Optimization for constant assembly (#128)

* Optimization added for repeated int constants under 2**7 w/ tests

* fixed type problem and formatted

* Expanded test and added comment for clarification

pyteal/compiler/constants.py

@@ -132,7 +132,14 @@ def createConstantBlocks(ops: List[TealComponent]) -> List[TealComponent]:
     sortedInts = sorted(intFreqs, key=lambda x: intFreqs[x], reverse=True)
     sortedBytes = sorted(byteFreqs, key=lambda x: byteFreqs[x], reverse=True)
 
-    intBlock = [i for i in sortedInts if intFreqs[i] > 1]
+    # Use Op.pushint if the constant does not occur in the top 4 most frequent and is smaller than
+    # 2 ** 7 to improve performance and save block space.
+    intBlock = [
+        val
+        for i, val in enumerate(sortedInts)
+        if intFreqs[val] > 1 and (i < 4 or isinstance(val, str) or val >= 2 ** 7)
+    ]
+
     byteBlock = [
         ("0x" + b.hex()) if type(b) is bytes else cast(str, b)
         for b in sortedBytes
@@ -151,13 +158,13 @@ def createConstantBlocks(ops: List[TealComponent]) -> List[TealComponent]:
 
             if basicOp == Op.int:
                 intValue = extractIntValue(op)
-                if intFreqs[intValue] == 1:
+                if intValue not in intBlock:
                     assembled.append(
                         TealOp(op.expr, Op.pushint, intValue, "//", *op.args)
                     )
                     continue
 
-                index = sortedInts.index(intValue)
+                index = intBlock.index(intValue)
                 if index == 0:
                     assembled.append(TealOp(op.expr, Op.intc_0, "//", *op.args))
                 elif index == 1:

pyteal/compiler/constants_test.py

@@ -545,3 +545,77 @@ def test_createConstantBlocks_tmpl_all():
 
     actual = createConstantBlocks(ops)
     assert actual == expected
+
+
+def test_createConstantBlocks_intc():
+    """Test scenario where there are more than 4 constants in the intcblock.
+    If the 4th constant can't fit in one varuint byte (more than 2**7) it
+    should be referenced with the Op.intc 4 command.
+    """
+
+    ops = [
+        TealOp(None, Op.int, 0),
+        TealOp(None, Op.int, 0),
+        TealOp(None, Op.int, 1),
+        TealOp(None, Op.int, 1),
+        TealOp(None, Op.int, 2),
+        TealOp(None, Op.int, 2),
+        TealOp(None, Op.int, 3),
+        TealOp(None, Op.int, 3),
+        TealOp(None, Op.int, 2 ** 7),
+        TealOp(None, Op.int, 2 ** 7),
+    ]
+
+    expected = [
+        TealOp(None, Op.intcblock, 0, 1, 2, 3, 2 ** 7),
+        TealOp(None, Op.intc_0, "//", 0),
+        TealOp(None, Op.intc_0, "//", 0),
+        TealOp(None, Op.intc_1, "//", 1),
+        TealOp(None, Op.intc_1, "//", 1),
+        TealOp(None, Op.intc_2, "//", 2),
+        TealOp(None, Op.intc_2, "//", 2),
+        TealOp(None, Op.intc_3, "//", 3),
+        TealOp(None, Op.intc_3, "//", 3),
+        TealOp(None, Op.intc, 4, "//", 2 ** 7),
+        TealOp(None, Op.intc, 4, "//", 2 ** 7),
+    ]
+
+    actual = createConstantBlocks(ops)
+    assert actual == expected
+
+
+def test_createConstantBlocks_small_constant():
+    """If a constant cannot be referenced using the intc_[0..3] commands
+    and it can be stored in one varuint it byte then Op.pushint is used.
+    """
+
+    for cur in range(4, 2 ** 7):
+        ops = [
+            TealOp(None, Op.int, 0),
+            TealOp(None, Op.int, 0),
+            TealOp(None, Op.int, 1),
+            TealOp(None, Op.int, 1),
+            TealOp(None, Op.int, 2),
+            TealOp(None, Op.int, 2),
+            TealOp(None, Op.int, 3),
+            TealOp(None, Op.int, 3),
+            TealOp(None, Op.int, cur),
+            TealOp(None, Op.int, cur),
+        ]
+
+        expected = [
+            TealOp(None, Op.intcblock, 0, 1, 2, 3),
+            TealOp(None, Op.intc_0, "//", 0),
+            TealOp(None, Op.intc_0, "//", 0),
+            TealOp(None, Op.intc_1, "//", 1),
+            TealOp(None, Op.intc_1, "//", 1),
+            TealOp(None, Op.intc_2, "//", 2),
+            TealOp(None, Op.intc_2, "//", 2),
+            TealOp(None, Op.intc_3, "//", 3),
+            TealOp(None, Op.intc_3, "//", 3),
+            TealOp(None, Op.pushint, cur, "//", cur),
+            TealOp(None, Op.pushint, cur, "//", cur),
+        ]
+
+        actual = createConstantBlocks(ops)
+        assert actual == expected