VCVTSH2SS - Convert Low FP16 Value to FP32 Value

Opcode/ Instruction

Op/ En

64/32 bit Mode Support

CPUID Feature Flag

Description

EVEX.LLIG.NP.MAP6.W0 13 /r VCVTSH2SS xmm1{k1}{z}, xmm2, xmm3/m16 {sae}

A

V/V

AVX512-FP16

Convert the low FP16 element in xmm3/m16 to an FP32 value and store in the low element of xmm1 subject to writemask k1. Bits 127:32 of xmm2 are copied to xmm1[127:32].

Instruction Operand Encoding

Op/En

Tuple

Operand 1

Operand 2

Operand 3

Operand 4

A

Scalar

ModRM:reg (w)

VEX.vvvv (r)

ModRM:r/m (r)

N/A

Description

This instruction converts the low FP16 element in the second source operand to the low FP32 element of the desti- nation operand.

Bits 127:32 of the destination operand are copied from the corresponding bits of the first source operand. Bits MAXVL-1:128 of the destination operand are zeroed. The low FP16 element of the destination is updated according to the writemask.

Operation

VCVTSH2SS dest, src1, src2 

IF k1[0] OR *no writemask*:
   DEST.fp32[0] := Convert_fp16_to_fp32(SRC2.fp16[0])
ELSE IF *zeroing*:
   DEST.fp32[0] := 0
// else dest.fp32[0] remains unchanged
DEST[127:32] := SRC1[127:32]
DEST[MAXVL-1:128] := 0

Intel C/C++ Compiler Intrinsic Equivalent 

VCVTSH2SS __m128 _mm_cvt_roundsh_ss (__m128 a, __m128h b, const int sae);
VCVTSH2SS __m128 _mm_mask_cvt_roundsh_ss (__m128 src, __mmask8 k, __m128 a, __m128h b, const int sae);
VCVTSH2SS __m128 _mm_maskz_cvt_roundsh_ss (__mmask8 k, __m128 a, __m128h b, const int sae);
VCVTSH2SS __m128 _mm_cvtsh_ss (__m128 a, __m128h b);
VCVTSH2SS __m128 _mm_mask_cvtsh_ss (__m128 src, __mmask8 k, __m128 a, __m128h b);
VCVTSH2SS __m128 _mm_maskz_cvtsh_ss (__mmask8 k, __m128 a, __m128h b);

SIMD Floating-Point Exceptions

Invalid, Denormal.

Other Exceptions

EVEX-encoded instructions, see Table 2-47, "Type E3 Class Exception Conditions."