[flang] Enable SimplifyIntrinsics pass in driver.

[vzakhari]

Summary

The pass is enabled for O1/O2/O3 optlevels now.

[Leporacanthicus]

LGTM! Thanks for the work on this!

flang/include/flang/Tools/CLOptions.inc

inline void createDefaultFIROptimizerPassPipeline(
   // simplify the IR
   mlir::GreedyRewriteConfig config;
   config.enableRegionSimplification = false;
   pm.addPass(mlir::createCSEPass());
   fir::addAVC(pm);
   pm.addNestedPass<mlir::func::FuncOp>(fir::createCharacterConversionPass());
   pm.addPass(mlir::createCanonicalizerPass(config));
   pm.addPass(fir::createSimplifyRegionLitePass());
-  // Algebraic simplifications may increase code size.
-  if (optLevel.isOptimizingForSpeed())
+  if (optLevel.isOptimizingForSpeed()) {
+    // These passes may increase code size.
+    pm.addPass(fir::createSimplifyIntrinsicsPass());
     pm.addPass(fir::createAlgebraicSimplificationPass(config));
+  }
   pm.addPass(mlir::createCSEPass());
   fir::addMemoryAllocationOpt(pm);
 
   // The default inliner pass adds the canonicalizer pass with the default
   // configuration. Create the inliner pass with tco config.
   llvm::StringMap<mlir::OpPassManager> pipelines;
   pm.addPass(
       mlir::createInlinerPass(pipelines, defaultFlangInlinerOptPipeline));

flang/test/Driver/bbc-mlir-pass-pipeline.f90

 ! CHECK-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 ! CHECK-NEXT: 'func.func' Pipeline
 ! CHECK-NEXT:   ArrayValueCopy
 ! CHECK-NEXT:   CharacterConversion
 
 ! CHECK-NEXT: Canonicalizer
 ! CHECK-NEXT: SimplifyRegionLite
+! CHECK-NEXT: SimplifyIntrinsics
 ! CHECK-NEXT: AlgebraicSimplification
 ! CHECK-NEXT: CSE
 ! CHECK-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 ! CHECK-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 ! CHECK-NEXT: 'func.func' Pipeline
 ! CHECK-NEXT:   MemoryAllocationOpt
 

flang/test/Driver/mlir-pass-pipeline.f90

 ! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 ! ALL-NEXT: 'func.func' Pipeline
 ! ALL-NEXT:   ArrayValueCopy
 ! ALL-NEXT:   CharacterConversion
 
 ! ALL-NEXT: Canonicalizer
 ! ALL-NEXT: SimplifyRegionLite
+!  O2-NEXT: SimplifyIntrinsics
 !  O2-NEXT: AlgebraicSimplification
 ! ALL-NEXT: CSE
 ! ALL-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 ! ALL-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 ! ALL-NEXT: 'func.func' Pipeline
 ! ALL-NEXT:   MemoryAllocationOpt
 

flang/test/Fir/basic-program.fir

 // PASSES-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 // PASSES-NEXT: 'func.func' Pipeline
 // PASSES-NEXT:   ArrayValueCopy
 // PASSES-NEXT:   CharacterConversion
 
 // PASSES-NEXT: Canonicalizer
 // PASSES-NEXT: SimplifyRegionLite
+// PASSES-NEXT: SimplifyIntrinsics
 // PASSES-NEXT: AlgebraicSimplification
 // PASSES-NEXT: CSE
 // PASSES-NEXT:   (S) 0 num-cse'd - Number of operations CSE'd
 // PASSES-NEXT:   (S) 0 num-dce'd - Number of operations DCE'd
 
 // PASSES-NEXT: 'func.func' Pipeline
 // PASSES-NEXT:   MemoryAllocationOpt