SSA CFG: Add outputsOf helper that returns a range over inst id

Author: clonker

libyul/backends/evm/ssa/CodeTransform.cpp

@@ -309,16 +309,14 @@ void CodeTransform::operator()(InstId _instId, StackData const& _operationInputL
 	for (size_t i = 0; i < _inst.inputs.size(); ++i)
 		m_stack.pop<false>();
 	// simulate that the outputs are produced
-	std::vector<InstId> outputs;
-	outputs.reserve(m_cfg.numReturnsOf(_instId));
-	m_cfg.forEachOutput(_instId, [&](InstId const id) { outputs.push_back(id); });
-	for (InstId const id: outputs)
+	auto const numOutputs = m_cfg.numReturnsOf(_instId);
+	for (InstId const id: m_cfg.outputsOf(_instId))
 		m_stack.push<false>(StackSlot::makeValue(m_cfg, id));
 
-	yulAssert(m_stack.size() == baseHeight + outputs.size());
+	yulAssert(m_stack.size() == baseHeight + numOutputs);
 	for (auto const& [stackEntry, output]: ranges::views::zip(
-		m_stack.data() | ranges::views::take_last(outputs.size()),
-		outputs
+		m_stack.data() | ranges::views::take_last(numOutputs),
+		m_cfg.outputsOf(_instId)
 	))
 		yulAssert(stackEntry.isValue() && stackEntry.value() == output);
 	yulAssert(

libyul/backends/evm/ssa/SSACFG.h

@@ -32,9 +32,10 @@
 
 #include <libsolutil/Numeric.h>
 
+#include <range/v3/range/concepts.hpp>
 #include <range/v3/range/conversion.hpp>
+#include <range/v3/range/traits.hpp>
 #include <range/v3/view/iota.hpp>
-#include <range/v3/view/subrange.hpp>
 #include <range/v3/view/transform.hpp>
 
 #include <concepts>
@@ -47,6 +48,9 @@ namespace solidity::yul::ssa
 class LivenessAnalysis;
 struct ControlFlowGraphs;
 
+template<typename R, typename T>
+concept InputRangeOf = ranges::input_range<R> && std::same_as<ranges::range_value_t<R>, T>;
+
 class SSACFG
 {
 public:
@@ -316,7 +320,7 @@ class SSACFG
 	/// View over the contiguous trailing Projections of `_producer` in `m_insts`. Empty for ops with <= 1 returns.
 	/// Note this relies on the m_insts-contiguity invariant established by `make(Builtin)CallWithProjections`:
 	/// projections live at `m_insts[_producer.value+1..+numReturns]`.
-	auto projectionsOf(InstId const _producer) const
+	InputRangeOf<InstId> auto projectionsOf(InstId const _producer) const
 	{
 		std::size_t const n = numReturnsOf(_producer);
 		std::size_t const count = n >= 2 ? n : 0;
@@ -341,26 +345,33 @@ class SSACFG
 		}
 		return
 			ranges::views::iota(static_cast<InstId::ValueType>(firstIdx), static_cast<InstId::ValueType>(lastIdx)) |
-			ranges::views::transform([](InstId::ValueType const _idVal) { return InstId{_idVal}; });
+			ranges::views::transform(&toInstId);
+	}
+
+	/// View over the logical outputs of `_producer` in stack order: the producer itself if it has a single return,
+	/// the trailing Projections if it has multiple, and an empty range otherwise.
+	InputRangeOf<InstId> auto outputsOf(InstId const _producer) const
+	{
+		std::size_t const n = numReturnsOf(_producer);
+		if (n >= 2)
+			return projectionsOf(_producer);
+		auto const firstIdx = static_cast<InstId::ValueType>(_producer.value);
+		return
+			ranges::views::iota(firstIdx, static_cast<InstId::ValueType>(firstIdx + n)) |
+			ranges::views::transform(&toInstId);
 	}
 
 	/// Invokes `_fn(InstId)` once per logical output of `_producer` in stack order.
 	template<std::invocable<InstId> Fn>
 	void forEachOutput(InstId const _producer, Fn&& _fn) const
 	{
-		auto const n = numReturnsOf(_producer);
-		if (n == 0)
-			return;
-		if (n == 1)
-		{
-			_fn(_producer);
-			return;
-		}
-		for (InstId const id: projectionsOf(_producer))
+		for (InstId const id: outputsOf(_producer))
 			_fn(id);
 	}
 
 private:
+	static InstId toInstId(InstId::ValueType const _v) { return InstId{_v}; }
+
 	InstId makeBuiltinCall(
 		BlockId const _block,
 		BuiltinCall _payload,

libyul/backends/evm/ssa/SSACFGBuilder.cpp

@@ -430,10 +430,10 @@ void SSACFGBuilder::assign(std::vector<std::reference_wrapper<Scope::Variable co
 		}
 		else
 		{
-			std::vector<InstId> outputs;
-			m_graph.forEachOutput(callId, [&](InstId const id) { outputs.push_back(id); });
+			yulAssert(m_graph.numReturnsOf(callId) == _variables.size());
+			auto const outputs = m_graph.outputsOf(callId);
 			yulAssert(outputs.size() == _variables.size());
-			for (auto const& [var, output]: ranges::zip_view(_variables, outputs))
+			for (auto const& [var, output]: ranges::views::zip(_variables, outputs))
 				writeVariable(var, m_currentBlock, output);
 		}
 		return;

libyul/backends/evm/ssa/StackLayoutGenerator.cpp

@@ -231,7 +231,7 @@ void StackLayoutGenerator::visitBlock(SSACFG::BlockId const& _blockId)
 	auto const& operationsLiveOut = m_liveness.operationsLiveOut(_blockId);
 	blockLayout.operationIn.reserve(operationsLiveOut.size());
 	std::size_t operationIndex = 0;
-	m_cfg.forEachOperation(block, [&](InstId const _instId, SSACFG::Inst const& _inst){
+	m_cfg.forEachOperation(block, [&](InstId const _instId, SSACFG::Inst const& _inst) {
 		auto opLiveOutWithoutOutputs = operationsLiveOut[operationIndex];
 		m_cfg.forEachOutput(_instId, [&](InstId const id) { opLiveOutWithoutOutputs.erase(id); });
 

libyul/backends/evm/ssa/io/JSONExporter.cpp

@@ -70,9 +70,7 @@ Json toJson(Json& _ret, SSACFG const& _cfg, InstId const _instId, ControlFlowGra
 	}
 
 	opJson["in"] = toJson(_cfg, inst.inputs);
-	std::vector<InstId> outputs;
-	_cfg.forEachOutput(_instId, [&](InstId const id) { outputs.push_back(id); });
-	opJson["out"] = toJson(_cfg, outputs);
+	opJson["out"] = toJson(_cfg, _cfg.outputsOf(_instId));
 
 	return opJson;
 }