From 5824f5d42ffe9fe6c40168cd4aa4f1ab20169351 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 14 May 2019 15:14:24 +0200
Subject: [PATCH] Use shift directly instead of multiplication in constant
 optimizer.

---
 libevmasm/ConstantOptimiser.cpp | 11 ++++++++---
 test/libsolidity/GasCosts.cpp   |  4 ++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/libevmasm/ConstantOptimiser.cpp b/libevmasm/ConstantOptimiser.cpp
index 267daa5e5..cb5955b3e 100644
--- a/libevmasm/ConstantOptimiser.cpp
+++ b/libevmasm/ConstantOptimiser.cpp
@@ -211,11 +211,16 @@ AssemblyItems ComputeMethod::findRepresentation(u256 const& _value)
 			if (lowerPart != 0)
 				newRoutine += findRepresentation(u256(abs(lowerPart)));
 			if (m_params.evmVersion.hasBitwiseShifting())
-				newRoutine += AssemblyItems{u256(1), u256(bits), Instruction::SHL};
+			{
+				newRoutine += findRepresentation(upperPart);
+				newRoutine += AssemblyItems{u256(bits), Instruction::SHL};
+			}
 			else
+			{
 				newRoutine += AssemblyItems{u256(bits), u256(2), Instruction::EXP};
-			if (upperPart != 1)
-				newRoutine += findRepresentation(upperPart) + AssemblyItems{Instruction::MUL};
+				if (upperPart != 1)
+					newRoutine += findRepresentation(upperPart) + AssemblyItems{Instruction::MUL};
+			}
 			if (lowerPart > 0)
 				newRoutine += AssemblyItems{Instruction::ADD};
 			else if (lowerPart < 0)
diff --git a/test/libsolidity/GasCosts.cpp b/test/libsolidity/GasCosts.cpp
index bb8be7807..a255d694d 100644
--- a/test/libsolidity/GasCosts.cpp
+++ b/test/libsolidity/GasCosts.cpp
@@ -75,12 +75,12 @@ BOOST_AUTO_TEST_CASE(string_storage)
 	else if (Options::get().useABIEncoderV2)
 	{
 		if (Options::get().optimizeYul)
-			CHECK_GAS(153631, 130633, 100);
+			CHECK_GAS(153631, 129829, 100);
 		else
 			CHECK_GAS(153631, 138351, 100);
 	}
 	else
-		CHECK_GAS(129037, 122500, 100);
+		CHECK_GAS(129037, 121703, 100);
 	if (Options::get().evmVersion() >= EVMVersion::byzantium())
 	{
 		callContractFunction("f()");