Author: nickdesaulniers Date: Thu Aug 22 13:47:12 2019 New Revision: 369705
URL: http://llvm.org/viewvc/llvm-project?rev=369705&view=rev Log: [Clang][CodeGen] set alias linkage on QualType Summary: It seems that CodeGen was always using ExternalLinkage when emitting a GlobalDecl with __attribute__((alias)). This leads to symbol redefinitions (ODR) that cause failures at link time for static aliases. This is readily attempting to link an ARM (32b) allyesconfig Linux kernel built with Clang. Reported-by: nathanchance Suggested-by: ihalip Link: https://bugs.llvm.org/show_bug.cgi?id=42377 Link: https://github.com/ClangBuiltLinux/linux/issues/631 Reviewers: rsmith, aaron.ballman, erichkeane Reviewed By: aaron.ballman Subscribers: javed.absar, kristof.beyls, cfe-commits, srhines, ihalip, nathanchance Tags: #clang Differential Revision: https://reviews.llvm.org/D66492 Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp cfe/trunk/test/CodeGen/alias.c Modified: cfe/trunk/lib/CodeGen/CodeGenModule.cpp URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenModule.cpp?rev=369705&r1=369704&r2=369705&view=diff ============================================================================== --- cfe/trunk/lib/CodeGen/CodeGenModule.cpp (original) +++ cfe/trunk/lib/CodeGen/CodeGenModule.cpp Thu Aug 22 13:47:12 2019 @@ -4363,17 +4363,22 @@ void CodeGenModule::EmitAliasDefinition( // Create a reference to the named value. This ensures that it is emitted // if a deferred decl. llvm::Constant *Aliasee; - if (isa<llvm::FunctionType>(DeclTy)) + llvm::GlobalValue::LinkageTypes LT; + if (isa<llvm::FunctionType>(DeclTy)) { Aliasee = GetOrCreateLLVMFunction(AA->getAliasee(), DeclTy, GD, /*ForVTable=*/false); - else + LT = getFunctionLinkage(GD); + } else { Aliasee = GetOrCreateLLVMGlobal(AA->getAliasee(), llvm::PointerType::getUnqual(DeclTy), /*D=*/nullptr); + LT = getLLVMLinkageVarDefinition(cast<VarDecl>(GD.getDecl()), + D->getType().isConstQualified()); + } // Create the new alias itself, but don't set a name yet. - auto *GA = llvm::GlobalAlias::create( - DeclTy, 0, llvm::Function::ExternalLinkage, "", Aliasee, &getModule()); + auto *GA = + llvm::GlobalAlias::create(DeclTy, 0, LT, "", Aliasee, &getModule()); if (Entry) { if (GA->getAliasee() == Entry) { Modified: cfe/trunk/test/CodeGen/alias.c URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/alias.c?rev=369705&r1=369704&r2=369705&view=diff ============================================================================== --- cfe/trunk/test/CodeGen/alias.c (original) +++ cfe/trunk/test/CodeGen/alias.c Thu Aug 22 13:47:12 2019 @@ -2,6 +2,7 @@ // RUN: %clang_cc1 -triple i386-pc-linux-gnu -emit-llvm -o - %s | FileCheck -check-prefix=CHECKBASIC %s // RUN: %clang_cc1 -triple armv7a-eabi -mfloat-abi hard -emit-llvm -o - %s | FileCheck -check-prefix=CHECKCC %s // RUN: %clang_cc1 -triple armv7a-eabi -mfloat-abi hard -S -o - %s | FileCheck -check-prefix=CHECKASM %s +// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck -check-prefix=CHECKGLOBALS %s int g0; // CHECKBASIC-DAG: @g0 = common global i32 0 @@ -88,3 +89,13 @@ void test8_zed() __attribute__((alias("t void test9_bar(void) { } void test9_zed(void) __attribute__((section("test"))); void test9_zed(void) __attribute__((alias("test9_bar"))); + +// Test that the alias gets its linkage from its declared qual type. +// CHECKGLOBALS: @test10_foo = internal +// CHECKGLOBALS-NOT: @test10_foo = dso_local +int test10; +static int test10_foo __attribute__((alias("test10"))); +// CHECKGLOBALS: @test11_foo = internal +// CHECKGLOBALS-NOT: @test11_foo = dso_local +void test11(void) {} +static void test11_foo(void) __attribute__((alias("test11"))); _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
