1//===- FunctionAttrs.h - Compute function attributes ------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9/// \file
10/// Provides passes for computing function attributes based on interprocedural
11/// analyses.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
16#define LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
17
18#include "llvm/Analysis/AliasAnalysis.h"
19#include "llvm/Analysis/CGSCCPassManager.h"
20#include "llvm/Analysis/LazyCallGraph.h"
21#include "llvm/IR/PassManager.h"
22#include "llvm/Support/Compiler.h"
23
24namespace llvm {
25
26class GlobalValueSummary;
27class ModuleSummaryIndex;
28class Function;
29class Module;
30
31/// Returns the memory access properties of this copy of the function.
32LLVM_ABI MemoryEffects computeFunctionBodyMemoryAccess(Function &F,
33 AAResults &AAR);
34
35/// Propagate function attributes for function summaries along the index's
36/// callgraph during thinlink
37LLVM_ABI bool thinLTOPropagateFunctionAttrs(
38 ModuleSummaryIndex &Index,
39 function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
40 isPrevailing);
41
42/// Computes function attributes in post-order over the call graph.
43///
44/// By operating in post-order, this pass computes precise attributes for
45/// called functions prior to processsing their callers. This "bottom-up"
46/// approach allows powerful interprocedural inference of function attributes
47/// like memory access patterns, etc. It can discover functions that do not
48/// access memory, or only read memory, and give them the readnone/readonly
49/// attribute. It also discovers function arguments that are not captured by
50/// the function and marks them with the nocapture attribute.
51struct PostOrderFunctionAttrsPass : PassInfoMixin<PostOrderFunctionAttrsPass> {
52 PostOrderFunctionAttrsPass(bool SkipNonRecursive = false)
53 : SkipNonRecursive(SkipNonRecursive) {}
54 LLVM_ABI PreservedAnalyses run(LazyCallGraph::SCC &C,
55 CGSCCAnalysisManager &AM, LazyCallGraph &CG,
56 CGSCCUpdateResult &UR);
57
58 LLVM_ABI void
59 printPipeline(raw_ostream &OS,
60 function_ref<StringRef(StringRef)> MapClassName2PassName);
61
62private:
63 bool SkipNonRecursive;
64};
65
66/// A pass to do RPO deduction and propagation of function attributes.
67///
68/// This pass provides a general RPO or "top down" propagation of
69/// function attributes. For a few (rare) cases, we can deduce significantly
70/// more about function attributes by working in RPO, so this pass
71/// provides the complement to the post-order pass above where the majority of
72/// deduction is performed.
73// FIXME: Currently there is no RPO CGSCC pass structure to slide into and so
74// this is a boring module pass, but eventually it should be an RPO CGSCC pass
75// when such infrastructure is available.
76class ReversePostOrderFunctionAttrsPass
77 : public PassInfoMixin<ReversePostOrderFunctionAttrsPass> {
78public:
79 LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
80};
81
82/// Additional 'norecurse' attribute deduction during postlink LTO phase.
83///
84/// This is a module pass that infers 'norecurse' attribute on functions.
85/// It runs during LTO and analyzes the module's call graph to find functions
86/// that are guaranteed not to call themselves, either directly or indirectly.
87/// The pass uses a module-wide flag which checks if any function's address is
88/// taken or any function in the module has external linkage, to safely handle
89/// indirect and library function calls from current function.
90class NoRecurseLTOInferencePass
91 : public PassInfoMixin<NoRecurseLTOInferencePass> {
92public:
93 LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &MAM);
94};
95} // end namespace llvm
96
97#endif // LLVM_TRANSFORMS_IPO_FUNCTIONATTRS_H
98