PRFW (scalar plus scalar)
Contiguous prefetch words (scalar index)
Contiguous prefetch of word elements from the memory address generated by a 64-bit scalar base and scalar index which is multiplied by 4 and added to the base address. After each element prefetch the index value is incremented, but the index register is not updated.
The predicate may be used to suppress prefetches from unwanted addresses.
Green
True
1
0
0
0
0
1
0
1
0
0
0
1
1
0
0
PRFW <prfop>, <Pg>, [<Xn|SP>, <Xm>, LSL #2]
if !IsFeatureImplemented(FEAT_SVE) && !IsFeatureImplemented(FEAT_SME) then UNDEFINED;
if Rm == '11111' then UNDEFINED;
constant integer esize = 32;
constant integer g = UInt(Pg);
constant integer n = UInt(Rn);
constant integer m = UInt(Rm);
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;
<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.
<Xm>
Is the 64-bit name of the general-purpose offset register, encoded in the "Rm" 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;
bits(64) offset;
if AnyActiveElement(mask, esize) then
base = if n == 31 then SP[] else X[n, 64];
offset = X[m, 64];
for e = 0 to elements-1
if ActivePredicateElement(mask, e, esize) then
constant integer eoff = UInt(offset) + e;
constant bits(64) addr = base + (eoff << scale);
Hint_Prefetch(addr, pref_hint, level, stream);