From 24a669d225f9cacf1cd3846e333f9690a06d1e1c Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Thu, 27 Mar 2014 15:26:56 +0000 Subject: 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. llvm-svn: 204934 --- llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp index 0249df1c6d8..df1549d405c 100644 --- a/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp +++ b/llvm/lib/Transforms/Instrumentation/DataFlowSanitizer.cpp @@ -554,8 +554,7 @@ bool DataFlowSanitizer::runOnModule(Module &M) { ++i; // Don't stop on weak. We assume people aren't playing games with the // instrumentedness of overridden weak aliases. - if (Function *F = dyn_cast( - GA->resolveAliasedGlobal(/*stopOnWeak=*/false))) { + if (Function *F = dyn_cast(GA->getAliasedGlobal())) { bool GAInst = isInstrumented(GA), FInst = isInstrumented(F); if (GAInst && FInst) { addGlobalNamePrefix(GA); -- cgit v1.2.3