diff --git a/Ghidra/Processors/x86/data/languages/x86-64-gcc.cspec b/Ghidra/Processors/x86/data/languages/x86-64-gcc.cspec
index 4ba8333c33..888f56c24e 100644
--- a/Ghidra/Processors/x86/data/languages/x86-64-gcc.cspec
+++ b/Ghidra/Processors/x86/data/languages/x86-64-gcc.cspec
@@ -129,42 +129,62 @@
   </default_proto>
 	<prototype name="MSABI" extrapop="8" stackshift="8">
 	  <input pointermax="8">
-	    <pentry minsize="4" maxsize="8" metatype="float">
-	      <register name="XMM0_Qa"/>
-	    </pentry>
-	    <pentry minsize="4" maxsize="8" metatype="float">
-	      <register name="XMM1_Qa"/>
-	    </pentry>
-	    <pentry minsize="4" maxsize="8" metatype="float">
-	      <register name="XMM2_Qa"/>
-	    </pentry>
-	    <pentry minsize="4" maxsize="8" metatype="float">
-	      <register name="XMM3_Qa"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="8">
-	      <register name="RCX"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="8">
-	      <register name="RDX"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="8">
-	      <register name="R8"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="8">
-	      <register name="R9"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="500" align="8">
-	      <addr offset="40" space="stack"/>
-	    </pentry>
-	  </input>
-	  <output>
-	    <pentry minsize="4" maxsize="8" metatype="float">
-	      <register name="XMM0_Qa"/>
-	    </pentry>
-	    <pentry minsize="1" maxsize="8">
-	      <register name="RAX"/>
-	    </pentry>
-	  </output>
+	  <!--  Use same grouping setup as x86-64-win.cspec. If the nth general-purpose register is 
+	  		consumed, consume the nth floating point register, and vice-versa -->
+	  <group>
+        <pentry minsize="4" maxsize="8" metatype="float">
+          <register name="XMM0_Qa"/>
+        </pentry>
+        <pentry minsize="1" maxsize="8">
+          <register name="RCX"/>
+        </pentry>
+      </group>
+      <group>
+        <pentry minsize="4" maxsize="8" metatype="float">
+          <register name="XMM1_Qa"/>
+        </pentry>
+        <pentry minsize="1" maxsize="8">
+          <register name="RDX"/>
+        </pentry>
+      </group>
+      <group>
+        <pentry minsize="4" maxsize="8" metatype="float">
+          <register name="XMM2_Qa"/>
+        </pentry>
+        <pentry minsize="1" maxsize="8">
+          <register name="R8"/>
+        </pentry>
+      </group>
+      <group>
+        <pentry minsize="4" maxsize="8" metatype="float">
+          <register name="XMM3_Qa"/>
+        </pentry>
+        <pentry minsize="1" maxsize="8">
+          <register name="R9"/>
+        </pentry>
+      </group>
+      <pentry minsize="1" maxsize="500" align="8">
+        <addr offset="40" space="stack"/>
+      </pentry>
+      <!-- only structs of size 8,16,32,64 bits can be packed to register -->  
+      <rule>
+      	<datatype name="struct" sizes="3,5,6,7"/>
+      	<convert_to_ptr/>
+      </rule>
+    </input> 
+  	<output>
+      <pentry minsize="4" maxsize="8" metatype="float">
+        <register name="XMM0_Qa"/>
+      </pentry>
+      <pentry minsize="1" maxsize="8">
+        <register name="RAX"/>
+      </pentry>
+      <!-- only structs of size 8,16,32,64 bits can be returned via register -->
+      <rule>
+      	<datatype name="struct" sizes="3,5,6,7"/>
+      	<hidden_return/>
+      </rule>
+	</output>
 	  <unaffected>
 	    <varnode space="ram" offset="0" size="8"/>
 	    <register name="RBX"/>
diff --git a/Ghidra/Processors/x86/data/languages/x86-64-win.cspec b/Ghidra/Processors/x86/data/languages/x86-64-win.cspec
index b341497319..846134c13f 100644
--- a/Ghidra/Processors/x86/data/languages/x86-64-win.cspec
+++ b/Ghidra/Processors/x86/data/languages/x86-64-win.cspec
@@ -78,7 +78,12 @@
       </group>
       <pentry minsize="1" maxsize="500" align="8">
         <addr offset="40" space="stack"/>
-      </pentry>  
+      </pentry>
+      <!-- only structs of size 8,16,32,64 bits can be packed to register -->  
+      <rule>
+      	<datatype name="struct" sizes="3,5,6,7"/>
+      	<convert_to_ptr/>
+      </rule>
     </input> 
       <output>
         <pentry minsize="4" maxsize="8" metatype="float">
@@ -87,6 +92,11 @@
         <pentry minsize="1" maxsize="8">
           <register name="RAX"/>
         </pentry>
+        <!-- only structs of size 8,16,32,64 bits can be returned via register -->
+        <rule>
+      	  <datatype name="struct" sizes="3,5,6,7"/>
+      	  <hidden_return/>
+        </rule>
       </output>
       <unaffected>
         <varnode space="ram" offset="0" size="8"/>
diff --git a/Ghidra/Processors/x86/data/languages/x86gcc.cspec b/Ghidra/Processors/x86/data/languages/x86gcc.cspec
index f9d5d04bf2..839c0fe850 100644
--- a/Ghidra/Processors/x86/data/languages/x86gcc.cspec
+++ b/Ghidra/Processors/x86/data/languages/x86gcc.cspec
@@ -48,6 +48,11 @@
         <pentry minsize="5" maxsize="8">
           <addr space="join" piece1="EDX" piece2="EAX"/>
         </pentry>
+        <!-- Any struct type is returned by pointer, regardless of size -->
+        <rule>
+        	<datatype name="struct"/>
+        	<hidden_return/>
+        </rule>
       </output>
       <unaffected>
         <register name="ESP"/>