SUBSS (Subtract Scalar Single-Precision Floating-Point Values)

Opcodes

Opcode/Instruction Op/En 64/32 bit Mode Support CPUID Feature Flag Description
F3 0F 5C /r SUBSS xmm1, xmm2/m32 RM V/V SSE Subtract the lower single-precision floating-point values in xmm2/m32 from xmm1.
VEX.NDS.LIG.F3.0F.WIG 5C /r VSUBSS xmm1,xmm2, xmm3/m32 RVM V/V AVX Subtract the low single-precision floating-point value in xmm3/mem from xmm2 and store the result in xmm1.

Instruction Operand Encoding

Op/En Operand 1 Operand 2 Operand 3 Operand 4
RM ModRM:reg (r, w) ModRM:r/m (r) NA NA
RVM ModRM:reg (w) VEX.vvvv (r) ModRM:r/m (r) NA

Description

Subtracts the low single-precision floating-point value in the source operand (second operand) from the low single-precision floating-point value in the destination operand (first operand), and stores the single-precision floating-point result in the destination operand. The source operand can be an XMM register or a 32-bit memory location. The destination operand is an XMM register. The three high-order doublewords of the destination operand remain unchanged. See Figure 10-6 in the Intel® 64 and IA-32 Architectures Software Developer’s Manual, Volume 1, for an illustration of a scalar single-precision floating-point operation.

In 64-bit mode, using a REX prefix in the form of REX.R permits this instruction to access additional registers (XMM8-XMM15).

128-bit Legacy SSE version: The destination and first source operand are the same. Bits (VLMAX-1:32) of the corresponding YMM destination register remain unchanged.

VEX.128 encoded version: Bits (127:32) of the XMM register destination are copied from corresponding bits in the first source operand. Bits (VLMAX-1:128) of the destination YMM register are zeroed.

Operation

SUBSS (128-bit Legacy SSE version)

DEST[31:0] ← DEST[31:0] - SRC[31:0]
DEST[VLMAX-1:32] (Unmodified)

VSUBSS (VEX.128 encoded version)

DEST[31:0] ← SRC1[31:0] - SRC2[31:0]
DEST[127:32] ← SRC1[127:32]
DEST[VLMAX-1:128] ← 0

Intel C/C++ Compiler Intrinsic Equivalent

SUBSS:

__m128 _mm_sub_ss(__m128 a, __m128 b)

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Precision, Denormal.

Other Exceptions

See Exceptions Type 3.