모두의 코드
RCPPS (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 857 번 읽혔습니다.

RCPPS

Compute Reciprocals of Packed Single-Precision Floating-Point Values

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

0F 53 /r
RCPPS xmm1, xmm2/m128

RM

V/V

SSE

Computes the approximate reciprocals of the packed single-precision floating-point values in xmm2/m128 and stores the results in xmm1.

VEX.128.0F.WIG 53 /r
VRCPPS xmm1, xmm2/m128

RM

V/V

AVX

Computes the approximate reciprocals of packed single-precision values in xmm2/mem and stores the results in xmm1.

VEX.256.0F.WIG 53 /r
VRCPPS ymm1, ymm2/m256

RM

V/V

AVX

Computes the approximate reciprocals of packed single-precision values in ymm2/mem and stores the results 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 approximate reciprocals of the four packed single-precision floating-point values in the source operand (second operand) stores the packed single-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 10-5 in the Intel(R) 64 and IA-32 Architectures Software Developer's Manual, Volume 1, for an illustration of a SIMD single-precision floating-point operation.

The relative error for this approximation is:

|Relative Error| <= 1.5 \esc{*} 2-12

The RCPPS instruction is not affected by the rounding control bits in the MXCSR register. When a source value is a 0.0, an $\infty$ of the sign of the source value is returned. A denormal source value is treated as a 0.0 (of the same sign). Tiny results (see Section 4.9.1.5, "Numeric Underflow Exception (#U)" in Intel(R) 64 and IA-32 Architectures Soft-ware Developer's Manual, Volume 1) are always flushed to 0.0, with the sign of the operand. (Input values greater than or equal to |1.11111111110100000000000B\esc{*}2125 | are guaranteed to not produce tiny results; input values less than or equal to |1.00000000000110000000001B\esc{*}2126 | are guaranteed to produce tiny results, which are in turn flushed to 0.0; and input values in between this range may or may not produce tiny results, depending on the implementation.) 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 second source can be an XMM register or an 128-bit memory location. The desti-nation 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 first source operand is an XMM register or 128-bit memory location. The destination operand is an XMM register. The upper bits (VLMAX-1:128) of the corresponding YMM register destination are zeroed.

VEX.256 encoded version: The first source operand is a YMM register. The second source operand can be 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

RCPPS (128-bit Legacy SSE version)

DEST[31:0] <-  APPROXIMATE(1/SRC[31:0])
DEST[63:32] <-  APPROXIMATE(1/SRC[63:32])
DEST[95:64] <-  APPROXIMATE(1/SRC[95:64])
DEST[127:96] <-  APPROXIMATE(1/SRC[127:96])
DEST[VLMAX-1:128] (Unmodified)

VRCPPS (VEX.128 encoded version)

DEST[31:0] <-  APPROXIMATE(1/SRC[31:0])
DEST[63:32] <-  APPROXIMATE(1/SRC[63:32])
DEST[95:64] <-  APPROXIMATE(1/SRC[95:64])
DEST[127:96] <-  APPROXIMATE(1/SRC[127:96])
DEST[VLMAX-1:128] <-  0

VRCPPS (VEX.256 encoded version)

DEST[31:0] <-  APPROXIMATE(1/SRC[31:0])
DEST[63:32] <-  APPROXIMATE(1/SRC[63:32])
DEST[95:64] <-  APPROXIMATE(1/SRC[95:64])
DEST[127:96] <-  APPROXIMATE(1/SRC[127:96])
DEST[159:128] <-  APPROXIMATE(1/SRC[159:128])
DEST[191:160] <-  APPROXIMATE(1/SRC[191:160])
DEST[223:192] <-  APPROXIMATE(1/SRC[223:192])
DEST[255:224] <-  APPROXIMATE(1/SRC[255:224])

Intel C/C++ Compiler Intrinsic Equivalent

RCCPS : __m128 _mm_rcp_ps(__m128 a) RCPPS : __m256 _mm256_rcp_ps(__m256 a);

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 4; additionally

#UD If VEX.vvvv -> 1111B.

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