commit 7ef210d0531eb74c45d5f16ddd3ca48e87b601db
author Erich Keane <erich.keane@intel.com> Mon Oct 22 21:20:45 2018 +0000
committer Erich Keane <erich.keane@intel.com> Mon Oct 22 21:20:45 2018 +0000
tree 47ae49f998d64370859f4205bb8273e01d29e25e
parent 95abadec0bace0093993f6320c741e2b1e0ec14b

Give Multiversion-inline functions linkonce linkage

Since multiversion variant functions can be inline, in C they become
available-externally linkage.  This ends up causing the variants to not
be emitted, and not available to the linker.

The solution is to make sure that multiversion functions are always
emitted by marking them linkonce.

Change-Id: I897aa37c7cbba0c1eb2c57ee881d5000a2113b75
llvm-svn: 344957

clang/lib/CodeGen/CodeGenModule.cpp

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index c8aea63..c8e672a 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -3669,6 +3669,10 @@
       return llvm::GlobalVariable::WeakAnyLinkage;
   }
 
+  if (const auto *FD = D->getAsFunction())
+    if (FD->isMultiVersion() && Linkage == GVA_AvailableExternally)
+      return llvm::GlobalVariable::LinkOnceAnyLinkage;
+
   // We are guaranteed to have a strong definition somewhere else,
   // so we can use available_externally linkage.
   if (Linkage == GVA_AvailableExternally)

clang/test/CodeGen/attr-target-mv.c

diff --git a/clang/test/CodeGen/attr-target-mv.c b/clang/test/CodeGen/attr-target-mv.c
index 48e1558..3ccb5b3 100644
--- a/clang/test/CodeGen/attr-target-mv.c
+++ b/clang/test/CodeGen/attr-target-mv.c
@@ -88,19 +88,19 @@
 
 // CHECK: declare i32 @foo.arch_sandybridge()
 
-// CHECK: define available_externally i32 @foo_inline.sse4.2()
+// CHECK: define linkonce i32 @foo_inline.sse4.2()
 // CHECK: ret i32 0
 
 // CHECK: declare i32 @foo_inline.arch_sandybridge()
 //
-// CHECK: define available_externally i32 @foo_inline.arch_ivybridge()
+// CHECK: define linkonce i32 @foo_inline.arch_ivybridge()
 // CHECK: ret i32 1
-// CHECK: define available_externally i32 @foo_inline()
+// CHECK: define linkonce i32 @foo_inline()
 // CHECK: ret i32 2
 
-// CHECK: define available_externally void @foo_decls()
-// CHECK: define available_externally void @foo_decls.sse4.2()
+// CHECK: define linkonce void @foo_decls()
+// CHECK: define linkonce void @foo_decls.sse4.2()
 
-// CHECK: define available_externally void @foo_multi.avx_sse4.2()
-// CHECK: define available_externally void @foo_multi.fma4_sse4.2()
-// CHECK: define available_externally void @foo_multi.arch_ivybridge_fma4_sse4.2()
+// CHECK: define linkonce void @foo_multi.avx_sse4.2()
+// CHECK: define linkonce void @foo_multi.fma4_sse4.2()
+// CHECK: define linkonce void @foo_multi.arch_ivybridge_fma4_sse4.2()