78 lines
2.9 KiB
C++
78 lines
2.9 KiB
C++
//===- FunctionAttrs.h - Compute function attributes ------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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/// \file
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/// Provides passes for computing function attributes based on interprocedural
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/// analyses.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
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#define LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
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#include "llvm/Analysis/CGSCCPassManager.h"
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#include "llvm/Analysis/LazyCallGraph.h"
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#include "llvm/IR/PassManager.h"
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namespace llvm {
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class AAResults;
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class Function;
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class Module;
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class Pass;
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/// The three kinds of memory access relevant to 'readonly' and
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/// 'readnone' attributes.
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enum MemoryAccessKind {
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MAK_ReadNone = 0,
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MAK_ReadOnly = 1,
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MAK_MayWrite = 2,
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MAK_WriteOnly = 3
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};
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/// Returns the memory access properties of this copy of the function.
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MemoryAccessKind computeFunctionBodyMemoryAccess(Function &F, AAResults &AAR);
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/// Computes function attributes in post-order over the call graph.
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///
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/// By operating in post-order, this pass computes precise attributes for
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/// called functions prior to processsing their callers. This "bottom-up"
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/// approach allows powerful interprocedural inference of function attributes
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/// like memory access patterns, etc. It can discover functions that do not
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/// access memory, or only read memory, and give them the readnone/readonly
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/// attribute. It also discovers function arguments that are not captured by
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/// the function and marks them with the nocapture attribute.
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struct PostOrderFunctionAttrsPass : PassInfoMixin<PostOrderFunctionAttrsPass> {
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PreservedAnalyses run(LazyCallGraph::SCC &C, CGSCCAnalysisManager &AM,
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LazyCallGraph &CG, CGSCCUpdateResult &UR);
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};
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/// Create a legacy pass manager instance of a pass to compute function attrs
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/// in post-order.
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Pass *createPostOrderFunctionAttrsLegacyPass();
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/// A pass to do RPO deduction and propagation of function attributes.
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///
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/// This pass provides a general RPO or "top down" propagation of
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/// function attributes. For a few (rare) cases, we can deduce significantly
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/// more about function attributes by working in RPO, so this pass
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/// provides the complement to the post-order pass above where the majority of
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/// deduction is performed.
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// FIXME: Currently there is no RPO CGSCC pass structure to slide into and so
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// this is a boring module pass, but eventually it should be an RPO CGSCC pass
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// when such infrastructure is available.
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class ReversePostOrderFunctionAttrsPass
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: public PassInfoMixin<ReversePostOrderFunctionAttrsPass> {
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public:
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PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
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