fix[venom]: remove liveness requests (#4058)

This commit sanitizes the requests/invalidations of liveness analysis in
the various passes.

Additionally it renames the property `in_vars` to `liveness_in_vars` to
make it clear that this property is liveness dependent

vyper/venom/analysis/dfg.py

@@ -1,6 +1,7 @@
 from typing import Optional
 
 from vyper.venom.analysis.analysis import IRAnalysesCache, IRAnalysis
+from vyper.venom.analysis.liveness import LivenessAnalysis
 from vyper.venom.basicblock import IRInstruction, IRVariable
 from vyper.venom.function import IRFunction
 
@@ -67,5 +68,8 @@ def as_graph(self) -> str:
         lines.append("}")
         return "\n".join(lines)
 
+    def invalidate(self):
+        self.analyses_cache.invalidate_analysis(LivenessAnalysis)
+
     def __repr__(self) -> str:
         return self.as_graph()

vyper/venom/basicblock.py

@@ -509,7 +509,7 @@ def is_terminal(self) -> bool:
         return len(self.cfg_out) == 0
 
     @property
-    def in_vars(self) -> OrderedSet[IRVariable]:
+    def liveness_in_vars(self) -> OrderedSet[IRVariable]:
         for inst in self.instructions:
             if inst.opcode != "phi":
                 return inst.liveness

vyper/venom/passes/make_ssa.py

@@ -19,6 +19,8 @@ def run_pass(self):
 
         self.analyses_cache.request_analysis(CFGAnalysis)
         self.dom = self.analyses_cache.request_analysis(DominatorTreeAnalysis)
+
+        # Request liveness analysis so the `liveness_in_vars` field is valid
         self.analyses_cache.request_analysis(LivenessAnalysis)
 
         self._add_phi_nodes()
@@ -28,6 +30,8 @@ def run_pass(self):
         self._rename_vars(fn.entry)
         self._remove_degenerate_phis(fn.entry)
 
+        self.analyses_cache.invalidate_analysis(LivenessAnalysis)
+
     def _add_phi_nodes(self):
         """
         Add phi nodes to the function.
@@ -54,7 +58,7 @@ def _add_phi_nodes(self):
                         defs.append(dom)
 
     def _place_phi(self, var: IRVariable, basic_block: IRBasicBlock):
-        if var not in basic_block.in_vars:
+        if var not in basic_block.liveness_in_vars:
             return
 
         args: list[IROperand] = []

vyper/venom/passes/mem2var.py

@@ -19,7 +19,6 @@ class Mem2Var(IRPass):
     def run_pass(self):
         self.analyses_cache.request_analysis(CFGAnalysis)
         dfg = self.analyses_cache.request_analysis(DFGAnalysis)
-        self.analyses_cache.request_analysis(LivenessAnalysis)
 
         self.var_name_count = 0
         for var, inst in dfg.outputs.items():

vyper/venom/passes/remove_unused_variables.py

@@ -1,5 +1,6 @@
 from vyper.utils import OrderedSet
 from vyper.venom.analysis.dfg import DFGAnalysis
+from vyper.venom.analysis.liveness import LivenessAnalysis
 from vyper.venom.basicblock import IRInstruction
 from vyper.venom.passes.base_pass import IRPass
 
@@ -25,6 +26,8 @@ def run_pass(self):
             inst = work_list.pop()
             self._process_instruction(inst)
 
+        self.analyses_cache.invalidate_analysis(LivenessAnalysis)
+
     def _process_instruction(self, inst):
         if inst.output is None:
             return