Merge pull request #8270 from ethereum/sol2yul-ExternalCall

Finishes external call implementation.

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -622,13 +622,13 @@ void IRGeneratorForStatements::endVisit(FunctionCall const& _functionCall)
 		}
 		solAssert(indexedArgs.size() <= 4, "Too many indexed arguments.");
 		Whiskers templ(R"({
-			let <pos> := mload(<freeMemoryPointer>)
+			let <pos> := <freeMemory>
 			let <end> := <encode>(<pos> <nonIndexedArgs>)
 			<log>(<pos>, sub(<end>, <pos>) <indexedArgs>)
 		})");
 		templ("pos", m_context.newYulVariable());
 		templ("end", m_context.newYulVariable());
-		templ("freeMemoryPointer", to_string(CompilerUtils::freeMemoryPointer));
+		templ("freeMemory", freeMemory());
 		templ("encode", abi.tupleEncoder(nonIndexedArgTypes, nonIndexedParamTypes));
 		templ("nonIndexedArgs", nonIndexedArgs);
 		templ("log", "log" + to_string(indexedArgs.size()));
@@ -1173,7 +1173,7 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 	bool useStaticCall = funKind == FunctionType::Kind::BareStaticCall || (funType.stateMutability() <= StateMutability::View && m_context.evmVersion().hasStaticCall());
 
 	bool haveReturndatacopy = m_context.evmVersion().supportsReturndata();
-	unsigned retSize = 0;
+	unsigned estimatedReturnSize = 0;
 	bool dynamicReturnSize = false;
 	TypePointers returnTypes;
 	if (!returnSuccessConditionAndReturndata)
@@ -1188,13 +1188,13 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 			{
 				solAssert(haveReturndatacopy, "");
 				dynamicReturnSize = true;
-				retSize = 0;
+				estimatedReturnSize = 0;
 				break;
 			}
 			else if (retType->decodingType())
-				retSize += retType->decodingType()->calldataEncodedSize();
+				estimatedReturnSize += retType->decodingType()->calldataEncodedSize();
 			else
-				retSize += retType->calldataEncodedSize();
+				estimatedReturnSize += retType->calldataEncodedSize();
 	}
 
 	TypePointers argumentTypes;
@@ -1204,7 +1204,7 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 		argumentTypes.emplace_back(&type(*arg));
 		argumentStrings.emplace_back(IRVariable(*arg).commaSeparatedList());
 	}
-	string argumentString = joinHumanReadable(argumentStrings);
+	string argumentString = ", " + joinHumanReadable(argumentStrings);
 
 	solUnimplementedAssert(funKind != FunctionType::Kind::ECRecover, "");
 
@@ -1214,8 +1214,8 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 		// (which we would have to subtract from the gas left)
 		// We could also just use MLOAD; POP right before the gas calculation, but the optimizer
 		// would remove that, so we use MSTORE here.
-		if (!funType.gasSet() && retSize > 0)
-			m_code << "mstore(add(" << fetchFreeMem() << ", " << to_string(retSize) << "), 0)\n";
+		if (!funType.gasSet() && estimatedReturnSize > 0)
+			m_code << "mstore(add(" << freeMemory() << ", " << to_string(estimatedReturnSize) << "), 0)\n";
 	}
 
 	ABIFunctions abi(m_context.evmVersion(), m_context.revertStrings(), m_context.functionCollector());
@@ -1226,26 +1226,29 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 			if iszero(extcodesize(<address>)) { revert(0, 0) }
 		</checkExistence>
 
-		let <pos> := <freeMem>
+		let <pos> := <freeMemory>
+
 		mstore(<pos>, <shl28>(<funId>))
 		let <end> := <encodeArgs>(add(<pos>, 4) <argumentString>)
 
-		let <result> := <call>(<gas>, <address>, <value>, <pos>, sub(<end>, <pos>), <pos>, <retSize>)
-		if iszero(<result>) { <forwardingRevert> }
+		let <result> := <call>(<gas>, <address>, <?hasValue> <value>, </hasValue> <pos>, sub(<end>, <pos>), <pos>, <reservedReturnSize>)
+		if iszero(<result>) { <forwardingRevert>() }
 
 		<?dynamicReturnSize>
 			returndatacopy(<pos>, 0, returndatasize())
 		</dynamicReturnSize>
-		<allocate>
-		mstore(<freeMem>, add(<pos>, and(add(<retSize>, 0x1f), not(0x1f))))
-		<?returns> let <retvars> := </returns> <abiDecode>(<pos>, <retSize>)
+
+		mstore(<freeMemoryPointer>, add(<pos>, and(add(<returnSize>, 0x1f), not(0x1f))))
+		<?returns> let <retVars> := </returns> <abiDecode>(<pos>, add(<pos>, <returnSize>))
 	)");
 	templ("pos", m_context.newYulVariable());
 	templ("end", m_context.newYulVariable());
 	templ("result", m_context.newYulVariable());
-	templ("freeMem", fetchFreeMem());
+	templ("freeMemory", freeMemory());
+	templ("freeMemoryPointer", to_string(CompilerUtils::freeMemoryPointer));
 	templ("shl28", m_utils.shiftLeftFunction(8 * (32 - 4)));
 	templ("funId", IRVariable(_functionCall.expression()).part("functionIdentifier").name());
+	templ("address", IRVariable(_functionCall.expression()).part("address").name());
 
