feat: add simple pass to collapse constants repeated >= 2 times by us…

…ing a dupn

src/puya/parse.py

@@ -156,9 +156,12 @@ def __repr__(self) -> str:
                 result += f"-{self.end_column}"
         return result
 
-    def __add__(self, other: "SourceLocation") -> "SourceLocation":
+    def __add__(self, other: "SourceLocation | None") -> "SourceLocation":
         from puya.errors import InternalError
 
+        if other is None:
+            return self
+
         if self.file != other.file:
             raise InternalError("uh oh")
         # BEGIN: YIKES

src/puya/teal/models.py

@@ -13,7 +13,7 @@ class TealOp:
     op_code: str
     consumes: int
     produces: int
-    source_location: SourceLocation | None
+    source_location: SourceLocation | None = attrs.field(eq=False)
     comment: str | None = None
     """A comment that is always emitted, should only be used for user comments related to an
     op such as assert or err"""

src/puya/teal/optimize/constant_stack_shuffling.py

@@ -1,3 +1,6 @@
+import functools
+import operator
+
 from puya.teal import models
 from puya.teal.optimize._data import LOAD_OP_CODES
 
@@ -31,3 +34,39 @@ def perform_constant_stack_shuffling(block: models.TealBlock) -> bool:
         result.extend(loads)
     block.ops = result
     return modified
+
+
+def constant_dupn_insertion(block: models.TealBlock) -> bool:
+    result = list[models.TealOp]()
+    loads = list[models.TealOp]()
+    modified = False
+    for op in block.ops:
+        if loads and op == loads[0]:
+            loads.append(op)
+        else:
+            if loads:
+                modified = _collapse_loads(loads) or modified
+                result.extend(loads)
+                loads = []
+            if op.op_code in LOAD_OP_CODES or (
+                op.op_code == "frame_dig" and int(op.immediates[0]) < 0
+            ):
+                loads.append(op)
+            else:
+                result.append(op)
+    if loads:
+        modified = _collapse_loads(loads) or modified
+        result.extend(loads)
+    block.ops = result
+    return modified
+
+
+def _collapse_loads(loads: list[models.TealOp]) -> bool:
+    n = len(loads) - 1
+    if n >= 2:
+        dupn_source_location = functools.reduce(
+            operator.add, (op.source_location for op in loads[1:])
+        )
+        loads[1:] = [models.DupN(n=n, source_location=dupn_source_location)]
+        return True
+    return False