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Replace COA.call with COA.callWithSigAndArgs for reduced computation cost #207

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Merged
joshuahannan merged 4 commits into from
Apr 9, 2026
Merged

Replace COA.call with COA.callWithSigAndArgs for reduced computation cost #207

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ae1fbc4
Replace COA.call with COA.callWithSigAndArgs for reduced computation …
m-Peter Mar 18, 2026
e9246a2
Avoid creating EVM.Balance structs for value of 0
m-Peter Apr 3, 2026
f931ba9
Use the Cadence String interpolation feature instead of concat()
m-Peter Apr 3, 2026
f8c0d1b
Update EVM dependency source from mainnet to testnet
joshuahannan Apr 9, 2026
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88 changes: 32 additions & 56 deletions cadence/contracts/bridge/FlowEVMBridge.cdc
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26 changes: 12 additions & 14 deletions cadence/contracts/bridge/FlowEVMBridgeAccessor.cdc
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ contract FlowEVMBridgeAccessor {
): @{NonFungibleToken.NFT} {
// Define a callback function, enabling the bridge to act on the ephemeral COA reference in scope
var executed = false
fun callback(target: EVM.EVMAddress): EVM.Result {
fun callback(target: EVM.EVMAddress): EVM.ResultDecoded {
pre {
!executed: "Callback can only be executed once"
FlowEVMBridge.getAssociatedEVMAddress(with: type) ?? FlowEVMBridgeConfig.getLegacyEVMAddressAssociated(with: type) != nil:
Expand All @@ -69,14 +69,13 @@ contract FlowEVMBridgeAccessor {
message: "Target EVM contract \(target.toString()) is not association with NFT Type \(type.identifier) - COA `safeTransferFrom` callback rejected")

executed = true
return caller.call(
return caller.callWithSigAndArgs(
to: target,
data: EVM.encodeABIWithSignature(
"safeTransferFrom(address,address,uint256)",
[caller.address(), FlowEVMBridge.getBridgeCOAEVMAddress(), id]
),
signature: "safeTransferFrom(address,address,uint256)",
args: [caller.address(), FlowEVMBridge.getBridgeCOAEVMAddress(), id],
gasLimit: FlowEVMBridgeConfig.gasLimit,
value: EVM.Balance(attoflow: 0)
value: 0,
resultTypes: nil
)
}
// Execute the bridge request
Expand Down Expand Up @@ -129,22 +128,21 @@ contract FlowEVMBridgeAccessor {
let roundedAmount = FlowEVMBridgeUtils.castERC20AmountToCadencePrecision(amount, erc20Address: associatedEVMAddress)
// Define a callback function, enabling the bridge to act on the ephemeral COA reference in scope
var executed = false
fun callback(): EVM.Result {
fun callback(): EVM.ResultDecoded {
pre {
!executed: "Callback can only be executed once"
}
post {
executed: "Callback must be executed"
}
executed = true
return caller.call(
return caller.callWithSigAndArgs(
to: associatedEVMAddress,
data: EVM.encodeABIWithSignature(
"transfer(address,uint256)",
[FlowEVMBridge.getBridgeCOAEVMAddress(), roundedAmount]
),
signature: "transfer(address,uint256)",
args: [FlowEVMBridge.getBridgeCOAEVMAddress(), roundedAmount],
gasLimit: FlowEVMBridgeConfig.gasLimit,
value: EVM.Balance(attoflow: 0)
value: 0,
resultTypes: nil
)
}
// Execute the bridge request
Expand Down
57 changes: 21 additions & 36 deletions cadence/contracts/bridge/FlowEVMBridgeHandlers.cdc
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ access(all) contract FlowEVMBridgeHandlers {
let amount = tokens.balance
let uintAmount = FlowEVMBridgeUtils.convertCadenceAmountToERC20Amount(amount, erc20Address: evmAddress)

assert(uintAmount > UInt256(0), message: "Amount to bridge must be greater than 0")
assert(uintAmount > 0, message: "Amount to bridge must be greater than 0")

Burner.burn(<-tokens)

Expand All @@ -127,7 +127,7 @@ access(all) contract FlowEVMBridgeHandlers {
owner: EVM.EVMAddress,
type: Type,
amount: UInt256,
protectedTransferCall: fun (): EVM.Result
protectedTransferCall: fun (): EVM.ResultDecoded
): @{FungibleToken.Vault} {
let evmAddress = self.getTargetEVMAddress()!

