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//===--- Visibility.h - Visibility enumeration and utilities ----*- 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
//
//===----------------------------------------------------------------------===//
///
/// \file
/// Defines the clang::Visibility enumeration and various utility
/// functions.
///
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_BASIC_VISIBILITY_H
#define LLVM_CLANG_BASIC_VISIBILITY_H
#include "clang/Basic/Linkage.h"
#include "llvm/ADT/STLForwardCompat.h"
#include <cassert>
#include <cstdint>
namespace clang {
/// Describes the different kinds of visibility that a declaration
/// may have.
///
/// Visibility determines how a declaration interacts with the dynamic
/// linker. It may also affect whether the symbol can be found by runtime
/// symbol lookup APIs.
///
/// Visibility is not described in any language standard and
/// (nonetheless) sometimes has odd behavior. Not all platforms
/// support all visibility kinds.
enum Visibility {
/// Objects with "hidden" visibility are not seen by the dynamic
/// linker.
HiddenVisibility,
/// Objects with "protected" visibility are seen by the dynamic
/// linker but always dynamically resolve to an object within this
/// shared object.
ProtectedVisibility,
/// Objects with "default" visibility are seen by the dynamic linker
/// and act like normal objects.
DefaultVisibility
};
inline Visibility minVisibility(Visibility L, Visibility R) {
return L < R ? L : R;
}
class LinkageInfo {
LLVM_PREFERRED_TYPE(Linkage)
uint8_t linkage_ : 3;
LLVM_PREFERRED_TYPE(Visibility)
uint8_t visibility_ : 2;
LLVM_PREFERRED_TYPE(bool)
uint8_t explicit_ : 1;
void setVisibility(Visibility V, bool E) { visibility_ = V; explicit_ = E; }
public:
LinkageInfo()
: linkage_(llvm::to_underlying(Linkage::External)),
visibility_(DefaultVisibility), explicit_(false) {}
LinkageInfo(Linkage L, Visibility V, bool E)
: linkage_(llvm::to_underlying(L)), visibility_(V), explicit_(E) {
assert(getLinkage() == L && getVisibility() == V &&
isVisibilityExplicit() == E && "Enum truncated!");
}
static LinkageInfo external() {
return LinkageInfo();
}
static LinkageInfo internal() {
return LinkageInfo(Linkage::Internal, DefaultVisibility, false);
}
static LinkageInfo uniqueExternal() {
return LinkageInfo(Linkage::UniqueExternal, DefaultVisibility, false);
}
static LinkageInfo none() {
return LinkageInfo(Linkage::None, DefaultVisibility, false);
}
static LinkageInfo visible_none() {
return LinkageInfo(Linkage::VisibleNone, DefaultVisibility, false);
}
Linkage getLinkage() const { return static_cast<Linkage>(linkage_); }
Visibility getVisibility() const { return (Visibility)visibility_; }
bool isVisibilityExplicit() const { return explicit_; }
void setLinkage(Linkage L) { linkage_ = llvm::to_underlying(L); }
void mergeLinkage(Linkage L) {
setLinkage(minLinkage(getLinkage(), L));
}
void mergeLinkage(LinkageInfo other) {
mergeLinkage(other.getLinkage());
}
void mergeExternalVisibility(Linkage L) {
Linkage ThisL = getLinkage();
if (!isExternallyVisible(L)) {
if (ThisL == Linkage::VisibleNone)
ThisL = Linkage::None;
else if (ThisL == Linkage::External)
ThisL = Linkage::UniqueExternal;
}
setLinkage(ThisL);
}
void mergeExternalVisibility(LinkageInfo Other) {
mergeExternalVisibility(Other.getLinkage());
}
/// Merge in the visibility 'newVis'.
void mergeVisibility(Visibility newVis, bool newExplicit) {
Visibility oldVis = getVisibility();
// Never increase visibility.
if (oldVis < newVis)
return;
// If the new visibility is the same as the old and the new
// visibility isn't explicit, we have nothing to add.
if (oldVis == newVis && !newExplicit)
return;
// Otherwise, we're either decreasing visibility or making our
// existing visibility explicit.
setVisibility(newVis, newExplicit);
}
void mergeVisibility(LinkageInfo other) {
mergeVisibility(other.getVisibility(), other.isVisibilityExplicit());
}
/// Merge both linkage and visibility.
void merge(LinkageInfo other) {
mergeLinkage(other);
mergeVisibility(other);
}
/// Merge linkage and conditionally merge visibility.
void mergeMaybeWithVisibility(LinkageInfo other, bool withVis) {
mergeLinkage(other);
if (withVis) mergeVisibility(other);
}
};
}
#endif // LLVM_CLANG_BASIC_VISIBILITY_H
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