[TLS] use emulated TLS if the target supports only this mode

Emulated TLS is enabled by llc flag -emulated-tls,
which is passed by clang driver.
When llc is called explicitly or from other drivers like LTO,
missing -emulated-tls flag would generate wrong TLS code for targets
that supports only this mode.
Now use useEmulatedTLS() instead of Options.EmulatedTLS to decide whether
emulated TLS code should be generated.
Unit tests are modified to run with and without the -emulated-tls flag.

Differential Revision: https://reviews.llvm.org/D42999

llvm-svn: 326341

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/ExecutionEngine/TargetSelect.cpp b/llvm/lib/ExecutionEngine/TargetSelect.cpp
index 18dfa4e3c31..9626b8d3ffa 100644
--- a/llvm/lib/ExecutionEngine/TargetSelect.cpp
+++ b/llvm/lib/ExecutionEngine/TargetSelect.cpp
@@ -97,6 +97,8 @@ TargetMachine *EngineBuilder::selectTarget(const Triple &TargetTriple,
                                      Options, RelocModel, CMModel, OptLevel,
 				     /*JIT*/ true);
   Target->Options.EmulatedTLS = EmulatedTLS;
+  Target->Options.ExplicitEmulatedTLS = true;
+
   assert(Target && "Could not allocate target machine!");
   return Target;
 }