Gather load first-fault unsigned words to vector (immediate index)
Gather load with first-faulting behavior of unsigned words to active elements of a vector register from memory addresses generated by a vector base plus immediate index. The index is a multiple of 4 in the range 0 to 124. Inactive elements will not cause a read from Device memory or signal faults, and are set to zero in the destination vector.
This instruction is illegal when executed in Streaming SVE mode, unless FEAT_SME_FA64 is implemented and enabled.
It has encodings from 2 classes: 32-bit element and 64-bit element
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 | 0 | 0 | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | imm5 | 1 | 1 | 1 | Pg | Zn | Zt | ||||||||||||||
msz<1> | msz<0> | U | ff |
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED; constant integer t = UInt(Zt); constant integer n = UInt(Zn); constant integer g = UInt(Pg); constant integer esize = 32; constant integer msize = 32; constant boolean unsigned = TRUE; constant integer offset = UInt(imm5);
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 | 1 | 0 | 1 | 0 | 0 | 1 | imm5 | 1 | 1 | 1 | Pg | Zn | Zt | ||||||||||||||
msz<1> | msz<0> | U | ff |
if !IsFeatureImplemented(FEAT_SVE) then UNDEFINED; constant integer t = UInt(Zt); constant integer n = UInt(Zn); constant integer g = UInt(Pg); constant integer esize = 64; constant integer msize = 32; constant boolean unsigned = TRUE; constant integer offset = UInt(imm5);
<Zt> |
Is the name of the scalable vector register to be transferred, encoded in the "Zt" field. |
<Pg> |
Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field. |
<Zn> |
Is the name of the base scalable vector register, encoded in the "Zn" field. |
<imm> |
Is the optional unsigned immediate byte offset, a multiple of 4 in the range 0 to 124, defaulting to 0, encoded in the "imm5" field. |
CheckNonStreamingSVEEnabled(); constant integer VL = CurrentVL; constant integer PL = VL DIV 8; constant integer elements = VL DIV esize; constant bits(PL) mask = P[g, PL]; bits(VL) base; bits(VL) result; constant bits(VL) orig = Z[t, VL]; bits(msize) data; constant integer mbytes = msize DIV 8; boolean fault = FALSE; boolean faulted = FALSE; boolean unknown = FALSE; constant boolean contiguous = FALSE; constant boolean tagchecked = TRUE; AccessDescriptor accdesc = CreateAccDescSVEFF(contiguous, tagchecked); if AnyActiveElement(mask, esize) then base = Z[n, VL]; assert accdesc.first; for e = 0 to elements-1 if ActivePredicateElement(mask, e, esize) then constant bits(64) baddr = ZeroExtend(Elem[base, e, esize], 64); constant bits(64) addr = AddressAdd(baddr, offset * mbytes, accdesc); if accdesc.first then // Mem[] will not return if a fault is detected for the first active element data = Mem[addr, mbytes, accdesc]; accdesc.first = FALSE; else // MemNF[] will return fault=TRUE if access is not performed for any reason (data, fault) = MemNF[addr, mbytes, accdesc]; else (data, fault) = (Zeros(msize), FALSE); // FFR elements set to FALSE following a suppressed access/fault faulted = faulted || fault; if faulted then ElemFFR[e, esize] = '0'; // Value becomes CONSTRAINED UNPREDICTABLE after an FFR element is FALSE unknown = unknown || ElemFFR[e, esize] == '0'; if unknown then if !fault && ConstrainUnpredictableBool(Unpredictable_SVELDNFDATA) then Elem[result, e, esize] = Extend(data, esize, unsigned); elsif ConstrainUnpredictableBool(Unpredictable_SVELDNFZERO) then Elem[result, e, esize] = Zeros(esize); else // merge Elem[result, e, esize] = Elem[orig, e, esize]; else Elem[result, e, esize] = Extend(data, esize, unsigned); Z[t, VL] = result;
Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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