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/infinite-loop.ll b/llvm/test/CodeGen/AMDGPU/infinite-loop.ll
index 7233aa5..3e0b695 100644
--- a/llvm/test/CodeGen/AMDGPU/infinite-loop.ll
+++ b/llvm/test/CodeGen/AMDGPU/infinite-loop.ll
@@ -1,5 +1,5 @@
-; RUN: llc -march=amdgcn -mcpu=SI -verify-machineinstrs < %s | FileCheck -check-prefix=SI %s
-; RUN: llc -march=amdgcn -mcpu=tonga -verify-machineinstrs < %s | FileCheck -check-prefix=SI %s
+; RUN: llc -march=amdgcn -verify-machineinstrs < %s | FileCheck -check-prefix=SI %s
+; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -verify-machineinstrs < %s | FileCheck -check-prefix=SI %s
 
 ; SI-LABEL: {{^}}infinite_loop:
 ; SI: v_mov_b32_e32 [[REG:v[0-9]+]], 0x3e7