feat(assex): add calloutputat interface (#50)

* feat: add callOutputAt precompile interface

* test: cover reverted callOutputAt cases

Author: makemake-kbo

README.md

@@ -154,6 +154,7 @@ Access these via the `ph` instance inherited from `Credible`:
 | `getDelegateCallInputs(address, bytes4)` | Get DELEGATECALL inputs |
 | `getAllCallInputs(address, bytes4)` | Get all call types |
 | `callinputAt(uint256)` | Get full recorded calldata for one call id |
+| `callOutputAt(uint256)` | Get full recorded return or revert bytes for one call id |
 | `getStateChanges(address, bytes32)` | Get state changes for a slot |
 | `getAssertionAdopter()` | Get the adopter contract address |
 

src/PhEvm.sol

@@ -219,6 +219,11 @@ interface PhEvm {
     /// @return calls Array of CallInputs from CALLCODE opcodes
     function getCallCodeInputs(address target, bytes4 selector) external view returns (CallInputs[] memory calls);
 
+    /// @notice Returns the raw return or revert bytes for a traced call.
+    /// @param callId The call identifier from CallInputs.id.
+    /// @return output The raw ABI-encoded return bytes or revert bytes.
+    function callOutputAt(uint256 callId) external view returns (bytes memory output);
+
     /// @notice Returns the calldata of a specific call.
     /// @param callId The call ID to read input from.
     /// @return input The raw calldata bytes (selector + ABI-encoded arguments).

src/test-cases/precompiles/CallOutputAt.sol

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.13;
+
+import {Assertion} from "../../Assertion.sol";
+import {PhEvm} from "../../PhEvm.sol";
+import {Target, TARGET} from "../common/Target.sol";
+
+contract TestCallOutputAt is Assertion {
+    constructor() payable {}
+
+    function callOutputAtReturnsEncodedReturnData() external view {
+        PhEvm.CallInputs[] memory readCalls = ph.getStaticCallInputs(address(TARGET), Target.readStorage.selector);
+        require(readCalls.length == 1, "expected one readStorage call");
+
+        bytes memory output = ph.callOutputAt(readCalls[0].id);
+        require(abi.decode(output, (uint256)) == 7, "unexpected readStorage output");
+    }
+
+    function callOutputAtReturnsEmptyBytesForVoidCall() external view {
+        bytes memory output = ph.callOutputAt(_successfulNestedWriteId());
+        require(output.length == 0, "void call should return empty bytes");
+    }
+
+    function callOutputAtReturnsRevertData() external view {
+        bytes memory output = ph.callOutputAt(_revertedWriteStorageAndRevertId());
+        require(output.length >= 4, "reverting call should return revert bytes");
+    }
+
+    function callOutputAtRejectsRevertedSubtreeCallId() external view {
+        uint256 revertedCallId = _revertedSubtreeChildCallId();
+        bytes memory calldata_ = abi.encodeWithSelector(PhEvm.callOutputAt.selector, revertedCallId);
+        (bool success,) = address(ph).staticcall(calldata_);
+        require(!success, "reverted subtree call should revert");
+    }
+
+    function _successfulNestedWriteId() internal view returns (uint256 successfulNestedWriteId) {
+        PhEvm.CallInputs[] memory writeCalls = ph.getCallInputs(address(TARGET), Target.writeStorage.selector);
+
+        bool found;
+        for (uint256 i = 0; i < writeCalls.length; i++) {
+            uint256 param = abi.decode(writeCalls[i].input, (uint256));
+            if (param == 7) {
+                successfulNestedWriteId = writeCalls[i].id;
+                found = true;
+                break;
+            }
+        }
+
+        require(found, "expected nested writeStorage call");
+    }
+
+    function _revertedWriteStorageAndRevertId() internal view returns (uint256) {
+        return _successfulNestedWriteId() + 1;
+    }
+
+    function _revertedSubtreeChildCallId() internal view returns (uint256) {
+        return _revertedWriteStorageAndRevertId() + 2;
+    }
+
+    function triggers() external view override {
+        registerCallTrigger(this.callOutputAtReturnsEncodedReturnData.selector);
+        registerCallTrigger(this.callOutputAtReturnsEmptyBytesForVoidCall.selector);
+        registerCallTrigger(this.callOutputAtReturnsRevertData.selector);
+        registerCallTrigger(this.callOutputAtRejectsRevertedSubtreeCallId.selector);
+    }
+}
+
+contract TriggeringTx {
+    constructor() payable {
+        TARGET.writeStorage(5);
+
+        CallFrameTrigger callFrameTrigger = new CallFrameTrigger();
+        callFrameTrigger.trigger();
+
+        RevertingSubtreeTrigger revertingSubtreeTrigger = new RevertingSubtreeTrigger();
+        try revertingSubtreeTrigger.trigger() {
+            revert("expected reverting subtree to revert");
+        } catch {}
+
+        uint256 value = TARGET.readStorage();
+        require(value == 7, "readStorage call failed");
+    }
+}
+
+contract CallFrameTrigger {
+    function trigger() external {
+        TARGET.writeStorage(7);
+
+        try TARGET.writeStorageAndRevert(11) {
+            revert("expected writeStorageAndRevert to revert");
+        } catch {}
+    }
+}
+
+contract RevertingSubtreeTrigger {
+    function trigger() external {
+        TARGET.writeStorage(9);
+        revert("reverted subtree");
+    }
+}