Fix crash in the pass pipeline when local reproducer is enabled

[mehdi_amini]

Summary

This crash only happens when a function pass is followed by a module
pass. In this case the splitting of the pass pipeline didn't handle
properly the verifier passes and ended up with an odd number of pass in
the pipeline, breaking an assumption of the local crash reproducer
executor and hitting an assertion.

mlir/lib/Pass/Pass.cpp

void OpPassManagerImpl::coalesceAdjacentAdaptorPasses() {
   llvm::erase_if(passes, std::logical_not<std::unique_ptr<Pass>>());
 }
 
 void OpPassManagerImpl::splitAdaptorPasses() {
   std::vector<std::unique_ptr<Pass>> oldPasses;
   std::swap(passes, oldPasses);
 
   for (std::unique_ptr<Pass> &pass : oldPasses) {
+    // Ignore verifier passes, they are added back in the "addPass()" calls.
+    if (isa<VerifierPass>(pass.get()))
+      continue;
+
     // If this pass isn't an adaptor, move it directly to the new pass list.
     auto *currentAdaptor = dyn_cast<OpToOpPassAdaptor>(pass.get());
     if (!currentAdaptor) {
-      passes.push_back(std::move(pass));
+      addPass(std::move(pass));
       continue;
     }
 
     // Otherwise, split the adaptors of each manager within the adaptor.
     for (OpPassManager &adaptorPM : currentAdaptor->getPassManagers()) {
       adaptorPM.getImpl().splitAdaptorPasses();
 
       // Add all non-verifier passes to this pass manager.

mlir/test/Pass/crash-recovery.mlir

 // RUN: mlir-opt %s -pass-pipeline='func(test-function-pass, test-pass-crash)' -pass-pipeline-crash-reproducer=%t -verify-diagnostics
 // RUN: cat %t | FileCheck -check-prefix=REPRO %s
 // RUN: mlir-opt %s -pass-pipeline='func(test-function-pass, test-pass-crash)' -pass-pipeline-crash-reproducer=%t -verify-diagnostics -pass-pipeline-local-reproducer
 // RUN: cat %t | FileCheck -check-prefix=REPRO_LOCAL %s
 
+// Check that we correctly handle verifiers passes with local reproducer, this use to crash.
+// RUN: mlir-opt %s -test-function-pass -test-function-pass  -test-module-pass -pass-pipeline-crash-reproducer=%t -pass-pipeline-local-reproducer
+
 // expected-error@+1 {{A failure has been detected while processing the MLIR module}}
 module {
   func @foo() {
     return
   }
 }
 
 // REPRO: configuration: -pass-pipeline='func(test-function-pass, test-pass-crash)'