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Prevent alias from pointing to weak aliases.

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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
This commit is contained in:
Rafael Espindola
2014-03-26 04:48:47 +00:00
parent 577708be42
commit 33845aa8c4
18 changed files with 58 additions and 61 deletions
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2
lib/Target/XCore/XCoreISelLowering.cpp
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@@ -277,7 +277,7 @@ getGlobalAddressWrapper(SDValue GA, const GlobalValue *GV,
const GlobalValue *UnderlyingGV = GV;
// If GV is an alias then use the aliasee to determine the wrapper type
if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
UnderlyingGV = GA->resolveAliasedGlobal();
UnderlyingGV = GA->getAliasedGlobal();
if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(UnderlyingGV)) {
if ( ( GVar->isConstant() &&
UnderlyingGV->isLocalLinkage(GV->getLinkage()) )