SHUFPS—Shuffle Packed Single-Precision Floating-Point Values

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

0F C6 /r ib

SHUFPS xmm1, xmm2/m128, imm8

 RMI V/V SSE Shuffle packed single-precision floating-point values selected by imm8 from xmm1 and xmm1/m128 to xmm1.

VEX.NDS.128.0F.WIG C6 /r ib

VSHUFPS xmm1, xmm2, xmm3/m128, imm8

 RVMI V/V AVX Shuffle Packed single-precision floating-point values selected by imm8 from xmm2 and xmm3/mem.

VEX.NDS.256.0F.WIG C6 /r ib

VSHUFPS ymm1, ymm2, ymm3/m256, imm8

 RVMI V/V AVX Shuffle Packed single-precision floating-point values selected by imm8 from ymm2 and ymm3/mem.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RMI ModRM:reg (r, w) ModRM:r/m (r) imm8 NA
RVMI ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) imm8

Description

Moves two of the four packed single-precision floating-point values from the destination operand (first operand) into the low quadword of the destination operand; moves two of the four packed single-precision floating-point values from the source operand (second operand) into to the high quadword of the destination operand (see Figure 4-22). The select operand (third operand) determines which values are moved to the destination operand.

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 source can be an XMM register or an 128-bit memory location. The destination 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.

determines which values are moved to the destination operand.

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.

DEST SRC DEST X3 ... X0 X2 Y2 X3 X1 X0 Y3 Y1 Y0 Y3 ... Y0 Y3 ... Y0 X3 ... X0

Figure 4-22. SHUFPS Shuffle Operation

The source operand can be an XMM register or a 128-bit memory location. The destination operand is an XMM register. The select operand is an 8-bit immediate: bits 0 and 1 select the value to be moved from the destination operand to the low doubleword of the result, bits 2 and 3 select the value to be moved from the destination operand to the second doubleword of the result, bits 4 and 5 select the value to be moved from the source operand to the third doubleword of the result, and bits 6 and 7 select the value to be moved from the source operand to the high doubleword of the result.

Operation

CASE (SELECT[1:0]) OF
    0:
         DEST[31:0]  ← DEST[31:0];
    1:
         DEST[31:0]  ← DEST[63:32];
    2:
         DEST[31:0]  ← DEST[95:64];
    3:
         DEST[31:0]  ← DEST[127:96];
ESAC;
CASE (SELECT[3:2]) OF
    0:
         DEST[63:32]  ← DEST[31:0];
    1:
         DEST[63:32]  ← DEST[63:32];
    2:
         DEST[63:32]  ← DEST[95:64];
    3:
         DEST[63:32]  ← DEST[127:96];
ESAC;
CASE (SELECT[5:4]) OF
    0:
         DEST[95:64]  ← SRC[31:0];
    1:
         DEST[95:64]  ← SRC[63:32];
    2:
         DEST[95:64]  ← SRC[95:64];
    3:
         DEST[95:64]  ← SRC[127:96];
ESAC;
CASE (SELECT[7:6]) OF
    0:
         DEST[127:96]  ← SRC[31:0];
    1:
         DEST[127:96]  ← SRC[63:32];
    2:
         DEST[127:96]  ← SRC[95:64];
    3:
         DEST[127:96]  ← SRC[127:96];
ESAC;

SHUFPS (128-bit Legacy SSE version)

DEST[31:0] ← Select4(SRC1[127:0], imm8[1:0]);
DEST[63:32] ← Select4(SRC1[127:0], imm8[3:2]);
DEST[95:64] ← Select4(SRC2[127:0], imm8[5:4]);
DEST[127:96] ← Select4(SRC2[127:0], imm8[7:6]);
DEST[VLMAX-1:128] (Unmodified)

VSHUFPS (VEX.128 encoded version)

DEST[31:0] ← Select4(SRC1[127:0], imm8[1:0]);
DEST[63:32] ← Select4(SRC1[127:0], imm8[3:2]);
DEST[95:64] ← Select4(SRC2[127:0], imm8[5:4]);
DEST[127:96] ← Select4(SRC2[127:0], imm8[7:6]);
DEST[VLMAX-1:128] ← 0

VSHUFPS (VEX.256 encoded version)

DEST[31:0] ← Select4(SRC1[127:0], imm8[1:0]);
DEST[63:32] ← Select4(SRC1[127:0], imm8[3:2]);
DEST[95:64] ← Select4(SRC2[127:0], imm8[5:4]);
DEST[127:96] ← Select4(SRC2[127:0], imm8[7:6]);
DEST[159:128] ← Select4(SRC1[255:128], imm8[1:0]);
DEST[191:160] ← Select4(SRC1[255:128], imm8[3:2]);
DEST[223:192] ← Select4(SRC2[255:128], imm8[5:4]);
DEST[255:224] ← Select4(SRC2[255:128], imm8[7:6]);

Intel C/C++ Compiler Intrinsic Equivalent

SHUFPS:

__m128 _mm_shuffle_ps(__m128 a, __m128 b, unsigned int imm8)

VSHUFPS:

__m256 _mm256_shuffle_ps (__m256 a, __m256 b, const int select);

SIMD Floating-Point Exceptions

None.

Other Exceptions

See Exceptions Type 4.