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Avoid comparing unreachable constructor deployments #1249

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43 changes: 27 additions & 16 deletions src/EVM/Equivalence.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -256,22 +256,33 @@ equivalenceCheck' solvers sess branchesA branchesB create = do
-- code is equivalent. The constraints from the undeployed code (aProps,bProps) influence this check.
deployedCodeDiffer :: Expr Buf -> Expr Buf -> [Prop] -> [Prop] -> m EqIssues
deployedCodeDiffer aOut bOut aProps bProps = do
let simpA = Expr.simplify aOut
simpB = Expr.simplify bOut
conf <- readConfig
case (simpA, simpB) of
(ConcreteBuf codeA, ConcreteBuf codeB) -> do
-- TODO: use aProps/bProps to constrain the deployed code
-- since symbolic code (with constructors taking arguments) is not supported,
-- this is currently not necessary
when conf.debug $ liftIO $ do
liftIO $ putStrLn $ "create deployed code A: " <> bsToHex codeA
<> " with constraints: " <> (T.unpack . T.unlines $ map formatProp aProps)
liftIO $ putStrLn $ "create deployed code B: " <> bsToHex codeB
<> " with constraints: " <> (T.unpack . T.unlines $ map formatProp bProps)
(calldata, _) <- mkCalldata Nothing []
equivalenceCheck solvers sess codeA codeB defaultVeriOpts calldata False
_ -> internalError $ "Symbolic code returned from constructor." <> " A: " <> show simpA <> " B: " <> show simpB
-- Compare deployed runtimes only when both constructor paths can occur for
-- the same input. Otherwise an impossible pair of paths can create a
-- spurious runtime difference (notably for --create).
pathOverlap <- checkSatWithProps solvers (aProps <> bProps)
case pathOverlap of
Qed -> pure mempty
Cex _ -> do
let simpA = Expr.simplify aOut
simpB = Expr.simplify bOut
conf <- readConfig
case (simpA, simpB) of
(ConcreteBuf codeA, ConcreteBuf codeB) -> do
when conf.debug $ liftIO $ do
liftIO $ putStrLn $ "create deployed code A: " <> bsToHex codeA
<> " with constraints: " <> (T.unpack . T.unlines $ map formatProp aProps)
liftIO $ putStrLn $ "create deployed code B: " <> bsToHex codeB
<> " with constraints: " <> (T.unpack . T.unlines $ map formatProp bProps)
(calldata, _) <- mkCalldata Nothing []
equivalenceCheck solvers sess codeA codeB defaultVeriOpts calldata False
_ -> internalError $ "Symbolic code returned from constructor." <> " A: " <> show simpA <> " B: " <> show simpB
Unknown reason -> pure $ EqIssues
[(Unknown ("Unable to establish constructor-path compatibility: " <> reason),
"Could not establish compatible constructor paths before comparing deployed code.")]
mempty
Error err -> pure $ EqIssues
[(Error err, "Failed to check constructor-path compatibility before comparing deployed code.")]
mempty

statesDiffer :: Map (Expr EAddr) (Expr EContract) -> Map (Expr EAddr) (Expr EContract) -> Prop
statesDiffer aState bState
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7 changes: 6 additions & 1 deletion test/EVM/Equivalence/EquivalenceTests.hs
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Expand Up @@ -444,7 +444,12 @@ deploymentSolidityEquivalenceTests = testGroup "Solidity deployment equivalence"

bytecodeEquivalenceTests :: TestTree
bytecodeEquivalenceTests = testGroup "Bytecode equivalence"
[ testCase "eq-issue-with-length-cex-bug679" $ do -- check bug https://github.com/argotorg/hevm/issues/679
[ testCase "constructor-crossed-paths-do-not-compare-impossible-deployments" $ do
let a = "34600c5760fe5f5360015ff35b60005f5360015ff3"
b = "3415600d5760005f5360015ff35b60fe5f5360015ff3"
eq <- eqBytecode False a b
assertEqual "impossible constructor paths must not create a difference" [] (map fst eq.res)
, testCase "eq-issue-with-length-cex-bug679" $ do -- check bug https://github.com/argotorg/hevm/issues/679
let a = fromJust (hexByteString "5f610100526020610100f3")
b = fromJust (hexByteString "5f356101f40115610100526020610100f3")
eq <- Effects.runApp $ withSolvers Z3 1 Nothing defMemLimit $ \s -> do
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