From 0e2b975eb6814eced739aacd8baa6051dc7b171a Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Fri, 4 Sep 2015 21:49:21 +0000 Subject: Don't crash on a self-alias declaration We were crashing in CodeGen given input like this: int self_alias(void) __attribute__((weak, alias("self_alias"))); such a self-alias is invalid, but instead of diagnosing the situation, we'd proceed to produce IR for both the function declaration and the alias. Because we already had a function named 'self_alias', the alias could not be named the same thing, and so LLVM would pick a different name ('self_alias1' for example) for that value. When we later called CodeGenModule::checkAliases, we'd look up the IR value corresponding to the alias name, find the function declaration instead, and then assert in a cast to llvm::GlobalAlias. The easiest way to prevent this is simply to avoid creating the wrongly-named alias value in the first place and issue the diagnostic there (instead of in checkAliases). We detect a related cycle case in CodeGenModule::EmitAliasDefinition already, so this just adds a second such check. Even though the other test cases for this 'alias definition is part of a cycle' diagnostic are in test/Sema/attr-alias-elf.c, I've added a separate regression test for this case. This is because I can't add this check to test/Sema/attr-alias-elf.c without disturbing the other test cases in that file. In order to avoid construction of the bad IR values, this diagnostic is emitted from within CodeGenModule::EmitAliasDefinition (and the relevant declaration is not added to the Aliases vector). The other cycle checks are done within the CodeGenModule::checkAliases function based on the Aliases vector, called from CodeGenModule::Release. However, if there have been errors earlier, HandleTranslationUnit does not call Release, and so checkAliases is never called, and so none of the other diagnostics would be produced. Fixes PR23509. llvm-svn: 246882 --- clang/lib/CodeGen/CodeGenModule.cpp | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'clang/lib/CodeGen/CodeGenModule.cpp') diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp index b9eefac2d9fb..1177557aca01 100644 --- a/clang/lib/CodeGen/CodeGenModule.cpp +++ b/clang/lib/CodeGen/CodeGenModule.cpp @@ -2613,6 +2613,11 @@ void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) { StringRef MangledName = getMangledName(GD); + if (AA->getAliasee() == MangledName) { + Diags.Report(AA->getLocation(), diag::err_cyclic_alias); + return; + } + // If there is a definition in the module, then it wins over the alias. // This is dubious, but allow it to be safe. Just ignore the alias. llvm::GlobalValue *Entry = GetGlobalValue(MangledName); -- cgit v1.2.3