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-rw-r--r--libsolidity/SolidityOptimizer.cpp36
1 files changed, 36 insertions, 0 deletions
diff --git a/libsolidity/SolidityOptimizer.cpp b/libsolidity/SolidityOptimizer.cpp
index 4986b146..e50469dd 100644
--- a/libsolidity/SolidityOptimizer.cpp
+++ b/libsolidity/SolidityOptimizer.cpp
@@ -272,6 +272,42 @@ BOOST_AUTO_TEST_CASE(storage_write_in_loops)
compareVersions("f(uint256)", 36);
}
+BOOST_AUTO_TEST_CASE(retain_information_in_branches)
+{
+ // This tests that the optimizer knows that we already have "z == sha3(y)" inside both branches.
+ char const* sourceCode = R"(
+ contract c {
+ bytes32 d;
+ uint a;
+ function f(uint x, bytes32 y) returns (uint r_a, bytes32 r_d) {
+ bytes32 z = sha3(y);
+ if (x > 8) {
+ z = sha3(y);
+ a = x;
+ } else {
+ z = sha3(y);
+ a = x;
+ }
+ r_a = a;
+ r_d = d;
+ }
+ }
+ )";
+ compileBothVersions(sourceCode);
+ compareVersions("f(uint256,bytes32)", 0, "abc");
+ compareVersions("f(uint256,bytes32)", 8, "def");
+ compareVersions("f(uint256,bytes32)", 10, "ghi");
+
+ m_optimize = true;
+ bytes optimizedBytecode = compileAndRun(sourceCode, 0, "c");
+ size_t numSHA3s = 0;
+ eth::eachInstruction(optimizedBytecode, [&](Instruction _instr, u256 const&) {
+ if (_instr == eth::Instruction::SHA3)
+ numSHA3s++;
+ });
+ BOOST_CHECK_EQUAL(1, numSHA3s);
+}
+
BOOST_AUTO_TEST_CASE(cse_intermediate_swap)
{
eth::KnownState state;