[Sol -> Yul] Implement if statements

libsolidity/codegen/ir/IRGeneratorForStatements.cpp

@@ -152,6 +152,25 @@ bool IRGeneratorForStatements::visit(TupleExpression const& _tuple)
 	return false;
 }
 
+bool IRGeneratorForStatements::visit(IfStatement const& _ifStatement)
+{
+	_ifStatement.condition().accept(*this);
+	string condition = expressionAsType(_ifStatement.condition(), *TypeProvider::boolean());
+
+	if (_ifStatement.falseStatement())
+	{
+		m_code << "switch " << condition << "\n" "case 0 {\n";
+		_ifStatement.falseStatement()->accept(*this);
+		m_code << "}\n" "default {\n";
+	}
+	else
+		m_code << "if " << condition << " {\n";
+	_ifStatement.trueStatement().accept(*this);
+	m_code << "}\n";
+
+	return false;
+}
+
 bool IRGeneratorForStatements::visit(ForStatement const& _forStatement)
 {
 	generateLoop(

libsolidity/codegen/ir/IRGeneratorForStatements.h

@@ -48,6 +48,7 @@ public:
 	void endVisit(VariableDeclarationStatement const& _variableDeclaration) override;
 	bool visit(Assignment const& _assignment) override;
 	bool visit(TupleExpression const& _tuple) override;
+	bool visit(IfStatement const& _ifStatement) override;
 	bool visit(ForStatement const& _forStatement) override;
 	bool visit(WhileStatement const& _whileStatement) override;
 	bool visit(Continue const& _continueStatement) override;

test/libsolidity/semanticTests/viaYul/if.sol

@@ -0,0 +1,82 @@
+contract C {
+    function f(bool condition) public returns (uint x) {
+        x = 23;
+        if (condition)
+            x = 42;
+    }
+    function g(bool condition) public returns (uint x) {
+        x = 0;
+        if (condition)
+            x = 42;
+        else
+            x = 23;
+    }
+    function h(bool condition) public returns (uint x) {
+        if (condition)
+            return 42;
+        x = 23;
+    }
+    function i(bool condition) public returns (uint x) {
+        if (condition)
+            x = 10;
+        else
+            return 23;
+        x = 42;
+    }
+    function j(uint a, uint b) public returns (uint x, uint y) {
+        x = 42;
+        if (a + b < 10)
+            x = a;
+        else
+            x = b;
+        y = 100;
+    }
+    function k(uint a, uint b) public returns (uint x, uint y) {
+        x = 42;
+        do {
+            if (a + b < 10)
+            {
+                if (a == b)
+                {
+                    x = 99; y = 99;
+                    break;
+                }
+                else
+                {
+                    x = a;
+                }
+            }
+            else
+            {
+                x = b;
+                if (a != b)
+                    y = 17;
+                else
+                    y = 13;
+                break;
+            }
+            y = 100;
+        } while(false);
+    }
+}
+// ====
+// compileViaYul: true
+// ----
+// f(bool): 0 -> 23
+// f(bool): 1 -> 42
+// g(bool): 0 -> 23
+// g(bool): 1 -> 42
+// h(bool): 0 -> 23
+// h(bool): 1 -> 42
+// i(bool): 0 -> 23
+// i(bool): 1 -> 42
+// j(uint256,uint256): 1, 3 -> 1, 100
+// j(uint256,uint256): 3, 1 -> 3, 100
+// j(uint256,uint256): 10, 23 -> 23, 100
+// j(uint256,uint256): 23, 10 -> 10, 100
+// k(uint256,uint256): 1, 3 -> 1, 100
+// k(uint256,uint256): 3, 1 -> 3, 100
+// k(uint256,uint256): 3, 3 -> 99, 99
+// k(uint256,uint256): 10, 23 -> 23, 17
+// k(uint256,uint256): 23, 10 -> 10, 17
+// k(uint256,uint256): 23, 23 -> 23, 13