[mlir][Pass] Add a timing scope for the verifier runs

[rriddle]

Summary

We lost this when the verifier was changed to no longer
be a pass. The verifier can often be long running, and
without a proper scope it gets included into the pass time
(which can give an incorrect idea of where time is being
spent).

Depends on D143807

mlir/lib/Pass/Pass.cpp

if (!passFailed && verifyPasses) {
     //
     //  1) If the pass said that it preserved all analyses then it can't have
     //     permuted the IR.
     //
     // We run these checks in EXPENSIVE_CHECKS mode out of caution.
 #ifndef EXPENSIVE_CHECKS
     runVerifierNow = !pass->passState->preservedAnalyses.isAll();
 #endif
-    if (runVerifierNow)
+    if (runVerifierNow) {
+      // Push a timing scope for the verifier.
+      TimingScope timingScope;
+      if (pi)
+        timingScope = pi->getCurrentTimer().nest("Verifier");
+
       passFailed = failed(verify(op, runVerifierRecursively));
     }
+  }
 
   // Instrument after the pass has run.
   if (pi) {
     if (passFailed)
       pi->runAfterPassFailed(pass, op);
     else
       pi->runAfterPass(pass, op);
   }

mlir/test/Pass/pass-timing.mlir

 // LIST-DAG: CSE
 // LIST-DAG: DominanceInfo
 // LIST: Total
 
 // PIPELINE: Execution time report
 // PIPELINE: Total Execution Time:
 // PIPELINE: Name
 // PIPELINE-NEXT: Parser
-// PIPELINE-NEXT: 'func.func' Pipeline
+// PIPELINE-NEXT:  func.func' Pipeline
 // PIPELINE-NEXT:   CSE
 // PIPELINE-NEXT:     (A) DominanceInfo
 // PIPELINE-NEXT:   Canonicalizer
+// PIPELINE-NEXT:     Verifier
 // PIPELINE-NEXT:   CSE
 // PIPELINE-NEXT:     (A) DominanceInfo
 // PIPELINE-NEXT:   TestTimingScopePass
 // PIPELINE-NEXT:     Test Timing Scope
+// PIPELINE-NEXT:     Verifier
+// PIPELINE-NEXT:  Verifier
 // PIPELINE-NEXT: Output
 // PIPELINE-NEXT: Rest
 // PIPELINE-NEXT: Total
 
 // MT_LIST: Execution time report
 // MT_LIST: Total Execution Time:
 // MT_LIST: Name
 // MT_LIST-DAG: Canonicalizer
 // MT_LIST-DAG: CSE
 // MT_LIST-DAG: DominanceInfo
 // MT_LIST: Total
 
 // MT_PIPELINE: Execution time report
 // MT_PIPELINE: Total Execution Time:
 // MT_PIPELINE: Name
 // MT_PIPELINE-NEXT: Parser
-// MT_PIPELINE-NEXT: 'func.func' Pipeline
-// MT_PIPELINE-NEXT:   CSE
-// MT_PIPELINE-NEXT:     (A) DominanceInfo
-// MT_PIPELINE-NEXT:   Canonicalizer
-// MT_PIPELINE-NEXT:   CSE
-// MT_PIPELINE-NEXT:     (A) DominanceInfo
+// MT_PIPELINE-NEXT:   Verifier
+// MT_PIPELINE-NEXT:   'func.func' Pipeline
+// MT_PIPELINE-NEXT:     CSE
+// MT_PIPELINE-NEXT:       (A) DominanceInfo
+// MT_PIPELINE-NEXT:     Canonicalizer
+// MT_PIPELINE-NEXT:       Verifier
+// MT_PIPELINE-NEXT:     CSE
+// MT_PIPELINE-NEXT:       (A) DominanceInfo
 // MT_PIPELINE-NEXT: Output
 // MT_PIPELINE-NEXT: Rest
 // MT_PIPELINE-NEXT: Total
 
 // NESTED_PIPELINE: Execution time report
 // NESTED_PIPELINE: Total Execution Time:
 // NESTED_PIPELINE: Name
 // NESTED_PIPELINE-NEXT: Parser