Take termination into account for data flow analyzer.

libyul/optimiser/DataFlowAnalyzer.cpp

@@ -43,10 +43,12 @@ using namespace solidity::yul;
 
 DataFlowAnalyzer::DataFlowAnalyzer(
 	Dialect const& _dialect,
-	map<YulString, SideEffects> _functionSideEffects
+	map<YulString, SideEffects> _functionSideEffects,
+	map<YulString, ControlFlowSideEffects> _controlFlowSideEffects
 ):
 	m_dialect(_dialect),
 	m_functionSideEffects(std::move(_functionSideEffects)),
+	m_controlFlowSideEffects(std::move(_controlFlowSideEffects)),
 	m_knowledgeBase(_dialect, m_value)
 {
 	if (auto const* builtin = _dialect.memoryStoreFunction(YulString{}))
@@ -120,9 +122,10 @@ void DataFlowAnalyzer::operator()(If& _if)
 	unordered_map<YulString, YulString> memory = m_memory;
 
 	ASTModifier::operator()(_if);
+	joinKnowledge(storage, memory, _if.body);
 
-	joinKnowledge(storage, memory);
-
+	// TODO we can do the same optimization here, but maybe this is already done in the ssa
+	// transform or some other step?
 	clearValues(assignedVariableNames(_if.body));
 }
 
@@ -136,8 +139,8 @@ void DataFlowAnalyzer::operator()(Switch& _switch)
 		unordered_map<YulString, YulString> storage = m_storage;
 		unordered_map<YulString, YulString> memory = m_memory;
 		(*this)(_case.body);
-		//TODO throw away knowledge if it is terminating
-		joinKnowledge(storage, memory);
+
+		joinKnowledge(storage, memory, _case.body);
 
 		set<YulString> variables = assignedVariableNames(_case.body);
 		assignedVariables += variables;
@@ -343,7 +346,8 @@ void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Block const& _block)
 
 void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Expression const& _expr)
 {
-	// TODO with the extended side-effects, this could also be more precise now.
+	// TODO with the extended side-effects, this could also be more precise now,
+	// I.e. we should check collisions like we do for sstore and mstore
 	SideEffectsCollector sideEffects(m_dialect, _expr, &m_functionSideEffects);
 	if (sideEffects.invalidatesStorage())
 		m_storage.clear();
@@ -353,11 +357,25 @@ void DataFlowAnalyzer::clearKnowledgeIfInvalidated(Expression const& _expr)
 
 void DataFlowAnalyzer::joinKnowledge(
 	unordered_map<YulString, YulString> const& _olderStorage,
-	unordered_map<YulString, YulString> const& _olderMemory
+	unordered_map<YulString, YulString> const& _olderMemory,
+	Block const& _branch
 )
 {
-	joinKnowledgeHelper(m_storage, _olderStorage);
-	joinKnowledgeHelper(m_memory, _olderMemory);
+	if (
+		_branch.statements.empty() ||
+		TerminationFinder(m_dialect, &m_controlFlowSideEffects).controlFlowKind(_branch.statements.back()) ==
+		TerminationFinder::ControlFlow::FlowOut
+	)
+	{
+		joinKnowledgeHelper(m_storage, _olderStorage);
+		joinKnowledgeHelper(m_memory, _olderMemory);
+	}
+	else
+	{
+		// TOOD test that this works with 'break' and 'continue'
+		m_storage = _olderStorage;
+		m_memory = _olderMemory;
+	}
 }
 
 void DataFlowAnalyzer::joinKnowledgeHelper(

libyul/optimiser/DataFlowAnalyzer.h

@@ -28,6 +28,7 @@
 #include <libyul/YulString.h>
 #include <libyul/AST.h> // Needed for m_zero below.
 #include <libyul/SideEffects.h>
+#include <libyul/ControlFlowSideEffects.h>
 
