ZERO (tiles) -- A64

ZERO (tiles)

Zero a list of 64-bit element ZA tiles

This instruction zeroes all bytes within each of the up to eight listed 64-bit element tiles named ZA0.D to ZA7.D, leaving the other 64-bit element tiles unmodified.

This instruction does not require the PE to be in Streaming SVE mode, and it is expected that this instruction will not experience a significant slowdown due to contention with other PEs that are executing in Streaming SVE mode.

For programmer convenience an assembler must also accept the names of 32-bit, 16-bit, and 8-bit element tiles that are converted into the corresponding set of 64-bit element tiles.

In accordance with the architecturally defined mapping between different element size tiles:

Zeroing the 8-bit element tile name ZA0.B, or the entire array name ZA, is equivalent to zeroing all eight 64-bit element tiles named ZA0.D to ZA7.D.
Zeroing the 16-bit element tile name ZA0.H is equivalent to zeroing 64-bit element tiles named ZA0.D, ZA2.D, ZA4.D, and ZA6.D.
Zeroing the 16-bit element tile name ZA1.H is equivalent to zeroing 64-bit element tiles named ZA1.D, ZA3.D, ZA5.D, and ZA7.D.
Zeroing the 32-bit element tile name ZA0.S is equivalent to zeroing 64-bit element tiles named ZA0.D and ZA4.D.
Zeroing the 32-bit element tile name ZA1.S is equivalent to zeroing 64-bit element tiles named ZA1.D and ZA5.D.
Zeroing the 32-bit element tile name ZA2.S is equivalent to zeroing 64-bit element tiles named ZA2.D and ZA6.D.
Zeroing the 32-bit element tile name ZA3.S is equivalent to zeroing 64-bit element tiles named ZA3.D and ZA7.D.

The preferred disassembly of this instruction uses the shortest list of tile names that represent the encoded immediate mask.

For example:

An immediate that encodes 64-bit element tiles ZA0.D, ZA1.D, ZA4.D, and ZA5.D is disassembled as {ZA0.S, ZA1.S}.
An immediate that encodes 64-bit element tiles ZA0.D, ZA2.D, ZA4.D, and ZA6.D is disassembled as {ZA0.H}.
An all-ones immediate is disassembled as {ZA}.
An all-zeros immediate is disassembled as an empty list { }.

SME
(FEAT_SME)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	0	0	0	0	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0	0	0	imm8

Encoding

ZERO { {<mask>} }

Decode for this encoding

if !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let mask : bits(8) = imm8; let esize : integer{} = 64;

Assembler Symbols

<mask>

Is the optional list of up to eight 64-bit element tile names separated by commas, encoded in the "imm8" field.

Operation

CheckSMEAndZAEnabled(); let SVL : integer{} = CurrentSVL(); let dim : integer{} = SVL DIV esize; let result : bits(dim*dim*esize) = Zeros{}; for i = 0 to 7 do if mask[i] == '1' then ZAtile{dim*dim*esize}(i, esize) = result; end; end;