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<instructionsection id="whilewr_p_rr" title="WHILEWR" type="instruction">
  <docvars>
    <docvar key="instr-class" value="sve2" />
    <docvar key="isa" value="A64" />
    <docvar key="mnemonic" value="WHILEWR" />
  </docvars>
  <heading>WHILEWR</heading>
  <desc>
    <brief>While free of write-after-read/write conflicts</brief>
    <description>
      <para>This instruction checks two addresses for a conflict or overlap between address ranges of the form [addr,addr+<arm-defined-word>VL</arm-defined-word>÷8), where <arm-defined-word>VL</arm-defined-word> is the accessible vector length in bits, that could result in a loop-carried dependency through memory due to the use of these addresses by contiguous load and store instructions within the same iteration of a loop. Generate a predicate whose elements are true while the addresses cannot conflict within the same iteration, and false thereafter. Sets the <arm-defined-word>First</arm-defined-word> (N), <arm-defined-word>None</arm-defined-word> (Z), <arm-defined-word>!Last</arm-defined-word> (C) condition flags based on the predicate result, and the V flag to zero.</para>
    </description>
    <status>Green</status>
    <predicated>False</predicated>
    <uses_dit condition="FEAT_SVE2 is implemented or FEAT_SME is implemented">True</uses_dit>
  </desc>
  <alias_list howmany="0"></alias_list>
  <classes>
    <iclass name="SVE2" oneof="1" id="iclass_sve2" no_encodings="1" isa="A64">
      <docvars>
        <docvar key="instr-class" value="sve2" />
        <docvar key="isa" value="A64" />
        <docvar key="mnemonic" value="WHILEWR" />
      </docvars>
      <iclassintro count="1"></iclassintro>
      <regdiagram form="32" psname="WHILEWR-P.RR-_" tworows="1">
        <box hibit="31" width="8" settings="8">
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>0</c>
          <c>1</c>
        </box>
        <box hibit="23" width="2" name="size" usename="1">
          <c colspan="2"></c>
        </box>
        <box hibit="21" settings="1">
          <c>1</c>
        </box>
        <box hibit="20" width="5" name="Rm" usename="1">
          <c colspan="5"></c>
        </box>
        <box hibit="15" width="6" settings="6">
          <c>0</c>
          <c>0</c>
          <c>1</c>
          <c>1</c>
          <c>0</c>
          <c>0</c>
        </box>
        <box hibit="9" width="5" name="Rn" usename="1">
          <c colspan="5"></c>
        </box>
        <box hibit="4" name="rw" usename="1" settings="1">
          <c>0</c>
        </box>
        <box hibit="3" width="4" name="Pd" usename="1">
          <c colspan="4"></c>
        </box>
      </regdiagram>
      <encoding name="whilewr_p_rr_" oneofinclass="1" oneof="1" label="">
        <docvars>
          <docvar key="instr-class" value="sve2" />
          <docvar key="isa" value="A64" />
          <docvar key="mnemonic" value="WHILEWR" />
        </docvars>
        <asmtemplate><text>WHILEWR </text><a link="sa_pd" hover="Destination scalable predicate register (field &quot;Pd&quot;)">&lt;Pd&gt;</a><text>.</text><a link="sa_t" hover="Size specifier (field &quot;size&quot;) [B,D,H,S]">&lt;T&gt;</a><text>, </text><a link="sa_xn" hover="First 64-bit source general-purpose register (field &quot;Rn&quot;)">&lt;Xn&gt;</a><text>, </text><a link="sa_xm" hover="Second 64-bit source general-purpose register (field &quot;Rm&quot;)">&lt;Xm&gt;</a></asmtemplate>
      </encoding>
      <ps_section howmany="1">
        <ps name="WHILEWR-P.RR-_" mylink="WHILEWR-P.RR-_" enclabels="" sections="1" secttype="noheading">
          <pstext mayhavelinks="1" section="Decode" rep_section="decode">if !<a link="impl-aarch64.HaveSVE2.0" file="shared_pseudocode.xml" hover="function: boolean HaveSVE2()">HaveSVE2</a>() &amp;&amp; !<a link="impl-aarch64.HaveSME.0" file="shared_pseudocode.xml" hover="function: boolean HaveSME()">HaveSME</a>() then UNDEFINED;
constant integer esize = 8 &lt;&lt; <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(size);
integer n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn);
integer m = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rm);
integer d = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Pd);</pstext>
        </ps>
      </ps_section>
