1//===----------------------------------------------------------------------===//
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/// This file contains the declaration of TrapReasonBuilder and related classes.
11///
12//===----------------------------------------------------------------------===//
13#ifndef LLVM_CLANG_CODEGEN_TRAP_REASON_BUILDER_H
14#define LLVM_CLANG_CODEGEN_TRAP_REASON_BUILDER_H
15#include "clang/Basic/Diagnostic.h"
16
17namespace clang {
18namespace CodeGen {
19
20/// Helper class for \class TrapReasonBuilder. \class TrapReason stores the
21/// "trap reason" built by \class TrapReasonBuilder. This consists of
22/// a trap message and trap category.
23///
24/// It is intended that this object be allocated on the stack.
25class TrapReason {
26public:
27 TrapReason() = default;
28 /// \return The trap message. Note the lifetime of the underlying storage for
29 /// the returned StringRef lives in this class which means the returned
30 /// StringRef should not be used after this class is destroyed.
31 StringRef getMessage() const { return Message; }
32
33 /// \return the trap category (e.g. "Undefined Behavior Sanitizer")
34 StringRef getCategory() const { return Category; }
35
36 bool isEmpty() const {
37 // Note both Message and Category are checked because it is legitimate for
38 // the Message to be empty but for the Category to be non-empty when the
39 // trap category is known but the specific reason is not available during
40 // codegen.
41 return Message.size() == 0 && Category.size() == 0;
42 }
43
44private:
45 llvm::SmallString<64> Message;
46 // The Category doesn't need its own storage because the StringRef points
47 // to a global constant string.
48 StringRef Category;
49
50 // Only this class can set the private fields.
51 friend class TrapReasonBuilder;
52};
53
54/// Class to make it convenient to initialize TrapReason objects which can be
55/// used to attach the "trap reason" to trap instructions.
56///
57/// Although this class inherits from \class DiagnosticBuilder it has slightly
58/// different semantics.
59///
60/// * This class should only be used with trap diagnostics (declared in
61/// `DiagnosticTrapKinds.td`).
62/// * The `TrapReasonBuilder` does not emit diagnostics to the normal
63/// diagnostics consumers on destruction like normal Diagnostic builders.
64/// Instead on destruction it assigns to the TrapReason object passed into
65/// the constructor.
66///
67/// Given that this class inherits from `DiagnosticBuilder` it inherits all of
68/// its abilities to format diagnostic messages and consume various types in
69/// class (e.g. Type, Exprs, etc.). This makes it particularly suited to
70/// printing types and expressions from the AST while codegen-ing runtime
71/// checks.
72///
73///
74/// Example use via the `CodeGenModule::BuildTrapReason` helper.
75///
76/// \code
77/// {
78/// TrapReason TR;
79/// CGM.BuildTrapReason(diag::trap_diagnostic, TR) << 0 << SomeExpr;
80/// consume(&TR);
81/// }
82/// \endcode
83///
84///
85class TrapReasonBuilder : public DiagnosticBuilder {
86public:
87 TrapReasonBuilder(DiagnosticsEngine *DiagObj, unsigned DiagID,
88 TrapReason &TR);
89 ~TrapReasonBuilder();
90
91 // Prevent accidentally copying or assigning
92 TrapReasonBuilder &operator=(const TrapReasonBuilder &) = delete;
93 TrapReasonBuilder &operator=(const TrapReasonBuilder &&) = delete;
94 TrapReasonBuilder(const TrapReasonBuilder &) = delete;
95 TrapReasonBuilder(const TrapReasonBuilder &&) = delete;
96
97private:
98 /// \return Format the trap message into `Storage`.
99 void getMessage(SmallVectorImpl<char> &Storage);
100
101 /// \return Return the trap category. These are the `CategoryName` property
102 /// of `trap` diagnostics declared in `DiagnosticTrapKinds.td`.
103 StringRef getCategory();
104
105private:
106 TrapReason &TR;
107};
108
109} // namespace CodeGen
110} // namespace clang
111
112#endif
113