llvm-capstone/llvm/lib/Support/BuryPointer.cpp
Fangrui Song b81244fa4f Add LLVM_ATTRIBUTE_USED to fix problems which could be exposed by aggressive global pointer variable removal
Note to BuryPointer.cpp:GraveYard. 'unused' cannot prevent (1) dead store
elimination and (2) removal of the global pointer variable (D69428) but 'used' can.

Discovered when comparing link maps between HEAD+D69428 and HEAD.

Reviewed By: lattner

Differential Revision: https://reviews.llvm.org/D101217
2021-04-26 13:31:37 -07:00

31 lines
1.1 KiB
C++

//===- BuryPointer.cpp - Memory Manipulation/Leak ---------------*- 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
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/BuryPointer.h"
#include "llvm/Support/Compiler.h"
#include <atomic>
namespace llvm {
void BuryPointer(const void *Ptr) {
// This function may be called only a small fixed amount of times per each
// invocation, otherwise we do actually have a leak which we want to report.
// If this function is called more than kGraveYardMaxSize times, the pointers
// will not be properly buried and a leak detector will report a leak, which
// is what we want in such case.
static const size_t kGraveYardMaxSize = 16;
LLVM_ATTRIBUTE_USED static const void *GraveYard[kGraveYardMaxSize];
static std::atomic<unsigned> GraveYardSize;
unsigned Idx = GraveYardSize++;
if (Idx >= kGraveYardMaxSize)
return;
GraveYard[Idx] = Ptr;
}
} // namespace llvm