[flang-commits] [flang] FIR TBAA Pass (PR #68414)

[Slava Zakharin via flang-commits]

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@@ -0,0 +1,198 @@
+//===- AddAliasTags.cpp ---------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+/// \file
+/// Adds TBAA alias tags to fir loads and stores, based on information from
+/// fir::AliasAnalysis. More are added later in CodeGen - see fir::TBAABuilder
+//===----------------------------------------------------------------------===//
+
+#include "flang/Optimizer/Analysis/AliasAnalysis.h"
+#include "flang/Optimizer/Analysis/TBAAForest.h"
+#include "flang/Optimizer/Dialect/FIRDialect.h"
+#include "flang/Optimizer/Dialect/FirAliasAnalysisOpInterface.h"
+#include "flang/Optimizer/Transforms/Passes.h"
+#include "mlir/Pass/Pass.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include <optional>
+
+namespace fir {
+#define GEN_PASS_DEF_ADDALIASTAGS
+#include "flang/Optimizer/Transforms/Passes.h.inc"
+} // namespace fir
+
+#define DEBUG_TYPE "fir-add-alias-tags"
+
+static llvm::cl::opt<bool>
+    enableDummyArgs("dummy-arg-tbaa", llvm::cl::init(true), llvm::cl::Hidden,
+                    llvm::cl::desc("Add TBAA tags to dummy arguments"));
+// These two are **known unsafe** (misscompare in spec2017/wrf_r). They should
+// not be enabled by default.
+// The code is kept so that these may be tried with new benchmarks to see if
+// this is worth fixing in the future.
+static llvm::cl::opt<bool>
+    enableGlobals("globals-tbaa", llvm::cl::init(false), llvm::cl::Hidden,
+                  llvm::cl::desc("Add TBAA tags to dummy arguments. UNSAFE."));
+static llvm::cl::opt<bool> enableLocalAllocs(
+    "local-alloc-tbaa", llvm::cl::init(false), llvm::cl::Hidden,
+    llvm::cl::desc("Add TBAA tags to dummy arguments. UNSAFE."));
+
+namespace {
+
+/// Shared state per-module
+class PassState {
+public:
+  /// memoised call to fir::AliasAnalysis::getSource
+  inline const fir::AliasAnalysis::Source &getSource(mlir::Value value) {
+    if (!analysisCache.contains(value))
+      analysisCache.insert({value, analysis.getSource(value)});
+    return analysisCache[value];
+  }
+
+  /// get the per-function TBAATree for this function
+  inline const fir::TBAATree &getFuncTree(mlir::func::FuncOp func) {
+    return forrest[func];
+  }
+
+private:
+  fir::AliasAnalysis analysis;
+  llvm::DenseMap<mlir::Value, fir::AliasAnalysis::Source> analysisCache;
+  fir::TBAAForrest forrest;
+};
+
+class AddAliasTagsPass : public fir::impl::AddAliasTagsBase<AddAliasTagsPass> {
+public:
+  void runOnOperation() override;
+
+private:
+  /// The real workhorse of the pass. This is a runOnOperation() which
+  /// operates on fir::FirAliasAnalysisOpInterface, using some extra state
+  void runOnAliasInterface(fir::FirAliasAnalysisOpInterface op,
+                           PassState &state);
+};
+
+} // namespace
+
+/// Get the name of a function argument using the "fir.bindc_name" attribute,
+/// or ""
+static std::string getFuncArgName(mlir::Value arg) {
+  // always succeeds because arg is a function argument
+  mlir::BlockArgument blockArg = mlir::cast<mlir::BlockArgument>(arg);
+  assert(blockArg.getOwner() && blockArg.getOwner()->isEntryBlock() &&
+         "arg is a function argument");
+  mlir::FunctionOpInterface func =
+      mlir::cast<mlir::FunctionOpInterface>(blockArg.getOwner()->getParentOp());
+  mlir::StringAttr attr = func.getArgAttrOfType<mlir::StringAttr>(
+      blockArg.getArgNumber(), "fir.bindc_name");
+  if (!attr)
+    return "";
+  return attr.str();
+}
+
+void AddAliasTagsPass::runOnAliasInterface(fir::FirAliasAnalysisOpInterface op,
+                                           PassState &state) {
+  mlir::func::FuncOp func = op->getParentOfType<mlir::func::FuncOp>();
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vzakhari wrote:

I think this may return null for operations like OpenACC's recipe operations (e.g. see example here https://github.com/llvm/llvm-project/pull/68422/files#diff-ae16511219ce6e2967395ff571a85894541b0e134851ced07bf150662793b667).  I would suggest bailing out for such operations temporarily.

https://github.com/llvm/llvm-project/pull/68414