Merge pull request #9367 from ethereum/wasm-dialect

Add ctz and popcnt to WasmDialect

Changelog.md

@@ -1,5 +1,8 @@
 ### 0.6.12 (unreleased)
 
+Language Features:
+ * Wasm backend: Add ``i32.ctz``, ``i64.ctz``, ``i32.popcnt``, and ``i64.popcnt``.
+
 Compiler Features:
  * Code Generator: Evaluate ``keccak256`` of string literals at compile-time.
 

libyul/backends/wasm/WasmDialect.cpp

@@ -38,13 +38,18 @@ WasmDialect::WasmDialect()
 			"add",
 			"sub",
 			"mul",
+			// TODO: div_s
 			"div_u",
+			// TODO: rem_s
 			"rem_u",
 			"and",
 			"or",
 			"xor",
 			"shl",
+			// TODO: shr_s
 			"shr_u",
+			// TODO: rotl
+			// TODO: rotr
 		})
 			addFunction(t.str() + "." + name, {t, t}, {t});
 
@@ -52,9 +57,13 @@ WasmDialect::WasmDialect()
 		for (auto const& name: {
 			"eq",
 			"ne",
+			// TODO: lt_s
 			"lt_u",
+			// TODO: gt_s
 			"gt_u",
+			// TODO: le_s
 			"le_u",
+			// TODO: ge_s
 			"ge_u"
 		})
 			addFunction(t.str() + "." + name, {t, t}, {i32});
@@ -62,8 +71,13 @@ WasmDialect::WasmDialect()
 	addFunction("i32.eqz", {i32}, {i32});
 	addFunction("i64.eqz", {i64}, {i32});
 
-	addFunction("i32.clz", {i32}, {i32});
-	addFunction("i64.clz", {i64}, {i64});
+	for (auto t: types)
+		for (auto const& name: {
+			"clz",
+			"ctz",
+			"popcnt",
+		})
+			addFunction(t.str() + "." + name, {t}, {t});
 
 	addFunction("i32.wrap_i64", {i64}, {i32});
 
@@ -73,6 +87,7 @@ WasmDialect::WasmDialect()
 	m_functions["i32.store"_yulstring].sideEffects.invalidatesStorage = false;
 	addFunction("i64.store", {i32, i64}, {}, false);
 	m_functions["i64.store"_yulstring].sideEffects.invalidatesStorage = false;
+	// TODO: add i32.store16, i64.store8, i64.store16, i64.store32
 
 	addFunction("i32.store8", {i32, i32}, {}, false);
 	m_functions["i32.store8"_yulstring].sideEffects.invalidatesStorage = false;
@@ -89,6 +104,7 @@ WasmDialect::WasmDialect()
 	m_functions["i64.load"_yulstring].sideEffects.invalidatesMemory = false;
 	m_functions["i64.load"_yulstring].sideEffects.sideEffectFree = true;
 	m_functions["i64.load"_yulstring].sideEffects.sideEffectFreeIfNoMSize = true;
+	// TODO: add i32.load8, i32.load16, i64.load8, i64.load16, i64.load32
 
 	// Drop is actually overloaded for all types, but Yul does not support that.
 	// Because of that, we introduce "i32.drop" and "i64.drop".

test/tools/yulInterpreter/EwasmBuiltinInterpreter.cpp

@@ -67,6 +67,50 @@ uint64_t clz64(uint64_t _v)
 	return r;
 }
 
+/// Count trailing zeros for uint32. Following WebAssembly rules, it returns 32 for @a _v being zero.
+/// NOTE: the ctz builtin of the compiler may or may not do this
+uint32_t ctz32(uint32_t _v)
+{
+	if (_v == 0)
+		return 32;
+
+	uint32_t r = 0;
+	while (!(_v & 1))
+	{
+		r++;
+		_v >>= 1;
+	}
+	return r;
+}
+
+/// Count trailing zeros for uint64. Following WebAssembly rules, it returns 64 for @a _v being zero.
+/// NOTE: the ctz builtin of the compiler may or may not do this
+uint64_t ctz64(uint64_t _v)
+{
+	if (_v == 0)
+		return 64;
+
+	uint64_t r = 0;
+	while (!(_v & 1))
+	{
+		r++;
+		_v >>= 1;
+	}
+	return r;
+}
+
+/// Count number of bits set for uint64
+uint64_t popcnt(uint64_t _v)
+{
+	uint64_t r = 0;
+	while (_v)
+	{
+		r += (_v & 1);
+		_v >>= 1;
+	}
+	return r;
+}
+
 }
 
 using u512 = boost::multiprecision::number<boost::multiprecision::cpp_int_backend<512, 256, boost::multiprecision::unsigned_magnitude, boost::multiprecision::unchecked, void>>;
@@ -139,6 +183,10 @@ u256 EwasmBuiltinInterpreter::evalBuiltin(YulString _fun, vector<u256> const& _a
 		return clz64(arg[0] & uint32_t(-1)) - 32;
 	else if (_fun == "i64.clz"_yulstring)
 		return clz64(arg[0]);
+	else if (_fun == "i32.ctz"_yulstring)
+		return ctz32(uint32_t(arg[0] & uint32_t(-1)));
+	else if (_fun == "i64.ctz"_yulstring)
+		return ctz64(arg[0]);
 
 	string prefix = _fun.str();
 	string suffix;
@@ -207,6 +255,8 @@ u256 EwasmBuiltinInterpreter::evalWasmBuiltin(string const& _fun, vector<Word> c
 		return arg[0] != arg[1] ? 1 : 0;
 	else if (_fun == "eqz")
 		return arg[0] == 0 ? 1 : 0;
+	else if (_fun == "popcnt")
+		return popcnt(arg[0]);
 	else if (_fun == "lt_u")
 		return arg[0] < arg[1] ? 1 : 0;
 	else if (_fun == "gt_u")