From bd52beedfff7196070880abbd396f5c7469314d0 Mon Sep 17 00:00:00 2001
From: chriseth <chris@ethereum.org>
Date: Tue, 18 Dec 2018 16:38:25 +0100
Subject: [PATCH] Cache hash computations.

---
 libsolidity/interface/CompilerStack.cpp | 25 +++++++++++++++++++------
 libsolidity/interface/CompilerStack.h   |  8 ++++++--
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/libsolidity/interface/CompilerStack.cpp b/libsolidity/interface/CompilerStack.cpp
index 625a665d3..adfb94bda 100644
--- a/libsolidity/interface/CompilerStack.cpp
+++ b/libsolidity/interface/CompilerStack.cpp
@@ -619,6 +619,22 @@ tuple<int, int, int, int> CompilerStack::positionFromSourceLocation(SourceLocati
 	return make_tuple(++startLine, ++startColumn, ++endLine, ++endColumn);
 }
 
+
+h256 const& CompilerStack::Source::keccak256() const
+{
+	if (keccak256HashCached == h256{})
+		keccak256HashCached = dev::keccak256(scanner->source());
+	return keccak256HashCached;
+}
+
+h256 const& CompilerStack::Source::swarmHash() const
+{
+	if (swarmHashCached == h256{})
+		swarmHashCached = dev::swarmHash(scanner->source());
+	return swarmHashCached;
+}
+
+
 StringMap CompilerStack::loadMissingSources(SourceUnit const& _ast, std::string const& _sourcePath)
 {
 	solAssert(m_stackState < ParsingSuccessful, "");
@@ -860,16 +876,13 @@ string CompilerStack::createMetadata(Contract const& _contract) const
 			continue;
 
 		solAssert(s.second.scanner, "Scanner not available");
-		meta["sources"][s.first]["keccak256"] =
-			"0x" + toHex(dev::keccak256(s.second.scanner->source()).asBytes());
+		meta["sources"][s.first]["keccak256"] = "0x" + toHex(s.second.keccak256().asBytes());
 		if (m_metadataLiteralSources)
 			meta["sources"][s.first]["content"] = s.second.scanner->source();
 		else
 		{
 			meta["sources"][s.first]["urls"] = Json::arrayValue;
-			meta["sources"][s.first]["urls"].append(
-				"bzzr://" + toHex(dev::swarmHash(s.second.scanner->source()).asBytes())
-			);
+			meta["sources"][s.first]["urls"].append("bzzr://" + toHex(s.second.swarmHash().asBytes()));
 		}
 	}
 	meta["settings"]["optimizer"]["enabled"] = m_optimize;
@@ -896,7 +909,7 @@ string CompilerStack::createMetadata(Contract const& _contract) const
 	return jsonCompactPrint(meta);
 }
 
-bytes CompilerStack::createCBORMetadata(string _metadata, bool _experimentalMode)
+bytes CompilerStack::createCBORMetadata(string const& _metadata, bool _experimentalMode)
 {
 	bytes cborEncodedHash =
 		// CBOR-encoding of the key "bzzr0"
diff --git a/libsolidity/interface/CompilerStack.h b/libsolidity/interface/CompilerStack.h
index 740331702..81d5009f5 100644
--- a/libsolidity/interface/CompilerStack.h
+++ b/libsolidity/interface/CompilerStack.h
@@ -261,7 +261,11 @@ private:
 		std::shared_ptr<langutil::Scanner> scanner;
 		std::shared_ptr<SourceUnit> ast;
 		bool isLibrary = false;
-		void reset() { scanner.reset(); ast.reset(); }
+		h256 mutable keccak256HashCached;
+		h256 mutable swarmHashCached;
+		void reset() { *this = Source(); }
+		h256 const& keccak256() const;
+		h256 const& swarmHash() const;
 	};
 
 	/// The state per contract. Filled gradually during compilation.
@@ -315,7 +319,7 @@ private:
 	std::string createMetadata(Contract const& _contract) const;
 
 	/// @returns the metadata CBOR for the given serialised metadata JSON.
-	static bytes createCBORMetadata(std::string _metadata, bool _experimentalMode);
+	static bytes createCBORMetadata(std::string const& _metadata, bool _experimentalMode);
 
 	/// @returns the computer source mapping string.
 	std::string computeSourceMapping(eth::AssemblyItems const& _items) const;