diff --git a/Ghidra/Processors/AARCH64/data/languages/AARCH64.cspec b/Ghidra/Processors/AARCH64/data/languages/AARCH64.cspec
index 9e90855b14..98879ad29d 100644
--- a/Ghidra/Processors/AARCH64/data/languages/AARCH64.cspec
+++ b/Ghidra/Processors/AARCH64/data/languages/AARCH64.cspec
@@ -125,11 +125,20 @@
         <rule>
           <datatype name="homogeneous-float-aggregate"/>
           <join_per_primitive storage="float"/>
+        </rule>
+         <rule>
+          <datatype name="homogeneous-float-aggregate"/>
+          <goto_stack/>					<!-- Don't consume general purpose registers -->
+          <consume_extra storage="float"/> <!-- Once the stack has been used, don't go back to registers -->
         </rule>
         <rule>
           <datatype name="struct" minsize="17"/>
           <convert_to_ptr/>
         </rule>
+        <rule>
+          <datatype name="union" minsize="17"/>
+          <convert_to_ptr/>
+        </rule>
         <rule>
           <datatype name="float"/>
           <consume storage="float"/>
@@ -147,16 +156,37 @@
         <pentry minsize="1" maxsize="16" storage="float">
           <register name="q0"/>
         </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q1"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q2"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q3"/>
+        </pentry>
         <pentry minsize="1" maxsize="8" extension="zero">
           <register name="x0"/>
         </pentry>
-        <pentry minsize="9" maxsize="16" extension="zero">
-          <addr space="join" piece1="x1" piece2="x0"/>
+        <pentry minsize="1" maxsize="8" extension="zero">
+          <register name="x1"/>
         </pentry>
+        <rule>
+          <datatype name="homogeneous-float-aggregate"/>
+          <join_per_primitive storage="float"/>
+        </rule>
+        <rule>
+          <datatype name="float"/>
+          <consume storage="float"/>
+        </rule>
         <rule>
           <datatype name="any" minsize="17"/>
           <hidden_return voidlock="true"/>
         </rule>
+        <rule>
+          <datatype name="any"/>
+          <join/>
+        </rule>
       </output>
       <unaffected>
         <register name="x19"/>
diff --git a/Ghidra/Processors/AARCH64/data/languages/AARCH64_win.cspec b/Ghidra/Processors/AARCH64/data/languages/AARCH64_win.cspec
index b9a835d89f..df92794582 100644
--- a/Ghidra/Processors/AARCH64/data/languages/AARCH64_win.cspec
+++ b/Ghidra/Processors/AARCH64/data/languages/AARCH64_win.cspec
@@ -74,29 +74,32 @@
   <default_proto>
     <prototype name="__cdecl" extrapop="0" stackshift="0">
       <input>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d0"/>
+      	<pentry minsize="8" maxsize="8" storage="hiddenret">
+          <register name="x8"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d1"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q0"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d2"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q1"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d3"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q2"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d4"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q3"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d5"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q4"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d6"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q5"/>
         </pentry>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d7"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q6"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q7"/>
         </pentry>
         <pentry minsize="1" maxsize="8" extension="zero">
           <register name="x0"/>
@@ -125,14 +128,93 @@
         <pentry minsize="1" maxsize="500" align="8">
           <addr offset="0" space="stack"/>
         </pentry>
+        <!-- Variadic functions do not use floating-point registers -->
+        <rule>
+          <datatype name="float"/>
+          <varargs/>
+          <join align="true"/>
+        </rule>
+        <rule>
+          <datatype name="float"/>
+          <varargs/>
+          <goto_stack/>
+        </rule>
+        <!-- Homogeneous float aggregates become regular structs in variadic calls -->
+        <rule>
+          <datatype name="homogeneous-float-aggregate" maxsize="16"/>
+          <varargs/>
+          <join align="true"/>
+        </rule>
+        <rule>
+          <datatype name="homogeneous-float-aggregate" minsize="17"/>
+          <varargs/>
+          <convert_to_ptr/>
+        </rule>
+        <rule>
+          <datatype name="homogeneous-float-aggregate"/>
+          <join_per_primitive storage="float"/>
+        </rule>
+        <rule>
+          <datatype name="homogeneous-float-aggregate"/>
+          <goto_stack/>					<!-- Don't consume general purpose registers -->
+		  <consume_extra storage="float"/> <!-- Once the stack has been used, don't go back to registers -->
+        </rule>
+        <rule>
+          <datatype name="float"/>
+          <consume storage="float"/>
+        </rule>
+        <rule>
+          <datatype name="float"/>
+          <goto_stack/>					<!-- Don't consume general purpose registers -->
+        </rule>
+        <rule>
+          <datatype name="struct" minsize="17"/>
+          <convert_to_ptr/>
+        </rule>
+        <rule>
+          <datatype name="union" minsize="17"/>
+          <convert_to_ptr/>
+        </rule>
+        <rule>
+          <datatype name="any"/>
+          <join align="true"/>          <!-- Chunk from general purpose registers -->
+        </rule>
       </input>
       <output>
-        <pentry minsize="1" maxsize="8" metatype="float">
-          <register name="d0"/>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q0"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q1"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q2"/>
+        </pentry>
+        <pentry minsize="1" maxsize="16" storage="float">
+          <register name="q3"/>
         </pentry>
         <pentry minsize="1" maxsize="8" extension="zero">
           <register name="x0"/>
         </pentry>
+        <pentry minsize="1" maxsize="8" extension="zero">
+          <register name="x1"/>
+        </pentry>
+        <rule>
+          <datatype name="homogeneous-float-aggregate"/>
+          <join_per_primitive storage="float"/>
+        </rule>
+        <rule>
+          <datatype name="float"/>
+          <consume storage="float"/>
+        </rule>
+        <rule>
+          <datatype name="any" minsize="17"/>
+          <hidden_return voidlock="true"/>
+        </rule>
+        <rule>
+          <datatype name="any"/>
+          <join/>
+        </rule>
       </output>
       <unaffected>
         <register name="x19"/>