Merge pull request #116 from github/aibaars/cfg-loop-post-order

CFG: make loop expressions post order

Author: aibaars

ql/src/codeql_ruby/controlflow/internal/Completion.qll

@@ -54,6 +54,9 @@ private predicate nestedEnsureCompletion(Completion outer, int nestLevel) {
 
 pragma[noinline]
 private predicate completionIsValidForStmt(AstNode n, Completion c) {
+  n instanceof In and
+  c instanceof EmptinessCompletion
+  or
   n instanceof Break and
   c = TBreakCompletion()
   or

ql/src/codeql_ruby/controlflow/internal/ControlFlowGraphImpl.qll

@@ -339,15 +339,14 @@ private class LeftToRightPostOrderTree extends StandardPostOrderTree, LeftToRigh
 }
 
 private class LeftToRightPreOrderNodes =
-  @alias or @block_parameters or @class or @do or @else or @ensure or @in or @lambda_parameters or
+  @alias or @block_parameters or @class or @do or @else or @ensure or @lambda_parameters or
       @method_parameters or @pattern or @program or @then or @undef or @yield;
 
 private class LeftToRightPreOrderTree extends StandardPreOrderTree, LeftToRightPreOrderNodes {
   override predicate isHidden() {
     this instanceof BlockParameters or
     this instanceof Do or
     this instanceof Else or
-    this instanceof In or
     this instanceof LambdaParameters or
     this instanceof MethodParameters or
     this instanceof Pattern or
@@ -593,66 +592,71 @@ module Trees {
    * ```
    *           args
    *            |
-   *          for------<-----
+   *           in------<-----
    *           / \           \
    *          /   \          |
    *         /     \         |
    *        /       \        |
    *     empty    non-empty  |
    *       |          \      |
-   *  puts "done"      \     |
-   *                  arg    |
-   *                    |    |
-   *                puts arg |
+   *      for          \     |
+   *       |          arg    |
+   *       |            |    |
+   *  puts "done"   puts arg |
    *                     \___/
    * ```
    */
-  private class ForTree extends ControlFlowTree, For {
+  private class ForTree extends PostOrderTree, For {
     final override predicate propagatesAbnormal(AstNode child) {
-      child = this.getPattern() or child = this.getValue()
+      child = this.getPattern() or child = this.getArray()
     }
 
-    final override predicate first(AstNode node) { node = this.getValue() }
+    final override predicate first(AstNode first) { first(this.getArray(), first) }
 
-    final override predicate last(AstNode last, Completion c) {
-      last = this and
-      c.(EmptinessCompletion).getValue() = true
-      or
-      last(this.getBody(), last, c) and
-      not c.continuesLoop() and
-      not c instanceof BreakCompletion and
-      not c instanceof RedoCompletion
-      or
-      last(this.getBody(), last, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
-    }
+    private In getIn() { result = this.getValue() }
+
+    private UnderscoreArg getArray() { result = this.getValue().getChild() }
 
     /**
-     * for pattern in value do body end
+     * for pattern in array do body end
      * ```
-     * value +-> for +--[non empty]--> pattern -> body -> for
-     *               |--[empty]--> exit
+     * array +-> in +--[non empty]--> pattern -> body -> in
+     *              |--[empty]--> for
      * ```
      */
     final override predicate succ(AstNode pred, AstNode succ, Completion c) {
-      last(this.getValue(), pred, c) and
-      succ = this and
+      last(this.getArray(), pred, c) and
+      first(this.getIn(), succ) and
       c instanceof SimpleCompletion
       or
-      pred = this and
+      last(this.getIn(), pred, c) and
       first(this.getPattern(), succ) and
       c.(EmptinessCompletion).getValue() = false
       or
-      first(this.getBody(), succ) and
       last(this.getPattern(), pred, c) and
+      first(this.getBody(), succ) and
       c instanceof NormalCompletion
       or
       last(this.getBody(), pred, c) and
-      succ = this and
+      first(this.getIn(), succ) and
       c.continuesLoop()
       or
       last(this.getBody(), pred, c) and
       first(this.getBody(), succ) and
       c instanceof RedoCompletion
+      or
+      succ = this and
+      (
+        last(this.getIn(), pred, c) and
+        c.(EmptinessCompletion).getValue() = true
+        or
+        last(this.getBody(), pred, c) and
+        not c.continuesLoop() and
+        not c instanceof BreakCompletion and
+        not c instanceof RedoCompletion
+        or
+        last(this.getBody(), pred, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
+      )
     }
   }
 
@@ -712,6 +716,8 @@ module Trees {
     }
   }
 
+  private class InTree extends LeafTree, In { }
+
   private class InstanceVariableTree extends LeafTree, InstanceVariable { }
 
   private class IntegerTree extends LeafTree, Integer { }
@@ -1224,26 +1230,12 @@ module Trees {
     }
   }
 
-  private class ConditionalLoopTree extends PreOrderTree, ConditionalLoopAstNode {
+  private class ConditionalLoopTree extends PostOrderTree, ConditionalLoopAstNode {
     final override predicate propagatesAbnormal(AstNode child) { child = this.getConditionNode() }
 
-    final override predicate last(AstNode last, Completion c) {
-      last(this.getConditionNode(), last, c) and
-      this.endLoop(c)
-      or
-      last(this.getBodyNode(), last, c) and
-      not c.continuesLoop() and
-      not c instanceof BreakCompletion and
-      not c instanceof RedoCompletion
-      or
-      last(this.getBodyNode(), last, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
-    }
+    final override predicate first(AstNode first) { first(this.getConditionNode(), first) }
 
     final override predicate succ(AstNode pred, AstNode succ, Completion c) {
-      pred = this and
-      first(this.getConditionNode(), succ) and
-      c instanceof SimpleCompletion
-      or
       last(this.getConditionNode(), pred, c) and
       this.continueLoop(c) and
       first(this.getBodyNode(), succ)
@@ -1255,6 +1247,19 @@ module Trees {
       last(this.getBodyNode(), pred, c) and
       first(this.getBodyNode(), succ) and
       c instanceof RedoCompletion
+      or
+      succ = this and
+      (
+        last(this.getConditionNode(), pred, c) and
+        this.endLoop(c)
+        or
+        last(this.getBodyNode(), pred, c) and
+        not c.continuesLoop() and
+        not c instanceof BreakCompletion and
+        not c instanceof RedoCompletion
+        or
+        last(this.getBodyNode(), pred, c.(NestedBreakCompletion).getAnInnerCompatibleCompletion())
+      )
     }
   }
 }