Expand All @@ -147,7 +147,7 @@ access(all) contract FlowEVMBridgeHandlers {

// After state confirmation, mint the tokens and return
let minter = self.borrowMinter()
?? panic("Cannot bridge - Minter not set in ".concat(self.getType().identifier))
?? panic("Cannot bridge - Minter not set in \(self.getType().identifier)")
let minted <- minter.mint(amount: ufixAmount)
return <-minted
}
Expand All @@ -170,7 +170,7 @@ access(all) contract FlowEVMBridgeHandlers {
access(FlowEVMBridgeHandlerInterfaces.Admin)
fun setMinter(_ minter: @{FlowEVMBridgeHandlerInterfaces.TokenMinter}) {
pre {
self.minter == nil: "Minter has already been set in ".concat(self.getType().identifier)
self.minter == nil: "Minter has already been set in \(self.getType().identifier)"
}
self.minter <-! minter
}
Expand All @@ -179,7 +179,7 @@ access(all) contract FlowEVMBridgeHandlers {
access(FlowEVMBridgeHandlerInterfaces.Admin)
fun enableBridging() {
pre {
self.minter != nil: "Cannot enable ".concat(self.getType().identifier).concat(" without a minter")
self.minter != nil: "Cannot enable \(self.getType().identifier) without a minter"
}
self.enabled = true
}
Expand Down Expand Up @@ -262,12 +262,13 @@ access(all) contract FlowEVMBridgeHandlers {
let preBalance = FlowEVMBridgeUtils.balanceOf(owner: coa.address(), evmContractAddress: wflowAddress)

// Wrap the deposited FLOW as WFLOW, giving the bridge COA the necessary WFLOW to transfer
let wrapResult = FlowEVMBridgeUtils.call(
let wrapResult = FlowEVMBridgeUtils.callWithSigAndArgs(
signature: "deposit()",
targetEVMAddress: wflowAddress,
args: [],
gasLimit: FlowEVMBridgeConfig.gasLimit,
value: balance
value: balance,
resultTypes: nil
)
assert(wrapResult.status == EVM.Status.successful, message: "Failed to wrap FLOW as WFLOW")

Expand All @@ -276,16 +277,12 @@ access(all) contract FlowEVMBridgeHandlers {
// Cover underflow
assert(
postBalance > preBalance,
message: "Escrowed WFLOW balance did not increment after wrapping FLOW - pre: "
.concat(preBalance.toString()).concat(" | post: ").concat(postBalance.toString())
message: "Escrowed WFLOW balance did not increment after wrapping FLOW - pre: \(preBalance.toString()) | post: \(postBalance.toString())"
)
// Confirm bridge COA's WFLOW balance has incremented by the expected amount
assert(
postBalance - preBalance == uintAmount,
message: "Escrowed WFLOW balance after wrapping does not match requested amount - expected: "
.concat((preBalance + uintAmount).toString())
.concat(" | actual: ")
.concat((postBalance - preBalance).toString())
message: "Escrowed WFLOW balance after wrapping does not match requested amount - expected: \(preBalance + uintAmount).toString()) | actual: \(postBalance - preBalance).toString())"
)

// Transfer WFLOW to recipient
Expand All @@ -307,7 +304,7 @@ access(all) contract FlowEVMBridgeHandlers {
owner: EVM.EVMAddress,
type: Type,
amount: UInt256,
protectedTransferCall: fun (): EVM.Result
protectedTransferCall: fun (): EVM.ResultDecoded
): @{FungibleToken.Vault} {
let wflowAddress = self.getTargetEVMAddress()!

