Enable FeatureFlatForGlobal on Volcanic Islands

This switches to the workaround that HSA defaults to
for the mesa path.

This should be applied to the 4.0 branch.

Patch by Vedran Miletić <vedran@miletic.net>

llvm-svn: 292982
diff --git a/llvm/test/CodeGen/AMDGPU/llvm.memcpy.ll b/llvm/test/CodeGen/AMDGPU/llvm.memcpy.ll
index ccb383e..009338d 100644
--- a/llvm/test/CodeGen/AMDGPU/llvm.memcpy.ll
+++ b/llvm/test/CodeGen/AMDGPU/llvm.memcpy.ll
@@ -1,5 +1,5 @@
 ; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
-; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
+; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs < %s | FileCheck -check-prefix=SI -check-prefix=FUNC %s
 
 declare void @llvm.memcpy.p3i8.p3i8.i32(i8 addrspace(3)* nocapture, i8 addrspace(3)* nocapture, i32, i32, i1) nounwind
 declare void @llvm.memcpy.p1i8.p1i8.i64(i8 addrspace(1)* nocapture, i8 addrspace(1)* nocapture, i64, i32, i1) nounwind