 #include <libsolutil/Common.h>
 
@@ -85,7 +86,8 @@ public:
 	///            The parameter is mostly used to determine movability of expressions.
 	explicit DataFlowAnalyzer(
 		Dialect const& _dialect,
-		std::map<YulString, SideEffects> _functionSideEffects = {}
+		std::map<YulString, SideEffects> _functionSideEffects = {},
+		std::map<YulString, ControlFlowSideEffects> _controlFlowSideEffects = {}
 	);
 
 	using ASTModifier::operator();
@@ -123,9 +125,12 @@ protected:
 	/// Joins knowledge about storage and memory with an older point in the control-flow.
 	/// This only works if the current state is a direct successor of the older point,
 	/// i.e. `_otherStorage` and `_otherMemory` cannot have additional changes.
+	/// If the last statement in the vector is not continuing, replace the current knowledge
+	/// with the old instead.
 	void joinKnowledge(
 		std::unordered_map<YulString, YulString> const& _olderStorage,
-		std::unordered_map<YulString, YulString> const& _olderMemory
+		std::unordered_map<YulString, YulString> const& _olderMemory,
+		Block const& _branch
 	);
 
 	static void joinKnowledgeHelper(
@@ -163,6 +168,7 @@ protected:
 	/// Side-effects of user-defined functions. Worst-case side-effects are assumed
 	/// if this is not provided or the function is not found.
 	std::map<YulString, SideEffects> m_functionSideEffects;
+	std::map<YulString, ControlFlowSideEffects> m_controlFlowSideEffects;
 
 	/// Current values of variables, always movable.
 	std::map<YulString, AssignedValue> m_value;

libyul/optimiser/LoadResolver.cpp

@@ -26,6 +26,7 @@
 #include <libyul/backends/evm/EVMMetrics.h>
 #include <libyul/optimiser/Semantics.h>
 #include <libyul/optimiser/CallGraphGenerator.h>
+#include <libyul/ControlFlowSideEffectsCollector.h>
 #include <libyul/SideEffects.h>
 #include <libyul/AST.h>
 #include <libyul/Utilities.h>
@@ -47,6 +48,7 @@ void LoadResolver::run(OptimiserStepContext& _context, Block& _ast)
 	LoadResolver{
 		_context.dialect,
 		SideEffectsPropagator::sideEffects(_context.dialect, CallGraphGenerator::callGraph(_ast)),
+		ControlFlowSideEffectsCollector{_context.dialect, _ast}.functionSideEffectsNamed(),
 		containsMSize,
 		_context.expectedExecutionsPerDeployment
 	}(_ast);

libyul/optimiser/LoadResolver.h

@@ -24,6 +24,7 @@
 
 #include <libyul/optimiser/DataFlowAnalyzer.h>
 #include <libyul/optimiser/OptimiserStep.h>
+#include <libyul/ControlFlowSideEffects.h>
 
 namespace solidity::yul
 {
@@ -50,10 +51,11 @@ private:
 	LoadResolver(
 		Dialect const& _dialect,
 		std::map<YulString, SideEffects> _functionSideEffects,
+		std::map<YulString, ControlFlowSideEffects> _controlFlowSideEffects,
 		bool _containsMSize,
 		std::optional<size_t> _expectedExecutionsPerDeployment
 	):
-		DataFlowAnalyzer(_dialect, std::move(_functionSideEffects)),
+		DataFlowAnalyzer(_dialect, std::move(_functionSideEffects), std::move(_controlFlowSideEffects)),
 		m_containsMSize(_containsMSize),
 		m_expectedExecutionsPerDeployment(std::move(_expectedExecutionsPerDeployment))
 	{}

test/libsolidity/semanticTests/array/copying/array_copy_storage_storage_static_dynamic.sol

@@ -14,6 +14,6 @@ contract c {
 // compileViaYul: also
 // ----
 // test() -> 9, 4
-// gas irOptimized: 123162
+// gas irOptimized: 123195
 // gas legacy: 123579
 // gas legacyOptimized: 123208

test/libsolidity/semanticTests/array/copying/copy_function_internal_storage_array.sol

@@ -18,6 +18,6 @@ contract C {
 // compileViaYul: also
 // ----
 // test() -> 7
-// gas irOptimized: 124041
+// gas irOptimized: 124024
 // gas legacy: 205196
 // gas legacyOptimized: 204987

test/libsolidity/semanticTests/array/fixed_arrays_in_constructors.sol

@@ -11,7 +11,7 @@ contract Creator {
 // compileViaYul: also
 // ----
 // constructor(): 1, 2, 3, 4 ->
-// gas irOptimized: 129908
+// gas irOptimized: 127748
 // gas legacy: 176789
 // gas legacyOptimized: 129585
 // r() -> 4

