Merging r369705 and r369713 for PR43243:

zmodem · zmodem · commit 7b927f75f226 · 2019-09-09T08:44:55.000Z
------------------------------------------------------------------------ r369705 | nickdesaulniers | 2019-08-22 22:47:12 +0200 (Thu, 22 Aug 2019) | 23 lines [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: ClangBuiltLinux/linux#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 ------------------------------------------------------------------------ ------------------------------------------------------------------------ r369713 | nickdesaulniers | 2019-08-23 01:18:46 +0200 (Fri, 23 Aug 2019) | 17 lines [Bugfix] fix r369705 unit test Summary: Aliases aren't supported on OSX. Add a GNU target triple. Reported-by: leonardchan Reported-by: erik.pilkington Reviewers: leonardchan, erik.pilkington Reviewed By: leonardchan, erik.pilkington Subscribers: dexonsmith, cfe-commits Tags: #clang Differential Revision: https://reviews.llvm.org/D66622 ------------------------------------------------------------------------ llvm-svn: 371372
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -4355,17 +4355,22 @@ void CodeGenModule::EmitAliasDefinition(GlobalDecl GD) {
   // 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) {
diff --git a/clang/test/CodeGen/alias.c b/clang/test/CodeGen/alias.c
@@ -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 -triple aarch64-linux-gnu -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("test8_foo")));
 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")));
