tmp

src/main/scala/uclid/UclidMain.scala

@@ -468,6 +468,9 @@ object UclidMain {
     passManager.addPass(new ModuleTypeChecker())
     // optimisation, has previously been called
     passManager.addPass(new SemanticAnalyzer())
+    // reorder statements if necessary. 
+    // Pass MUST be run after variable renamers
+    passManager.addPass(new BlockSorter())
     // known bugs in the following passes
     if (config.enumToNumeric) passManager.addPass(new EnumTypeAnalysis())
     if (config.enumToNumeric) passManager.addPass(new EnumTypeRenamer("BV"))

src/main/scala/uclid/lang/BlockFlattener.scala

@@ -138,9 +138,11 @@ class BlockFlattenerPass extends RewritePass {
     val stmtsP = rewriter.rewriteStatements(blk.stmts, context + blk.vars)
     (stmtsP, varDecls)
   }
+
   override def rewriteBlock(blkStmt : BlockStmt, context : Scope) : Option[Statement] = {
     logger.debug("==> [%s] Input:\n%s".format(analysis.passName, blkStmt.toString()))
     val init = (List.empty[Statement], Map.empty[Identifier, Type])
+
     val (stmtsP, mapOut) = blkStmt.stmts.foldLeft(init) {
       (acc, st) => {
         val (stP, mapOut) = st match {
@@ -150,6 +152,7 @@ class BlockFlattenerPass extends RewritePass {
         (acc._1 ++ stP, mapOut)
       }
     }
+
     val vars = mapOut.map(p => BlockVarsDecl(List(p._1), p._2))
     val result = BlockStmt(blkStmt.vars ++ vars, stmtsP)
     logger.debug("<== Result:\n" + result.toString())
@@ -170,6 +173,61 @@ class BlockFlattener() extends ASTRewriter(BlockFlattener.getName(), new BlockFl
   override val repeatUntilNoChange = true
 }
 
+// This pass changes the order of any statements in a block so that
+// assignments to state variables are moved to the end of the block.
+// This avoids issues where one submodule reads from a variable after another
+// submodule has written to it, without introducing additional variables
+// It must be run after the procedures have been inlined and converted into SSA.
+class BlockSorterPass extends RewritePass {
+  lazy val logger = Logger(classOf[BlockSorterPass])
+
+  override def rewriteBlock(blkStmt : BlockStmt, context : Scope) : Option[Statement] = {
+    logger.debug("==> [%s] Input:\n%s".format(analysis.passName, blkStmt.toString()))
+    val init = (List.empty[Statement], Map.empty[Identifier, Type])
+
+    def isStateVarAssign(st : Statement) : Boolean = {
+      st match {
+        case AssignStmt(lhss, rhs) => {
+          lhss.exists {
+            case LhsId(id) => context.map.contains(id) && context.map(id).isInstanceOf[Scope.StateVar] && !(id.toString contains "_ucld_")
+            case _ => false
+          }
+        }
+        case _ => false
+      }
+    }
+
+    val endStmts = blkStmt.stmts.filter(st => isStateVarAssign(st))
+    logger.debug("Moving the following statements to the end of the block: " + endStmts.toString())
+    val filteredStmts = blkStmt.stmts.filter(endStmts.contains(_)==false)
+    logger.debug("Moving these statements to the start of the block " + filteredStmts.toString())
+    val result = BlockStmt(blkStmt.vars, filteredStmts++endStmts)
+    logger.debug("<== Result:\n" + result.toString())
+    Some(result)
+  }
+}
+
+object BlockSorter {
+  var index = 0
+  def getName() : String = {
+    index += 1
+    "BlockSorter:" + index.toString()
+  }
+}
+
+class BlockSorter() extends ASTRewriter(BlockSorter.getName(), new BlockSorterPass())
+{
+  override val repeatUntilNoChange = true
+   // Don't reorder procedural code
+  override def visitInit(init : InitDecl, context : Scope) : Option[InitDecl] = Some(init)
+  // Don't reorder procedural code
+  override def visitProcedure(proc : ProcedureDecl, contextIn : Scope) : Option[ProcedureDecl] = Some(proc);
+
+}
+
+
+
+
 object Optimizer {
   var index = 0
   def getName() : String = {

src/test/scala/VerifierSpec.scala

@@ -484,6 +484,9 @@ class ModuleVerifSpec extends AnyFlatSpec {
   "test-module-import-0.ucl" should "verify all assertions." in {
     VerifierSpec.expectedFails("./test/test-module-import-0.ucl", 0)
   }
+  "test-module-ordering.ucl" should "verify all assertions." in {
+    VerifierSpec.expectedFails("./test/test-module-ordering.ucl", 0)
+  }
   "test-type-import.ucl" should "verify all assertions." in {
     VerifierSpec.expectedFails("./test/test-type-import.ucl", 0)
   }

test/test-module-ordering.ucl

@@ -0,0 +1,45 @@
+module test {
+  input a : integer;
+  output b : integer;
+
+  init {
+    b = 0;
+  }
+
+  next {
+    b' = a+1;
+  }
+}
+
+module main {
+  var x: integer;
+  var y: integer;
+
+  // test1 reads in x and updates y'=x+1
+  instance test1 : test(a : (x), b: (y));
+  // test2 reads in y and updates x'=y+1
+  instance test2 : test(a : (y), b: (x));
+
+  init {
+    x = 0;
+    y = 0;
+
+  }
+
+  next {
+    // both assertions should pass regardless of the ordering of these statements
+    next(test1);
+    next(test2);
+  }
+
+  invariant test1_lt2: test1.b < 2;
+  invariant test2lt2: test2.b < 2;
+
+  control {
+    print_module;
+    v = bmc(1);
+    check;
+    print_results;
+    v.print_cex;
+  }
+}