[flang] Move AddAliasTags pass after BoxedProcedurePass. (#156780)

Move AddAliasTags after BoxedProcedurePass to be able to compute
the size of Fortran variables by converting their types to LLVM
types and applying DL size/alignment computations.
This is one of the approaches to unblock #156558.

This change does not affect performance in my testing.

Author: vzakhari

flang/lib/Optimizer/Passes/Pipelines.cpp

@@ -217,9 +217,6 @@ void createDefaultFIROptimizerPassPipeline(mlir::PassManager &pm,
   pm.addPass(fir::createSimplifyFIROperations(
       {/*preferInlineImplementation=*/pc.OptLevel.isOptimizingForSpeed()}));
 
-  if (pc.AliasAnalysis && !disableFirAliasTags && !useOldAliasTags)
-    pm.addPass(fir::createAddAliasTags());
-
   addNestedPassToAllTopLevelOperations<PassConstructor>(
       pm, fir::createStackReclaim);
   // convert control flow to CFG form
@@ -345,6 +342,9 @@ void createDefaultFIRCodeGenPassPipeline(mlir::PassManager &pm,
                                          MLIRToLLVMPassPipelineConfig config,
                                          llvm::StringRef inputFilename) {
   fir::addBoxedProcedurePass(pm);
+  if (config.OptLevel.isOptimizingForSpeed() && config.AliasAnalysis &&
+      !disableFirAliasTags && !useOldAliasTags)
+    pm.addPass(fir::createAddAliasTags());
   addNestedPassToAllTopLevelOperations<PassConstructor>(
       pm, fir::createAbstractResultOpt);
   addPassToGPUModuleOperations<PassConstructor>(pm,

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

@@ -109,7 +109,6 @@
 ! O2-NEXT:    OptimizeArrayRepacking
 ! ALL-NEXT: LowerRepackArraysPass
 ! ALL-NEXT: SimplifyFIROperations
-! O2-NEXT:  AddAliasTags
 
 ! ALL-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
 ! ALL-NEXT:    'fir.global' Pipeline
@@ -134,6 +133,7 @@
 ! O2-NEXT:  'func.func' Pipeline
 ! O2-NEXT:    SetRuntimeCallAttributes
 ! ALL-NEXT: BoxedProcedurePass
+! O2-NEXT:  AddAliasTags
 
 ! ALL-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'gpu.module', 'omp.declare_reduction', 'omp.private']
 ! ALL-NEXT:   'fir.global' Pipeline

flang/test/Fir/basic-program.fir

@@ -107,7 +107,6 @@ func.func @_QQmain() {
 // PASSES-NEXT:   OptimizeArrayRepacking
 // PASSES-NEXT: LowerRepackArraysPass
 // PASSES-NEXT: SimplifyFIROperations
-// PASSES-NEXT: AddAliasTags
 
 // PASSES-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'omp.declare_reduction', 'omp.private']
 // PASSES-NEXT: 'fir.global' Pipeline
@@ -132,6 +131,7 @@ func.func @_QQmain() {
 // PASSES-NEXT: 'func.func' Pipeline
 // PASSES-NEXT:   SetRuntimeCallAttributes
 // PASSES-NEXT: BoxedProcedurePass
+// PASSES-NEXT: AddAliasTags
 
 // PASSES-NEXT: Pipeline Collection : ['fir.global', 'func.func', 'gpu.module', 'omp.declare_reduction', 'omp.private']
 // PASSES-NEXT:  'fir.global' Pipeline