AMDGPU: Annotate features from x work item/group IDs.

This wasn't necessary before since they are always enabled
for kernels, but this is necessary if they need to be
forwarded to a callable function.

llvm-svn: 308226
diff --git a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
index 05aa249..a9a229d 100644
--- a/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
+++ b/llvm/lib/Target/AMDGPU/SIMachineFunctionInfo.h
@@ -119,6 +119,11 @@
   unsigned WorkGroupInfoSystemSGPR;
   unsigned PrivateSegmentWaveByteOffsetSystemSGPR;
 
+  // VGPR inputs. These are always v0, v1 and v2 for entry functions.
+  unsigned WorkItemIDXVGPR;
+  unsigned WorkItemIDYVGPR;
+  unsigned WorkItemIDZVGPR;
+
   // Graphics info.
   unsigned PSInputAddr;
   unsigned PSInputEnable;