CVTTSD2SI—Convert with Truncation Scalar Double-Precision Floating-Point Value to Signed Integer

NOTES: 1. For this specific instruction, VEX.W/EVEX.W in non-64 bit is ignored; the instructions behaves as if the W0 ver-

sion is used.

Instruction Operand Encoding

Description

Converts a double-precision floating-point value in the source operand (the second operand) to a signed double-word 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 64-bit memory location. The destination operand is a general purpose register. When the source operand is an XMM register, the double-precision floating-point value is contained in the low quadword of the register.

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

If a converted result exceeds the range limits of signed doubleword integer (in non-64-bit modes or 64-bit mode with REX.W/VEX.W/EVEX.W=0), the floating-point invalid exception is raised, and if this exception is masked, the indefinite integer value (80000000H) is returned.

If a converted result exceeds the range limits of signed quadword integer (in 64-bit mode and REX.W/VEX.W/EVEX.W = 1), the floating-point invalid exception is raised, and if this exception is masked, the indefinite integer value (80000000_00000000H) is returned.

Legacy SSE instructions: In 64-bit mode, Use of the REX.W prefix promotes the instruction to 64-bit operation. 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 VCVTTSD2SI is encoded with VEX.L=0. Encoding VCVTTSD2SI with VEX.L=1 may encounter unpredictable behavior across different processor generations.

Operation

IF 64-Bit Mode and OperandSize = 64
    THEN
    DEST[63:0] (cid:197) Convert_Double_Precision_Floating_Point_To_Integer_Truncate(SRC[63:0]);
    ELSE
    DEST[31:0] (cid:197) Convert_Double_Precision_Floating_Point_To_Integer_Truncate(SRC[63:0]);
FI;

Intel C/C++ Compiler Intrinsic Equivalent

VCVTTSD2SI int _mm_cvttsd_i32( __m128d a);
VCVTTSD2SI int _mm_cvtt_roundsd_i32( __m128d a, int sae);
VCVTTSD2SI __int64 _mm_cvttsd_i64( __m128d a);
VCVTTSD2SI __int64 _mm_cvtt_roundsd_i64( __m128d a, int sae);
CVTTSD2SI int _mm_cvttsd_si32( __m128d a);
CVTTSD2SI __int64 _mm_cvttsd_si64( __m128d a);

SIMD Floating-Point Exceptions

Invalid, Precision

Other Exceptions