모두의 코드
VGATHERDPS, VGATHERDPDs (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 865 번 읽혔습니다.

VGATHERDPS, VGATHERDPD

Gather Packed Single, Packed Double with Signed Dword

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

EVEX.128.66.0F38.W0 92 /vsib
VGATHERDPS xmm1 {k1} vm32x

T1S

V/V

AVX512VL
AVX512F

Using signed dword indices, gather single-precision floating-point values from memory using k1 as completion mask.

EVEX.256.66.0F38.W0 92 /vsib
VGATHERDPS ymm1 {k1} vm32y

T1S

V/V

AVX512VL
AVX512F

Using signed dword indices, gather single-precision floating-point values from memory using k1 as completion mask.

EVEX.512.66.0F38.W0 92 /vsib
VGATHERDPS zmm1 {k1} vm32z

T1S

V/V

AVX512F

Using signed dword indices, gather single-precision floating-point values from memory using k1 as completion mask.

EVEX.128.66.0F38.W1 92 /vsib
VGATHERDPD xmm1 {k1} vm32x

T1S

V/V

AVX512VL
AVX512F

Using signed dword indices, gather float64 vector into float64 vector xmm1 using k1 as completion mask.

EVEX.256.66.0F38.W1 92 /vsib
VGATHERDPD ymm1 {k1} vm32x

T1S

V/V

AVX512VL
AVX512F

Using signed dword indices, gather float64 vector into float64 vector ymm1 using k1 as completion mask.

EVEX.512.66.0F38.W1 92 /vsib
VGATHERDPD zmm1 {k1} vm32y

T1S

V/V

AVX512F

Using signed dword indices, gather float64 vector into float64 vector zmm1 using k1 as completion mask.

Instruction Operand Encoding

Op/En

Operand 1

Operand 2

Operand 3

Operand 4

T1S

ModRM:reg (w)

BaseReg (R): VSIB:base,VectorReg(R): VSIB:index

NA

NA

Description

A set of single-precision/double-precision faulting-point memory locations pointed by base address BASEADDR and index vector VINDEX with scale SCALE are gathered. The result is written into a vector register. The elements are specified via the VSIB (i.e., the index register is a vector register, holding packed indices). Elements will only be loaded if their corresponding mask bit is one. If an element's mask bit is not set, the corresponding element of the destination register is left unchanged. The entire mask register will be set to zero by this instruction unless it triggers an exception.

This instruction can be suspended by an exception if at least one element is already gathered (i.e., if the exception is triggered by an element other than the right most one with its mask bit set). When this happens, the destination register and the mask register (k1) are partially updated; those elements that have been gathered are placed into the destination register and have their mask bits set to zero. If any traps or interrupts are pending from already gathered elements, they will be delivered in lieu of the exception; in this case, EFLAG.RF is set to one so an instruc-tion breakpoint is not re-triggered when the instruction is continued.

If the data element size is less than the index element size, the higher part of the destination register and the mask register do not correspond to any elements being gathered. This instruction sets those higher parts to zero. It may update these unused elements to one or both of those registers even if the instruction triggers an exception, and even if the instruction triggers the exception before gathering any elements.

Note that:

  • The values may be read from memory in any order. Memory ordering with other instructions follows the Intel-64 memory-ordering model.

  • Faults are delivered in a right-to-left manner. That is, if a fault is triggered by an element and delivered, all elements closer to the LSB of the destination zmm will be completed (and non-faulting). Individual elements closer to the MSB may or may not be completed. If a given element triggers multiple faults, they are delivered in the conventional order.

  • Elements may be gathered in any order, but faults must be delivered in a right-to left order; thus, elements to the left of a faulting one may be gathered before the fault is delivered. A given implementation of this instruction is repeatable - given the same input values and architectural state, the same set of elements to the left of the faulting one will be gathered.

  • This instruction does not perform AC checks, and so will never deliver an AC fault.

  • Not valid with 16-bit effective addresses. Will deliver a #UD fault.

Note that the presence of VSIB byte is enforced in this instruction. Hence, the instruction will #UD fault if ModRM.rm is different than 100b.

This instruction has special disp8\esc{*}N and alignment rules. N is considered to be the size of a single vector element.

The scaled index may require more bits to represent than the address bits used by the processor (e.g., in 32-bit mode, if the scale is greater than one). In this case, the most significant bits beyond the number of address bits are ignored.

The instruction will #UD fault if the destination vector zmm1 is the same as index vector VINDEX. The instruction will #UD fault if the k0 mask register is specified.

Operation

VGATHERDPS (EVEX encoded version)

(KL, VL) = (4, 128), (8, 256), (16, 512)
FOR j <-  0 TO KL-1
    i <-  j * 32
    IF k1[j] 
          THEN DEST[i+31:i] <-  
                MEM[BASE_ADDR +SignExtend(VINDEX[i+31:i]) * SCALE + DISP]
                k1[j] <-  0
          ELSE *DEST[i+31:i] <-  remains unchanged*
    FI;
ENDFOR
k1[MAX_KL-1:KL] <-  0
DEST[MAX_VL-1:VL] <-  0

VGATHERDPD (EVEX encoded version)

(KL, VL) = (2, 128), (4, 256), (8, 512)
FOR j <-  0 TO KL-1
    i <-  j * 64
    k <-  j * 32
    IF k1[j] 
          THEN DEST[i+63:i] <-  MEM[BASE_ADDR +SignExtend(VINDEX[k+31:k]) * SCALE + DISP]
                k1[j] <-  0
          ELSE *DEST[i+63:i] <-  remains unchanged*
    FI;
ENDFOR
k1[MAX_KL-1:KL] <-  0
DEST[MAX_VL-1:VL] <-  0

Intel C/C++ Compiler Intrinsic Equivalent

VGATHERDPD __m512d _mm512_i32gather_pd(__m256i vdx, void* base, int scale);
VGATHERDPD __m512d _mm512_mask_i32gather_pd(__m512d s, __mmask8 k, __m256i vdx,
                                            void* base, int scale);
VGATHERDPD __m256d _mm256_mmask_i32gather_pd(__m256d s, __mmask8 k, __m128i vdx,
                                             void* base, int scale);
VGATHERDPD __m128d _mm_mmask_i32gather_pd(__m128d s, __mmask8 k, __m128i vdx,
                                          void* base, int scale);
VGATHERDPS __m512 _mm512_i32gather_ps(__m512i vdx, void* base, int scale);
VGATHERDPS __m512 _mm512_mask_i32gather_ps(__m512 s, __mmask16 k, __m512i vdx,
                                           void* base, int scale);
VGATHERDPS __m256 _mm256_mmask_i32gather_ps(__m256 s, __mmask8 k, __m256i vdx,
                                            void* base, int scale);
GATHERDPS __m128 _mm_mmask_i32gather_ps(__m128 s, __mmask8 k, __m128i vdx,
                                        void* base, int scale);

SIMD Floating-Point Exceptions

None

Other Exceptions

See Exceptions Type E12.

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