Remove trivial blocks

Author: blishko

libevmasm/Assembly.cpp

@@ -29,6 +29,7 @@
 #include <libevmasm/JumpdestRemover.h>
 #include <libevmasm/BlockDeduplicator.h>
 #include <libevmasm/ConstantOptimiser.h>
+#include <libevmasm/TrivialBlockRemover.h>
 
 #include <liblangutil/CharStream.h>
 #include <liblangutil/Exceptions.h>
@@ -933,6 +934,16 @@ std::map<u256, u256> const& Assembly::optimiseInternal(
 				}
 			}
 
+		if (_settings.runInliner && !m_eofVersion.has_value())
+		{
+			for (auto& codeSection: m_codeSections)
+			{
+				TrivialBlockRemover trivialBlockRemover{codeSection.items};
+				if (trivialBlockRemover.optimise(_tagsReferencedFromOutside))
+					count++;
+			}
+		}
+
 		// TODO: investigate for EOF
 		if (_settings.runCSE && !m_eofVersion.has_value())
 		{

libevmasm/CMakeLists.txt

@@ -45,6 +45,8 @@ set(sources
 	SimplificationRules.cpp
 	SimplificationRules.h
 	SubAssemblyID.h
+	TrivialBlockRemover.cpp
+	TrivialBlockRemover.h
 )
 
 add_library(evmasm ${sources})

libevmasm/TrivialBlockRemover.cpp

@@ -0,0 +1,63 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+#include <libevmasm/TrivialBlockRemover.h>
+
+#include <libevmasm/AssemblyItem.h>
+#include <libevmasm/BlockDeduplicator.h>
+#include <libevmasm/SemanticInformation.h>
+
+#include <range/v3/view/drop.hpp>
+#include <range/v3/view/enumerate.hpp>
+
+bool solidity::evmasm::TrivialBlockRemover::optimise(std::set<size_t> const& _tagsReferencedFromOutside)
+{
+	std::map<u256, u256> replacedTags;
+	for (auto&& [index, item]: m_items | ranges::views::enumerate | ranges::views::drop(1))
+	{
+		if (item.type() != Tag)
+			continue;
+		if (index >= m_items.size() - 2)
+			continue;
+		auto const & next = m_items[index + 1];
+		if (next.type() != PushTag)
+			continue;
+		if (next.data() == item.data())
+			continue;
+		auto const & nextNext = m_items[index + 2];
+		if (nextNext.type() != Operation)
+			continue;
+		if (nextNext.instruction() != Instruction::JUMP)
+			continue;
+		auto const & previous = m_items[index - 1];
+		if (previous.type() != Operation)
+			continue;
+		if (previous.instruction() != Instruction::JUMP && !SemanticInformation::terminatesControlFlow(previous))
+			continue;
+		auto const [subId, tag] = item.splitForeignPushTag();
+		solAssert(subId.empty(), "Sub-assembly tag used as label.");
+		if (_tagsReferencedFromOutside.contains(tag))
+			continue;
+		replacedTags.insert({item.data(), next.data()});
+	}
+	if (!replacedTags.empty())
+	{
+		return BlockDeduplicator::applyTagReplacement(m_items, replacedTags);
+	}
+	return false;
+}

libevmasm/TrivialBlockRemover.h

@@ -0,0 +1,44 @@
+/*
+	This file is part of solidity.
+
+	solidity is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 3 of the License, or
+	(at your option) any later version.
+
+	solidity is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
+*/
+// SPDX-License-Identifier: GPL-3.0
+
+#pragma once
+
+#include <libevmasm/SubAssemblyID.h>
+
+#include <set>
+
+namespace solidity::evmasm
+{
+
+class AssemblyItem;
+using AssemblyItems = std::vector<AssemblyItem>;
+
+class TrivialBlockRemover {
+public:
+	explicit TrivialBlockRemover(AssemblyItems& _items): m_items(_items) {}
+
+	bool optimise(std::set<size_t> const& _tagsReferencedFromOutside);
+
+private:
+	AssemblyItems& m_items;
+};
+
+}
+
+
+

test/cmdlineTests/function_debug_info/output

@@ -15,7 +15,7 @@
       },
       "function-debug-runtime": {
         "@f_14": {
-          "entryPoint": 124,
+          "entryPoint": 119,
           "id": 14,
           "parameterSlots": 2,
           "returnSlots": 1
@@ -26,12 +26,12 @@
           "returnSlots": 0
         },
         "abi_decode_tuple_t_array$_t_uint256_$dyn_calldata_ptr": {
-          "entryPoint": 158,
+          "entryPoint": 153,
           "parameterSlots": 2,
           "returnSlots": 2
         },
         "abi_decode_tuple_t_uint256": {
-          "entryPoint": 271,
+          "entryPoint": 266,
           "parameterSlots": 2,
           "returnSlots": 1
         },
@@ -40,7 +40,7 @@
           "returnSlots": 1
         },
         "panic_error_0x32": {
-          "entryPoint": 294,
+          "entryPoint": 289,
           "parameterSlots": 0,
           "returnSlots": 0
         }

