mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-10-04 16:01:46 +00:00
33845aa8c4
Aliases are just another name for a position in a file. As such, the
regular symbol resolutions are not applied. For example, given
define void @my_func() {
ret void
}
@my_alias = alias weak void ()* @my_func
@my_alias2 = alias void ()* @my_alias
We produce without this patch:
.weak my_alias
my_alias = my_func
.globl my_alias2
my_alias2 = my_alias
That is, in the resulting ELF file my_alias, my_func and my_alias are
just 3 names pointing to offset 0 of .text. That is *not* the
semantics of IR linking. For example, linking in a
@my_alias = alias void ()* @other_func
would require the strong my_alias to override the weak one and
my_alias2 would end up pointing to other_func.
There is no way to represent that with aliases being just another
name, so the best solution seems to be to just disallow it, converting
a miscompile into an error.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204781 91177308-0d34-0410-b5e6-96231b3b80d8
97 lines
3.0 KiB
C++
97 lines
3.0 KiB
C++
//===-------- llvm/GlobalAlias.h - GlobalAlias class ------------*- C++ -*-===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file contains the declaration of the GlobalAlias class, which
|
|
// represents a single function or variable alias in the IR.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#ifndef LLVM_IR_GLOBALALIAS_H
|
|
#define LLVM_IR_GLOBALALIAS_H
|
|
|
|
#include "llvm/ADT/Twine.h"
|
|
#include "llvm/ADT/ilist_node.h"
|
|
#include "llvm/IR/GlobalValue.h"
|
|
#include "llvm/IR/OperandTraits.h"
|
|
|
|
namespace llvm {
|
|
|
|
class Module;
|
|
template<typename ValueSubClass, typename ItemParentClass>
|
|
class SymbolTableListTraits;
|
|
|
|
class GlobalAlias : public GlobalValue, public ilist_node<GlobalAlias> {
|
|
friend class SymbolTableListTraits<GlobalAlias, Module>;
|
|
void operator=(const GlobalAlias &) LLVM_DELETED_FUNCTION;
|
|
GlobalAlias(const GlobalAlias &) LLVM_DELETED_FUNCTION;
|
|
|
|
void setParent(Module *parent);
|
|
|
|
public:
|
|
// allocate space for exactly one operand
|
|
void *operator new(size_t s) {
|
|
return User::operator new(s, 1);
|
|
}
|
|
/// GlobalAlias ctor - If a parent module is specified, the alias is
|
|
/// automatically inserted into the end of the specified module's alias list.
|
|
GlobalAlias(Type *Ty, LinkageTypes Linkage, const Twine &Name = "",
|
|
Constant* Aliasee = 0, Module *Parent = 0);
|
|
|
|
/// Provide fast operand accessors
|
|
DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
|
|
|
|
/// removeFromParent - This method unlinks 'this' from the containing module,
|
|
/// but does not delete it.
|
|
///
|
|
void removeFromParent() override;
|
|
|
|
/// eraseFromParent - This method unlinks 'this' from the containing module
|
|
/// and deletes it.
|
|
///
|
|
void eraseFromParent() override;
|
|
|
|
/// set/getAliasee - These methods retrive and set alias target.
|
|
void setAliasee(Constant *GV);
|
|
const Constant *getAliasee() const {
|
|
return getOperand(0);
|
|
}
|
|
Constant *getAliasee() {
|
|
return getOperand(0);
|
|
}
|
|
|
|
/// This method tries to ultimately resolve the alias by going through the
|
|
/// aliasing chain and trying to find the very last global. Returns NULL if a
|
|
/// cycle was found.
|
|
GlobalValue *getAliasedGlobal();
|
|
const GlobalValue *getAliasedGlobal() const {
|
|
return const_cast<GlobalAlias *>(this)->getAliasedGlobal();
|
|
}
|
|
|
|
static bool isValidLinkage(LinkageTypes L) {
|
|
return isExternalLinkage(L) || isLocalLinkage(L) ||
|
|
isWeakLinkage(L) || isLinkOnceLinkage(L);
|
|
}
|
|
|
|
// Methods for support type inquiry through isa, cast, and dyn_cast:
|
|
static inline bool classof(const Value *V) {
|
|
return V->getValueID() == Value::GlobalAliasVal;
|
|
}
|
|
};
|
|
|
|
template <>
|
|
struct OperandTraits<GlobalAlias> :
|
|
public FixedNumOperandTraits<GlobalAlias, 1> {
|
|
};
|
|
|
|
DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalAlias, Constant)
|
|
|
|
} // End llvm namespace
|
|
|
|
#endif
|