AMDGPU/SI: Don't allow unaligned scratch access

Summary: The hardware doesn't support this.

Reviewers: arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, llvm-commits, tony-tye

Differential Revision: https://reviews.llvm.org/D25523

llvm-svn: 284257
diff --git a/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h b/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
index 1dd6506..5682d99 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
+++ b/llvm/lib/Target/AMDGPU/AMDGPUSubtarget.h
@@ -76,6 +76,7 @@
   bool FP64Denormals;
   bool FPExceptions;
   bool FlatForGlobal;
+  bool UnalignedScratchAccess;
   bool UnalignedBufferAccess;
   bool EnableXNACK;
   bool DebuggerInsertNops;
@@ -277,6 +278,10 @@
     return UnalignedBufferAccess;
   }
 
+  bool hasUnalignedScratchAccess() const {
+    return UnalignedScratchAccess;
+  }
+
   bool isXNACKEnabled() const {
     return EnableXNACK;
   }