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https://github.com/c64scene-ar/llvm-6502.git
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f165cf7ce8
This adds back r204781.
Original message:
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@204934 91177308-0d34-0410-b5e6-96231b3b80d8
97 lines
3.0 KiB
C++
97 lines
3.0 KiB
C++
//===-------- llvm/GlobalAlias.h - GlobalAlias class ------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the declaration of the GlobalAlias class, which
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// represents a single function or variable alias in the IR.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_IR_GLOBALALIAS_H
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#define LLVM_IR_GLOBALALIAS_H
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#include "llvm/ADT/Twine.h"
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#include "llvm/ADT/ilist_node.h"
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#include "llvm/IR/GlobalValue.h"
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#include "llvm/IR/OperandTraits.h"
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namespace llvm {
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class Module;
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template<typename ValueSubClass, typename ItemParentClass>
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class SymbolTableListTraits;
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class GlobalAlias : public GlobalValue, public ilist_node<GlobalAlias> {
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friend class SymbolTableListTraits<GlobalAlias, Module>;
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void operator=(const GlobalAlias &) LLVM_DELETED_FUNCTION;
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GlobalAlias(const GlobalAlias &) LLVM_DELETED_FUNCTION;
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void setParent(Module *parent);
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public:
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// allocate space for exactly one operand
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void *operator new(size_t s) {
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return User::operator new(s, 1);
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}
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/// GlobalAlias ctor - If a parent module is specified, the alias is
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/// automatically inserted into the end of the specified module's alias list.
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GlobalAlias(Type *Ty, LinkageTypes Linkage, const Twine &Name = "",
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Constant* Aliasee = 0, Module *Parent = 0);
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/// Provide fast operand accessors
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DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Constant);
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/// removeFromParent - This method unlinks 'this' from the containing module,
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/// but does not delete it.
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///
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void removeFromParent() override;
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/// eraseFromParent - This method unlinks 'this' from the containing module
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/// and deletes it.
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///
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void eraseFromParent() override;
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/// set/getAliasee - These methods retrive and set alias target.
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void setAliasee(Constant *GV);
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const Constant *getAliasee() const {
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return getOperand(0);
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}
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Constant *getAliasee() {
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return getOperand(0);
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}
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/// This method tries to ultimately resolve the alias by going through the
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/// aliasing chain and trying to find the very last global. Returns NULL if a
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/// cycle was found.
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GlobalValue *getAliasedGlobal();
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const GlobalValue *getAliasedGlobal() const {
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return const_cast<GlobalAlias *>(this)->getAliasedGlobal();
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}
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static bool isValidLinkage(LinkageTypes L) {
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return isExternalLinkage(L) || isLocalLinkage(L) ||
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isWeakLinkage(L) || isLinkOnceLinkage(L);
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}
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// Methods for support type inquiry through isa, cast, and dyn_cast:
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static inline bool classof(const Value *V) {
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return V->getValueID() == Value::GlobalAliasVal;
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}
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};
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template <>
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struct OperandTraits<GlobalAlias> :
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public FixedNumOperandTraits<GlobalAlias, 1> {
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};
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DEFINE_TRANSPARENT_OPERAND_ACCESSORS(GlobalAlias, Constant)
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} // End llvm namespace
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#endif
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