[PATCH] c++: Don't upgrade TLS model if TLS model isn't set.

[H.J. Lu]

Don't upgrade TLS model when cplus_decl_attributes is called on a thread
local variable whose TLS model isn't set yet.

gcc/cp/

        PR c++/121889
        * decl2.cc (cplus_decl_attributes): Don't upgrade TLS model if
        TLS model isn't set yet.

gcc/testsuite/

        PR c++/121889
        * g++.dg/tls/pr121889.C: New test.

Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
 gcc/cp/decl2.cc                     | 10 +++++++---
 gcc/testsuite/g++.dg/tls/pr121889.C |  9 +++++++++
 2 files changed, 16 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/tls/pr121889.C

diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
index c9cca7b0270..4564fdc45e0 100644
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -2018,9 +2018,13 @@ cplus_decl_attributes (tree *decl, tree attributes, int 
flags)
     {
       // tls_model attribute can set a stronger TLS access model.
       tls_model model = DECL_TLS_MODEL (*decl);
-      tls_model default_model = decl_default_tls_model (*decl);
-      if (default_model > model)
-       set_decl_tls_model (*decl, default_model);
+      // Don't upgrade TLS model if TLS model isn't set yet.
+      if (model != TLS_MODEL_NONE)
+       {
+         tls_model default_model = decl_default_tls_model (*decl);
+         if (default_model > model)
+           set_decl_tls_model (*decl, default_model);
+       }
     }
 }
 
diff --git a/gcc/testsuite/g++.dg/tls/pr121889.C 
b/gcc/testsuite/g++.dg/tls/pr121889.C
new file mode 100644
index 00000000000..881855adc83
--- /dev/null
+++ b/gcc/testsuite/g++.dg/tls/pr121889.C
@@ -0,0 +1,9 @@
+// { dg-do compile { target c++11 } }
+// { dg-require-effective-target tls }
+// { dg-options "-O2" }
+// { dg-add-options tls }
+
+extern void pthread_key_create();
+static __typeof(pthread_key_create) __gthrw___pthread_key_create
+    __attribute__((__weakref__("")));
+template <class> void zeta_imp_odd_integer() { thread_local int digits; }
-- 
2.51.0