 	// If the function takes arbitrary parameters or is a bare call, copy dynamic length data in place.
 	// Move arguments to memory, will not update the free memory pointer (but will update the memory
@@ -1257,23 +1260,19 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 		encodeInPlace = false;
 	bool encodeForLibraryCall = funKind == FunctionType::Kind::DelegateCall;
 	solUnimplementedAssert(!encodeInPlace, "");
-	solUnimplementedAssert(!funType.padArguments(), "");
+	solUnimplementedAssert(funType.padArguments(), "");
 	templ("encodeArgs", abi.tupleEncoder(argumentTypes, funType.parameterTypes(), encodeForLibraryCall));
 	templ("argumentString", argumentString);
 
 	// Output data will replace input data, unless we have ECRecover (then, output
 	// area will be 32 bytes just before input area).
-	templ("retSize", to_string(retSize));
 	solUnimplementedAssert(funKind != FunctionType::Kind::ECRecover, "");
 
-	if (isDelegateCall)
-		solAssert(!funType.valueSet(), "Value set for delegatecall");
-	else if (useStaticCall)
-		solAssert(!funType.valueSet(), "Value set for staticcall");
-	else if (funType.valueSet())
-		templ("value", IRVariable(_functionCall.expression()).part("value").name());
-	else
-		templ("value", "0");
+	solAssert(!isDelegateCall || !funType.valueSet(), "Value set for delegatecall");
+	solAssert(!useStaticCall || !funType.valueSet(), "Value set for staticcall");
+
+	templ("hasValue", !isDelegateCall && !useStaticCall);
+	templ("value", funType.valueSet() ? IRVariable(_functionCall.expression()).part("value").name() : "0");
 
 	// Check that the target contract exists (has code) for non-low-level calls.
 	bool checkExistence = (funKind == FunctionType::Kind::External || funKind == FunctionType::Kind::DelegateCall);
@@ -1315,13 +1314,18 @@ void IRGeneratorForStatements::appendExternalFunctionCall(
 	if (haveReturndatacopy)
 		templ("returnSize", "returndatasize()");
 	else
-		templ("returnSize", to_string(retSize));
+		templ("returnSize", to_string(estimatedReturnSize));
+
+	templ("reservedReturnSize", dynamicReturnSize ? "0" : to_string(estimatedReturnSize));
+
 	templ("abiDecode", abi.tupleDecoder(returnTypes, true));
 	templ("returns", !returnTypes.empty());
 	templ("retVars", IRVariable(_functionCall).commaSeparatedList());
+
+	m_code << templ.render();
 }
 
-string IRGeneratorForStatements::fetchFreeMem() const
+string IRGeneratorForStatements::freeMemory()
 {
 	return "mload(" + to_string(CompilerUtils::freeMemoryPointer) + ")";
 }

libsolidity/codegen/ir/IRGeneratorForStatements.h

@@ -75,7 +75,9 @@ private:
 		std::vector<ASTPointer<Expression const>> const& _arguments
 	);
 
-	std::string fetchFreeMem() const;
+	/// @returns code that evaluates to the first unused memory slot (which does not have to
+	/// be empty).
+	static std::string freeMemory();
 
 	/// Generates the required conversion code and @returns an IRVariable referring to the value of @a _variable
 	/// converted to type @a _to.

test/libsolidity/semanticTests/array/memory.sol

@@ -0,0 +1,17 @@
+pragma solidity >= 0.6.0;
+
+contract C {
+    function h(uint[4] memory n) public pure returns (uint) {
+        return n[0] + n[1] + n[2] + n[3];
+    }
+
+    function i(uint[4] memory n) public view returns (uint) {
+        return this.h(n) * 2;
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// h(uint256[4]): 1, 2, 3, 4 -> 10
+// i(uint256[4]): 1, 2, 3, 4 -> 20

test/libsolidity/semanticTests/functionCall/external_call.sol

@@ -0,0 +1,17 @@
+pragma solidity >= 0.6.0;
+
+contract C {
+    function g(uint n) external pure returns (uint) {
+        return n + 1;
+    }
+
+    function f(uint n) public view returns (uint) {
+        return this.g(2 * n);
+    }
+}
+
+// ====
+// compileViaYul: also
+// ----
+// g(uint256): 4 -> 5
+// f(uint256): 2 -> 5

test/libsolidity/semanticTests/functionCall/external_call_dynamic_returndata.sol

@@ -0,0 +1,24 @@
+pragma solidity >= 0.6.0;
+
+contract C {
+    function d(uint n) external pure returns (uint[] memory) {
+        uint[] memory data = new uint[](n);
+        for (uint i = 0; i < data.length; ++i)
+            data[i] = i;
+        return data;
+    }
+
+    function dt(uint n) public view returns (uint) {
+        uint[] memory data = this.d(n);
+        uint sum = 0;
+        for (uint i = 0; i < data.length; ++i)
+            sum += data[i];
+        return sum;
+    }
+}
+
+// ====
+// compileViaYul: also
+// EVMVersion: >=byzantium
+// ----
+// dt(uint256): 4 -> 6