Add comdat to string literal variables on COFF.

llvm-svn: 226317

3 files changed, 10 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 72d7a6cd8e0..7845fba2305 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2876,12 +2876,18 @@ GenerateStringLiteral(llvm::Constant *C, llvm::GlobalValue::LinkageTypes LT,
   if (CGM.getLangOpts().OpenCL)
     AddrSpace = CGM.getContext().getTargetAddressSpace(LangAS::opencl_constant);
 
+  llvm::Module &M = CGM.getModule();
   // Create a global variable for this string
   auto *GV = new llvm::GlobalVariable(
-      CGM.getModule(), C->getType(), !CGM.getLangOpts().WritableStrings, LT, C,
-      GlobalName, nullptr, llvm::GlobalVariable::NotThreadLocal, AddrSpace);
+      M, C->getType(), !CGM.getLangOpts().WritableStrings, LT, C, GlobalName,
+      nullptr, llvm::GlobalVariable::NotThreadLocal, AddrSpace);
   GV->setAlignment(Alignment);
   GV->setUnnamedAddr(true);
+  if (GV->isWeakForLinker()) {
+    assert(CGM.supportsCOMDAT() && "Only COFF uses weak string literals");
+    GV->setComdat(M.getOrInsertComdat(GV->getName()));
+  }
+
   return GV;
 }
 
diff --git a/clang/test/CodeGen/c-strings.c b/clang/test/CodeGen/c-strings.c
index d82bc2572e4..36934e81d5a 100644
--- a/clang/test/CodeGen/c-strings.c
+++ b/clang/test/CodeGen/c-strings.c
@@ -6,7 +6,7 @@
 
 // CHECK: @align = global i8 [[ALIGN:[0-9]+]]
 // ITANIUM: @.str = private unnamed_addr constant [6 x i8] c"hello\00"
-// MSABI: @"\01??_C@_05CJBACGMB@hello?$AA@" = linkonce_odr unnamed_addr constant [6 x i8] c"hello\00", align 1
+// MSABI: @"\01??_C@_05CJBACGMB@hello?$AA@" = linkonce_odr unnamed_addr constant [6 x i8] c"hello\00", comdat, align 1
 // ITANIUM: @f1.x = internal global i8* getelementptr inbounds ([6 x i8]* @.str, i32 0, i32 0)
 // MSABI: @f1.x = internal global i8* getelementptr inbounds ([6 x i8]* @"\01??_C@_05CJBACGMB@hello?$AA@", i32 0, i32 0)
 // CHECK: @f2.x = internal global [6 x i8] c"hello\00", align [[ALIGN]]
diff --git a/clang/test/CodeGenCXX/ms_wide_predefined_expr.cpp b/clang/test/CodeGenCXX/ms_wide_predefined_expr.cpp
index 3949d39ad52..03c78d982f1 100644
--- a/clang/test/CodeGenCXX/ms_wide_predefined_expr.cpp
+++ b/clang/test/CodeGenCXX/ms_wide_predefined_expr.cpp
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 %s -fms-extensions -triple i686-pc-win32 -emit-llvm -o - | FileCheck %s
 
-// CHECK: @"\01??_C@_19DPFBEKIN@?$AAf?$AAu?$AAn?$AAc?$AA?$AA@" = linkonce_odr unnamed_addr constant [5 x i16] [i16 102, i16 117, i16 110, i16 99, i16 0], align 2
+// CHECK: @"\01??_C@_19DPFBEKIN@?$AAf?$AAu?$AAn?$AAc?$AA?$AA@" = linkonce_odr unnamed_addr constant [5 x i16] [i16 102, i16 117, i16 110, i16 99, i16 0], comdat, align 2
 
 void wprint(const wchar_t*);