Author: nickdesaulniers Date: Wed Jan 9 15:54:55 2019 New Revision: 350776
URL: http://llvm.org/viewvc/llvm-project?rev=350776&view=rev Log: [Sema] Mark target of __attribute__((alias("target"))) used for C Summary: Prevents -Wunneeded-internal-delcaration warnings when the target has no other references. This occurs frequently in device drivers in the Linux kernel. Sema would need to invoke the demangler on the target, since in C++ the target name is mangled: int f() { return 42; } int g() __attribute__((alias("_Z1fv"))); Sema does not have the ability to demangle names at this time. https://bugs.llvm.org/show_bug.cgi?id=39088 https://github.com/ClangBuiltLinux/linux/issues/232 Reviewers: rsmith, rjmccall Reviewed By: rsmith Subscribers: erik.pilkington, cfe-commits, pirama, srhines Differential Revision: https://reviews.llvm.org/D54188 Added: cfe/trunk/test/Sema/alias-unused.c Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp Modified: cfe/trunk/lib/Sema/SemaDeclAttr.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclAttr.cpp?rev=350776&r1=350775&r2=350776&view=diff ============================================================================== --- cfe/trunk/lib/Sema/SemaDeclAttr.cpp (original) +++ cfe/trunk/lib/Sema/SemaDeclAttr.cpp Wed Jan 9 15:54:55 2019 @@ -1898,7 +1898,16 @@ static void handleAliasAttr(Sema &S, Dec } } - // FIXME: check if target symbol exists in current file + // Mark target used to prevent unneeded-internal-declaration warnings. + if (!S.LangOpts.CPlusPlus) { + // FIXME: demangle Str for C++, as the attribute refers to the mangled + // linkage name, not the pre-mangled identifier. + const DeclarationNameInfo target(&S.Context.Idents.get(Str), AL.getLoc()); + LookupResult LR(S, target, Sema::LookupOrdinaryName); + if (S.LookupQualifiedName(LR, S.getCurLexicalContext())) + for (NamedDecl *ND : LR) + ND->markUsed(S.Context); + } D->addAttr(::new (S.Context) AliasAttr(AL.getRange(), S.Context, Str, AL.getAttributeSpellingListIndex())); Added: cfe/trunk/test/Sema/alias-unused.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/alias-unused.c?rev=350776&view=auto ============================================================================== --- cfe/trunk/test/Sema/alias-unused.c (added) +++ cfe/trunk/test/Sema/alias-unused.c Wed Jan 9 15:54:55 2019 @@ -0,0 +1,7 @@ +// RUN: %clang_cc1 -triple x86_64-linux-gnu -Wunneeded-internal-declaration -x c -verify %s +// expected-no-diagnostics +static int f() { return 42; } +int g() __attribute__((alias("f"))); + +static int foo [] = { 42, 0xDEAD }; +extern typeof(foo) bar __attribute__((unused, alias("foo"))); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
