PRFW (scalar plus immediate)
Contiguous prefetch words (immediate index)
Contiguous prefetch of word elements from the memory address generated by a 64-bit scalar base and immediate index in the range -32 to 31 which is multiplied by the vector's in-memory size, irrespective of predication, and added to the base address.
The predicate may be used to suppress prefetches from unwanted addresses.
Green
True
1
0
0
0
0
1
0
1
1
1
0
1
0
0
PRFW <prfop>, <Pg>, [<Xn|SP>{, #<imm>, MUL VL}]
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED;
constant integer esize = 32;
constant integer g = UInt(Pg);
constant integer n = UInt(Rn);
constant integer level = UInt(prfop<2:1>);
constant boolean stream = (prfop<0> == '1');
constant PrefetchHint pref_hint = if prfop<3> == '0' then Prefetch_READ else Prefetch_WRITE;
constant integer scale = 2;
constant integer offset = SInt(imm6);
<prfop>
Is the prefetch operation specifier,
prfop
<prfop>
0000
PLDL1KEEP
0001
PLDL1STRM
0010
PLDL2KEEP
0011
PLDL2STRM
0100
PLDL3KEEP
0101
PLDL3STRM
x11x
#uimm4
1000
PSTL1KEEP
1001
PSTL1STRM
1010
PSTL2KEEP
1011
PSTL2STRM
1100
PSTL3KEEP
1101
PSTL3STRM
<Pg>
Is the name of the governing scalable predicate register P0-P7, encoded in the "Pg" field.
<Xn|SP>
Is the 64-bit name of the general-purpose base register or stack pointer, encoded in the "Rn" field.
<imm>
Is the optional signed immediate vector offset, in the range -32 to 31, defaulting to 0, encoded in the "imm6" field.
CheckSVEEnabled();
constant integer VL = CurrentVL;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
constant bits(PL) mask = P[g, PL];
bits(64) base;
if AnyActiveElement(mask, esize) then
base = if n == 31 then SP[] else X[n, 64];
for e = 0 to elements-1
if ActivePredicateElement(mask, e, esize) then
constant integer eoff = (offset * elements) + e;
constant bits(64) addr = base + (eoff << scale);
Hint_Prefetch(addr, pref_hint, level, stream);