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/cgp-addressing-modes-flat.ll b/llvm/test/CodeGen/AMDGPU/cgp-addressing-modes-flat.ll
index 82f88a0..6db9a07 100644
--- a/llvm/test/CodeGen/AMDGPU/cgp-addressing-modes-flat.ll
+++ b/llvm/test/CodeGen/AMDGPU/cgp-addressing-modes-flat.ll
@@ -1,7 +1,7 @@
 ; RUN: opt -S -codegenprepare -mtriple=amdgcn-unknown-unknown -mcpu=bonaire < %s | FileCheck -check-prefix=OPT -check-prefix=OPT-CI %s
-; RUN: opt -S -codegenprepare -mtriple=amdgcn-unknown-unknown -mcpu=tonga < %s | FileCheck -check-prefix=OPT -check-prefix=OPT-VI %s
+; RUN: opt -S -codegenprepare -mtriple=amdgcn-unknown-unknown -mcpu=tonga -mattr=-flat-for-global < %s | FileCheck -check-prefix=OPT -check-prefix=OPT-VI %s
 ; RUN: llc -march=amdgcn -mcpu=bonaire -mattr=-promote-alloca < %s | FileCheck -check-prefix=GCN -check-prefix=CI %s
-; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-promote-alloca < %s | FileCheck -check-prefix=GCN -check-prefix=VI %s
+; RUN: llc -march=amdgcn -mcpu=tonga -mattr=-flat-for-global -mattr=-promote-alloca < %s | FileCheck -check-prefix=GCN -check-prefix=VI %s
 
 ; OPT-LABEL: @test_no_sink_flat_small_offset_i32(
 ; OPT: getelementptr i32, i32 addrspace(4)* %in