test/libsolidity/gasTests/abiv2_optimised.sol

@@ -19,12 +19,12 @@ contract C {
 // optimize-yul: true
 // ----
 // creation:
-//   codeDepositCost: 618200
+//   codeDepositCost: 615200
 //   executionCost: 649
-//   totalCost: 618849
+//   totalCost: 615849
 // external:
 //   a(): 2283
-//   b(uint256): 4649
+//   b(uint256): 4637
 //   f1(uint256): 304
 //   f2(uint256[],string[],uint16,address): infinite
 //   f3(uint16[],string[],uint16,address): infinite

test/libsolidity/gasTests/dispatch_large_optimised.sol

@@ -29,29 +29,29 @@ contract Large {
 // optimize-runs: 2
 // ----
 // creation:
-//   codeDepositCost: 224600
-//   executionCost: 267
-//   totalCost: 224867
+//   codeDepositCost: 213600
+//   executionCost: 255
+//   totalCost: 213855
 // external:
 //   a(): 2281
-//   b(uint256): 4934
-//   f0(uint256): 363
-//   f1(uint256): 47002
-//   f2(uint256): 24967
-//   f3(uint256): 25055
-//   f4(uint256): 25033
-//   f5(uint256): 25011
-//   f6(uint256): 24923
-//   f7(uint256): 24703
-//   f8(uint256): 24835
-//   f9(uint256): 24857
-//   g0(uint256): 603
-//   g1(uint256): 46714
-//   g2(uint256): 24701
-//   g3(uint256): 24789
-//   g4(uint256): 24767
-//   g5(uint256): 24855
-//   g6(uint256): 24635
-//   g7(uint256): 24745
-//   g8(uint256): 24723
-//   g9(uint256): 24569
+//   b(uint256): 4922
+//   f0(uint256): 351
+//   f1(uint256): 46990
+//   f2(uint256): 24955
+//   f3(uint256): 25043
+//   f4(uint256): 25021
+//   f5(uint256): 24999
+//   f6(uint256): 24911
+//   f7(uint256): 24691
+//   f8(uint256): 24823
+//   f9(uint256): 24845
+//   g0(uint256): 591
+//   g1(uint256): 46702
+//   g2(uint256): 24689
+//   g3(uint256): 24777
+//   g4(uint256): 24755
+//   g5(uint256): 24843
+//   g6(uint256): 24623
+//   g7(uint256): 24733
+//   g8(uint256): 24711
+//   g9(uint256): 24557

test/libsolidity/gasTests/dispatch_medium_optimised.sol

@@ -12,21 +12,20 @@ contract Medium {
 // ====
 // EVMVersion: =current
 // bytecodeFormat: legacy
-// ====
 // optimize: true
 // optimize-runs: 2
 // ----
 // creation:
-//   codeDepositCost: 126000
-//   executionCost: 169
-//   totalCost: 126169
+//   codeDepositCost: 118000
+//   executionCost: 163
+//   totalCost: 118163
 // external:
 //   a(): 2281
-//   b(uint256): 4692
-//   f1(uint256): 46782
-//   f2(uint256): 24725
-//   f3(uint256): 24769
-//   g0(uint256): 361
-//   g7(uint256): 24635
-//   g8(uint256): 24613
-//   g9(uint256): 24569
+//   b(uint256): 4680
+//   f1(uint256): 46770
+//   f2(uint256): 24713
+//   f3(uint256): 24757
+//   g0(uint256): 349
+//   g7(uint256): 24623
+//   g8(uint256): 24601
+//   g9(uint256): 24557

test/libsolidity/gasTests/dispatch_small_optimised.sol

@@ -6,16 +6,16 @@ contract Small {
 }
 // ====
 // EVMVersion: =current
+// bytecodeFormat: legacy
 // optimize: true
 // optimize-runs: 2
-// bytecodeFormat: legacy
 // ----
 // creation:
-//   codeDepositCost: 58200
-//   executionCost: 109
-//   totalCost: 58309
+//   codeDepositCost: 56200
+//   executionCost: 103
+//   totalCost: 56303
 // external:
 //   fallback: 117
 //   a(): 2259
-//   b(uint256): 4582
-//   f1(uint256): 46716
+//   b(uint256): 4570
+//   f1(uint256): 46704

test/libsolidity/semanticTests/abiEncodeDecode/abi_decode_simple_storage.sol

@@ -10,4 +10,4 @@ contract C {
 // f(bytes): 0x20, 0x80, 0x21, 0x40, 0x7, "abcdefg" -> 0x21, 0x40, 0x7, "abcdefg"
 // gas irOptimized: 135441
 // gas legacy: 137095
-// gas legacyOptimized: 135828
+// gas legacyOptimized: 135792