Add flag to return to the old tbaa behaviour

Author: tblah

flang/include/flang/Optimizer/CodeGen/CodeGen.h

@@ -54,6 +54,9 @@ struct FIRToLLVMPassOptions {
 
   // Generate TBAA information for FIR types and memory accessing operations.
   bool applyTBAA = false;
+
+  // force the usage of a unified tbaa tree in TBAABuilder
+  bool forceUnifiedTBAATree = false;
 };
 
 /// Convert FIR to the LLVM IR dialect with default options.

flang/include/flang/Optimizer/CodeGen/TypeConverter.h

@@ -45,7 +45,8 @@ namespace fir {
 /// This converts FIR types to LLVM types (for now)
 class LLVMTypeConverter : public mlir::LLVMTypeConverter {
 public:
-  LLVMTypeConverter(mlir::ModuleOp module, bool applyTBAA);
+  LLVMTypeConverter(mlir::ModuleOp module, bool applyTBAA,
+                    bool forceUnifiedTBAATree);
 
   // i32 is used here because LLVM wants i32 constants when indexing into struct
   // types. Indexing into other aggregate types is more flexible.

flang/include/flang/Tools/CLOptions.inc

@@ -64,7 +64,12 @@ DisableOption(CfgConversion, "cfg-conversion", "disable FIR to CFG pass");
 DisableOption(FirAvc, "avc", "array value copy analysis and transformation");
 DisableOption(
     FirMao, "memory-allocation-opt", "memory allocation optimization");
+
 DisableOption(FirAliasTags, "fir-alias-tags", "fir alias analysis");
+static llvm::cl::opt<bool> useOldAliasTags("use-old-alias-tags",
+    llvm::cl::desc("Use a single TBAA tree for all functions and do not use "
+                   "the FIR alias tags pass"),
+    llvm::cl::init(false), llvm::cl::Hidden);
 
 /// CodeGen Passes
 #if !defined(FLANG_EXCLUDE_CODEGEN)
@@ -157,6 +162,7 @@ inline void addFIRToLLVMPass(
   fir::FIRToLLVMPassOptions options;
   options.ignoreMissingTypeDescriptors = ignoreMissingTypeDescriptors;
   options.applyTBAA = optLevel.isOptimizingForSpeed();
+  options.forceUnifiedTBAATree = useOldAliasTags;
   addPassConditionally(pm, disableFirToLlvmIr,
       [&]() { return fir::createFIRToLLVMPass(options); });
 }
@@ -221,7 +227,7 @@ inline void createDefaultFIROptimizerPassPipeline(
   // Polymorphic types
   pm.addPass(fir::createPolymorphicOpConversionPass());
 
-  if (pc.AliasAnalysis && !disableFirAliasTags)
+  if (pc.AliasAnalysis && !disableFirAliasTags && !useOldAliasTags)
     pm.addPass(fir::createAliasTagsPass());
 
   // convert control flow to CFG form

flang/lib/Optimizer/CodeGen/CodeGen.cpp

@@ -3786,7 +3786,8 @@ class FIRToLLVMLowering
 
     auto *context = getModule().getContext();
     fir::LLVMTypeConverter typeConverter{getModule(),
-                                         options.applyTBAA || applyTBAA};
+                                         options.applyTBAA || applyTBAA,
+                                         options.forceUnifiedTBAATree};
     mlir::RewritePatternSet pattern(context);
     pattern.insert<
         AbsentOpConversion, AddcOpConversion, AddrOfOpConversion,

flang/lib/Optimizer/CodeGen/TypeConverter.cpp

@@ -26,7 +26,8 @@
 
 namespace fir {
 
-LLVMTypeConverter::LLVMTypeConverter(mlir::ModuleOp module, bool applyTBAA)
+LLVMTypeConverter::LLVMTypeConverter(mlir::ModuleOp module, bool applyTBAA,
+                                     bool forceUnifiedTBAATree)
     : mlir::LLVMTypeConverter(module.getContext(),
                               [&] {
                                 mlir::LowerToLLVMOptions options(
@@ -38,8 +39,8 @@ LLVMTypeConverter::LLVMTypeConverter(mlir::ModuleOp module, bool applyTBAA)
       specifics(CodeGenSpecifics::get(module.getContext(),
                                       getTargetTriple(module),
                                       getKindMapping(module))),
-      tbaaBuilder(
-          std::make_unique<TBAABuilder>(module->getContext(), applyTBAA)) {
+      tbaaBuilder(std::make_unique<TBAABuilder>(module->getContext(), applyTBAA,
+                                                forceUnifiedTBAATree)) {
   LLVM_DEBUG(llvm::dbgs() << "FIR type converter\n");
 
   // Each conversion should return a value of type mlir::Type.