diff --git a/osaca/data/isa/x86.yml b/osaca/data/isa/x86.yml
index a55e994..b06fdc2 100644
--- a/osaca/data/isa/x86.yml
+++ b/osaca/data/isa/x86.yml
@@ -32,10 +32,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: adc
@@ -45,10 +45,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: add
@@ -78,10 +78,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: add
@@ -91,10 +91,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: addsd
@@ -144,10 +144,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: and
@@ -157,10 +157,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: bts
@@ -190,10 +190,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: bts
@@ -203,10 +203,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: cmp
@@ -226,23 +226,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
-          source: true
-          destination: true
-    - name: cmp
-      operands:
-        - class: "immediate"
-          imd: "int"
-          source: true
-          destination: false
-        - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: cmp
@@ -262,23 +249,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
-          source: true
-          destination: false
-    - name: cmp
-      operands:
-        - class: "register"
-          name: "gpr"
-          source: true
-          destination: false
-        - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: false
     - name: dec
@@ -290,19 +264,10 @@ instruction_forms:
     - name: dec
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
-          source: true
-          destination: true
-    - name: dec
-      operands:
-        - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: imul
@@ -318,10 +283,10 @@ instruction_forms:
     - name: imul
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: false
         - class: "register"
@@ -337,19 +302,10 @@ instruction_forms:
     - name: inc
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
-          source: true
-          destination: true
-    - name: inc
-      operands:
-        - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: mulsd
@@ -399,10 +355,10 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: sub
@@ -412,36 +368,19 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: ~
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
     - name: vfmadd132pd
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: "gpr"
-          scale: 1
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: true
-    - name: vfmadd132pd
-      operands:
-        - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: "gpr"
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: false
         - class: "register"
@@ -455,27 +394,10 @@ instruction_forms:
     - name: vfmadd213pd
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: "gpr"
-          scale: 1
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: true
-    - name: vfmadd213pd
-      operands:
-        - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: "gpr"
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: false
         - class: "register"
@@ -489,27 +411,10 @@ instruction_forms:
     - name: vfmadd231pd
       operands:
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: "gpr"
-          scale: 1
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: false
-        - class: "register"
-          name: "ymm"
-          source: true
-          destination: true
-    - name: vfmadd231pd
-      operands:
-        - class: "memory"
-          base: "gpr"
-          offset: ~
-          index: "gpr"
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: false
         - class: "register"
@@ -545,9 +450,9 @@ instruction_forms:
           source: true
           destination: false
         - class: "memory"
-          base: "gpr"
-          offset: "imd"
-          index: "gpr"
-          scale: 1
+          base: "*"
+          offset: "*"
+          index: "*"
+          scale: "*"
           source: true
           destination: true
diff --git a/osaca/semantics/hw_model.py b/osaca/semantics/hw_model.py
index 26a9608..1e96790 100755
--- a/osaca/semantics/hw_model.py
+++ b/osaca/semantics/hw_model.py
@@ -12,6 +12,8 @@ from osaca.parser import ParserX86ATT
 
 
 class MachineModel(object):
+    WILDCARD = '*'
+
     def __init__(self, arch=None, path_to_yaml=None, isa=None, lazy=False):
         if not arch and not path_to_yaml:
             if not isa:
@@ -280,7 +282,9 @@ class MachineModel(object):
             operand_string += 'b' if operand['base'] is not None else ''
             operand_string += 'o' if operand['offset'] is not None else ''
             operand_string += 'i' if operand['index'] is not None else ''
-            operand_string += 's' if operand['scale'] > 1 else ''
+            operand_string += (
+                's' if operand['scale'] == self.WILDCARD or operand['scale'] > 1 else ''
+            )
             if 'pre-indexed' in operand:
                 operand_string += 'r' if operand['pre-indexed'] else ''
                 operand_string += 'p' if operand['post-indexed'] else ''
@@ -349,7 +353,7 @@ class MachineModel(object):
 
     def _check_operands(self, i_operand, operand):
         # check for wildcard
-        if '*' in operand:
+        if self.WILDCARD in operand:
             if (
                 'class' in i_operand
                 and i_operand['class'] == 'register'
@@ -450,10 +454,15 @@ class MachineModel(object):
     def _is_AArch64_mem_type(self, i_mem, mem):
         if (
             # check base
-            mem['base']['prefix'] == i_mem['base']
+            (
+                (mem['base'] is None and i_mem['base'] is None)
+                or i_mem['base'] == self.WILDCARD
+                or mem['base']['prefix'] == i_mem['base']
+            )
             # check offset
             and (
                 mem['offset'] == i_mem['offset']
+                or i_mem['offset'] == self.WILDCARD
                 or (
                     mem['offset'] is not None
                     and 'identifier' in mem['offset']
@@ -468,15 +477,29 @@ class MachineModel(object):
             # check index
             and (
                 mem['index'] == i_mem['index']
+                or i_mem['index'] == self.WILDCARD
                 or (
                     mem['index'] is not None
                     and 'prefix' in mem['index']
                     and mem['index']['prefix'] == i_mem['index']
                 )
             )
-            and (mem['scale'] == i_mem['scale'] or (mem['scale'] != 1 and i_mem['scale'] != 1))
-            and (('pre_indexed' in mem) == (i_mem['pre-indexed']))
-            and (('post_indexed' in mem) == (i_mem['post-indexed']))
+            # check scale
+            and (
+                mem['scale'] == i_mem['scale']
+                or i_mem['scale'] == self.WILDCARD
+                or (mem['scale'] != 1 and i_mem['scale'] != 1)
+            )
+            # check pre-indexing
+            and (
+                i_mem['pre-indexed'] == self.WILDCARD
+                or ('pre_indexed' in mem) == (i_mem['pre-indexed'])
+            )
+            # check post-indexing
+            and (
+                i_mem['post-indexed'] == self.WILDCARD
+                or ('post_indexed' in mem) == (i_mem['post-indexed'])
+            )
         ):
             return True
         return False
@@ -484,10 +507,15 @@ class MachineModel(object):
     def _is_x86_mem_type(self, i_mem, mem):
         if (
             # check base
-            self._is_x86_reg_type(i_mem['base'], mem['base'])
+            (
+                (mem['base'] is None and i_mem['base'] is None)
+                or i_mem['base'] == self.WILDCARD
+                or self._is_x86_reg_type(i_mem['base'], mem['base'])
+            )
             # check offset
             and (
                 mem['offset'] == i_mem['offset']
+                or i_mem['offset'] == self.WILDCARD
                 or (
                     mem['offset'] is not None
                     and 'identifier' in mem['offset']
@@ -510,13 +538,19 @@ class MachineModel(object):
             # check index
             and (
                 mem['index'] == i_mem['index']
+                or i_mem['index'] == self.WILDCARD
                 or (
                     mem['index'] is not None
                     and 'name' in mem['index']
                     and self._is_x86_reg_type(i_mem['index'], mem['index'])
                 )
             )
-            and (mem['scale'] == i_mem['scale'] or (mem['scale'] != 1 and i_mem['scale'] != 1))
+            # check scale
+            and (
+                mem['scale'] == i_mem['scale']
+                or i_mem['scale'] == self.WILDCARD
+                or (mem['scale'] != 1 and i_mem['scale'] != 1)
+            )
         ):
             return True
         return False