GlobalOpt: Don't optimize thread_local for initializers

Folding a reference to a thread_local variable into another global
variable's initializer is very problematic, there is no relocation that
exists to represent such an access.

llvm-svn: 211762

lib/Transforms/IPO/GlobalOpt.cpp

@@ -1980,9 +1980,10 @@ isSimpleEnoughValueToCommit(Constant *C,
 static bool isSimpleEnoughValueToCommitHelper(Constant *C,
                                    SmallPtrSet<Constant*, 8> &SimpleConstants,
                                    const DataLayout *DL) {
-  // Simple global addresses are supported, do not allow dllimport globals.
+  // Simple global addresses are supported, do not allow dllimport or
+  // thread-local globals.
   if (auto *GV = dyn_cast<GlobalValue>(C))
-    return !GV->hasDLLImportStorageClass();
+    return !GV->hasDLLImportStorageClass() && !GV->isThreadLocal();
 
   // Simple integer, undef, constant aggregate zero, etc are all supported.
   if (C->getNumOperands() == 0 || isa<BlockAddress>(C))

test/Transforms/GlobalOpt/constantfold-initializers.ll

@@ -72,9 +72,19 @@ entry:
   ret void
 }
 
+@threadlocalptr = global i32* null, align 4
+; CHECK: @threadlocalptr = global i32* null, align 4
+@threadlocalvar = external thread_local global i32
+define internal void @test5() {
+entry:
+  store i32* @threadlocalvar, i32** @threadlocalptr, align 4
+  ret void
+}
+
 @llvm.global_ctors = appending constant
-  [4 x { i32, void ()* }]
+  [5 x { i32, void ()* }]
   [{ i32, void ()* } { i32 65535, void ()* @test1 },
    { i32, void ()* } { i32 65535, void ()* @test2 },
    { i32, void ()* } { i32 65535, void ()* @test3 },
+   { i32, void ()* } { i32 65535, void ()* @test4 },
    { i32, void ()* } { i32 65535, void ()* @test4 }]