[flang-commits] [flang] [flang] handle alloca outside of entry blocks in MemoryAllocation (PR #98457)

[Tom Eccles via flang-commits]

================
@@ -0,0 +1,63 @@
+//===-- Optimizer/Transforms/MemoryUtils.h ----------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Coding style: https://mlir.llvm.org/getting_started/DeveloperGuide/
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a utility to replace fir.alloca by dynamic allocation and
+// deallocation. The exact kind of dynamic allocation is left to be defined by
+// the utility user via callbacks (could be fir.allocmem or custom runtime
+// calls).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef FORTRAN_OPTIMIZER_TRANSFORMS_MEMORYUTILS_H
+#define FORTRAN_OPTIMIZER_TRANSFORMS_MEMORYUTILS_H
+
+#include "flang/Optimizer/Dialect/FIROps.h"
+
+namespace mlir {
+class RewriterBase;
+}
+
+namespace fir {
+
+/// Type of callbacks that indicate if a given fir.alloca must be
+/// rewritten.
+using MustRewriteCallBack = llvm::function_ref<bool(fir::AllocaOp)>;
+
+/// Type of callbacks that produce the replacement for a given fir.alloca.
+/// It is provided extra information about the dominance of the deallocation
+/// points that have been identified, and may refuse to replace the alloca,
+/// even if the MustRewriteCallBack previously returned true, in which case
+/// it should return a null value.
+/// The callback should not delete the alloca, the utility will do it.
+using AllocaRewriterCallBack =
+    llvm::function_ref<mlir::Value(mlir::OpBuilder &, fir::AllocaOp,
+                                   bool /*allocaDominatesDeallocLocations*/)>;
+/// Type of callbacks that must generate deallocation of storage obtained via
+/// AllocaRewriterCallBack calls.
+using DeallocCallBack =
+    llvm::function_ref<void(mlir::Location, mlir::OpBuilder &, mlir::Value)>;
+
+/// Utility to replace fir.alloca by dynamic allocations inside \p parentOp.
+/// \p MustRewriteCallBack let the user control which fir.alloca should be
+/// replaced. \p AllocaRewriterCallBack let the user define how the new memory
+/// should be allocated. \p DeallocCallBack let the user decide how the memory
+/// should be deallocated. The boolean result indicate if the utility succeeded
+/// to replace all fir.alloca as requested by the user. Causes of failures are
+/// the presence of unregistered operations, or OpenMP/ACC recipe operation that
+/// returns memory allocated inside their region.
----------------
tblah wrote:

nit
```suggestion
/// \p MustRewriteCallBack lets the user control which fir.alloca should be
/// replaced. \p AllocaRewriterCallBack lets the user define how the new memory
/// should be allocated. \p DeallocCallBack lets the user decide how the memory
/// should be deallocated. The boolean result indicates if the utility succeeded
/// to replace all fir.alloca as requested by the user. Causes of failures are
/// the presence of unregistered operations, or OpenMP/ACC recipe operations that
/// return memory allocated inside their region.
```

https://github.com/llvm/llvm-project/pull/98457