llvm-project/clang/lib/CodeGen/SanitizerHandler.h
Anthony Tran 29992cfd62
[Clang][CodeGen] Emit “trap reasons” on UBSan traps (#145967)
This patch adds a human readable trap category and message to UBSan
traps. The category and message are encoded in a fake frame in the debug
info where the function is a fake inline function where the name encodes
the trap category and message. This is the same mechanism used by
Clang’s `__builtin_verbose_trap()`.

This change allows consumers of binaries built with trapping UBSan to
more easily identify the reason for trapping. In particular LLDB already
has a frame recognizer that recognizes the fake function names emitted
in debug info by this patch. A patch testing this behavior in LLDB will
be added in a separately.

The human readable trap messages are based on the messages currently
emitted by the userspace runtime for UBSan in compiler-rt. Note the
wording is not identical because the userspace UBSan runtime has access
to dynamic information that is not available during Clang’s codegen.

Test cases for each UBSan trap kind are included.

This complements the [`-fsanitize-annotate-debug-info`
feature](https://github.com/llvm/llvm-project/pull/141997). While
`-fsanitize-annotate-debug-info` attempts to annotate all UBSan-added
instructions, this feature (`-fsanitize-debug-trap-reasons`) only
annotates the final trap instruction using SanitizerHandler information.

This work is part of a GSoc 2025 project.
2025-07-26 08:50:25 -07:00

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//===-- SanitizerHandler.h - Definition of sanitizer handlers ---*- 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
//
//===----------------------------------------------------------------------===//
//
// This is the internal per-function state used for llvm translation.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_LIB_CODEGEN_SANITIZER_HANDLER_H
#define LLVM_CLANG_LIB_CODEGEN_SANITIZER_HANDLER_H
#define LIST_SANITIZER_CHECKS \
SANITIZER_CHECK(AddOverflow, add_overflow, 0, "Integer addition overflowed") \
SANITIZER_CHECK(BuiltinUnreachable, builtin_unreachable, 0, \
"_builtin_unreachable(), execution reached an unreachable " \
"program point") \
SANITIZER_CHECK(CFICheckFail, cfi_check_fail, 0, \
"Control flow integrity check failed") \
SANITIZER_CHECK(DivremOverflow, divrem_overflow, 0, \
"Integer divide or remainder overflowed") \
SANITIZER_CHECK(DynamicTypeCacheMiss, dynamic_type_cache_miss, 0, \
"Dynamic type cache miss, member call made on an object " \
"whose dynamic type differs from the expected type") \
SANITIZER_CHECK(FloatCastOverflow, float_cast_overflow, 0, \
"Floating-point to integer conversion overflowed") \
SANITIZER_CHECK(FunctionTypeMismatch, function_type_mismatch, 0, \
"Function called with mismatched signature") \
SANITIZER_CHECK(ImplicitConversion, implicit_conversion, 0, \
"Implicit integer conversion overflowed or lost data") \
SANITIZER_CHECK(InvalidBuiltin, invalid_builtin, 0, \
"Invalid use of builtin function") \
SANITIZER_CHECK(InvalidObjCCast, invalid_objc_cast, 0, \
"Invalid Objective-C cast") \
SANITIZER_CHECK(LoadInvalidValue, load_invalid_value, 0, \
"Loaded an invalid or uninitialized value for the type") \
SANITIZER_CHECK(MissingReturn, missing_return, 0, \
"Execution reached the end of a value-returning function " \
"without returning a value") \
SANITIZER_CHECK(MulOverflow, mul_overflow, 0, \
"Integer multiplication overflowed") \
SANITIZER_CHECK(NegateOverflow, negate_overflow, 0, \
"Integer negation overflowed") \
SANITIZER_CHECK( \
NullabilityArg, nullability_arg, 0, \
"Passing null as an argument which is annotated with _Nonnull") \
SANITIZER_CHECK(NullabilityReturn, nullability_return, 1, \
"Returning null from a function with a return type " \
"annotated with _Nonnull") \
SANITIZER_CHECK(NonnullArg, nonnull_arg, 0, \
"Passing null pointer as an argument which is declared to " \
"never be null") \
SANITIZER_CHECK(NonnullReturn, nonnull_return, 1, \
"Returning null pointer from a function which is declared " \
"to never return null") \
SANITIZER_CHECK(OutOfBounds, out_of_bounds, 0, "Array index out of bounds") \
SANITIZER_CHECK(PointerOverflow, pointer_overflow, 0, \
"Pointer arithmetic overflowed bounds") \
SANITIZER_CHECK(ShiftOutOfBounds, shift_out_of_bounds, 0, \
"Shift exponent is too large for the type") \
SANITIZER_CHECK(SubOverflow, sub_overflow, 0, \
"Integer subtraction overflowed") \
SANITIZER_CHECK(TypeMismatch, type_mismatch, 1, \
"Type mismatch in operation") \
SANITIZER_CHECK(AlignmentAssumption, alignment_assumption, 0, \
"Alignment assumption violated") \
SANITIZER_CHECK( \
VLABoundNotPositive, vla_bound_not_positive, 0, \
"Variable length array bound evaluates to non-positive value") \
SANITIZER_CHECK(BoundsSafety, bounds_safety, 0, \
"") // BoundsSafety Msg is empty because it is not considered
// part of UBSan; therefore, no trap reason is emitted for
// this case.
enum SanitizerHandler {
#define SANITIZER_CHECK(Enum, Name, Version, Msg) Enum,
LIST_SANITIZER_CHECKS
#undef SANITIZER_CHECK
};
#endif // LLVM_CLANG_LIB_CODEGEN_SANITIZER_HANDLER_H