[flang][NFC] Use tablegen to create simplifyRegionLite constructor (#89957)

This is a ModuleOp pass anyway so it doesn't need to be run on
particular top level operations.

Author: tblah

flang/include/flang/Optimizer/Transforms/Passes.h

@@ -68,7 +68,6 @@ std::unique_ptr<mlir::Pass> createLoopVersioningPass();
 std::unique_ptr<mlir::Pass>
 createMemoryAllocationPass(bool dynOnHeap, std::size_t maxStackSize);
 std::unique_ptr<mlir::Pass> createAnnotateConstantOperandsPass();
-std::unique_ptr<mlir::Pass> createSimplifyRegionLitePass();
 std::unique_ptr<mlir::Pass> createAlgebraicSimplificationPass();
 std::unique_ptr<mlir::Pass>
 createAlgebraicSimplificationPass(const mlir::GreedyRewriteConfig &config);

flang/include/flang/Optimizer/Transforms/Passes.td

@@ -286,7 +286,6 @@ def SimplifyRegionLite : Pass<"simplify-region-lite", "mlir::ModuleOp"> {
   let description = [{
     Run region DCE and erase unreachable blocks in regions.
   }];
-  let constructor = "::fir::createSimplifyRegionLitePass()";
 }
 
 def AlgebraicSimplification : Pass<"flang-algebraic-simplification"> {

flang/include/flang/Tools/CLOptions.inc

@@ -245,7 +245,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   fir::addAVC(pm, pc.OptLevel);
   addNestedPassToAllTopLevelOperations(pm, fir::createCharacterConversion);
   pm.addPass(mlir::createCanonicalizerPass(config));
-  pm.addPass(fir::createSimplifyRegionLitePass());
+  pm.addPass(fir::createSimplifyRegionLite());
   if (pc.OptLevel.isOptimizingForSpeed()) {
     // These passes may increase code size.
     pm.addPass(fir::createSimplifyIntrinsicsPass());
@@ -267,7 +267,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   llvm::StringMap<mlir::OpPassManager> pipelines;
   pm.addPass(mlir::createInlinerPass(
       pipelines, addCanonicalizerPassWithoutRegionSimplification));
-  pm.addPass(fir::createSimplifyRegionLitePass());
+  pm.addPass(fir::createSimplifyRegionLite());
   pm.addPass(mlir::createCSEPass());
 
   // Polymorphic types
@@ -281,7 +281,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   pm.addPass(mlir::createConvertSCFToCFPass());
 
   pm.addPass(mlir::createCanonicalizerPass(config));
-  pm.addPass(fir::createSimplifyRegionLitePass());
+  pm.addPass(fir::createSimplifyRegionLite());
   pm.addPass(mlir::createCSEPass());
 }
 

flang/lib/Optimizer/Transforms/SimplifyRegionLite.cpp

@@ -45,7 +45,3 @@ void SimplifyRegionLitePass::runOnOperation() {
   (void)mlir::eraseUnreachableBlocks(rewriter, regions);
   (void)mlir::runRegionDCE(rewriter, regions);
 }
-
-std::unique_ptr<mlir::Pass> fir::createSimplifyRegionLitePass() {
-  return std::make_unique<SimplifyRegionLitePass>();
-}