FCMGE (zero)

Floating-point compare greater than or equal to zero (vector)

This instruction reads each floating-point value in the source SIMD&FP register and if the value is greater than or equal to zero sets every bit of the corresponding vector element in the destination SIMD&FP register to one, otherwise sets every bit of the corresponding vector element in the destination SIMD&FP register to zero.

This instruction can generate a floating-point exception. Depending on the settings in FPCR, the exception results in either a flag being set in FPSR or a synchronous exception being generated. For more information, see Floating-point exceptions and exception traps.

Depending on the settings in the CPACR_EL1, CPTR_EL2, and CPTR_EL3 registers, and the current Security state and Exception level, an attempt to execute the instruction might be trapped.

It has encodings from 4 classes: Scalar half-precision , Scalar single-precision and double-precision , Vector half-precision and Vector single-precision and double-precision

Scalar half-precision
(FEAT_AdvSIMD && FEAT_FP16)

313029282726252423222120191817161514131211109876543210
0111111011111000110010RnRd
Uaop

Encoding

FCMGE <Hd>, <Hn>, #0.0

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) || !IsFeatureImplemented(FEAT_FP16) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let esize : integer{} = 16; let datasize : integer{} = esize; let elements : integer = 1;

Scalar single-precision and double-precision
(FEAT_AdvSIMD)

313029282726252423222120191817161514131211109876543210
011111101sz100000110010RnRd
Uop

Encoding

FCMGE <V><d>, <V><n>, #0.0

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let esize : integer{} = 32 << UInt(sz); let datasize : integer{} = esize; let elements : integer = 1;

Vector half-precision
(FEAT_AdvSIMD && FEAT_FP16)

313029282726252423222120191817161514131211109876543210
0Q10111011111000110010RnRd
Uaop

Encoding

FCMGE <Vd>.<T>, <Vn>.<T>, #0.0

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) || !IsFeatureImplemented(FEAT_FP16) then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let esize : integer{} = 16; let datasize : integer{} = 64 << UInt(Q); let elements : integer = datasize DIV esize;

Vector single-precision and double-precision
(FEAT_AdvSIMD)

313029282726252423222120191817161514131211109876543210
0Q1011101sz100000110010RnRd
Uop

Encoding

FCMGE <Vd>.<T>, <Vn>.<T>, #0.0

Decode for this encoding

if !IsFeatureImplemented(FEAT_AdvSIMD) then EndOfDecode(Decode_UNDEF); end; if sz::Q == '10' then EndOfDecode(Decode_UNDEF); end; let d : integer{} = UInt(Rd); let n : integer{} = UInt(Rn); let esize : integer{} = 32 << UInt(sz); let datasize : integer{} = 64 << UInt(Q); let elements : integer = datasize DIV esize;

Assembler Symbols

<Hd>

Is the 16-bit name of the SIMD&FP destination register, encoded in the "Rd" field.

<Hn>

Is the 16-bit name of the SIMD&FP source register, encoded in the "Rn" field.

<V>

Is a width specifier, encoded in sz:

sz <V>
0 S
1 D
<d>

Is the number of the SIMD&FP destination register, encoded in the "Rd" field.

<n>

Is the number of the SIMD&FP source register, encoded in the "Rn" field.

<Vd>

Is the name of the SIMD&FP destination register, encoded in the "Rd" field.

<T>

For the "Vector half-precision" variant: is an arrangement specifier, encoded in Q:

Q <T>
0 4H
1 8H

For the "Vector single-precision and double-precision" variant: is an arrangement specifier, encoded in (sz :: Q):

sz Q <T>
0 0 2S
0 1 4S
1 0 RESERVED
1 1 2D
<Vn>

Is the name of the SIMD&FP source register, encoded in the "Rn" field.

Operation

AArch64_CheckFPAdvSIMDEnabled(); let operand : bits(datasize) = V{}(n); var result : bits(datasize); let zero : bits(esize) = FPZero{}('0'); var element : bits(esize); var test_passed : boolean; for e = 0 to elements-1 do element = operand[e*:esize]; test_passed = FPCompareGE{esize}(element, zero, FPCR()); result[e*:esize] = if test_passed then Ones{esize} else Zeros{esize}; end; V{datasize}(d) = result;


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

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