Add variable declaration initializer.

test/libyul/YulOptimizerTest.cpp

@@ -23,6 +23,7 @@
 
 #include <libyul/optimiser/BlockFlattener.h>
 #include <libyul/optimiser/VarDeclPropagator.h>
+#include <libyul/optimiser/VarDeclInitializer.h>
 #include <libyul/optimiser/Disambiguator.h>
 #include <libyul/optimiser/CommonSubexpressionEliminator.h>
 #include <libyul/optimiser/NameCollector.h>
@@ -112,6 +113,8 @@ bool YulOptimizerTest::run(ostream& _stream, string const& _linePrefix, bool con
 		disambiguate();
 		VarDeclPropagator{}(*m_ast);
 	}
+	else if (m_optimizerStep == "varDeclInitializer")
+		VarDeclInitializer{}(*m_ast);
 	else if (m_optimizerStep == "forLoopInitRewriter")
 	{
 		disambiguate();

test/libyul/yulOptimizerTests/varDeclInitializer/ambiguous.yul

@@ -0,0 +1,29 @@
+{
+  // This component does not need the disambiguator
+  function f() -> x, y {
+    let a, b
+    mstore(a, b)
+    let d
+    d := 2
+  }
+  let a
+  a := 4
+  let b := 2
+  let x, y := f()
+}
+// ----
+// varDeclInitializer
+// {
+//     function f() -> x, y
+//     {
+//         let a := 0
+//         let b := 0
+//         mstore(a, b)
+//         let d := 0
+//         d := 2
+//     }
+//     let a := 0
+//     a := 4
+//     let b := 2
+//     let x, y := f()
+// }

test/libyul/yulOptimizerTests/varDeclInitializer/inside_func.yul

@@ -0,0 +1,24 @@
+{
+  function f() -> x, y {
+    let a, b
+    mstore(a, b)
+    let d
+    d := 2
+  }
+  let r
+  r := 4
+}
+// ----
+// varDeclInitializer
+// {
+//     function f() -> x, y
+//     {
+//         let a := 0
+//         let b := 0
+//         mstore(a, b)
+//         let d := 0
+//         d := 2
+//     }
+//     let r := 0
+//     r := 4
+// }

test/libyul/yulOptimizerTests/varDeclInitializer/multi.yul

@@ -0,0 +1,14 @@
+{
+  let x, y, z
+  let a
+  let b
+}
+// ----
+// varDeclInitializer
+// {
+//     let x := 0
+//     let y := 0
+//     let z := 0
+//     let a := 0
+//     let b := 0
+// }

test/libyul/yulOptimizerTests/varDeclInitializer/multi_assign.yul

@@ -0,0 +1,21 @@
+{
+  function f() -> x, y {
+    let a, b := f()
+	let u
+  }
+  let r
+  let s := 3
+  let t
+}
+// ----
+// varDeclInitializer
+// {
+//     function f() -> x, y
+//     {
+//         let a, b := f()
+//         let u := 0
+//     }
+//     let r := 0
+//     let s := 3
+//     let t := 0
+// }

test/libyul/yulOptimizerTests/varDeclInitializer/simple.yul

@@ -0,0 +1,8 @@
+{
+  let a
+}
+// ----
+// varDeclInitializer
+// {
+//     let a := 0
+// }