diff --git a/examples/cfg/filter.yml b/examples/cfg/filter.yml
index 6c61233b..8862b90e 100644
--- a/examples/cfg/filter.yml
+++ b/examples/cfg/filter.yml
@@ -9,6 +9,7 @@ filter:
     - RVSMode
     - RVDebug
     - RV32I
+    - RV64I
     - RVNMod
   instructions:
     # drop: [CV_CLIPU, CV_CLIPR, CV_CLIPUR, CV_SLET, CV_SLETU, SEAL5_CV_SHUFFLE2_B, SEAL5_CV_SHUFFLE2_H, ".*_(SC|SCI)_.*"]
diff --git a/seal5/backends/patterngen/writer.py b/seal5/backends/patterngen/writer.py
index 01ff02ef..e1a0e636 100644
--- a/seal5/backends/patterngen/writer.py
+++ b/seal5/backends/patterngen/writer.py
@@ -40,6 +40,7 @@ def main():
     parser.add_argument("--index", default=None, help="Output index to file")
     parser.add_argument("--ext", type=str, default="td", help="Default file extension (if using --splitted)")
     parser.add_argument("--parallel", type=int, default=1, help="How many instructions should be processed in parallel")
+    # parser.add_argument("--xlen", type=int, default=32, help="RISC-V XLEN")
     args = parser.parse_args()
 
     # initialize logging
@@ -109,6 +110,7 @@ def main():
 
         assert out_path.is_dir(), "Expecting output directory when using --splitted"
         for set_name, set_def in model["sets"].items():
+            xlen = set_def.xlen
             artifacts[set_name] = []
             metrics["n_sets"] += 1
             ext_settings = set_def.settings
@@ -161,6 +163,7 @@ def process_instrunction(instr_def):
                         skip_formats=not args.formats,
                         ext=predicate,
                         mattr=mattr,
+                        xlen=xlen,
                     )
                     if output_file.is_file():
                         metrics["n_success"] += 1
diff --git a/seal5/backends/riscv_instr_info/writer.py b/seal5/backends/riscv_instr_info/writer.py
index f5ac72f4..50fb5d2a 100644
--- a/seal5/backends/riscv_instr_info/writer.py
+++ b/seal5/backends/riscv_instr_info/writer.py
@@ -345,6 +345,7 @@ def main():
         for set_name, set_def in model["sets"].items():
             set_name_lower = set_name.lower()
             artifacts[set_name] = []
+            xlen = set_def.xlen
             includes = []
             set_dir = out_path / set_name
             set_dir.mkdir(exist_ok=True)
@@ -360,7 +361,7 @@ def main():
                 content = gen_riscv_instr_info_str(instr_def)
                 if len(content) > 0:
                     assert pred is not None
-                    predicate_str = f"Predicates = [{pred}, IsRV32]"
+                    predicate_str = f"Predicates = [{pred}, IsRV{xlen}]"
                     content = f"let {predicate_str} in {{\n{content}\n}}"
                     with open(output_file, "w") as f:
                         f.write(content)
diff --git a/seal5/model.py b/seal5/model.py
index 39f48539..88977fa3 100644
--- a/seal5/model.py
+++ b/seal5/model.py
@@ -18,6 +18,7 @@
     Function,
     BaseNode,
     InstrAttribute,
+    MemoryAttribute,
     BitField,
     BitVal,
     DataType,
@@ -53,6 +54,17 @@ def __init__(
         self.registers = registers
         self.register_groups = register_groups
         self.settings: ExtensionsSettings = None
+        self._xlen = None
+
+    @property
+    def xlen(self):
+        if self._xlen is None:
+            for mem_name, mem_def in self.memories.items():
+                if mem_name == "X" or MemoryAttribute.IS_MAIN_REG in mem_def.attributes:
+                    self._xlen = mem_def.size
+                    break
+        assert self._xlen is not None, "Could not determine XLEN"
+        return self._xlen
 
 
 class Seal5RegisterClass(IntEnum):
diff --git a/seal5/tools/cdsl2llvm.py b/seal5/tools/cdsl2llvm.py
index 2efd969d..9cca9163 100644
--- a/seal5/tools/cdsl2llvm.py
+++ b/seal5/tools/cdsl2llvm.py
@@ -124,6 +124,7 @@ def run_pattern_gen(
     verbose: bool = False,
     ext=None,
     mattr=None,
+    xlen=None,
     skip_formats=False,
     skip_patterns=False,
     skip_verify=True,
@@ -139,7 +140,9 @@ def run_pattern_gen(
 
     if ext:
         # pattern_gen_args.extend(["--ext", ext])
-        pattern_gen_args.extend(["-p", f"Has{ext}"])
+        preds = [f"Has{ext}", f"IsRV{xlen}"]
+        preds_str = ", ".join(preds)
+        pattern_gen_args.extend(["-p", preds_str])
 
     if mattr is None:
         attrs = ["+m", "+fast-unaligned-access"]
@@ -152,6 +155,10 @@ def run_pattern_gen(
     if mattr:
         pattern_gen_args.extend(["--mattr2", mattr])
 
+    if xlen:
+        assert xlen in [32, 64]
+        pattern_gen_args.extend(["--riscv-xlen", str(xlen)])
+
     if skip_patterns:
         pattern_gen_args.append("--skip-patterns")