f

Author: clonker

libyul/backends/evm/SSACFGEVMCodeTransform.cpp

@@ -331,12 +331,17 @@ void SSACFGEVMCodeTransform::operator()(SSACFG::BlockId const _block)
 			yulAssert(static_cast<size_t>(m_assembly.stackHeight()) == m_stack.size());
 			m_assembly.setStackHeight(m_assembly.stackHeight()+1);
 			std::vector<SSACFGStackLayout::Slot> returnSlots;
+
+			// [label, ret1, ret2, ..., retn]
 			if (!_return.returnValues.empty())
 			{
 				returnSlots.assign(_return.returnValues.begin()+1, _return.returnValues.end());
 				returnSlots.emplace_back(_return.returnValues.front());
+
 				shuffleStack(returnSlots);
+				// stack = [..., label, ret2, ..., retn, ret1]
 				m_assembly.appendInstruction(evmasm::swapInstruction(static_cast<unsigned>(_return.returnValues.size())));
+				// swapN -> stack = [..., ret1, ret2, ..., retn, label]
 			}
 			else
 				shuffleStack(returnSlots);

libyul/backends/evm/ssa/OperationForwardShuffler.h

@@ -358,6 +358,9 @@ class OperationForwardShuffler
 		yulAssert(_stack.empty() || std::holds_alternative<JunkSlot>(_stack.top()) || ops.stackStats.argsCount(_stack.top()) > 0 || ops.stackStats.tailCount(_stack.top()) > 0 || ops.isArgsCompatible(0, 0));
 
 		// if the top is junk and popping it fixes more positions in args than not popping it, pop it, next step
+		// want: [arg3, arg2, arg1]
+		// have: [arg3, arg2, arg1, JUNK]
+		// -> popping JUNK fixes three arg positions immediately
 		if (!_stack.empty() && std::holds_alternative<JunkSlot>(_stack.top()))
 		{
 			std::ptrdiff_t score = 0;

libyul/backends/evm/ssa/StackLayoutGenerator.cpp

@@ -421,6 +421,7 @@ void StackLayoutGenerator::visitBlock(SSACFG::BlockId const& _blockId)
 		//auto const nonZeroUsed = m_liveness.used(cjump->nonZero);
 		//auto const zeroUsed = m_liveness.used(cjump->zero);
 
+		// todo isn't this the same as looking at the live-out of the current block!?
 		LivenessAnalysis::LivenessData liveOutUnion;
 		for (auto const& [liveIn, target]: { std::pair{&zeroLiveIn, cjump->zero}, std::pair{&nonZeroLiveIn, cjump->nonZero} }) {
 			ReversePhiFunctionTransform transf(m_cfg, _blockId, target);

tools/yulBench/main.cpp

@@ -81,15 +81,15 @@ solidity::yul::ssa::ControlFlowLiveness computeLiveness(solidity::yul::ssa::Cont
 }
 
 static void BM_BuildSSACFG(benchmark::State& state) {
-	auto const& object = parse("/home/mho/dev/solidity/PoolManager_optimized.yul");
+	auto const& object = parse("/home/mho/dev/solidity/deposit_ir.yul");
 	for (auto _ : state) {
 		auto cfg = buildSSACFG(*object);
 		benchmark::DoNotOptimize(cfg);
 	}
 }
 
 static void BM_SSACFGLiveness(benchmark::State& state) {
-	auto const& object = parse("/home/mho/dev/solidity/PoolManager_optimized.yul");
+	auto const& object = parse("/home/mho/dev/solidity/deposit_ir.yul");
 	auto const cfg = buildSSACFG(*object);
 	for (auto _ : state) {
 		auto cfgLiveness = computeLiveness(*cfg);
@@ -98,7 +98,7 @@ static void BM_SSACFGLiveness(benchmark::State& state) {
 }
 
 static void BM_SSACFGStackLayoutGenerator(benchmark::State& state) {
-	auto const& object = parse("/home/mho/dev/solidity/PoolManager_optimized.yul");
+	auto const& object = parse("/home/mho/dev/solidity/deposit_ir.yul");
 	auto const cfg = buildSSACFG(*object);
 	auto const cfgLiveness = computeLiveness(*cfg);
 	for (auto _ : state) {