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Source code

VCVTSD2SH

Convert Low FP64 Value to an FP16 Value

stableVMJITAOTinstruction

Encodings

OpcodeInstructionOp/En64-bitCompat/LegacyDescription
EVEX.LLIG.F2.MAP5.W1 5A /rVCVTSD2SH xmm1{k1}{z}, xmm2, xmm3/m64 {er}AValidValidConvert the low FP64 value in xmm3/m64 to an OR AVX10.1 FP16 value and store the result in the low element of xmm1 subject to writemask k1. Bits 127:16 of xmm2 are copied to xmm1[127:16].

Operand encoding

Each mode is a value of the Op/En column above. It says which field of the encoded instruction carries each operand, in the order they are written, and whether the instruction reads it, writes it or both.

A

  1. modrm.reg escrituraModRM byte, reg field (bits 5-3)
  2. vex.vvvv lecturaVEX prefix, vvvv field (inverted)
  3. modrm.rm lecturaModRM byte, r/m field (bits 2-0); with the SIB byte and the displacement when the mod field asks for them

Tupla: Scalar

Measured cost

Loading measurements from arch-data...

Description

This instruction converts the low FP64 value in the second source operand to an FP16 value, and stores the result in the low element of the destination operand.

When the conversion is inexact, the value returned is rounded according to the rounding control bits in the MXCSR register.

Bits 127:16 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

VCVTSD2SH dest, src1, src2
IF *SRC2 is a register* and (EVEX.b = 1):

    SET_RM(EVEX.RC)
ELSE:

    SET_RM(MXCSR.RC)

IF k1[0] OR *no writemask*:
    DEST.fp16[0] := Convert_fp64_to_fp16(SRC2.fp64[0])

ELSE IF *zeroing*:
    DEST.fp16[0] := 0

// else dest.fp16[0] remains unchanged

DEST[127:16] := SRC1[127:16]
DEST[MAXVL-1:128] := 0

Intel C/C++ compiler intrinsics

VCVTSD2SH __m128h _mm_cvt_roundsd_sh (__m128h a, __m128d b, const int rounding);
VCVTSD2SH __m128h _mm_mask_cvt_roundsd_sh (__m128h src, __mmask8 k, __m128h a, __m128d b, const int rounding);
VCVTSD2SH __m128h _mm_maskz_cvt_roundsd_sh (__mmask8 k, __m128h a, __m128d b, const int rounding);
VCVTSD2SH __m128h _mm_cvtsd_sh (__m128h a, __m128d b);
VCVTSD2SH __m128h _mm_mask_cvtsd_sh (__m128h src, __mmask8 k, __m128h a, __m128d b);
VCVTSD2SH __m128h _mm_maskz_cvtsd_sh (__mmask8 k, __m128h a, __m128d b);

SIMD Floating-Point Exceptions

Invalid, Underflow, Overflow, Precision, Denormal.

Other Exceptions

EVEX-encoded instructions, see Table 2-49, "Type E3 Class Exception Conditions."

Sources