From 2f5098ca7d2d90b2baae76f7447fb16e55aeb4fd Mon Sep 17 00:00:00 2001 From: Tom Stellard Date: Wed, 11 Nov 2015 21:45:36 +0000 Subject: [PATCH] Merging r246882: ------------------------------------------------------------------------ r246882 | hfinkel | 2015-09-04 17:49:21 -0400 (Fri, 04 Sep 2015) | 32 lines 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. ------------------------------------------------------------------------ git-svn-id: https://llvm.org/svn/llvm-project/cfe/branches/release_37@252808 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/CodeGenModule.cpp | 5 +++++ test/Sema/attr-self-alias.c | 4 ++++ 2 files changed, 9 insertions(+) create mode 100644 test/Sema/attr-self-alias.c diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp index a179ad42ea..c9c48c7628 100644 --- a/lib/CodeGen/CodeGenModule.cpp +++ b/lib/CodeGen/CodeGenModule.cpp @@ -2493,6 +2493,11 @@ 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); diff --git a/test/Sema/attr-self-alias.c b/test/Sema/attr-self-alias.c new file mode 100644 index 0000000000..7c50458be3 --- /dev/null +++ b/test/Sema/attr-self-alias.c @@ -0,0 +1,4 @@ +// RUN: %clang_cc1 -triple x86_64-pc-linux -fsyntax-only -verify -emit-llvm-only %s + +int self_alias(void) __attribute__((weak, alias("self_alias"))); // expected-error {{alias definition is part of a cycle}} + -- 2.40.0