diff --git a/powershell/ql/lib/semmle/code/powershell/controlflow/BasicBlocks.qll b/powershell/ql/lib/semmle/code/powershell/controlflow/BasicBlocks.qll
index 9037bea54ef5..ed24f23309c0 100644
--- a/powershell/ql/lib/semmle/code/powershell/controlflow/BasicBlocks.qll
+++ b/powershell/ql/lib/semmle/code/powershell/controlflow/BasicBlocks.qll
@@ -85,6 +85,29 @@ final class BasicBlock extends BasicBlocksImpl::BasicBlock {
    */
   BasicBlock getImmediateDominator() { result = super.getImmediateDominator() }
 
+  /**
+   * Holds if the edge with successor type `s` out of this basic block is a
+   * dominating edge for `dominated`.
+   *
+   * That is, all paths reaching `dominated` from the entry point basic
+   * block must go through the `s` edge out of this basic block.
+   *
+   * Edge dominance is similar to node dominance except it concerns edges
+   * instead of nodes: A basic block is dominated by a _basic block_ `bb` if it
+   * can only be reached through `bb` and dominated by an _edge_ `s` if it can
+   * only be reached through `s`.
+   *
+   * Note that where all basic blocks (except the entry basic block) are
+   * strictly dominated by at least one basic block, a basic block may not be
+   * dominated by any edge. If an edge dominates a basic block `bb`, then
+   * both endpoints of the edge dominates `bb`. The converse is not the case,
+   * as there may be multiple paths between the endpoints with none of them
+   * dominating.
+   */
+  predicate edgeDominates(BasicBlock dominated, SuccessorType s) {
+    super.edgeDominates(dominated, s)
+  }
+
   /**
    * Holds if this basic block strictly post-dominates basic block `bb`.
    *
@@ -133,23 +156,4 @@ final class JoinBlockPredecessor extends BasicBlock, BasicBlocksImpl::JoinPredec
  * A basic block that terminates in a condition, splitting the subsequent
  * control flow.
  */
-final class ConditionBlock extends BasicBlock, BasicBlocksImpl::ConditionBasicBlock {
-  /**
-   * Holds if basic block `succ` is immediately controlled by this basic
-   * block with conditional value `s`. That is, `succ` is an immediate
-   * successor of this block, and `succ` can only be reached from
-   * the callable entry point by going via the `s` edge out of this basic block.
-   */
-  predicate immediatelyControls(BasicBlock succ, ConditionalSuccessor s) {
-    super.immediatelyControls(succ, s)
-  }
-
-  /**
-   * Holds if basic block `controlled` is controlled by this basic block with
-   * conditional value `s`. That is, `controlled` can only be reached from the
-   * callable entry point by going via the `s` edge out of this basic block.
-   */
-  predicate controls(BasicBlock controlled, ConditionalSuccessor s) {
-    super.controls(controlled, s)
-  }
-}
+final class ConditionBlock extends BasicBlock, BasicBlocksImpl::ConditionBasicBlock { }
diff --git a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
index 05d8128d035c..deb814e50854 100644
--- a/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
+++ b/powershell/ql/lib/semmle/code/powershell/dataflow/internal/SsaImpl.qll
@@ -19,8 +19,6 @@ module SsaInput implements SsaImplCommon::InputSig<Location> {
 
   BasicBlock getABasicBlockSuccessor(BasicBlock bb) { result = bb.getASuccessor() }
 
-  class ExitBasicBlock extends BasicBlock, BasicBlocks::ExitBasicBlock { }
-
   class SourceVariable = LocalScopeVariable;
 
   /**