UMAX (immediate)

Unsigned maximum with immediate (unpredicated)

This instruction determines the unsigned maximum of an immediate and each element of the source vector, and destructively places the results in the corresponding elements of the source vector. The immediate is an unsigned 8-bit value in the range 0 to 255, inclusive. This instruction is unpredicated.

SVE
(FEAT_SVE || FEAT_SME)

313029282726252423222120191817161514131211109876543210
00100101size101001110imm8Zdn
Uo2

Encoding

UMAX <Zdn>.<T>, <Zdn>.<T>, #<imm>

Decode for this encoding

if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then EndOfDecode(Decode_UNDEF); end; let esize : integer{} = 8 << UInt(size); let dn : integer = UInt(Zdn); let unsigned : boolean = TRUE; let imm : integer = if unsigned then UInt(imm8) else SInt(imm8);

Assembler Symbols

<Zdn>

Is the name of the source and destination scalable vector register, encoded in the "Zdn" field.

<T>

Is the size specifier, encoded in size:

size <T>
00 B
01 H
10 S
11 D
<imm>

Is the unsigned immediate operand, in the range 0 to 255, encoded in the "imm8" field.

Operation

CheckSVEEnabled(); let VL : integer{} = CurrentVL(); let elements : integer = VL DIV esize; let operand1 : bits(VL) = Z{}(dn); var result : bits(VL); for e = 0 to elements-1 do let op1elt : bits(esize) = operand1[e*:esize]; let element1 : integer = if unsigned then UInt(op1elt) else SInt(op1elt); result[e*:esize] = Max(element1, imm)[esize-1:0]; end; Z{VL}(dn) = result;

Operational information

This instruction is a data-independent-time instruction as described in About PSTATE.DIT.

This instruction might be immediately preceded in program order by a MOVPRFX instruction. The MOVPRFX must conform to all of the following requirements, otherwise the behavior of the MOVPRFX and this instruction is CONSTRAINED UNPREDICTABLE:


2026-03_rel 2026-03-26 20:48:11

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