[llvm] [VPlan] Add `-vplan-print-after=` option (PR #178700)

[Ramkumar Ramachandra via llvm-commits]

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@@ -52,7 +54,11 @@ struct VPlanTransforms {
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
       // Make sure to print before verification, so that output is more useful
       // in case of failures:
-      if (PrintAfterEachVPlanPass) {
+      if (PrintAfterEachVPlanPass ||
+          (PrintAfterVPlanPasses.getNumOccurrences() > 0 &&
+           any_of(PrintAfterVPlanPasses, [PassName](StringRef Entry) {
+             return Regex(Entry).match(PassName);
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artagnon wrote:

I personally think this is a nice innovation, that will be useful in practice.

https://github.com/llvm/llvm-project/pull/178700