test/libsolidity/semanticTests/array/function_array_cross_calls.sol

@@ -45,6 +45,6 @@ contract C {
 // compileViaYul: also
 // ----
 // test() -> 5, 6, 7
-// gas irOptimized: 298983
+// gas irOptimized: 298177
 // gas legacy: 452172
 // gas legacyOptimized: 285017

test/libsolidity/semanticTests/constructor/arrays_in_constructors.sol

@@ -26,6 +26,6 @@ contract Creator {
 // compileViaYul: also
 // ----
 // f(uint256,address[]): 7, 0x40, 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 -> 7, 8
-// gas irOptimized: 443960
+// gas irOptimized: 446570
 // gas legacy: 590683
 // gas legacyOptimized: 448326

test/libsolidity/semanticTests/constructor/bytes_in_constructors_packer.sol

@@ -26,6 +26,6 @@ contract Creator {
 // compileViaYul: also
 // ----
 // f(uint256,bytes): 7, 0x40, 78, "abcdefghijklmnopqrstuvwxyzabcdef", "ghijklmnopqrstuvwxyzabcdefghijkl", "mnopqrstuvwxyz" -> 7, "h"
-// gas irOptimized: 300804
+// gas irOptimized: 299178
 // gas legacy: 428917
 // gas legacyOptimized: 298128

test/libsolidity/semanticTests/constructor/constructor_arguments_external.sol

@@ -19,7 +19,7 @@ contract Main {
 // compileViaYul: also
 // ----
 // constructor(): "abc", true
-// gas irOptimized: 107175
+// gas irOptimized: 105225
 // gas legacy: 145838
 // gas legacyOptimized: 104017
 // getFlag() -> true

test/libsolidity/semanticTests/constructor/constructor_static_array_argument.sol

@@ -12,7 +12,7 @@ contract C {
 // compileViaYul: also
 // ----
 // constructor(): 1, 2, 3, 4 ->
-// gas irOptimized: 174905
+// gas irOptimized: 175559
 // gas legacy: 221377
 // gas legacyOptimized: 177671
 // a() -> 1

test/libsolidity/semanticTests/constructor_inheritance_init_order.sol

@@ -15,5 +15,5 @@ contract B is A {
 // compileViaYul: true
 // ----
 // constructor() ->
-// gas irOptimized: 122017
+// gas irOptimized: 120289
 // y() -> 42

test/libsolidity/semanticTests/constructor_inheritance_init_order_2.sol

@@ -12,7 +12,7 @@ contract B is A {
 // compileViaYul: also
 // ----
 // constructor() ->
-// gas irOptimized: 122017
+// gas irOptimized: 120289
 // gas legacy: 135046
 // gas legacyOptimized: 116176
 // y() -> 42

test/libsolidity/semanticTests/constructor_with_params.sol

@@ -11,7 +11,7 @@ contract C {
 // compileViaYul: also
 // ----
 // constructor(): 2, 0 ->
-// gas irOptimized: 104227
+// gas irOptimized: 102283
 // gas legacy: 117158
 // i() -> 2
 // k() -> 0

test/libsolidity/semanticTests/constructor_with_params_diamond_inheritance.sol

@@ -23,7 +23,7 @@ contract D is B, C {
 // compileViaYul: also
 // ----
 // constructor(): 2, 0 ->
-// gas irOptimized: 160166
+// gas irOptimized: 159086
 // gas legacy: 170665
 // gas legacyOptimized: 145396
 // i() -> 2

test/libsolidity/semanticTests/constructor_with_params_inheritance.sol

@@ -14,7 +14,7 @@ contract D is C {
 // compileViaYul: also
 // ----
 // constructor(): 2, 0 ->
-// gas irOptimized: 124844
+// gas irOptimized: 122900
 // gas legacy: 139250
 // gas legacyOptimized: 119367
 // i() -> 2

test/libsolidity/semanticTests/externalContracts/strings.sol

@@ -51,7 +51,7 @@ contract test {
 // compileViaYul: also
 // ----
 // constructor()
-// gas irOptimized: 707330
+// gas irOptimized: 708410
 // gas legacy: 1130761
 // gas legacyOptimized: 750416
 // toSlice(string): 0x20, 11, "hello world" -> 11, 0xa0
@@ -71,6 +71,6 @@ contract test {
 // gas legacy: 31621
 // gas legacyOptimized: 27914
 // benchmark(string,bytes32): 0x40, 0x0842021, 8, "solidity" -> 0x2020
-// gas irOptimized: 2040045
+// gas irOptimized: 2040061
 // gas legacy: 4381235
 // gas legacyOptimized: 2317529

