Merge 87ce29542c into 72671d6c88

Changelog.md

@@ -81,6 +81,7 @@ Compiler Features:
  * SMTChecker: Properties that are proved safe are now reported explicitly at the end of analysis. By default, only the number of safe properties is shown. The CLI option ``--model-checker-show-proved-safe`` and the JSON option ``settings.modelChecker.showProvedSafe`` can be enabled to show the full list of safe properties.
  * Standard JSON Interface: Add experimental support for importing ASTs via Standard JSON.
  * Yul EVM Code Transform: If available, use ``push0`` instead of ``codesize`` to produce an arbitrary value on stack in order to create equal stack heights between branches.
+ * Yul IR Code Generation: Cheaper code for reverting with errors of a static small encoding size.
 
 
 Bugfixes:

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -47,6 +47,7 @@
 #include <libsolutil/FunctionSelector.h>
 #include <libsolutil/Visitor.h>
 
+#include <range/v3/algorithm/all_of.hpp>
 #include <range/v3/view/transform.hpp>
 
 using namespace solidity;
@@ -57,6 +58,18 @@ using namespace std::string_literals;
 namespace
 {
 
+optional<size_t> staticEncodingSize(vector<Type const*> const& _parameterTypes)
+{
+	size_t encodedSize = 0;
+	for (auto const* type: _parameterTypes)
+	{
+		if (type->isDynamicallyEncoded())
+			return nullopt;
+		encodedSize += type->calldataHeadSize();
+	}
+	return encodedSize;
+}
+
 struct CopyTranslate: public yul::ASTCopier
 {
 	using ExternalRefsMap = std::map<yul::Identifier const*, InlineAssemblyAnnotation::ExternalIdentifierInfo>;
@@ -3362,8 +3375,16 @@ void IRGeneratorForStatements::revertWithError(
 	std::vector<ASTPointer<Expression const>> const& _errorArguments
 )
 {
+	bool needsAllocation = true;
+	if (optional<size_t> size = staticEncodingSize(_parameterTypes))
+		if (ranges::all_of(_parameterTypes, [](auto const* type) { return type && type->isValueType(); }))
+			needsAllocation = *size + 4 > CompilerUtils::generalPurposeMemoryStart;
 	Whiskers templ(R"({
+		<?needsAllocation>
 		let <pos> := <allocateUnbounded>()
+		<!needsAllocation>
+		let <pos> := 0
+		</needsAllocation>
 		mstore(<pos>, <hash>)
 		let <end> := <encode>(add(<pos>, 4) <argumentVars>)
 		revert(<pos>, sub(<end>, <pos>))
@@ -3371,6 +3392,8 @@ void IRGeneratorForStatements::revertWithError(
 	templ("pos", m_context.newYulVariable());
 	templ("end", m_context.newYulVariable());
 	templ("hash", util::selectorFromSignatureU256(_signature).str());
+	templ("needsAllocation", needsAllocation);
+	if (needsAllocation)
 		templ("allocateUnbounded", m_utils.allocateUnboundedFunction());
 
 	std::vector<std::string> errorArgumentVars;

test/libsolidity/semanticTests/errors/small_error_optimization.sol

@@ -0,0 +1,19 @@
+error E();
+contract A {
+	uint8[] x;
+	function f() public {
+		for (uint i = 0; i < 100; ++i)
+			x.push(uint8(i));
+		revert E();
+	}
+}
+contract B {
+	function f() public {
+		(new A()).f();
+	}
+}
+// ----
+// f() -> FAILURE, hex"92bbf6e8"
+// gas irOptimized: 270934
+// gas legacy: 310592
+// gas legacyOptimized: 273662