subss
Subtract Scalar Single-Precision
Subtracts the low single-precision floating-point value.
Pseudocode Operation
xmm1[31:0] ← xmm1[31:0] - src[31:0] (IEEE 754 single-precision)
xmm1[127:32] ← unchanged
FP_exceptions may be raisedEncoding
Operands
-
dest
128-bit XMM SIMD register -
src
128-bit XMM SIMD register or Memory operand
Related
More in SSE
Reference
Instruction Forms
| Opcode | Instruction | Op/En | 64/32-bit Mode | CPUID | Description |
|---|---|---|---|---|---|
| F3 0F 5C /r | SUBSS xmm1, xmm2/m32 | A | V/V | SSE | Subtract the low single precision floating-point value in xmm2/m32 from xmm1 and store the result in xmm1. |
| VEX.LIG.F3.0F.WIG 5C /r | VSUBSS xmm1,xmm2, xmm3/m32 | B | V/V | AVX | Subtract the low single precision floating-point value in xmm3/m32 from xmm2 and store the result in xmm1. |
| EVEX.LLIG.F3.0F.W0 5C /r | VSUBSS xmm1 {k1}{z}, xmm2, xmm3/m32{er} | C | V/V | AVX512F OR AVX10.1 | Subtract the low single precision floating-point value in xmm3/m32 from xmm2 and store the result in xmm1 under writemask k1. |
Instruction Operand Encoding
| Op/En | Tuple Type | Operand 1 | Operand 2 | Operand 3 | Operand 4 |
|---|---|---|---|---|---|
| A | N/A | ModRM:reg (r, w) | ModRM:r/m (r) | N/A | N/A |
| B | N/A | ModRM:reg (w) | VEX.vvvv (r) | ModRM:r/m (r) | N/A |
| C | Tuple1 Scalar | ModRM:reg (w) | EVEX.vvvv (r) | ModRM:r/m (r) | N/A |
Description
Subtract the low single precision floating-point value from the second source operand and the first source operand and store the double precision floating-point result in the low doubleword of the destination operand. The second source operand can be an XMM register or a 32-bit memory location. The first source and destination operands are XMM registers. 128-bit Legacy SSE version: The destination and first source operand are the same. Bits (MAXVL-1:32) of the corresponding destination register remain unchanged. VEX.128 and EVEX encoded versions: Bits (127:32) of the XMM register destination are copied from corresponding bits in the first source operand. Bits (MAXVL-1:128) of the destination register are zeroed. EVEX encoded version: The low doubleword element of the destination operand is updated according to the writemask. Software should ensure VSUBSS is encoded with VEX.L=0. Encoding VSUBSD with VEX.L=1 may encounter unpredictable behavior across different processor generations.
Operation
VSUBSS (EVEX Encoded Version) IF (SRC2 *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 k1[0] or *no writemask* THEN DEST[31:0] := SRC1[31:0] - SRC2[31:0] ELSE IF *merging-masking* ; merging-masking THEN *DEST[31:0] remains unchanged* ELSE ; zeroing-masking THEN DEST[31:0] := 0 FI; FI; DEST[127:32] := SRC1[127:32] DEST[MAXVL-1:128] := 0 VSUBSS (VEX.128 Encoded Version) DEST[31:0] := SRC1[31:0] - SRC2[31:0] DEST[127:32] := SRC1[127:32] DEST[MAXVL-1:128] := 0 SUBSS (128-bit Legacy SSE Version) DEST[31:0] := DEST[31:0] - SRC[31:0] DEST[MAXVL-1:32] (Unmodified)
Intel C/C++ Compiler Intrinsic Equivalent
VSUBSS __m128 _mm_mask_sub_ss (__m128 s, __mmask8 k, __m128 a, __m128 b); VSUBSS __m128 _mm_maskz_sub_ss (__mmask8 k, __m128 a, __m128 b); VSUBSS __m128 _mm_sub_round_ss (__m128 a, __m128 b, int); VSUBSS __m128 _mm_mask_sub_round_ss (__m128 s, __mmask8 k, __m128 a, __m128 b, int); VSUBSS __m128 _mm_maskz_sub_round_ss (__mmask8 k, __m128 a, __m128 b, int); SUBSS __m128 _mm_sub_ss (__m128 a, __m128 b);