refactor[venom]: remove dup_requirements analysis (vyperlang#4262)

this commit updates `next_liveness` to reflect `out_vars` when the
instruction is the last instruction in the basic block.

after this change, membership in `dup_requirements` is the same as
membership in `next_liveness`, so we can remove the `dup_requirements`
analysis.

vyper/venom/basicblock.py

@@ -209,7 +209,6 @@ class IRInstruction:
     output: Optional[IROperand]
     # set of live variables at this instruction
     liveness: OrderedSet[IRVariable]
-    dup_requirements: OrderedSet[IRVariable]
     parent: "IRBasicBlock"
     fence_id: int
     annotation: Optional[str]
@@ -228,7 +227,6 @@ def __init__(
         self.operands = list(operands)  # in case we get an iterator
         self.output = output
         self.liveness = OrderedSet()
-        self.dup_requirements = OrderedSet()
         self.fence_id = -1
         self.annotation = None
         self.ast_source = None

vyper/venom/venom_to_assembly.py

@@ -12,7 +12,6 @@
 )
 from vyper.utils import MemoryPositions, OrderedSet
 from vyper.venom.analysis.analysis import IRAnalysesCache
-from vyper.venom.analysis.dup_requirements import DupRequirementsAnalysis
 from vyper.venom.analysis.liveness import LivenessAnalysis
 from vyper.venom.basicblock import (
     IRBasicBlock,
@@ -153,7 +152,6 @@ def generate_evm(self, no_optimize: bool = False) -> list[str]:
 
                 NormalizationPass(ac, fn).run_pass()
                 self.liveness_analysis = ac.request_analysis(LivenessAnalysis)
-                ac.request_analysis(DupRequirementsAnalysis)
 
                 assert fn.normalized, "Non-normalized CFG!"
 
@@ -231,7 +229,12 @@ def _stack_reorder(
         return cost
 
     def _emit_input_operands(
-        self, assembly: list, inst: IRInstruction, ops: list[IROperand], stack: StackModel
+        self,
+        assembly: list,
+        inst: IRInstruction,
+        ops: list[IROperand],
+        stack: StackModel,
+        next_liveness: OrderedSet[IRVariable],
     ) -> None:
         # PRE: we already have all the items on the stack that have
         # been scheduled to be killed. now it's just a matter of emitting
@@ -241,7 +244,7 @@ def _emit_input_operands(
         # it with something that is wanted
         if ops and stack.height > 0 and stack.peek(0) not in ops:
             for op in ops:
-                if isinstance(op, IRVariable) and op not in inst.dup_requirements:
+                if isinstance(op, IRVariable) and op not in next_liveness:
                     self.swap_op(assembly, stack, op)
                     break
 
@@ -264,7 +267,7 @@ def _emit_input_operands(
                 stack.push(op)
                 continue
 
-            if op in inst.dup_requirements and op not in emitted_ops:
+            if op in next_liveness and op not in emitted_ops:
                 self.dup_op(assembly, stack, op)
 
             if op in emitted_ops:
@@ -288,7 +291,9 @@ def _generate_evm_for_basicblock_r(
         all_insts = sorted(basicblock.instructions, key=lambda x: x.opcode != "param")
 
         for i, inst in enumerate(all_insts):
-            next_liveness = all_insts[i + 1].liveness if i + 1 < len(all_insts) else OrderedSet()
+            next_liveness = (
+                all_insts[i + 1].liveness if i + 1 < len(all_insts) else basicblock.out_vars
+            )
 
             asm.extend(self._generate_evm_for_instruction(inst, stack, next_liveness))
 
@@ -327,10 +332,9 @@ def clean_stack_from_cfg_in(
             self.pop(asm, stack)
 
     def _generate_evm_for_instruction(
-        self, inst: IRInstruction, stack: StackModel, next_liveness: OrderedSet = None
+        self, inst: IRInstruction, stack: StackModel, next_liveness: OrderedSet
     ) -> list[str]:
         assembly: list[str | int] = []
-        next_liveness = next_liveness or OrderedSet()
         opcode = inst.opcode
 
         #
@@ -375,7 +379,7 @@ def _generate_evm_for_instruction(
             # example, for `%56 = %label1 %13 %label2 %14`, we will
             # find an instance of %13 *or* %14 in the stack and replace it with %56.
             to_be_replaced = stack.peek(depth)
-            if to_be_replaced in inst.dup_requirements:
+            if to_be_replaced in next_liveness:
                 # %13/%14 is still live(!), so we make a copy of it
                 self.dup(assembly, stack, depth)
                 stack.poke(0, ret)
@@ -390,7 +394,7 @@ def _generate_evm_for_instruction(
             return apply_line_numbers(inst, assembly)
 
         # Step 2: Emit instruction's input operands
-        self._emit_input_operands(assembly, inst, operands, stack)
+        self._emit_input_operands(assembly, inst, operands, stack, next_liveness)
 
         # Step 3: Reorder stack before join points
         if opcode == "jmp":