Do not use named function labels if function names are not unique.

Author: chriseth

Changelog.md

@@ -19,6 +19,7 @@ Bugfixes:
  * Commandline Interface: Don't return zero exit code when writing linked files to disk fails.
  * SMTChecker: Fix internal error in magic type access (``block``, ``msg``, ``tx``).
  * TypeChecker: Fix internal error when using user defined value types in public library functions.
+ * Yul Assembler: Fix internal error when function names are not unique.
  * Yul IR Generator: Do not output empty switches/if-bodies for empty contracts.
 
 

libyul/backends/evm/EVMObjectCompiler.cpp

@@ -30,6 +30,30 @@
 using namespace solidity::yul;
 using namespace std;
 
+namespace
+{
+class AreFunctionNamesUnique: ASTWalker
+{
+public:
+	static bool check(Block& _block)
+	{
+		AreFunctionNamesUnique instance;
+		instance(_block);
+		return instance.m_unique;
+	}
+private:
+	using ASTWalker::operator();
+	void operator()(FunctionDefinition const& _functionDefinition) override
+	{
+		ASTWalker::operator()(_functionDefinition);
+		if (!m_functionNames.insert(_functionDefinition.name).second)
+			m_unique = false;
+	}
+	bool m_unique = true;
+	std::set<YulString> m_functionNames;
+};
+}
+
 void EVMObjectCompiler::compile(Object& _object, AbstractAssembly& _assembly, EVMDialect const& _dialect, bool _optimize)
 {
 	EVMObjectCompiler compiler(_assembly, _dialect);
@@ -62,6 +86,10 @@ void EVMObjectCompiler::run(Object& _object, bool _optimize)
 
 	yulAssert(_object.analysisInfo, "No analysis info.");
 	yulAssert(_object.code, "No code.");
+
+	// We cannot use named labels if the function names are not unique.
+	bool useNamedLabelsForFunctions = AreFunctionNamesUnique::check(*_object.code);
+
 	// We do not catch and re-throw the stack too deep exception here because it is a YulException,
 	// which should be native to this part of the code.
 	CodeTransform transform{
@@ -72,7 +100,7 @@ void EVMObjectCompiler::run(Object& _object, bool _optimize)
 		context,
 		_optimize,
 		{},
-		true /* _useNamedLabelsForFunctions */
+		useNamedLabelsForFunctions
 	};
 	transform(*_object.code);
 	if (!transform.stackErrors().empty())

libyul/optimiser/Disambiguator.h

@@ -55,7 +55,7 @@ class Disambiguator: public ASTCopier
 	void enterScope(Block const& _block) override;
 	void leaveScope(Block const& _block) override;
 	void enterFunction(FunctionDefinition const& _function) override;
-	void leaveFunction(FunctionDefinition const& _function) override;
+	void leaveFunction	(FunctionDefinition const& _function) override;
 	YulString translateIdentifier(YulString _name) override;
 
 	void enterScopeInternal(Scope& _scope);

test/cmdlineTests/yul_function_name_clashes/args

@@ -0,0 +1 @@
+--strict-assembly

test/cmdlineTests/yul_function_name_clashes/err

@@ -0,0 +1 @@
+Warning: Yul is still experimental. Please use the output with care.

test/cmdlineTests/yul_function_name_clashes/input.yul

@@ -0,0 +1,17 @@
+object "object" {
+    code {
+        let a
+        let b
+        {
+            function z() -> y
+            { y := calldataload(0) }
+            a := z()
+        }
+        {
+            function z() -> y
+            { y := calldataload(0x20) }
+            b := z()
+        }
+        sstore(a, b)
+    }
+}

test/cmdlineTests/yul_function_name_clashes/output

@@ -0,0 +1,88 @@
+
+======= yul_function_name_clashes/input.yul (EVM) =======
+
+Pretty printed source:
+object "object" {
+    code {
+        let a
+        let b
+        {
+            function z() -> y
+            { y := calldataload(0) }
+            a := z()
+        }
+        {
+            function z() -> y
+            { y := calldataload(0x20) }
+            b := z()
+        }
+        sstore(a, b)
+    }
+}
+
+
+Binary representation:
+600080600f565b60008035905090565b60156006565b91506025565b6000602035905090565b602b601b565b90508082555050
+
+Text representation:
+    /* "yul_function_name_clashes/input.yul":37:42   */
+  0x00
+    /* "yul_function_name_clashes/input.yul":51:56   */
+  dup1
+    /* "yul_function_name_clashes/input.yul":79:133   */
+  jump(tag_2)
+tag_1:
+    /* "yul_function_name_clashes/input.yul":95:96   */
+  0x00
+    /* "yul_function_name_clashes/input.yul":129:130   */
+  dup1
+    /* "yul_function_name_clashes/input.yul":116:131   */
+  calldataload
+    /* "yul_function_name_clashes/input.yul":111:131   */
+  swap1
+  pop
+    /* "yul_function_name_clashes/input.yul":79:133   */
+  swap1
+  jump	// out
+tag_2:
+    /* "yul_function_name_clashes/input.yul":151:154   */
+  tag_4
+  tag_1
+  jump	// in
+tag_4:
+    /* "yul_function_name_clashes/input.yul":146:154   */
+  swap2
+  pop
+    /* "yul_function_name_clashes/input.yul":187:244   */
+  jump(tag_6)
+tag_5:
+    /* "yul_function_name_clashes/input.yul":203:204   */
+  0x00
+    /* "yul_function_name_clashes/input.yul":237:241   */
+  0x20
+    /* "yul_function_name_clashes/input.yul":224:242   */
+  calldataload
+    /* "yul_function_name_clashes/input.yul":219:242   */
+  swap1
+  pop
+    /* "yul_function_name_clashes/input.yul":187:244   */
+  swap1
+  jump	// out
+tag_6:
+    /* "yul_function_name_clashes/input.yul":262:265   */
+  tag_8
+  tag_5
+  jump	// in
+tag_8:
+    /* "yul_function_name_clashes/input.yul":257:265   */
+  swap1
+  pop
+    /* "yul_function_name_clashes/input.yul":294:295   */
+  dup1
+    /* "yul_function_name_clashes/input.yul":291:292   */
+  dup3
+    /* "yul_function_name_clashes/input.yul":284:296   */
+  sstore
+    /* "yul_function_name_clashes/input.yul":27:302   */
+  pop
+  pop

test/cmdlineTests/yul_function_name_clashes_different_params/args

@@ -0,0 +1 @@
+--strict-assembly

test/cmdlineTests/yul_function_name_clashes_different_params/err

@@ -0,0 +1 @@
+Warning: Yul is still experimental. Please use the output with care.

test/cmdlineTests/yul_function_name_clashes_different_params/input.yul

@@ -0,0 +1,17 @@
+object "object" {
+    code {
+        let a
+        let b
+        {
+            function z() -> y
+            { y := calldataload(0) }
+            a := z()
+        }
+        {
+            function z(r) -> y
+            { y := calldataload(r) }
+            b := z(0x70)
+        }
+        sstore(a, b)
+    }
+}