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+//===- FunctionAttrs.h - Compute function attributes ------------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// Provides passes for computing function attributes based on interprocedural
+/// analyses.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
+#define LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
+
+#include "llvm/Analysis/CGSCCPassManager.h"
+#include "llvm/Analysis/LazyCallGraph.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+class AAResults;
+class Function;
+class Module;
+class Pass;
+
+/// The three kinds of memory access relevant to 'readonly' and
+/// 'readnone' attributes.
+enum MemoryAccessKind {
+  MAK_ReadNone = 0,
+  MAK_ReadOnly = 1,
+  MAK_MayWrite = 2,
+  MAK_WriteOnly = 3
+};
+
+/// Returns the memory access properties of this copy of the function.
+MemoryAccessKind computeFunctionBodyMemoryAccess(Function &F, AAResults &AAR);
+
+/// Computes function attributes in post-order over the call graph.
+///
+/// By operating in post-order, this pass computes precise attributes for
+/// called functions prior to processsing their callers. This "bottom-up"
+/// approach allows powerful interprocedural inference of function attributes
+/// like memory access patterns, etc. It can discover functions that do not
+/// access memory, or only read memory, and give them the readnone/readonly
+/// attribute. It also discovers function arguments that are not captured by
+/// the function and marks them with the nocapture attribute.
+struct PostOrderFunctionAttrsPass : PassInfoMixin<PostOrderFunctionAttrsPass> {
+  PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
+                        LazyCallGraph &CG, CGSCCUpdateResult &UR);
+};
+
+/// Create a legacy pass manager instance of a pass to compute function attrs
+/// in post-order.
+Pass *createPostOrderFunctionAttrsLegacyPass();
+
+/// A pass to do RPO deduction and propagation of function attributes.
+///
+/// This pass provides a general RPO or "top down" propagation of
+/// function attributes. For a few (rare) cases, we can deduce significantly
+/// more about function attributes by working in RPO, so this pass
+/// provides the complement to the post-order pass above where the majority of
+/// deduction is performed.
+// FIXME: Currently there is no RPO CGSCC pass structure to slide into and so
+// this is a boring module pass, but eventually it should be an RPO CGSCC pass
+// when such infrastructure is available.
+class ReversePostOrderFunctionAttrsPass
+    : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> {
+public:
+  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
+};
+
+} // end namespace llvm
+
+#endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H