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fix[venom]: liveness assumption venom to assembly #4716

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fix[venom]: liveness assumption venom to assembly #4716

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d8873c7
refactor[venom]: strengthen an assumption in venom lowering
charles-cooper Jul 8, 2025
7379391
Merge branch 'master' into fix/liveness-assumption-venom-to-assembly
charles-cooper Jul 8, 2025
1f353b5
removed duplicated `phi` instructions
HodanPlodky Jul 18, 2025
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19 changes: 18 additions & 1 deletion vyper/venom/passes/phi_elimination.py
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
from vyper.venom.analysis import DFGAnalysis, LivenessAnalysis
from vyper.venom.basicblock import IRInstruction, IRVariable
from vyper.venom.basicblock import IRBasicBlock, IRInstruction, IROperand, IRVariable

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Code scanning / CodeQL

Unused import Note

Import of 'IROperand' is not used.
from vyper.venom.passes.base_pass import InstUpdater, IRPass


Expand All @@ -11,6 +11,9 @@
self.updater = InstUpdater(self.dfg)
self._calculate_phi_origins()

for bb in self.function.get_basic_blocks():
self._deduplicate_phis(bb)

for _, inst in self.dfg.outputs.copy().items():
if inst.opcode != "phi":
continue
Expand All @@ -22,6 +25,20 @@

self.analyses_cache.invalidate_analysis(LivenessAnalysis)

def _deduplicate_phis(self, bb: IRBasicBlock):
phis: dict[tuple, IRVariable] = dict()

for inst in bb.instructions:
if inst.opcode != "phi":
continue
ops = tuple(inst.operands)
if ops in phis:
self.updater.mk_assign(inst, phis[ops])
continue

assert inst.output is not None
phis[ops] = inst.output

def _process_phi(self, inst: IRInstruction):
srcs = self.phi_to_origins[inst]

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10 changes: 3 additions & 7 deletions vyper/venom/venom_to_assembly.py
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Original file line number Diff line number Diff line change
Expand Up @@ -436,13 +436,9 @@ 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 next_liveness:
# this branch seems unreachable (maybe due to make_ssa)
# %13/%14 is still live(!), so we make a copy of it
self.dup(assembly, stack, depth)
stack.poke(0, ret)
else:
stack.poke(depth, ret)
# precondition from SSA
assert to_be_replaced not in next_liveness
stack.poke(depth, ret)
return apply_line_numbers(inst, assembly)

if opcode == "offset":
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