test/libsolidity/semanticTests/functionCall/failed_create.sol

@@ -18,7 +18,7 @@ contract C {
 // compileViaYul: also
 // ----
 // constructor(), 20 wei
-// gas irOptimized: 219285
+// gas irOptimized: 218415
 // gas legacy: 294569
 // gas legacyOptimized: 174699
 // f(uint256): 20 -> 1370859564726510389319704988634906228201275401179

test/libsolidity/semanticTests/functionCall/gas_and_value_basic.sol

@@ -41,7 +41,7 @@ contract test {
 // compileViaYul: also
 // ----
 // constructor(), 20 wei ->
-// gas irOptimized: 283040
+// gas irOptimized: 281960
 // gas legacy: 402654
 // gas legacyOptimized: 274470
 // sendAmount(uint256): 5 -> 5

test/libsolidity/semanticTests/functionCall/gas_and_value_brace_syntax.sol

@@ -40,7 +40,7 @@ contract test {
 // compileViaYul: also
 // ----
 // constructor(), 20 wei ->
-// gas irOptimized: 283040
+// gas irOptimized: 281960
 // gas legacy: 402654
 // gas legacyOptimized: 274470
 // sendAmount(uint256): 5 -> 5

test/libsolidity/semanticTests/immutable/multi_creation.sol

@@ -29,7 +29,7 @@ contract C {
 // compileViaYul: also
 // ----
 // f() -> 3, 7, 5
-// gas irOptimized: 127347
+// gas irOptimized: 127321
 // gas legacy: 151334
 // gas legacyOptimized: 125166
 // x() -> 7

test/libsolidity/semanticTests/inheritance/inherited_function_calldata_memory_interface.sol

@@ -25,6 +25,6 @@ contract B {
 // compileViaYul: also
 // ----
 // g() -> 42
-// gas irOptimized: 111794
+// gas irOptimized: 112591
 // gas legacy: 185053
 // gas legacyOptimized: 114598

test/libsolidity/semanticTests/inheritance/value_for_constructor.sol

@@ -42,7 +42,7 @@ contract Main {
 // compileViaYul: also
 // ----
 // constructor(), 22 wei ->
-// gas irOptimized: 284287
+// gas irOptimized: 281653
 // gas legacy: 402045
 // gas legacyOptimized: 266772
 // getFlag() -> true

test/libsolidity/semanticTests/salted_create/salted_create_with_value.sol

@@ -22,6 +22,6 @@ contract A {
 // compileViaYul: also
 // ----
 // f(), 10 ether -> 3007, 3008, 3009
-// gas irOptimized: 272413
+// gas irOptimized: 273010
 // gas legacy: 422501
 // gas legacyOptimized: 287472

test/libsolidity/semanticTests/state/blockhash_basic.sol

@@ -14,7 +14,7 @@ contract C {
 // compileViaYul: also
 // ----
 // constructor()
-// gas irOptimized: 115297
+// gas irOptimized: 114001
 // gas legacy: 155081
 // gas legacyOptimized: 107997
 // genesisHash() -> 0x3737373737373737373737373737373737373737373737373737373737373737

test/libsolidity/semanticTests/various/address_code.sol

@@ -17,7 +17,7 @@ contract C {
 // compileViaYul: also
 // ----
 // constructor() ->
-// gas irOptimized: 199723
+// gas irOptimized: 199084
 // gas legacy: 241124
 // gas legacyOptimized: 155549
 // initCode() -> 0x20, 0

test/libsolidity/semanticTests/various/destructuring_assignment.sol

@@ -36,6 +36,6 @@ contract C {
 // compileViaYul: also
 // ----
 // f(bytes): 0x20, 0x5, "abcde" -> 0
-// gas irOptimized: 240691
+// gas irOptimized: 240688
 // gas legacy: 240358
 // gas legacyOptimized: 239682

test/libyul/yulOptimizerTests/fullSuite/loadrestest.yul

@@ -23,6 +23,6 @@
 //             mstore(_1, sload(0))
 //             return(_1, 32)
 //         }
-//         case 0xc2985578 { return(mload(64), 0) }
+//         case 0xc2985578 { return(_1, 0) }
 //     }
 // }