feat[venom]: range value propagation (will get a better name eventually)

tests/unit/compiler/venom/test_rvp.py

@@ -0,0 +1,120 @@
+import pytest
+
+from tests.venom_utils import PrePostChecker
+from vyper.venom.basicblock import IRLabel, IRVariable
+from vyper.venom.passes.rvp import Interval, RangeValuePropagationPass, _inf
+
+pytestmark = pytest.mark.hevm
+
+_check_pre_post = PrePostChecker([RangeValuePropagationPass])
+
+
+def test_simple_range_propagation():
+    pre = """
+    _global:
+        %1 = param
+        %2 = 32
+        %3 = 64
+        %4 = add %2, %3
+        %5 = sub %4, %2
+        %6 = add %1, %5  ; can't be optimized since %1 is a variable
+        exit
+    """
+
+    post = """
+    _global:
+        %1 = param
+        %2 = 32
+        %3 = 64
+        %4 = add 32, 64
+        %5 = sub 96, 32
+        %6 = add %1, 64
+        exit
+    """
+
+    passes = _check_pre_post(pre, post)
+    rvp = passes[0]
+
+    assert rvp.lattice[IRVariable("%1")] == Interval(-_inf, _inf)
+    assert rvp.lattice[IRVariable("%2")] == Interval(32, 32)
+    assert rvp.lattice[IRVariable("%3")] == Interval(64, 64)
+    assert rvp.lattice[IRVariable("%4")] == Interval(96, 96)
+    assert rvp.lattice[IRVariable("%5")] == Interval(64, 64)
+    assert rvp.lattice[IRVariable("%6")] == Interval(-_inf, _inf)
+
+
+def test_branch_elimination_with_ranges():
+    pre = """
+    main:
+        %1 = 10
+        %2 = 20
+        %3 = add %1, %2
+        jnz %3, @then, @else
+    then:
+        exit
+    else:
+        exit
+    """
+
+    post = """
+    main:
+        %1 = 10
+        %2 = 20
+        %3 = add 10, 20
+        jmp @then
+    then:
+        exit
+    else:  # unreachable
+        exit
+    """
+
+    passes = _check_pre_post(pre, post)
+    rvp = passes[0]
+
+    assert rvp.lattice[IRVariable("%1")] == Interval(10, 10)
+    assert rvp.lattice[IRVariable("%2")] == Interval(20, 20)
+    assert rvp.lattice[IRVariable("%3")] == Interval(30, 30)
+
+
+def test_branch_range_propagation():
+    pre = """
+    main:
+        %1 = param
+        %2 = 0
+        jnz %1, @then, @else
+    then:
+        %3 = add %1, %2  ; %1 is non-zero here
+        exit
+    else:
+        %4 = add %1, %2  ; %1 is zero here
+        exit
+    """
+
+    post = """
+    main:
+        %1 = param
+        %2 = 0
+        jnz %1, @then, @else
+    then:
+        %3 = add %1, 0  ; %1 is non-zero here
+        exit
+    else:
+        %4 = add 0, 0  ; %1 is zero here
+        exit
+    """
+
+    passes = _check_pre_post(pre, post)
+    rvp = passes[0]
+
+    assert rvp.lattice[IRVariable("%1")] == Interval(-_inf, _inf)
+    assert rvp.lattice[IRVariable("%2")] == Interval(0, 0)
+
+    then_ctx = rvp._get_context("then")
+    assert then_ctx.lattice[IRVariable("%1")] == Interval(-_inf, -1, 1, _inf)
+    assert then_ctx.lattice[IRVariable("%2")] == Interval(0, 0)
+    assert then_ctx.lattice[IRVariable("%3")] == Interval(-_inf, -1, 1, _inf)
+
+    else_ctx = rvp._get_context("else")
+    assert else_ctx.lattice[IRVariable("%1")] == Interval(0, 0)
+    assert else_ctx.lattice[IRVariable("%2")] == Interval(0, 0)
+    assert else_ctx.lattice[IRVariable("%4")] == Interval(0, 0)

vyper/venom/passes/__init__.py

@@ -13,6 +13,7 @@
 from .normalization import NormalizationPass
 from .remove_unused_variables import RemoveUnusedVariablesPass
 from .revert_to_assert import RevertToAssert
+from .rvp import RangeValuePropagationPass
 from .sccp import SCCP
 from .simplify_cfg import SimplifyCFGPass
 from .store_elimination import StoreElimination