fix[venom]: liveness analysis in some loops

tests/unit/compiler/venom/test_convert_basicblock_simple.py

@@ -0,0 +1,51 @@
+from vyper.codegen.ir_node import IRnode
+from vyper.compiler.settings import OptimizationLevel
+from vyper.venom import generate_ir
+
+
+def test_simple():
+    ir = ["calldatacopy", 32, 0, ["calldatasize"]]
+    ir_node = IRnode.from_list(ir)
+    deploy, runtime = generate_ir(ir_node, OptimizationLevel.NONE)
+    assert deploy is None
+    assert runtime is not None
+
+    bb = runtime.basic_blocks[0]
+    assert bb.instructions[0].opcode == "calldatasize"
+    assert bb.instructions[1].opcode == "calldatacopy"
+
+
+def test_simple_2():
+    ir = [
+        "seq",
+        [
+            "seq",
+            [
+                "mstore",
+                ["add", 64, 0],
+                [
+                    "with",
+                    "x",
+                    ["calldataload", ["add", 4, 0]],
+                    [
+                        "with",
+                        "ans",
+                        ["add", "x", 1],
+                        ["seq", ["assert", ["ge", "ans", "x"]], "ans"],
+                    ],
+                ],
+            ],
+        ],
+        32,
+    ]
+    ir_node = IRnode.from_list(ir)
+    deploy, runtime = generate_ir(ir_node, OptimizationLevel.NONE)
+    assert deploy is None
+    assert runtime is not None
+
+    print(runtime)
+
+
+if __name__ == "__main__":
+    test_simple()
+    test_simple_2()

tests/unit/compiler/venom/test_liveness_simple_loop.py

@@ -0,0 +1,16 @@
+import vyper
+
+source = """
+@external
+def foo(a: uint256):
+    _numBids: uint256 = 20
+    b: uint256 = 10
+
+    for i: uint256 in range(128):
+        b = 1 + _numBids
+"""
+
+
+def test_liveness_simple_loop():
+    vyper.compile_code(source, ["opcodes"])
+    assert True

vyper/venom/__init__.py

@@ -61,11 +61,15 @@ def _run_passes(ctx: IRFunction, optimize: OptimizationLevel) -> None:
             break
 
 
-def generate_ir(ir: IRnode, optimize: OptimizationLevel) -> tuple[IRFunction, IRFunction]:
+def generate_ir(
+    ir: IRnode, optimize: OptimizationLevel
+) -> tuple[Optional[IRFunction], Optional[IRFunction]]:
     # Convert "old" IR to "new" IR
     ctx, ctx_runtime = convert_ir_basicblock(ir)
 
-    _run_passes(ctx, optimize)
-    _run_passes(ctx_runtime, optimize)
+    if ctx:
+        _run_passes(ctx, optimize)
+    if ctx_runtime:
+        _run_passes(ctx_runtime, optimize)
 
     return ctx, ctx_runtime

vyper/venom/analysis.py

@@ -42,10 +42,12 @@ def _reset_liveness(ctx: IRFunction) -> None:
             inst.liveness = OrderedSet()
 
 
-def _calculate_liveness_bb(bb: IRBasicBlock) -> None:
+def _calculate_liveness(bb: IRBasicBlock) -> bool:
     """
     Compute liveness of each instruction in the basic block.
+    Returns True if liveness changed
     """
+    orig_liveness = bb.instructions[0].liveness.copy()
     liveness = bb.out_vars.copy()
     for instruction in reversed(bb.instructions):
         ops = instruction.get_inputs()
@@ -60,29 +62,31 @@ def _calculate_liveness_bb(bb: IRBasicBlock) -> None:
             liveness.remove(out)
         instruction.liveness = liveness
 
+    return orig_liveness != bb.instructions[0].liveness
 
-def _calculate_liveness_r(bb: IRBasicBlock, visited: dict) -> None:
-    assert isinstance(visited, dict)
-    for out_bb in bb.cfg_out:
-        if visited.get(bb) == out_bb:
-            continue
-        visited[bb] = out_bb
-
-        # recurse
-        _calculate_liveness_r(out_bb, visited)
 
+def _calculate_out_vars(bb: IRBasicBlock) -> bool:
+    """
+    Compute out_vars of basic block.
+    Returns True if out_vars changed
+    """
+    out_vars = bb.out_vars.copy()
+    for out_bb in bb.cfg_out:
         target_vars = input_vars_from(bb, out_bb)
-
-        # the output stack layout for bb. it produces a stack layout
-        # which works for all possible cfg_outs from the bb.
         bb.out_vars = bb.out_vars.union(target_vars)
-
-    _calculate_liveness_bb(bb)
+    return out_vars != bb.out_vars
 
 
 def calculate_liveness(ctx: IRFunction) -> None:
     _reset_liveness(ctx)
-    _calculate_liveness_r(ctx.basic_blocks[0], dict())
+    while True:
+        changed = False
+        for bb in ctx.basic_blocks:
+            changed |= _calculate_out_vars(bb)
+            changed |= _calculate_liveness(bb)
+
+        if not changed:
+            break
 
 
 # calculate the input variables into self from source

vyper/venom/basicblock.py

@@ -410,8 +410,8 @@ def copy(self):
     def __repr__(self) -> str:
         s = (
             f"{repr(self.label)}:  IN={[bb.label for bb in self.cfg_in]}"
-            f" OUT={[bb.label for bb in self.cfg_out]} => {self.out_vars} \n"
+            f" OUT={[bb.label for bb in self.cfg_out]} => {self.out_vars}\n"
         )
         for instruction in self.instructions:
-            s += f"    {instruction}\n"
+            s += f"    {str(instruction).strip()}\n"
         return s

vyper/venom/function.py

@@ -163,4 +163,4 @@ def __repr__(self) -> str:
             str += "Data segment:\n"
             for inst in self.data_segment:
                 str += f"{inst}\n"
-        return str
+        return str.strip()