Merge pull request #7804 from ethereum/morePrune

Tune the suite.

libyul/optimiser/Suite.cpp

@@ -184,6 +184,18 @@ void OptimiserSuite::run(
 			}, ast);
 		}
 
+		{
+			// Prune a bit more in SSA
+			suite.runSequence({
+				ExpressionSplitter::name,
+				SSATransform::name,
+				RedundantAssignEliminator::name,
+				UnusedPruner::name,
+				RedundantAssignEliminator::name,
+				UnusedPruner::name,
+			}, ast);
+		}
+
 		{
 			// Turn into SSA again and simplify
 			suite.runSequence({

test/libyul/yulOptimizerTests/fullSuite/remove_redundant_assignments_in_switch.yul

@@ -0,0 +1,20 @@
+ {
+    let x := 0
+    switch mload(x)
+    case 0 { x := x }
+    case 1 { x := 1 }
+    default { invalid() }
+    mstore(1, 1)
+}
+// ====
+// step: fullSuite
+// ----
+// {
+//     {
+//         switch mload(0)
+//         case 0 { }
+//         case 1 { }
+//         default { invalid() }
+//         mstore(1, 1)
+//     }
+// }