Let the ComputeDominanceInfo pass also compute post-dominance info.

And use this in the recently added test.

Author: eeckstein

include/swift/SILOptimizer/PassManager/Passes.def

@@ -58,8 +58,8 @@ PASS(ClosureSpecializer, "closure-specialize",
 PASS(CodeSinking, "code-sinking",
      "Sinks code closer to users")
 PASS(ComputeDominanceInfo, "compute-dominance-info",
-     "Utility pass that computes dominance info for all functions in order to "
-     "help test dominanceinfo updating")
+     "Utility pass that computes (post-)dominance info for all functions in "
+     "order to help test dominanceinfo updating")
 PASS(ComputeLoopInfo, "compute-loop-info",
      "Utility pass that computes loop info for all functions in order to help "
      "test loop info updating")

lib/SILOptimizer/UtilityPasses/ComputeDominanceInfo.cpp

@@ -21,6 +21,7 @@ class ComputeDominanceInfo : public SILFunctionTransform {
 
   void run() override {
     PM->getAnalysis<DominanceAnalysis>()->get(getFunction());
+    PM->getAnalysis<PostDominanceAnalysis>()->get(getFunction());
   }
 
   StringRef getName() override { return "Compute Dominance Info"; }

test/SILOptimizer/postdomtree_verification_crash.sil

@@ -1,7 +1,6 @@
-// RUN: %target-sil-opt -enable-sil-verify-all  -sil-verify-without-invalidation %s -stack-promotion
+// RUN: %target-sil-opt -enable-sil-verify-all  -sil-verify-without-invalidation %s -compute-dominance-info
 
 // Check if post-dominator verification does not crash on multiple roots.
-// We run stack promotion because it requests the post-dominator analysis.
 
 sil_stage canonical