    </iclass>
  </classes>
  <explanations scope="all">
    <explanation enclist="whilewr_p_rr_" symboldefcount="1">
      <symbol link="sa_pd">&lt;Pd&gt;</symbol>
      <account encodedin="Pd">
        <intro>
          <para>Is the name of the destination scalable predicate register, encoded in the "Pd" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="whilewr_p_rr_" symboldefcount="1">
      <symbol link="sa_t">&lt;T&gt;</symbol>
      <definition encodedin="size">
        <intro>Is the size specifier, </intro>
        <table class="valuetable">
          <tgroup cols="2">
            <thead>
              <row>
                <entry class="bitfield">size</entry>
                <entry class="symbol">&lt;T&gt;</entry>
              </row>
            </thead>
            <tbody>
              <row>
                <entry class="bitfield">00</entry>
                <entry class="symbol">B</entry>
              </row>
              <row>
                <entry class="bitfield">01</entry>
                <entry class="symbol">H</entry>
              </row>
              <row>
                <entry class="bitfield">10</entry>
                <entry class="symbol">S</entry>
              </row>
              <row>
                <entry class="bitfield">11</entry>
                <entry class="symbol">D</entry>
              </row>
            </tbody>
          </tgroup>
        </table>
      </definition>
    </explanation>
    <explanation enclist="whilewr_p_rr_" symboldefcount="1">
      <symbol link="sa_xn">&lt;Xn&gt;</symbol>
      <account encodedin="Rn">
        <intro>
          <para>Is the 64-bit name of the first source general-purpose register, encoded in the "Rn" field.</para>
        </intro>
      </account>
    </explanation>
    <explanation enclist="whilewr_p_rr_" symboldefcount="1">
      <symbol link="sa_xm">&lt;Xm&gt;</symbol>
      <account encodedin="Rm">
        <intro>
          <para>Is the 64-bit name of the second source general-purpose register, encoded in the "Rm" field.</para>
        </intro>
      </account>
    </explanation>
  </explanations>
  <ps_section howmany="1">
    <ps name="WHILEWR-P.RR-_" mylink="execute" enclabels="" sections="1" secttype="Operation">
      <pstext mayhavelinks="1" section="Execute" rep_section="execute"><a link="impl-aarch64.CheckSVEEnabled.0" file="shared_pseudocode.xml" hover="function: CheckSVEEnabled()">CheckSVEEnabled</a>();
constant integer VL = <a link="impl-aarch64.CurrentVL.read.none" file="shared_pseudocode.xml" hover="accessor: integer CurrentVL">CurrentVL</a>;
constant integer PL = VL DIV 8;
constant integer elements = VL DIV esize;
bits(PL) mask = <a link="impl-shared.Ones.1" file="shared_pseudocode.xml" hover="function: bits(N) Ones(integer N)">Ones</a>(PL);
bits(64) src1 = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[n, 64];
bits(64) src2 = <a link="impl-aarch64.X.read.2" file="shared_pseudocode.xml" hover="accessor: bits(width) X[integer n, integer width]">X</a>[m, 64];
integer operand1 = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(src1);
integer operand2 = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(src2);
bits(PL) result;
constant integer psize = esize DIV 8;

integer diff = (operand2 - operand1) DIV (esize DIV 8);
for e = 0 to elements-1
    if diff &lt;= 0 || e &lt; diff then
        <a link="impl-shared.Elem.write.3" file="shared_pseudocode.xml" hover="accessor: Elem[bits(N) &amp;vector, integer e, integer size] = bits(size) value">Elem</a>[result, e, psize] = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>('1', psize);
    else
        <a link="impl-shared.Elem.write.3" file="shared_pseudocode.xml" hover="accessor: Elem[bits(N) &amp;vector, integer e, integer size] = bits(size) value">Elem</a>[result, e, psize] = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>('0', psize);

PSTATE.&lt;N,Z,C,V&gt; = <a link="impl-aarch64.PredTest.3" file="shared_pseudocode.xml" hover="function: bits(4) PredTest(bits(N) mask, bits(N) result, integer esize)">PredTest</a>(mask, result, esize);
<a link="impl-aarch64.P.write.2" file="shared_pseudocode.xml" hover="accessor: P[integer n, integer width] = bits(width) value">P</a>[d, PL] = result;</pstext>
    </ps>
  </ps_section>
</instructionsection>
