CVTSS2SI — Convert Scalar Single Precision Floating-Point Value to Doubleword Integer

Opcode/Instruction Op / En 64/32 bit Mode Support CPUID Feature Flag Description
F3 0F 2D /r CVTSS2SI r32, xmm1/m32 A V/V SSE Convert one single precision floating-point value from xmm1/m32 to one signed doubleword integer in r32.
F3 REX.W 0F 2D /r CVTSS2SI r64, xmm1/m32 A V/N.E. SSE Convert one single precision floating-point value from xmm1/m32 to one signed quadword integer in r64.
VEX.LIG.F3.0F.W0 2D /r 1 VCVTSS2SI r32, xmm1/m32 A V/V AVX Convert one single precision floating-point value from xmm1/m32 to one signed doubleword integer in r32.
VEX.LIG.F3.0F.W1 2D /r 1 VCVTSS2SI r64, xmm1/m32 A V/N.E.2 AVX Convert one single precision floating-point value from xmm1/m32 to one signed quadword integer in r64.
EVEX.LLIG.F3.0F.W0 2D /r VCVTSS2SI r32, xmm1/m32{er} B V/V AVX512F Convert one single precision floating-point value from xmm1/m32 to one signed doubleword integer in r32.
EVEX.LLIG.F3.0F.W1 2D /r VCVTSS2SI r64, xmm1/m32{er} B V/N.E.2 AVX512F Convert one single precision floating-point value from xmm1/m32 to one signed quadword integer in r64.

1. Software should ensure VCVTSS2SI is encoded with VEX.L=0. Encoding VCVTSS2SI with VEX.L=1 may encounter unpredictable behavior across different processor generations.

2. VEX.W1/EVEX.W1 in non-64 bit is ignored; the instructions behaves as if the W0 version is used.

Instruction Operand Encoding

Op/En Tuple Type Operand 1 Operand 2 Operand 3 Operand 4
A N/A ModRM:reg (w) ModRM:r/m (r) N/A N/A
B Tuple1 Fixed ModRM:reg (w) ModRM:r/m (r) N/A N/A

Description

Converts a single precision floating-point value in the source operand (the second operand) to a signed doubleword integer (or signed quadword integer if operand size is 64 bits) in the destination operand (the first operand). The source operand can be an XMM register or a memory location. The destination operand is a general-purpose register. When the source operand is an XMM register, the single precision floating-point value is contained in the low doubleword of the register.

When a conversion is inexact, the value returned is rounded according to the rounding control bits in the MXCSR register or the embedded rounding control bits. If a converted result cannot be represented in the destination format, the floating-point invalid exception is raised, and if this exception is masked, the indefinite integer value (2w-1, where w represents the number of bits in the destination format) is returned.

Legacy SSE instructions: In 64-bit mode, Use of the REX.W prefix promotes the instruction to produce 64-bit data. See the summary chart at the beginning of this section for encoding data and limits.

VEX.W1 and EVEX.W1 versions: promotes the instruction to produce 64-bit data in 64-bit mode.

Note: VEX.vvvv and EVEX.vvvv are reserved and must be 1111b, otherwise instructions will #UD.

Software should ensure VCVTSS2SI is encoded with VEX.L=0. Encoding VCVTSS2SI with VEX.L=1 may encounter unpredictable behavior across different processor generations.

Operation

VCVTSS2SI (EVEX Encoded Version)

IF (SRC *is register*) AND (EVEX.b = 1)
    THEN
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(EVEX.RC);
    ELSE
        SET_ROUNDING_MODE_FOR_THIS_INSTRUCTION(MXCSR.RC);
FI;
IF 64-bit Mode and OperandSize = 64
THEN
    DEST[63:0] := Convert_Single_Precision_Floating_Point_To_Integer(SRC[31:0]);
ELSE
    DEST[31:0] := Convert_Single_Precision_Floating_Point_To_Integer(SRC[31:0]);
FI;

(V)CVTSS2SI (Legacy and VEX.128 Encoded Version)

IF 64-bit Mode and OperandSize = 64
THEN
    DEST[63:0] := Convert_Single_Precision_Floating_Point_To_Integer(SRC[31:0]);
ELSE
    DEST[31:0] := Convert_Single_Precision_Floating_Point_To_Integer(SRC[31:0]);
FI;

Intel C/C++ Compiler Intrinsic Equivalent

VCVTSS2SI int _mm_cvtss_i32( __m128 a);

VCVTSS2SI int _mm_cvt_roundss_i32( __m128 a, int r);

VCVTSS2SI __int64 _mm_cvtss_i64( __m128 a);

VCVTSS2SI __int64 _mm_cvt_roundss_i64( __m128 a, int r);

SIMD Floating-Point Exceptions

Invalid, Precision.

Other Exceptions

VEX-encoded instructions, see Table 2-20, “Type 3 Class Exception Conditions,” additionally:

#UD If VEX.vvvv != 1111B.

EVEX-encoded instructions, see Table 2-48, “Type E3NF Class Exception Conditions.”