Test with high path complexity.

1 files changed, 40 insertions, 0 deletions

diff --git a/test/libsolidity/GasMeter.cpp b/test/libsolidity/GasMeter.cpp
index 0d66456c..f16d9abe 100644
--- a/test/libsolidity/GasMeter.cpp
+++ b/test/libsolidity/GasMeter.cpp
@@ -307,6 +307,46 @@ BOOST_AUTO_TEST_CASE(regular_functions_exclude_fallback)
 	testCreationTimeGas(sourceCode);
 	testRunTimeGas("x()", vector<bytes>{encodeArgs()});
 }
+
+BOOST_AUTO_TEST_CASE(complex_control_flow)
+{
+	// This crashed the gas estimator previously (or took a very long time).
+	// Now we do not follow branches if they start out with lower gas costs than the ones
+	// we previously considered. This of course reduces accuracy.
+	char const* sourceCode = R"(
+		contract log {
+			function ln(int128 x) constant returns (int128 result) {
+				int128 t = x / 256;
+				int128 y = 5545177;
+				x = t;
+				t = x * 16; if (t <= 1000000) { x = t; y = y - 2772588; }
+				t = x * 4; if (t <= 1000000) { x = t; y = y - 1386294; }
+				t = x * 2; if (t <= 1000000) { x = t; y = y - 693147; }
+				t = x + x / 2; if (t <= 1000000) { x = t; y = y - 405465; }
+				t = x + x / 4; if (t <= 1000000) { x = t; y = y - 223144; }
+				t = x + x / 8; if (t <= 1000000) { x = t; y = y - 117783; }
+				t = x + x / 16; if (t <= 1000000) { x = t; y = y - 60624; }
+				t = x + x / 32; if (t <= 1000000) { x = t; y = y - 30771; }
+				t = x + x / 64; if (t <= 1000000) { x = t; y = y - 15504; }
+				t = x + x / 128; if (t <= 1000000) { x = t; y = y - 7782; }
+				t = x + x / 256; if (t <= 1000000) { x = t; y = y - 3898; }
+				t = x + x / 512; if (t <= 1000000) { x = t; y = y - 1951; }
+				t = x + x / 1024; if (t <= 1000000) { x = t; y = y - 976; }
+				t = x + x / 2048; if (t <= 1000000) { x = t; y = y - 488; }
+				t = x + x / 4096; if (t <= 1000000) { x = t; y = y - 244; }
+				t = x + x / 8192; if (t <= 1000000) { x = t; y = y - 122; }
+				t = x + x / 16384; if (t <= 1000000) { x = t; y = y - 61; }
+				t = x + x / 32768; if (t <= 1000000) { x = t; y = y - 31; }
+				t = x + x / 65536; if (t <= 1000000) { y = y - 15; }
+				return y;
+			}
+		}
+	)";
+	testCreationTimeGas(sourceCode);
+	// max gas is used for small x
+	testRunTimeGas("ln(int128)", vector<bytes>{encodeArgs(0), encodeArgs(10), encodeArgs(105), encodeArgs(30000)});
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }