F 52 /rRSQRTSS xmm1, xmm2/m32RMV/VSSEComputes the approximate reciprocal of the square root of the low single-precision floating-point value in xmm2/m32 and stores the results in xmm1.VEX.LIG.F3.0F.WIG 52 /rVRSQRTSS xmm1, xmm2, xmm3/m32RVMV/VAVXComputes the approximate reciprocal of the 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].Op/EnOperand 1Operand 2Operand 3Operand 4RMModRM:reg (w)ModRM:r/m (r)NANARVMModRM:reg (w)VEX.vvvv (r)ModRM:r/m (r)NA

image/svg+xmlIntel C/C++ Compiler Intrinsic EquivalentRSQRTSS:__m128 _mm_rsqrt_ss(__m128 a)SIMD Floating-Point ExceptionsNone.Other ExceptionsSee Table2-22, “Type 5 Class Exception Conditions”.

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