Expand All @@ -318,8 +315,7 @@ access(all) contract FlowEVMBridgeHandlers {
)
assert(
ufixAmount > 0.0,
message: "Requested UInt256 amount ".concat(amount.toString()).concat(" converted to 0.0 ")
.concat(" - try bridging a larger amount to avoid UFix64 precision loss during conversion")
message: "Requested UInt256 amount \(amount.toString()) converted to 0.0 - try bridging a larger amount to avoid UFix64 precision loss during conversion"
)

// Transfers WFLOW to bridge COA as escrow
Expand All @@ -335,12 +331,13 @@ access(all) contract FlowEVMBridgeHandlers {
let preBalance = coa.balance().attoflow

// Unwrap the transferred WFLOW to FLOW, giving the bridge COA the necessary FLOW to withdraw from EVM
let unwrapResult = FlowEVMBridgeUtils.call(
let unwrapResult = FlowEVMBridgeUtils.callWithSigAndArgs(
signature: "withdraw(uint256)",
targetEVMAddress: wflowAddress,
args: [amount],
gasLimit: FlowEVMBridgeConfig.gasLimit,
value: 0.0
value: 0.0,
resultTypes: nil
)
assert(unwrapResult.status == EVM.Status.successful, message: "Failed to unwrap WFLOW as FLOW")

Expand All @@ -349,34 +346,24 @@ access(all) contract FlowEVMBridgeHandlers {
// Cover underflow
assert(
postBalance > preBalance,
message: "Escrowed FLOW Balance did not increment after unwrapping WFLOW - pre: ".concat(preBalance.toString())
.concat(" | post: ").concat(postBalance.toString())
message: "Escrowed FLOW Balance did not increment after unwrapping WFLOW - pre: \(preBalance.toString()) | post: \(postBalance.toString())"
)
// Confirm bridge COA's FLOW balance has incremented by the expected amount
assert(
UInt256(postBalance - preBalance) == amount,
message: "Escrowed WFLOW balance after unwrapping does not match requested amount - expected: "
.concat((UInt256(preBalance) + amount).toString())
.concat(" | actual: ")
.concat((postBalance - preBalance).toString())
message: "Escrowed WFLOW balance after unwrapping does not match requested amount - expected: \(UInt256(preBalance) + amount).toString()) | actual: \(postBalance - preBalance).toString())"
)

// Withdraw escrowed FLOW from bridge COA
let withdrawBalance = EVM.Balance(attoflow: UInt(amount))
assert(
UInt256(withdrawBalance.attoflow) == amount,
message: "Requested balance failed to convert to attoflow - expected: "
.concat(amount.toString())
.concat(" | actual: ")
.concat(withdrawBalance.attoflow.toString())
message: "Requested balance failed to convert to attoflow - expected: \(amount.toString()) | actual: \(withdrawBalance.attoflow.toString())"
)
let flowVault <- coa.withdraw(balance: withdrawBalance)
assert(
flowVault.balance == ufixAmount,
message: "Resulting FLOW Vault balance does not match requested amount - expected: "
.concat(ufixAmount.toString())
.concat(" | actual: ")
.concat(flowVault.balance.toString())
message: "Resulting FLOW Vault balance does not match requested amount - expected: \(ufixAmount.toString()) | actual: \(flowVault.balance.toString())"
)
return <-flowVault
}
Expand All @@ -388,15 +375,13 @@ access(all) contract FlowEVMBridgeHandlers {
/// Sets the target type for the handler
access(FlowEVMBridgeHandlerInterfaces.Admin)
fun setTargetType(_ type: Type) {
panic("WFLOWTokenHandler has targetType set to "
.concat(self.targetType.identifier).concat(" at initialization"))
panic("WFLOWTokenHandler has targetType set to \(self.targetType.identifier) at initialization")
}

/// Sets the target EVM address for the handler
access(FlowEVMBridgeHandlerInterfaces.Admin)
fun setTargetEVMAddress(_ address: EVM.EVMAddress) {
panic("WFLOWTokenHandler has EVMAddress set to "
.concat(self.targetEVMAddress.toString()).concat(" at initialization"))
panic("WFLOWTokenHandler has EVMAddress set to \(self.targetEVMAddress.toString()) at initialization")
}

/// Sets the target type for the handler
Expand Down
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