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Prevent alias from pointing to weak aliases.
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
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@@ -64,23 +64,15 @@ public:
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Constant *getAliasee() {
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return getOperand(0);
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}
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/// getAliasedGlobal() - Aliasee can be either global or bitcast of
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/// global. This method retrives the global for both aliasee flavours.
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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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/// resolveAliasedGlobal() - This method tries to ultimately resolve the alias
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/// by going through the aliasing chain and trying to find the very last
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/// global. Returns NULL if a cycle was found. If stopOnWeak is false, then
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/// the whole chain aliasing chain is traversed, otherwise - only strong
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/// aliases.
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GlobalValue *resolveAliasedGlobal(bool stopOnWeak = true);
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const GlobalValue *resolveAliasedGlobal(bool stopOnWeak = true) const {
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return const_cast<GlobalAlias *>(this)->resolveAliasedGlobal(stopOnWeak);
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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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