Aren't C names sometimes slightly mangled too? For example, on macOS they're prefixed by a _, doesn't that have to be undone there?
On Wed, Jan 9, 2019 at 6:58 PM Nick Desaulniers via cfe-commits < cfe-commits@lists.llvm.org> wrote: > 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 >
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