Vesta
English
Source code

SUBSS

Subtract Scalar Single Precision Floating-Point Value

stableVMJITAOTinstruction

Encodings

OpcodeInstructionOp/En64-bitCompat/LegacyDescription
F3 0F 5C /rSUBSS xmm1, xmm2/m32AValidValidSubtract the low single precision floating-point value in xmm2/m32 from xmm1 and store the result in xmm1.
VEX.LIG.F3.0F.WIG 5C /rVSUBSS xmm1,xmm2, xmm3/m32BValidValidSubtract the low single precision floating-point value in xmm3/m32 from xmm2 and store the result in xmm1.
EVEX.LLIG.F3.0F.W0 5C /rVSUBSS xmm1 {k1}{z}, xmm2, xmm3/m32{er}CValidValidSubtract the low single precision floating-point value in OR AVX10.1 xmm3/m32 from xmm2 and store the result in xmm1 under writemask k1.

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 lectura y escrituraModRM byte, reg field (bits 5-3)
  2. modrm.rm lecturaModRM byte, r/m field (bits 2-0); with the SIB byte and the displacement when the mod field asks for them

B

  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

C

  1. modrm.reg escrituraModRM byte, reg field (bits 5-3)
  2. evex.vvvv lecturaEVEX 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: Tuple1 Scalar

Measured cost

Loading measurements from arch-data...

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 intrinsics

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);

SIMD Floating-Point Exceptions

Overflow, Underflow, Invalid, Precision, Denormal.

Other Exceptions

VEX-encoded instructions, see Table 2-20, "Type 3 Class Exception Conditions." EVEX-encoded instructions, see Table 2-49, "Type E3 Class Exception Conditions."

Sources